text:
Invited Paper Silicon photonic resonator sensors and devices Lukas Chrostowskia , Samantha Grista , Jonas Flueckigera , Wei Shia , Xu Wanga , Eric Ouelletb , Han Yuna , Mitch Webba , Ben Niea , Zhen Lianga , Karen C. Cheunga , Shon A. Schmidtc , Daniel M. Ratnerc , and Nicolas A. F. Jaegera a Department of Electrical and Computer Engineering, and of Chemical and Biological Engineering, University of British Columbia, Vancouver, British Columbia, Canada c Department of Bioengineering, University of Washington, Seattle, Washington, USA b Department ABSTRACT Silicon photonic resonators, implemented using silicon-on-insulator substrates, are promising for numerous applications. The most commonly studied resonators are ring/racetrack resonators. We have fabricated these and other resonators including disk resonators, waveguide-grating resonators, ring resonator reflectors, contra-directional grating-coupler ring resonators, and racetrack-based multiplexer/demultiplexers. While numerous resonators have been demonstrated for sensing purposes, it remains unclear as to which structures provide the highest sensitivity and best limit of detection; for example, disc resonators and slot-waveguide-based ring resonators have been conjectured to provide an improved limit of detection. Here, we compare various resonators in terms of sensor metrics for label-free bio-sensing in a micro-fluidic environment. We have integrated resonator arrays with PDMS micro-fluidics for real-time detection of biomolecules in experiments such as antigen-antibody binding reaction experiments using Human Factor IX proteins. Numerous resonators are fabricated on the same wafer and experimentally compared. We identify that, while evanescent-field sensors all operate on the principle that the analyte's refractive index shifts the resonant frequency, there are important differences between implementations that lie in the relationship between the optical field overlap with the analyte and the relative contributions of the various loss mechanisms. The chips were fabricated in the context of the CMC-UBC Silicon Nanophotonics Fabrication course and workshop. This yearlong, design-based, graduate training program is offered to students from across Canada and, over the last four years, has attracted participants from nearly every Canadian university involved in photonics research. The course takes students through a full design cycle of a photonic circuit, including theory, modelling, design, and experimentation. Keywords: silicon photonics, lab-on-a-chip, microfluidics, evanescent optical field sensors, optical waveguides, disk resonators, ring resonators, slot waveguides 1. INTRODUCTION Silicon nanophotonic devices have great potential as highly integrated, low-cost biosensors for medical, point-of-care (POC) and home healthcare diagnostic applications. Recent advances in the silicon photonic biosensor literature have demonstrated clinically relevant sensitivities, and an expanded repertoire of biocompatible chemistries capable of interrogating a variety of biological molecules. Additionally, by leveraging existing CMOS fabrication processes, silicon photonic sensors offer significant advantages in economies of scale over traditional biosensing platforms, allowing for the integration of thousands of sensors on a single millimetre-scale chip. These sensors are poised to displace traditional assays that rely upon multi-step liquid handling processes, significant user intervention, and cumbersome bench-top instrumentation. However, numerous challenges must be overcome to realize a fully integrated silicon photonic biosensing platform, including understanding the optimal sensor characteristics, fluidic and analyte control and on-chip lasers and detectors. This paper discusses important sensor performance metrics in aqueous environments similar to saliva, serum or blood, essential for medical diagnostic applications. Evanescent field sensors such as Surface Plasmon Resonance (SPR) or planar waveguide based sensors are amongst the most popular optical detection techniques for sensitive and label free biomolecular detection.1 Compared to other sensing methods, optical sensors methods have the advantages of high sensitivity, no physical contact between sensor and detector, immunity to electromagnetic interference, and multiplexed interrogation. Waveguides with dimensions smaller Laser Resonators, Microresonators, and Beam Control XIV, edited by Alexis V. Kudryashov, Alan H. Paxton, Vladimir S. Ilchenko, Lutz Aschke, Kunihiko Washio, Proc. of SPIE Vol. 8236, 823620 · © 2012 SPIE · CCC code: 0277-786X/12/$18 · doi: 10.1117/12.916860 Proc. of SPIE Vol. 8236 823620-1 Downloaded from SPIE Digital Library on 02 Mar 2012 to 188.8.131.52. Terms of Use: http://spiedl.org/terms than the free-space wavelength of light have a strong evanescent field at the waveguide surface extending a few hundred nanometers into the surrounding media. Any interaction with molecules in proximity or surface bound will change the effective refractive index of the guided mode, which leads to a shift in the optical spectrum of the device. These sensors have shown promise for real time detection of biomolecules because of their sensitivity towards surface binding events. In the case of a straight waveguide-based sensor, such as a Mach-Zehnder, the interaction is limited by the physical length of the sensing waveguide. The degree of interaction of the evanescent field and the sample for a ring resonator is limited by the number of roundtrips by the light inside the ring and the footprint of the sensing area can be reduced without losing sensitivity. In general, high quality factor (Q) resonators are advantageous for reduced spectral noise of the sensor,2 leading to an improved detection limit. Optical sensors based on ring and racetrack resonators have been proposed and developed using a variety of materials and for a variety of applications such as chemical sensing3, 4 and sensing of biological molecules such as antibodies or antigens.5–10 In particular, the optical, label-free detection of biomolecules is a topic of considerable interest.11, 12 The sensitivity of a ring resonator is dependent on the overlap of the evanescent field and the sample.2 In a strip waveguide most of the field is contained inside the core and only a small portion propagates outside in the media. Most experiments have focused on TE-like polarized waveguide modes, likely since low loss TE waveguides have been available.13 However, the TM-like waveguide mode has been shown to offer 3X improved sensitivity (S, nm/RIU)14 as compared to the TE mode since it has a larger evanescent field component above the waveguide. To enhance the sensitivity, several alternative resonator structures have been proposed and demonstrated. Slot waveguide resonators4, 15–19 have shown even further enhanced sensitivity since there is much more optical field contained in the fluid. Other structures proposed and/or demonstrated include disk resonators,20, 21 disk resonators containing a fluorescent material,22 1D photonic crystals with holes in waveguide,23 2D photonic crystals, and Bragg grating cavities.24 Ring sensors have also been integrated on the end of an optical fibre.25 There has been significant interest in integrating optical sensors with microfluidic channels specifically for the detection of bio-species as well as other molecules.26 Several groups have integrated ring resonator sensors with microfluidic channels,7, 8 including multiplexing the slot-ring resonator sensors such that only one optical input is used for multiple sensors.8, 27 Resonator sensors have been arranged in folded-waveguide configurations to make the best possible use of space on the optical device.28 To advance biomedical applications, inkjet printing of chemicals29 on the resonant sensors has been demonstrated. 1.1 Biomedical Applications of Silicon Photonics Silicon photonic microring resonators, like those described previously, show great promise as label-free sensing and analysis tools in biomedical research, drug development, homeland security, food safety, environmental monitoring and healthcare in POC and low-resource settings.30 Notably, the sensitivity and multiplexing capability of silicon photonic biosensors has advanced to the point where the technology is now competitive with the enzyme-linked immunosorbent assay (ELISA), the current gold standard for clinical assays. Conventional ELISAs utilizes a multi-well microtiter plate containing immobilized antibodies that bind to a specific analytes of interest. ELISA-based analysis depends upon multiple time-consuming rinse cycles, the consumption of a significant volume of reagent, and the addition of an enzyme-labeled antibody for optical detection via formation of a chromophore or chemiluminescent reaction. While sensitive and reliable at clinically relevant levels, the ELISA involves costly reagents and a skilled operator, rendering it impractical for distributed, low-resource, and home healthcare settings. Label-free biosensors have been investigated as a competitive alternative to the ELISA.1 Similar to the ELISA, label-free biosensors leverage a functionalized surface to selectively capture targets species. However, unlike ELISA, label-free sensors directly detect the presence of analyte without additional reagents or labels, eliminating the need for multiple rinse steps and a secondary probes, and dramatically decreasing assay time. In medicine, accurately diagnosing a disease state often requires the detection and quantification of multiple biological markers (proteins, nucleic acids, lipids, carbohydrates and small organic biomolecules). Silicon photonic sensors facilitate simultaneous multi-analyte detection by interrogating matrixed sensor arrays on a single chip, referred to as multiplexed detection.31 For example, a single-marker assay for prostate-specific antigen (PSA) to detect prostate cancer possessed a meager 65% sensitivity and 35% specificity.32 By contrast, a multi-marker protein panel improved the sensitivity and specificity to 83% and 97%, respectively. This result highlights the inherent advantage of multiplexed detection in medical diagnostics. Proc. of SPIE Vol. 8236 823620-2 Downloaded from SPIE Digital Library on 02 Mar 2012 to 22.214.171.124. Terms of Use: http://spiedl.org/terms While a fully integrated, label-free silicon photonics biosensor has yet to be realized commercially, the technology has established its utility for medical diagnostics at clinically relevant sensitivities.1 Washburn et al. have demonstrated simultaneous analysis of multiple biomarkers on a single microring sensor array, successfully quantifying PSA, α-fetoprotein (AFP), carcinoembryonic antigen (CEA), tumor necrosis factor-α (TNF-α), and interleukin-8 (IL-8) at clinical concentrations.33 Like proteins, MicroRNAs (mRNAs) play a role in a variety of disease states, including cancer, heart disease, and central nervous system disorders, and can be used as markers for early disease detection and diagnosis. Using siliconbased photonic sensors, Qavi et al. demonstrated a multiplexed mRNA diagnostic capability by discriminating between single nucleotide polymorphisms of the let-7 family in concentrations of 150 fmol with minimal sample preparation.34 In addition, Ramachandran et al. have reported that whole bacteria can be successfully detected using microring resonators.6 These examples illustrate the transformative potential of label-free silicon-photonic sensors. At present, the aforementioned biosensing examples rely on external lasers and detectors, which limit their application for distributed multiplexed sensing and diagnosis. On-chip detectors capable of interrogating thousands of functionalized sensors are necessary to realize a fully distributable diagnostic device. Towards this goal, Yan et al. recently demonstrated an optical sensor fabricated in a commercially available 0.35 µm CMOS technology with integrated electronic detectors.35 Kirk et al. developed a method to rapidly functionalize individual rings in a 50 x 50 µm footprint using a commercially available non-contact piezo printer that can be scaled to print multiple chips in parallel.29 Finally, Hochberg et al. reported on the benefits of a shared-wafer fabrication consortium which offers low-cost prototyping through commercially available CMOS chip fabrication facilities.36 These strategies, coupled with low-cost LED light sources point to the significant role that a fully integrated label-free, silicon-based nanophotonic diagnostic device could play in both POC diagnostics and distributed healthcare. 1.2 Sensor Performance – Criteria This section describes the most important performance criteria which are useful for comparing different sensor geometries. The metrics are based on the work of White2 and Yoshie37 particularly for micro-resonator sensors. The most important are: 1. Sensitivity (S), which is the slope of wavelength shift versus bulk refractive index unit change [nm/RIU], also sometimes known as Responsivity (R). In a resonator, the wavelength shift is described by:38 ∆nfluid ∂neff ∆λ = . λ ng ∂nfluid (1) The contributions to the shift are from: a) the shift in the analyte's index of refraction (∆nfluid ), b) the material and waveguide dispersion (ng ) – a change in wavelength causes a further change in effective index, and c) the change in index slightly changes the mode profile resulting in the mode's effective index change (susceptibility, ∂neff /∂nfluid ). The same effect is found in the temperature dependence of waveguide-based resonators.39 In high-contrast silicon photonic devices, ng is typically 4-5, and ∂neff /∂nfluid is approximately 0.15 (for strip and ridge waveguides). In contrast free-space propagation would have ∂neff /∂nfluid = 1. The sensitivity is defined as ∆λ , ∆nfluid and the normalized sensitivity (useful for comparing different wavelength resonators) is S= S = S ∆λ 1 = . λ λ ∆nfluid (2) (3) 2. Q factor, which is the number of oscillations before the energy has decayed to the 1/e value. A high Q-factor means that light is present in the resonator longer and interacts more with the analyte. It is also advantageous in reducing the spectral noise of the sensor,2 which improves the limit of detection. The resonator Q can be found from the total distributed loss of the resonator (in m−1 , in dB/m, or in terms of the material complex index of refraction, n + ik), Q = ω0 E ω0 = ω0 τp = dE/dt α[m−1 ] · c ng = 2π · ng 2π · ng · 4.34 ng = = . λ0 · α[m−1 ] λ0 · α[dB/m] 2·k Proc. of SPIE Vol. 8236 823620-3 Downloaded from SPIE Digital Library on 02 Mar 2012 to 18.104.22.168. Terms of Use: http://spiedl.org/terms (4) These losses originate from waveguide scattering, material absorption (waveguide and analyte), waveguide radiation loss, mode mismatch losses, etc. Equation 4 is useful to identify the intrinsic Q for a resonator with a particular waveguide propagation loss, e.g., 3 dB/cm waveguides yield intrinsic Q values of 258,000 at 1550 nm; if this resonator was critically coupled, the Q value is reduced by a factor of two and becomes 129,000. 3. Limit of Detection (LOD, or Detection Limit, DL) which is the minimum detectable refractive index unit change [RIU]. The detection limit can be defined two ways: 1) change in index corresponding to one resonator linewidth (∆nmin ) – this is useful to compare the intrinsic device performance, and 2) a system detection limit (∆nmin,sys ) which corresponds to the index change for a standard deviation in the measurement noise (here, the wavelength reading noise). The highest performing systems have a detection limit on the order of 10−7 RIU.40 The limit of detection is calculated by37 ∆nmin = LOD = 1 QS (5) 4. The limit of detection can also be expressed in a biological perspective, e.g., in terms of the adsorbent's thickness. 1.3 Comparison of Experimental Sensitivity and Detection Limit Here, we compare several silicon photonics evanescent field sensors operating at 1550 nm. We compare the intrinsic detection limit, i.e., the change in index corresponding to one resonator linewidth (∆nmin ). This comparison allows one to compare the intrinsic device performance, independent of the read-out method, electronics and noise. The comparison includes previous literature on ring/racetrack resonators,5, 10, 25, 41 slot resonators,7 and 1D photonic crystals.23 It also includes the experimental results presented in Section 2. For each device, the normalized Sensitivity (S') and Q are identified (in water) and the results are plotted in Figure 1. The data points with the highest limit of detection are found towards the upper-right of the plot, and the limit of detection is identified by the contour lines using Equation 5. The highest reported limit of detection is for the TM-like mode strip waveguide,41 with the slot waveguides and photonic crystals having the worst performance. Since this plot is for volume index of refraction changes, not included is the single-molecule detection work of Vahala21 where the high-Q cavity results in locally heating the molecule and inducing a thermo-optic effect which results in enhanced wavelength shifts. SPR sensors42 are also not included. They work on the same principle as resonators, namely an evanescent field interacts with the sample, but the evanescent field originates from a surface plasmon in a metal film. Comparing dielectric and SPR sensors: a) SPR typically has a slightly longer field decay (200 nm vs. 100 nm), b) sensitivities are much higher, but the limit of detection is similar. As an example of a commercial SPR system, the Biacore X has a noise of 0.6 RU (where 1 RU is defined as 10−6 RIU ),43 hence a detection limit of 0.6 × 10−6 RIU . 2. EXPERIMENTAL RESULTS ON THE SAME WAFER Silicon photonic devices were fabricated using 193 nm lithography by IMEC accessed via CMC Microsystems and ePIXfab. All designs described in this section were fabricated on the same wafer to aid in the direct comparison of the resonators. SEM images of the fabricated devices are shown in Figs. 3, 5, and 6. 2.1 Lab-on-a-chip, PDMS Microfluidics The concept of a lab-on-a-chip combines sample handling and analysis in one single chip, thereby offering the possibility of a portable analysis platform. Picoliter sample volumes can be handled inside micrometer scale fluidic channels using valves and pumps integrated into silicon or polymer chips.44 It is of great interest to include sensor technology into these lab-on-chip devices to automate parallel processing and therefore lower cost and increase throughput. Ksendzov et al. clamped a flow cell down onto the sensor chip.45 They achieved sealing by using an O-ring and pressure. However they are not able to expose individual resonators with different analytes. Washburn et al. and Luchansky et al. used a laser cut Mylar gasket aligned over top of the microring arrays to define microfluidic channels.1, 9 They closed the channels off with a Teflon lid and sandwiched the different layers between aluminum chip holders. Because mass transport is diffusion limited, they are not suitable to determine dynamics of fast reactions, e.g. binding events of proteins. Moreover, in order to be able to run several experiments with different analytes or different concentrations in parallel individual resonators need Proc. of SPIE Vol. 8236 823620-4 Downloaded from SPIE Digital Library on 02 Mar 2012 to 184.108.40.206. Terms of Use: http://spiedl.org/terms 0 Normalized Sensitivity [/RIU] 1.0e−03 4.0e−04 1.6e−04 6.3e−04 2.5e−04 1.0e−04 Ring TM Ring TE Ring TE Ring TE 1D PC Disk TE (UBC) Ring TE (UBC) Slot (UBC) Slot TE 3 10 −1 10 2 10 1.0e−02 4.0e−03 −2 10 6.3e−03 3 10 4 10 Q factor Sensitivity [nm/RIU] 10 1.6e−03 2.5e−03 1.0e−03 5 10 Figure 1. Summary of experimental results for Limits of Detection (LOD) for linear 1550 nm silicon photonic biosensors. Here, LOD is calculated for a noise equivalent to one resonator linewidth, which is useful to compare the intrinsic device performance. The diagonal lines correspond to LOD values of ∆nmin = 10−2 to 10−4 . The right y-axis is the sensitivity, Eq. 2, while the left y-axis is the sensitivity normalized to the wavelength, Eq. 3. to be addressed and exposed. Carlborg et al. used a microfluidic channel network in poly(dimethylsiloxane) (PDMS), with a separate fluid channel to each sensor for sample delivery.8 PDMS is the most widely used polymer in the field of microfluidics. It is a biocompatible, transparent, rubber-like polymer and can be easily patterned using soft lithography, a well established fabrication method.46 The mold masters were fabricated with standard photolithography techniques on SU-8 2075 (MicroChem, USA). Through replica molding the patterns were transferred onto PDMS. The uncured PDMS (Sylgard 184, Dow Corning USA) was poured onto the mold master to a thickness of about 1 cm, degassed to remove air bubbles, and cured at 80◦ C for 2h on a hotplate. The hydrophobic surface properties can be altered in an oxygen plasma by replacing some of the surface methyl groups (CH3) by a hydroxyl groups (-OH). This activated surface can form covalent siloxane bonds (Si-O-Si) when in contact with glass or silicon substrates, forming an irreversible seal. However, we have found that we obtain sufficient sealing between the silicon chips and PDMS by performing reversible bonding. After punching access holes for the fluidic inlet and outlets the PDMS layer and the resonator substrate were aligned using a stereo microscope and bonded to each other. The PDMS channels were 100 µm wide, 100 µm tall, with a pitch of 300 µm. The bonded chips and measurement setup is shown in Fig. 2. 2.2 Optical Setup The optical test setup for the fabricated nanophotonics chips consisted of a tunable laser source (Agilent 81682A, Agilent Technologies, Inc., USA) with an output wavelength range from 1460 nm to 1580 nm; a polarization maintaining optical fibre was aligned with the fibre grating coupler to inject light into the SOI waveguides; the output light was collected with a single-mode optical fiber and measured with an optical power sensor (Agilent 81635A, Agilent Technologies, Inc., USA); the temperature of the substrate was kept constant with a Peltier element and a temperature controller (LDC501, Stanford Research System, USA) in a closed feedback loop configuration (typically 1-10 mK stability). A microscope system was Proc. of SPIE Vol. 8236 823620-5 Downloaded from SPIE Digital Library on 02 Mar 2012 to 188.8.131.52. Terms of Use: http://spiedl.org/terms optical fiber input optical fiber output PDMS with niicrochannels fluidic input microfluidic network SOl substrate with ring resonators PDMS with microchannels Figure 2. The measurement setup:48 the optical input fibre is connected to a tuneable laser source with wavelength at around 1550 nm and the output optical fibre is connected to an optical power sensor. The measurements are performed on a temperature controlled stage. Fluidic tubing are connected to a syringe pump. used for fibre alignment. A MATLAB script was used to sweep the laser wavelength in order to acquire the transmission spectra for the various devices (sweep interval 20s with 10,000 data points). For calibrating the sensors (sensitivity, Q), fluids of varying refractive index were flowed through the microfluidic channels under positive pressure, exposing the resonators to different immersion media refractive indices. Varying concentrations of glycerin in water were used as these varying known refractive indices.47 The positions of the resonance peaks were dynamically tracked by continuously sweeping the laser and curve fitting the spectrum. The wavelength tracking also proves useful when employing the resonators for biosensing applications, as it provides useful visual feedback when attaching proteins or antibodies to the resonators and is helpful to identify problems in the system (for example, a bubble in the channel). 2.3 Ring resonators Racetrack resonators are designed following Rouger et. al49 and using the Lumerical MODE Solutions eigen-mode solver.50 The resonators were designed for critically-coupled double-bus configurations with parameters calculated using the MODE Solutions simulated material losses, the MODE Solutions simulated bend losses (radiation and mode-mismatch from straight to bent waveguide), and the straight-waveguide scattering losses from previous findings as well as the literature (4 dB/cm for the strip waveguides) and 12 dB/cm for the slot waveguides.7 The round-trip resonator losses were used to calculate the coupling lengths, where the coupling coefficients were calculated from the effective indices of the coupler super-modes. Devices with both strip and slot waveguides were fabricated. Two of the fabricated chips were analyzed by SEM imaging and FIB cross-sectioning, as shown in figure 3. FIB cross-sectioning showed that the waveguides were narrower at their tops, with sidewall angles of approximately 9.5◦ . 2.4 Slot waveguide ring resonator Mode profiles and modelling results for the slot waveguide design are shown in Fig. 4. Figure 4d presents the simulated immersion medium index sensitivity versus simulated waveguide base width. This is simulated to take into account the IMEC exposure dose sweep that was applied across the wafer, and which results in changes in the waveguide thickness. The changes also result in changes in the slot waveguide gap, which leads to changes in the sensitivity. The sensitivity decreases with increasing waveguide width, as a result of the increasing optical confinement of the mode within the silicon and a decreasing slot width. The measured sensitivity of 345 nm/RIU is comparable to the 298 nm/RIU reported for a similar design (with a similarly low Q factor of 330) in SOI by Claes et al.7 Proc. of SPIE Vol. 8236 823620-6 Downloaded from SPIE Digital Library on 02 Mar 2012 to 126.96.36.199. Terms of Use: http://spiedl.org/terms a) b) Figure 3. a) SEM images of strip waveguide ring resonators. The inset shows an SEM image of the highlighted coupler region. b) SEM images of slot waveguide ring resonators. The inset shows an SEM image of an FIB cross-section of the through port coupler; the slots in these waveguides are well-defined, all the way through the 220 nm of silicon. 550 H20 Si Si c) III Sensitivity (nm/RIU) 5i02 a) b) 500 450 400 Fixed (350 nm) 350 300 Width d) 250 200 220 240 260 280 300 Waveguide−base Width (nm) 320 340 Figure 4. Simulations for the slot waveguide geometry: b) Material index profile. c) Electric field distribution for straight waveguide. d) Coupling super-mode 1 between parallel identical slot waveguides. d) Simulation results of immersion medium refractive index sensitivity vs. waveguide width for slot waveguide racetrack resonators. The blue points plot the sensitivity to a change from 0% to 2% glycerine, while the red points plot the sensitivity to a change from 2% to 4% glycerine. 2.5 Bragg Grating resonators Bragg gratings, as well as quarter-shifted grating cavities were fabricated on the wafer.51 It is expected that the sensitivity of the grating will be equivalent to its straight waveguide counterpart.24 The quarter-shifted Bragg grating resonators demonstrated high-Q values of 100,000 with air cladding. The transmission spectrum of the device and SEM image are shown in Fig. 5. 2.6 Disk resonators Ultra-compact, high-Q disk resonators have been theoretically investigated and experimental demonstrated.52–54 We use a similar geometry and size of disk54 in this investigation. We discuss two approaches to modelling disk resonators which we have verified to have excellent agreement. The first method is to do a full 3D FDTD simulation of the entire disk.55 This is possible since the geometry of the disk is relatively small. The objectives of the simulation are: a) find the resonant modes of the disk, for a given polarization, and b) find the sensitivity (nm/RIU). The simulation includes the disk, the oxide, and the water, surrounded by PML boundary conditions. Proc. of SPIE Vol. 8236 823620-7 Downloaded from SPIE Digital Library on 02 Mar 2012 to 126.96.36.199. Terms of Use: http://spiedl.org/terms 0.9 0 −2 0.7 −4 Transmission (dB) Transmission ~10 nm 0.8 0.6 0.5 0.4 0.3 0.2 a) −6 −8 −10 −12 −14 −16 0.1 0 1470 480 nm ~15 pm −18 1475 1480 Wavelength (nm) 1485 −20 1476.85 b) 1476.95 1477.05 Wavelength (nm) 1477.15 c) Sct Mg FWD EB.&, lift Dt HEW 2OO[) Figure 5. a) Measured transmission spectrum of the quarter-wave phase-shifted gratings, (b) enlarged plot around the transmission resonance, c) SEM image of the fabricated device, showing the quarter-shifted section. The disk is excited by several dipole sources placed inside the disk. In order to find the sensitivity, we perform several FDTD simulations with a variation of cladding index of refraction. We then inspect the spectrum of the cavity and observe the shift in the cavity modes (nm), versus the applied changes in refractive index (RIU). 2 og 1) Spot a) 0 b) 3 Mag FWD F-Beam 15.0 kX 5.127 5.00 kV Tilt -O.O Det SEQ HFW 10.1 pm c) Figure 6. a) 3D FDTD calculation showing the top-view TE mode profile of a 2.5 µm disk. Counting the number of nodes (48) indicates that this is mode #24. b) SEM image of the disk. c) Mode calculation for the cross-section of the disk, TE mode (top), TM mode (bottom). All simulation plots are for the E-field intensity. The second approach is similar to a conventional waveguide mode calculation,50 where we calculate the disk's crosssection mode profile, effective index, group index and loss for the lowest order TE and TM modes as a function of wavelength. The radius of the disk is included in the simulation by defining the bend radius as the actual radius of the disk. The advantage of this approach is that a much finer mesh can be employed since it is a 2D simulation, hence the accuracy can be improved. Similar to the 3D FDTD simulations, we vary the cladding index and record the shift in effective index. Next, we calculate the resonant modes by using simple Fabry-Perot theory, namely we find solutions where the round-trip phase is an integer multiple of 2π, using 2πM = 2πneff (λ)L/λ, where L = 2πr is the circumference of the disk. We re-write this as λ = neff (λ) (6) M 2πr and plot the results of the left-hand-side and right-hand-side of the equation in Figure 7a. The intersection of the neff (λ) line with the mode number lines provides the solution(s) to the equation and yields the resonant wavelength(s). This technique can further be used to find the modes of different sized disks by recalculating the neff versus wavelength graphs and re-plotting the above. The loss of the each mode is also calculated by the mode solver, including the water absorption. For TM modes, the Proc. of SPIE Vol. 8236 823620-8 Downloaded from SPIE Digital Library on 02 Mar 2012 to 188.8.131.52. Terms of Use: http://spiedl.org/terms 2.5 −44 2.4 2.3 1.335 Index of Refraction [RIU] 1.34 1.345 1.35 1.355 1.36 0.7 −46 0.6 −48 0.5 −50 0.4 −52 0.3 −54 0.2 −56 0.1 Neff, TE 2 N , TM eff Mode #16−25 1.9 1.8 1.7 1.6 Wavelength shift [nm] 2.1 Power [mdB] Index 2.2 1.5 1.5 a) 1.52 1.54 1.56 Wavelength [µm] 1.58 −58 1.6 1519.4 1519.5 1519.6 1519.7 1519.8 1519.9 1520 1520.1 b) 0 Wavelength [nm] Figure 7. a) Effective index of the 2.5 µm disk resonator modes versus wavelength. Upward trending lines are the required effective index values to achieve a resonant condition for mode numbers m = 16 up to m = 25. b) Experimental performance of a 5 µm disk resonator in water. The optical spectra (bottom and left axes) for the resonator show a Q of between 80,000 and 100,000. Varying the water index of refraction (top axis) by changing the concentration of glycerine changes the resonant wavelength (right axis); the sensitivity is 27.1 nm/RIU. radiation loss cannot be neglected.54 In particular, the TM mode 2.5 µm disk is impractical since the radiative losses are 600 dB/cm. Hence, larger disks are required for TM operation. Experimental results for a disk resonator are shown in Figure 7b. The Q value in water is approximately 90,000, while the sensitivity is 27.1 nm/RIU. 3. DISCUSSION AND ANALYSIS 3.1 Fundamental Limit for Water-Based Sensors We are interested in the fundamental limit of detection based on the water absorption and index change. We consider an ideal Fabry-Perot cavity and assume that the light travels entirely in the water, with no other loss mechanism other than water absorption. In this case ∂neff /∂nfluid = 1. Using Eq. 1, this yields ∆λ ∆nfluid = λ0 ng (7) or a sensitivity at λ = 1550 nm of Sideal = ∆λ λ0 = = 1550/1.33 = 1165nm/RIU ∆nfluid ng (8) Note that this fundamental limit applies to dielectric evanescent sensors. It also applies to grating-based SPR sensors,56 but not prism-coupled ones (which can achieve much higher nm/RIU values). Applying Eq. 4 for water absorption at 1550 nm (9.6 cm−1 ) we find the intrinsic Q is limited to 5,500. The intrinsic Q for water is plotted versus wavelength in Fig. 8a. The Q is calculated from the water absorption spectrum57 using Eq. 4. This assumes that the light travels entirely in the water, as in an ideal Fabry-Perot cavity. Hence, S=1165 nm/RIU, and the limit of detection is 2.4 × 10−4 RIU . This fundamental limit is included in Fig. 9. The intrinsic limit of detection is plotted versus wavelength in Fig. 8b, using Eqs. 4, 5 and 8. Also included is a curve with additional waveguide scattering loss of 5 dB/cm at 1550 nm (based on previous measurements58 ), scaled using Rayleigh's 1/λ4 dependance for other wavelengths. Finally, assuming a typical37 system readout sensitivity improvement of 100X, the system's limit of detection would be 2.4 × 10−6 RIU at 1550 nm, and is plotted in Fig. 8b versus wavelength. Proc. of SPIE Vol. 8236 823620-9 Downloaded from SPIE Digital Library on 02 Mar 2012 to 126.96.36.199. Terms of Use: http://spiedl.org/terms 6 10 −3 Detection Limit for 100% Water Ultimate Q in water 10 5 10 4 10 −4 10 −5 10 −6 10 Water Water + Scattering loss System limit for 100X readout 3 10 −7 1 1.2 a) 1.4 Wavelength [µm] 1.6 10 1.8 1.1 1.2 1.3 b) 1.4 1.5 1.6 Wavelength [µm] 1.7 1.8 1.9 Figure 8. a) Maximum resonator Q limited by optical absorption from water. b) Highest predicted limits of detection for water absorptionlimited sensing. Waveguide scattering is subsequently added and assumed to contribute 5 dB/cm loss at 1550 nm, and scale as 1/λ4 for other wavelengths. Finally, the system detection limit is shown, assuming a wavelength readout precision 100X better than the resonator linewidth. Note that silicon optical absorption, not included in here, dominates over water absorption for wavelengths <1.1 µm and is negligible for wavelengths > 1.1 µm. Table 1. Summary of silicon photonic sensors and their performance Sensor type Ring41 Ring5 Disk Sensor type Ring Ring Disk Slot Geometry TM, 260x450nm strip TE, 220x500 nm TE, 220x5µm Experimental results Q (in water) S [nm/RIU] 39,299 135 20,000 70 90,000 27 S' [/RIU] 0.088 0.045 0.0175 ∆nmin 2.9 × 10−4 1.1 × 10−3 6.4 × 10−4 Modelling results: 1550 nm, in water. Coupling losses not included (intrinsic resonator only). Geometry Q dB/cm FSR [nm] ∂neff /∂nfluid S S' ∆nmin TE, 220x500 nm strip 106,719 6.9 up to 6 0.152 56 0.036 2.57 × 10−4 TM, 220x500 nm strip 34,500 22.7 up to 6 0.52 179 0.116 2.51 × 10−4 TE, 220x2.5µm 232,854 2.8 45 0.064 27 0.017 2.49 × 10−4 TE, 220x550/110 nm 12,822 34 up to 6 0.80 460 0.30 2.63 × 10−4 3.2 Comparison of Modelling versus Experiments A summary of selected published resonator sensor results, together with the experimental and modelling results presented in this paper, are given in Table 1. Modelling of the strip waveguide ring resonator (TE and TM modes), disk resonator (TE and TM mode), and slot waveguide ring resonator (TE mode) were conducted using the methodology described in Section 2.6. Specifically, we consider an intrinsic resonator, without any out-coupling losses and with side-wall roughness scattering. The parameters of interest are the propagation loss (dB/cm) from the water absorption and radiation losses which determines the Q of the resonator, as well as the sensitivity (S, S') which is found by determining the waveguide susceptibility (∂neff /∂nfluid ). These values are used to find the intrinsic limit of detection, ∆nmin . Additionally, the resonator free-spectral range (FSR) is identified. The most important observation from the modelling results is that all resonators should theoretically have the same limit of detection, under the condition of a fixed wavelength and no scattering losses. The simulated results (S', Q, ∆nmin ) for the various structures are shown in Fig. 9. As shown, all sensors have the same sensitivity of ∆nmin ∼ 2.5 × 10−4 . This, according to Eq. 5, implies that the fundamental limit of the sensor is that the sensitivity is inversely proportional to the Q factor. Any increase in the sensitivity (e.g., by employing slot waveguides) will simply reduce the Q factor by the same amount. Similarly, high-Q structures (e.g., disks) that do not interact much with water will have a lower sensitivity. Proc. of SPIE Vol. 8236 823620-10 Downloaded from SPIE Digital Library on 02 Mar 2012 to 126.96.36.199. Terms of Use: http://spiedl.org/terms 0 10 0 3 10 −1 10 Ring TM Ring TE Ring TE Ring TE 1D PC Disk TE (UBC) Ring TE (UBC) Slot (UBC) Slot TE Limit at 1550 nm −2 10 −1 3 10 4 10 5 10 Q factor 10 2 −2 10 10 400 nm strip, TE 400 nm strip, TM 500 nm strip, TE 500 nm strip, TM 600 nm strip, TE 600 nm strip, TM TE disk, 2.5 µm TM disk, 2.5 µm 550/110 nm slot, TE Limit at 1550 nm 4 10 5 10 Q factor Sensitivity [nm/RIU] Normalized Sensitivity [/RIU] Normalized Sensitivity [/RIU] 10 6 10 Figure 9. Summary of model results for Limits of Detection (LD) for 1550 nm silicon photonic biosensors, for the various configurations studied in this work (data points). The theoretical maximum based on the water absorption limit is the line, in which the single data point represents light travelling exclusively in water. From this point, two limits are drawn: a) the line to the left of the point is the maximum sensitivity where light has 100% interaction with water, namely ∂neff /∂nfluid = 1, and b) the line diagonally down-right shows that the Q-factor limit due to the water absorption increases as the light interacts less with the water, i.e., ∂neff /∂nfluid < 1. These limits only depend on, respectively: a) the index of refraction of the analyte, b) the optical loss of the analyte, i.e., n(λ) + ik(λ). Inset: Experimental data points from Fig. 1 with the addition of the theoretical maximum lines. To understand why different resonators have various levels of sensitivity in Fig. 1, we need to consider the additional loss mechanisms in the resonators. The dominant loss in the TE-like mode devices is the side-wall roughness scattering. As a result, devices with a strong field overlap with the sidewall will have significantly increased propagation loss, hence reduced Q, and a reduced limit of detection. This can be quantified by comparing the total propagation losses versus losses induced by the water absorption. Ideally water absorption would dominate to achieve the highest limit of detection. In the case of the slot waveguide resonators, our measured Q values have been 1,450, while the intrinsic Q from water absorption would suggest a Q of over 12,000. Additionally, it is believed that the analyte does not penetrate the slot completely. Hence, S' is slightly reduced, Q is significantly reduced, which leads to a limit of detection, 2.4 × 10−3 , that is 10X lower than theoretically possible. Meanwhile, the TE disk resonators have a limit of detection of 5.5 × 10−4 , which is only 2X lower than theoretically possible. This is better than the TE mode strip waveguide resonators, and is explained as follows: a) the whispering gallery mode is only confined by one waveguide side-wall, rather than the two in the strip waveguides, hence the scattering losses are reduced, b) the mode-profile has a shape that is more similar to a 600 nm waveguide, and it is known that wider waveguides have lower losses13 due to reduced interaction with the side-walls. These two factors contribute to a higher Q factor. The disadvantage is that the electric field interacts less with the analyte, hence lower sensitivity. However, a potential advantage is that the field-analyte interaction is now primarily above the disk, as opposed to on the side of the waveguides as in TE strip waveguides, which may be beneficial for biological applications where the analyte (e.g., virus) can more easily diffuse and adsorb to the top surface. An interesting observation from Table 1 and Fig. 1 is that some of the demonstrated 1550 nm sensors already measure at the fundamental water absorption limit. Specifically, this was achieved in the system using TM polarization where a Proc. of SPIE Vol. 8236 823620-11 Downloaded from SPIE Digital Library on 02 Mar 2012 to 220.127.116.11. Terms of Use: http://spiedl.org/terms Table 2. Loss mechanisms in silicon photonic sensors. Resonators are assumed to be in isolation. If they were critically coupled, the total Q would be reduced by 2X, hence the limit of detection would be reduced by 2X. Sensor Qscattering Qwater Ideal, water only Ring TE, 220x500 nm strip Ring TE, 220x500 nm strip Ring TE, 220x500 nm strip Ring TM, 220x500 nm strip Disk TE, 220x2.5µm Slot TE, 220x550/110 nm Slot TE, 220x550/110 nm ∞ 258,000 147,000 43,000 147,000 124,000 58,643 1,450 5500 106,719 106,719 106,719 34,500 232,854 12,822 12,822 Qscattering Qwater ∞ 2.42 1.4 0.40 4.3 0.53 4.6 0.12 dB/cm (scattering) 0 3 558 18 5 – 127 5007 dB/cm (water) 43 6.9 6.9 6.9 22.7 – 34 34 dB/cm (total) 43 9.9 11.9 24.9 27.7 – 46 534 Predicted ∆nmin 2.4×10−4 3.7×10−4 4.5×10−4 9.1×10−4 3.1×10−4 7.3×10−4 3.2×10−4 2.6×10−3 large portion of the light is above the waveguide.41 In this case, the water absorption dominates, and the limit of detection almost matches that predicted in Fig. 9. In summary, the best device (as quantified by the limit of detection) would have no loss (except for water, and some for sensing itself via couplers) and the light would resonate primarily in the sensing fluid. In the case where the waveguide scattering and radiation losses can be reduced to below the water absorption losses, operating at different wavelengths can also be considered as shown in Fig. 8. With present fabrication technology (scattering loss limited), only the TM mode resonators would benefit from a reduced water absorption from a change in wavelength. It is interesting to consider whether there exist methods of beating this limit. For example, high group index structures such as Bragg gratings, photonic crystals, or plasmonic devices, will enable the light to travel more slowly through the water hence potentially have sensitivities higher than predicted by Eq. 3. However, this comes together with correspondingly higher optical loss, hence reduced Q. Indeed, SPR prism-coupled sensors have much higher sensitivity, albeit with a very broad linewidth (e.g., over 100 nm), and ultimately their limits of detection are comparable to these considered here (the different wavelength used in SPR prevents the direct comparison with this analysis). 3.3 Readout Until now, the discussion has focused on a limit of detection determined by the linewidth of the resonator. This was done specifically to compare the intrinsic performance of difference resonators, independent of the signal processing and detection methods. Measurement of the resonant wavelength typically involves measuring a spectrum. How the resonant wavelength is measured will impact the precision. This is particularly true when the spectrum contains amplitude (and wavelength) noise. Curve fitting the spectrum to an analytic transfer function is a method in which the algorithm takes into account contributions from the entire √ spectrum, rather than simply finding the peak. Similar to averaging, this improves the eventual signal-to-noise ratio by N , where N is the number of data points in the spectrum. If the noise is low enough, this technique can result in an interpolation of the resonant wavelength and achieve a wavelength resolution even below the original data sample spacing. Optical spectrum processing has been applied to silicon photonic sensors, and has resulted in a wavelength measurement precision that is 10s to 100s of times smaller than the resonator linewidth.37 For example, the Genolyte system achieves a 3σ wavelength measurement noise of 0.2 pm.10 Compare this to a typical 500x220 nm strip-waveguide ring resonator with a Q of 30,000 in water at 1550 nm, with a linewidth of ∆λ1/2 = 50pm, this implies an enhancement factor of over 250X in the spectrum readout as compared to the resonator linewidth used in the intrinsic limit of detection defined in Eq. 5. The limit of detection analysis can also be applied to temperature sensors. Assuming spectral sweep measurement can result in a 100X higher wavelength measurement precision than the resonator linewidth (typical37 ), and for a resonator with a Q=100,000, and a sensitivity of S = 0.08nm/K,49 the thermal detection limit is comparable to thermistors: DL = 1550 × 10−9 λ = = 2mK 100 · Q · S 100 · 106 · 0.08 × 10−9 Proc. of SPIE Vol. 8236 823620-12 Downloaded from SPIE Digital Library on 02 Mar 2012 to 126.96.36.199. Terms of Use: http://spiedl.org/terms 3.4 Biology Applications We have used the ring resonator sensors for biosensing using Human Factor IX and its corresponding antibody59 and verify that the devices are able to sense both the protein attachment during functionalization and the protein-antibody binding reaction. The silicon photonic sample preparation begins by cleaning it in a Piranha solution at 80◦ C for 20 min, then removing the Si native oxide on top of the waveguides using a hydrofluoric acid etchant for 20s. The samples were then thoroughly rinsed in DI water, activated in an air plasma, and incubated in a 1% APTMS solution (94% Ethanol, 5% DI water, APTMS (97%, Sigma-Aldrich)) for 3h. The Human Factor IX was covalently attached with a NHS/EDC chemistry to the amine group of the APTMS linker molecule (0.1 M N-Hydroxysuccinimide, NHS and 0.4 M 1-Ethyl-3(3- dimethylaminopropyl)carbodiimide, EDC, in equal parts, and 500 µg/mL Human Factor IX). The different deposition steps were characterized by X-ray photoelectron spectroscopy (XPS) and ellipsometry. The thickness of the APTMS was ˚ and the thickness of the protein layer was approximately 4 nm. The PDMS microfludic channels were approximately 8 A then aligned and reversibly bonded to the SOI substrate as described in Section 2.1. The resonance peak shift is then monitored as a function of time, Fig. 10 while functionalizing the racetrack with the protein Human Factor IX in a Phosphate buffered saline (PBS) solution. The position of the resonance peak corresponding to the racetrack in the control channel (which remained filled with PBS) is also monitored as a function of time in order to quantify measurement noise and thermal drift (3σ variation of 2.8 pm). The initial larger shift is caused by a combined effect of a bulk refractive index change of the protein solution and the deposition of a protein layer on top of the waveguide. After switching back to PBS, ∆λP is then a measurement of the mass change on the waveguides surface. 900 700 PBS PBS + HF IX PBS HF IX 600 500 400 O Sensing Channel Control Channel 300 ∆λP 200 OH 0 20 a) 40 60 80 100 Time [min] 120 140 b) H N OH Si OH OH OH O OH OH Silicon waveguide OH 100 OH Resonance peak shift [pm] 800 OH SiO2 Figure 10. a) Ring resonator resonance peak shift during attachment of the protein Human Factor IX (56 kDa, 500 µg/mL). The values for both the sensing (blue) and control (red) channels are plotted. The difference in peak location (∆λP ) before and after (both in PBS) is a measurement of the mass change due to the adsorption of the HF IX protein on the sensor. b) Diagram of the attached molecules on the silicon waveguide. 4. CONCLUSION Sensors operating in aqueous media are fundamentally limited by the optical absorption of water. In the cases where the water (or other sensing media) absorption is dominant, all sensor geometries (ring resonators based on strip or slot waveguides, disks, Bragg grating cavities, 1D photonic crystals, etc) and light polarizations (TE-like, TM-like) will theoretically offer the same performance in terms of limit of detection. The differences between sensor configurations is important where other loss mechanisms are present, such as waveguide scattering loss, waveguide material absorption, or resonator radiation loss. In these cases, it is important to minimize the ratio of other losses relative to analyte optical absorption losses. In particular, increasing the analyte absorption by resorting to TM modes, and moving the optical field away from the rough waveguide sidewall, improves this ratio and allows the sensor to approach the fundamental limits of detection. The structures that are most amenable to reaching the theoretical limit are in decreasing order: TM waveguides, disks, and TE waveguides. Slot waveguides and 1D photonic crystals are the furthest away from reaching fundamental limits. Proc. of SPIE Vol. 8236 823620-13 Downloaded from SPIE Digital Library on 02 Mar 2012 to 220.127.116.11. Terms of Use: http://spiedl.org/terms Of the sensors surveyed in this work, we find that many silicon photonics sensors are near the fundamental limit of detection. Hence, future sensor development should focus on additional system functionality and ease-of-use, e.g., very large array operation, low-cost point-of-care devices, electronic readout, further improvement in readout sensitivity and noise considerations, etc. Additionally, silicon photonic resonator sensor technology has matured to the point where commercially available systems are available10 and enable complex biological experimentation research to take place.29 The next steps will be for this technology to move to clinical, hospital, and point-of-care applications. ACKNOWLEDGMENTS The author would like to thank CMC Microsystems for enabling the fabrication of the chips via IMEC-ePIXfab and for providing the Design Workshop Technologies and Mentor Graphics Pyxis layout software packages, and to Lumerical Solutions, Inc. for supporting the CMC-UBC Silicon Nanophotonics Fabrication course and workshop by providing FDTD and MODE Solutions software. Funding for this research was provided by NSERC. SAS and DMR gratefully acknowledge support from US NSF CBET (award no. 0930411). Finally, the authors are grateful to Michael Hochberg, Mike Gould, and Jim Kirk at the University of Washington, and Miguel A.G. Torres at UBC for many useful discussions. We thank Ralph Azucena for the laser automation. REFERENCES 1. Washburn, A. L., Gunn, L. C., and Bailey, R. C., "Label-free quantitation of a cancer biomarker in complex media using silicon photonic microring resonators," Analytical Chemistry 81(22), 9499–9506 (2009). doi: 10.1021/ac902006p. 2. White, I. and Fan, X., "On the performance quantification of resonant refractive index sensors," Optics Express 16(2), 1020 (2008). 3. Yang, G. M., White, I. M., and Fan, X. D., "An opto-fluidic ring resonator biosensor for the detection of organophosphorus pesticides," Sensors and Actuators B: Chemical 133(1), 105–112 (2008). 4. Passaro, V. M. N., Dell'Olio, F., Ciminelli, C., and Armenise, M. N., "Efficient chemical sensing by coupled slot soi waveguides," Sensors 9(2), 1012–1032 (2009). 5. De Vos, K., Bartolozzi, I., Schacht, E., Bienstman, P., and Baets, R., "Silicon-on-insulator microring resonator for sensitive and label-free biosensing," Optics Express 15(12), 7610–7615 (2007). 6. Ramachandran, A., Wang, S., Clarke, J., Ja, S. J., Goad, D., Wald, L., Flood, E. M., Knobbe, E., Hryniewicz, J. V., Chu, S. T., Gill, D., Chen, W., King, O., and Little, B. E., "A universal biosensing platform based on optical micro-ring resonators," Biosensors and Bioelectronics 23(7), 939–944 (2008). 7. Claes, T., Molera, J. G., De Vos, K., Schacht, E., Baets, R., and Bienstman, P., "Label-free biosensing with a slotwaveguide-based ring resonator in silicon on insulator," IEEE Photonics Journal 1(3), 197–204 (2009). 8. Carlborg, C. F., Gylfason, K. B., Kazmierczak, A., Dortu, F., Polo, M. J. B., Catala, A. M., Kresbach, G. M., Sohlstrom, H., Moh, T., Vivien, L., Popplewell, J., Ronan, G., Barrios, C. A., Stemme, G., and van der Wijngaart, W., "A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips," Lab on a chip 10(3), 281–290 (2010). 9. Luchansky, M. and Bailey, R., "Silicon photonic microring resonators for quantitative cytokine detection and t-cell secretion analysis," Analytical chemistry 82(5), 1975–1981 (2010). 10. Iqbal, M., Gleeson, M., Spaugh, B., Tybor, F., Gunn, W., Hochberg, M., Baehr-Jones, T., Bailey, R., and Gunn, L., "Label-free biosensor arrays based on silicon ring resonators and high-speed optical scanning instrumentation," IEEE Journal of Selected Topics in Quantum Electronics 16(3), 654–661 (2010). 11. Fan, X. D., White, I. M., Shopoua, S. I., Zhu, H. Y., Suter, J. D., and Sun, Y. Z., "Sensitive optical biosensors for unlabeled targets: A review," Analytica Chimica Acta 620(1-2), 8–26 (2008). 12. Passaro, V. M. N., Dell'Olio, F., Casamassima, B., and De Leonardis, F., "Guided-wave optical biosensors," Sensors 7(4), 508–536 (2007). 13. Vlasov, Y. and McNab, S., "Losses in single-mode silicon-on-insulator strip waveguides and bends," Optics Express 12(8), 1622–1631 (2004). 14. Densmore, A., Xu, D., Waldron, P., Janz, S., Cheben, P., Lapointe, J., Delge, A., Lamontagne, B., Schmid, J., and Post, E., "A silicon-on-insulator photonic wire based evanescent field sensor," IEEE Photonics Technology Letters 18(23), 2520–2522 (2006). Proc. of SPIE Vol. 8236 823620-14 Downloaded from SPIE Digital Library on 02 Mar 2012 to 188.8.131.52. Terms of Use: http://spiedl.org/terms 15. Baehr-Jones, T., Hochberg, M., Walker, C., and Scherer, A., "High-Q optical resonators in silicon-on-insulator-based slot waveguides," Applied Physics Letters 86(8), – (2005). 16. Barrios, C. A., Gylfason, K. B., Sanchez, B., Griol, A., Sohlstrom, H., Holgado, M., and Casquel, R., "Slot-waveguide biochemical sensor," Optics Letters 32(21), 3080–3082 (2007). 17. Dell'Olio, F. and Passaro, V. M. N., "Optical sensing by optimized silicon slot waveguides," Optics Express 15(8), 4977–4993 (2007). 18. Barrios, C. A., Banuls, M. J., Gonzalez-Pedro, V., Gylfason, K. B., Sanchez, B., Griol, A., Maquieira, A., Sohlstrom, H., Holgado, M., and Casquel, R., "Label-free optical biosensing with slot-waveguides," Optics Letters 33(7), 708– 710 (2008). 19. Keivani, H. and Kargar, A., "Bending efficiency of bent multiple-slot waveguides," Chinese Physics Letters 26(12), – (2009). 20. Boyd, R. and Heebner, J., "Sensitive disk resonator photonic biosensor," Applied Optics 40(31), 5742–5747 (2001). 21. Armani, A., Kulkarni, R., Fraser, S., Flagan, R., and Vahala, K., "Label-free, single-molecule detection with optical microcavities," Science 317(5839), 783 (2007). 22. Jeong, H., Lee, S., Sung, G., and Shin, J., "Design and fabrication of Tb3+ -doped silicon oxy-nitride microdisk for biosensor applications," IEEE Photonics Technology Letters 23(2), 88–90 (2011). 23. Mandal, S. and Erickson, D., "Nanoscale optofluidic sensor arrays," Optics Express 16(3), 1623 (2008). 24. Prabhathan, P., Murukeshan, V., Jing, Z., and Ramana, P., "Compact SOI nanowire refractive index sensor using phase shifted bragg grating," Optics Express 17(17), 15330–15341 (2009). 25. Arce, C., De Vos, K., Claes, T., Komorowska, K., Van Thourhout, D., and Bienstman, P., "Silicon-on-insulator microring resonator sensor integrated on an optical fiber facet," IEEE Photonics Technology Letters 23(13) (2011). 26. Monat, C., Domachuk, P., and Eggleton, B. J., "Integrated optofluidics: A new river of light," Nature Photonics 1(2), 106–114 (2007). 27. Gylfason, K. B., Carlborg, C. F., Kazmierczak, A., Dortu, F., Sohlstrom, H., Vivien, L., Barrios, C. A., van der Wijngaart, W., and Stemme, G., "On-chip temperature compensation in an integrated slot-waveguide ring resonator refractive index sensor array," Optics Express 18(4), 3226–3237 (2010). 28. Xu, D. X., Densmore, A., Delage, A., Waldron, P., McKinnon, R., Janz, S., Lapointe, J., Lopinski, G., Mischki, T., Post, E., Cheben, P., and Schmid, J. H., "Folded cavity soi microring sensors for high sensitivity and real time measurement of biomolecular binding," Optics Express 16(19), 15137–15148 (2008). 29. Kirk, J., Fridley, G., Chamberlain, J., Christensen, E., Hochberg, M., and Ratner, D., "Multiplexed inkjet functionalization of silicon photonic biosensors," Lab on a Chip (2011). 30. Narayanaswamy, R. and Wolfbeis, O., [Optical sensors: industrial, environmental and diagnostic applications], vol. 1, Springer Verlag (2004). 31. Bailey, R. C., Washburn, A. L., Qavi, A. J., Iqbal, M., Gleeson, M., Tybor, F., and Gunn, L. C., "A robust silicon photonic platform for multiparameter biological analysis," 72200N–72200N–6 (2009). 32. Adam, B., Qu, Y., Davis, J., Ward, M., Clements, M., Cazares, L., Semmes, O., Schellhammer, P., Yasui, Y., and Feng, Z., "Serum protein fingerprinting coupled with a pattern-matching algorithm distinguishes prostate cancer from benign prostate hyperplasia and healthy men," Cancer Research 62(13), 3609 (2002). 33. Washburn, A., Luchansky, M., Bowman, A., and Bailey, R., "Quantitative, label-free detection of five protein biomarkers using multiplexed arrays of silicon photonic microring resonators," Anal Chem 82(1), 69–72 (2009). 34. Qavi, A. and Bailey, R., "Multiplexed detection and labelfree quantitation of micrornas using arrays of silicon photonic microring resonators," Angewandte Chemie International Edition 49(27), 4608–4611 (2010). 35. Yan, R., Kingry, L. C., Slayden, R. A., and Lear, K. L., "Immunoassay demonstration using a local evanescent array coupled biosensor," 75590D–75590D–7 (2010). 36. Hochberg, M. and Baehr-Jones, T., "Towards fabless silicon photonics," Nature Photonics 4(8), 492–494 (2010). 37. Yoshie, T., Tang, L., and Su, S., "Optical microcavity: Sensing down to single molecules and atoms," Sensors 11(2), 1972–1991 (2011). 38. Ackert, J., Doylend, J., Logan, D., Jessop, P., Vafaei, R., Chrostowski, L., and Knights, A., "Defect-mediated resonance shift of silicon-on-insulator racetrack resonators," Optics Express 19(13), 11969–11976 (2011). Proc. of SPIE Vol. 8236 823620-15 Downloaded from SPIE Digital Library on 02 Mar 2012 to 188.8.131.52. Terms of Use: http://spiedl.org/terms 39. Baehr-Jones, T., Hochberg, M., Walker, C., Chan, E., Koshinz, D., Krug, W., and Scherer, A., "Analysis of the tuning sensitivity of silicon-on-insulator optical ring resonators," IEEE Journal of Lightwave Technology 23(12), 4215 (2005). 40. Markov, D., Begari, D., and Bornhop, D., "Breaking the 10-7 barrier for ri measurements in nanoliter volumes," Analytical chemistry 74(20), 5438–5441 (2002). 41. Xu, D., Vachon, M., Densmore, A., Ma, R., Janz, S., Delge, A., Lapointe, J., Cheben, P., Schmid, J., Post, E., et al., "Real-time cancellation of temperature induced resonance shifts in soi wire waveguide ring resonator label-free biosensor arrays," Optics Express 18(22), 22867–22879 (2010). 42. Lukosz, W., "Principles and sensitivities of integrated optical and surface plasmon sensors for direct affinity sensing and immunosensing," Biosensors and Bioelectronics 6(3), 215–225 (1991). 43. "http://www.biacore.com/," 44. Unger, M., Chou, H., Thorsen, T., Scherer, A., and Quake, S., "Monolithic microfabricated valves and pumps by multilayer soft lithography," Science 288(5463), 113 (2000). 45. Ksendzov, A. and Lin, Y., "Integrated optics ring-resonator sensors for protein detection," Optics Letters 30(24), 3344–3346 (2005). 46. Xia, Y. N. and Whitesides, G. M., "Soft lithography," Annual Review of Materials Science 28, 153–184 (1998). 110TC Times Cited:1318 Cited References Count:184. 47. DowChemical, "Optim glycerine refractive index," (2011). 48. Flueckiger, J., Grist, S., Bisra, G., Chrostowski, L., and Cheung, K., "Cascaded silicon-on-insulator microring resonators for the detection of biomolecules in PDMS microfluidic channels," Proceedings of SPIE 7929, 79290I (2011). 49. Rouger, N., Chrostowski, L., and Vafaei, R., "Temperature effects on silicon-on-insulator (SOI) racetrack resonators: a coupled analytic and 2D finite difference approach," IEEE Journal of Lightwave Technology 28(9), 1380–1391 (2010). 50. "http://www.lumerical.com/mode/," Lumerical Solutions MODE . 51. Wang, X., Shi, W., Grist, S., Yun, H., and Chrostowski, N. A. F. J., "Narrow-band transmission filter using phaseshifted bragg gratings in SOI waveguide," IEEE Photonics Conference , ThZ1 (10/2011 2011). 52. Borselli, M., Johnson, T., and Painter, O., "Beyond the rayleigh scattering limit in high-q silicon microdisks: theory and experiment," Opt. Express 13, 1515–1530 (Mar 2005). 53. Morand, A., Zhang, Y., Martin, B., Huy, K. P., Amans, D., Benech, P., Verbert, J., Hadji, E., and F´ed´eli, J.-M., "Ultra-compact microdisk resonator filters on soi substrate," Opt. Express 14, 12814–12821 (Dec 2006). 54. Soltani, M., Li, Q., Yegnanarayanan, S., and Adibi, A., "Toward ultimate miniaturization of high Q silicon travelingwave microresonators," Optics Express 18(19), 19541–19557 (2010). 55. "http://www.lumerical.com/fdtd/," Lumerical Solutions FDTD . 56. Homola, J., Koudela, I., and Yee, S., "Surface plasmon resonance sensors based on diffraction gratings and prism couplers: sensitivity comparison," Sensors and Actuators B: Chemical 54(1-2), 16–24 (1999). 57. Kou, L., Labrie, D., and Chylek, P., "Refractive indices of water and ice in the 0.65- to 2.5-µm spectral range," Applied Optics 32, 3531–3540 (Jul 1993). 58. Shi, W., Vafaei, R., Torres, M., Jaeger, N., and Chrostowski, L., "Design and characterization of microring reflectors with a waveguide crossing," Optics Letters 35(17), 2901–2903 (2010). 59. Flueckiger, J., Grist, S. M., Ouellet, E., Chrostowski, L., and Cheung, K. C., "Label-free biosensing using cascaded silicon-on-insulator micro-racetrack resonators integrated with PDMS microfluidic channels," International Conference on Miniaturized Systems for Chemistry and Life Sciences (µTAS) , 565–567 (Oct. 2011). Proc. of SPIE Vol. 8236 823620-16 Downloaded from SPIE Digital Library on 02 Mar 2012 to 18.104.22.168. Terms of Use: http://spiedl.org/terms
UBC Faculty Research and Publications
Silicon photonic resonator sensors and devices. Chrostowski, Lukas; Grist, Samantha M.; Flueckiger, Jonas; Shi, Wei; Wang, Xu; Ouellet, Eric; Yun, Han; Webb, Mitch; Nie, Ben; Liang, Zhen; Cheung, Karen C.; Jaeger, Nicolas A. F. 2012-12-31
Item Metadata
- Media
- [if-you-see-this-DO-NOT-CLICK]
- Chrostowski_SPIE_8236_823620.pdf [ 1.62MB ]
- Metadata
- JSON: 1.0107567.json
- JSON-LD: 1.0107567+ld.json
- RDF/XML (Pretty): 1.0107567.xml
- RDF/JSON: 1.0107567+rdf.json
- Turtle: 1.0107567+rdf-turtle.txt
- N-Triples: 1.0107567+rdf-ntriples.txt
- Original Record: 1.0107567 +original-record.json
- Full Text
- 1.0107567.txt
- Citation
- 1.0107567.ris
Full Text
Citation Scheme:
Usage Statistics
|United States
|United Arab Emirates
|Republic of Lithuania
|Hong Kong
|Saint Petersburg
|{[{ mDataHeader[type] }]}
|{[{ month[type] }]}
|{[{ tData[type] }]}
Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
<div id="ubcOpenCollectionsWidgetDisplay">
<script id="ubcOpenCollectionsWidget"
async >
Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:


text:
realmagick.com The shrine of knowledge.
Jayadeva Gosvami
- Śrī Śrī Rādhā Govinda Gauďīya Mațh - Radha-govinda.net
- 1. leden 2016 103th Vyāsapūja of Nitya-līlā-pravişța Oń Vişņupād. 108 Śrī Śrīmad Bhakti Vaibhava Purī.
- www.radha-govinda.net
- Jayadeva and Gitagovinda - Odisha
- Jul 27, 2009 Jayadeva & Gita Govinda * Special Issue ... Jayadeva developed and reached its nadir in the ..... been seen by Rupa and Sanatan Goswamy.
- odisha.gov.in
- unconventional teachers - PureBhakti.com
- "Sri Jayadeva Gosvami, the court poet of the Sena dynasty, has welcomed the appearance of ... beautiful glorification of Srila Jayadeva Gosvami's work.
- www.purebhakti.com
- Vaishnava song book - Vaishnav Songs - ISKCON Desire Tree
- When will Srīla Rūpa Gosvāmī Prabhupāda, who ... Raghunātha dāsa Gosvāmī, Jīva Gosvāmī, and ..... Dasavatara Stotram by Jayadeva Goswami).
- vaishnavsongs.iskcondesiretree.com
- Krishna Voice - ISKCON Bangalore
- Therefore Jayadeva Gosvami sings in his prayer, "My Lord, in the shape of a fish ... Jayadeva therefore prayed: "You appeared as a tortoise just to be a resting ...
- www.iskconbangalore.org
- Now, cancer detection on wheels
- Efficient screening and early detection holds the key to contain the growing number of non-communicable diseases. The Kidwai Memorial Institute of Oncology, in this direction, will soon run a mobile cancer bus. Speaking on the sidelines of an event ...
- Bihar polls 2015: After Rahul Gandhi's 'feku' remark, BJP calls him Congress
- Rahul is called Pappu....and evrryone know why...people have watched his women empowerment interview with Goswami ....
- I Know You Mean Well
- But Shri Jayadeva Goswami wrote a very famous and beloved poem among the vaishnavas (even Prabhupada) called Dasavathara Stotra, in which Buddha is described as the incarnation of Krishna! So, Krishna incarnated as Buddha to spread the teaching ...
- CPI(M) slams PM Modi over removal of bureaucrats
- Goyal had taken over as Home Secretary nearly seven months back on February 5 in place of Anil Goswami who was sacked after he allegedly tried to prevent the CBI from arresting former Union Minister Matang Sinh in connection with Saradha chit fund ...
- Krishna, laddoos and rabdi in Jaipur
- Flee, says the Rajput king to the temple pandit, Shiva Ram Goswami. Take the idols and flee. Go via adjoining Bharatpur.
- Jayadeva - Wikipedia, the free encyclopedia
- Jayadeva (odia:ଜୟଦେବ) was a Sanskrit poet c. 1200. He is most known for his epic poem Gita Govinda, which depicts the divine love of Krishna and his consort, ...
- en.wikipedia.org
- Jayadeva Goswami | Gaudiya History
- Aug 3, 2011 Three hundred years before the appearance of Shri Chaitanya Mahaprabhu, Shri Jayadeva Goswami served as the court pandita of Shri ...
- gaudiyahistory.iskcondesiretree.com
- Jayadeva Goswami | Vaishnav Songs
- Jayadeva Goswami, the composer of the immortal Sanskrit devotional song Gita Govinda, which depicts the love story of Lord Krishna and his sweetheart Radha ...
- vaishnavsongs.iskcondesiretree.com
- Jayadeva Goswami - VRINDA
- Sri Jayadeva Goswami was the court pandit of Sri Lakshman Sena, the King of Bengal. Jayadeva's father was Bhojadeva, and his mother's name was Bamadevi ...
- www.vrindavan.org
- Gita Govinda of Jayadeva Goswami | Sri Narasingha Chaitanya
- Sep 5, 2005 Question: I purchased a copy of Gita-govinda from a devotee selling books in the streets of Bangalore (India) with a foreword by Srila ...
- gosai.com
Jayadeva Gosvami is described in multiple online sources, as addition to our editors' articles, see section below for printable documents, Jayadeva Gosvami books and related discussion.
Suggested Pdf Resources
Suggested News Resources
Suggested Web Resources
Great care has been taken to prepare the information on this page. Elements of the content come from factual and lexical knowledge databases, realmagick.com library and third-party sources. We appreciate your suggestions and comments on further improvements of the site.
Jayadeva Gosvami Topics
Related searcheskarl may literature
arboreal theory
culture of tonga church music
dream meaning dictionary murder
mobile alabama geography and climate
About - Contact - Advertising
© 2000 - 2016 Realmagick.com, All Rights Reserved.
© 2000 - 2016 Realmagick.com, All Rights Reserved.

subset: commoncrawl


text:
Better Living Through Building a Lego Marvel SHIELD Helicarrier
Earlier this year, Lego revealed its impressive Marvel Super Hero SHIELD Helicarrier set to the world at Toy Fair. The 2,996 pieces combine to form a mammoth 31"x17"x11" scaled replica of the vehicle du jour for Marvel's elite global security organization. Having recently rekindled my love of Lego with the Assault on Avengers Tower set, I convinced my wife that the SHIELD Helicarrier would be the perfect weekend activity for the two of us to share.


text:
realmagick.com The shrine of knowledge.
Christian Faith
A selection of articles related to christian faith.
Original articles from our library related to the Christian Faith. See Table of Contents for further available material (downloadable resources) on Christian Faith.
- The Pagan Origins Of Christian Mythology
- The Judeo-Christian religions were founded in a region of the world where savior religions existed for thousands of years. Much of the symbolism and many of the stories in the Bible may be traced to earlier myths of the Persians, Egyptians, and other people...
Religions >> Christianity & Paganism
- Historical Christian Jewelry
- The art of jewelry making evolved though the centuries. In a sense, jewelry is any ornamentation or adornment on the body. Jewelry has been used not only for aesthetic reasons but also as an indication of a person's status in life.
>> Body Mysteries
- King James Bible: Hebrews, Chapter 11
- Chapter 11 11:1 Now faith is the substance of things hoped for, the evidence of things not seen. 11:2 For by it the elders obtained a good report. 11:3 Through faith we understand that the worlds were framed by the word of God, so that things which are seen...
New Testament >> To the Hebrews
- Art during the Age of Faith
- The Age of Faith is the one thousand medieval years from 400 A.D. to 1400 A.D. It must be noted though that faith was not a uniquely medieval phenomenon as medieval pursuits were not purely geared towards faith only.
Saga of Times Past >> History & Anthropology
- Am I Damned?: Part 1
- (Excerpted from a planned website, much of this material has already appeared in answer to various questions on the boards, especially in General Earth Spirituality. I will attempt to redact it for this forum, as much of the arguments contained here are basic...
Religions >> Christianity & Paganism
Christian Faith is described in multiple online sources, as addition to our editors' articles, see section below for printable documents, Christian Faith books and related discussion.
Suggested News Resources
- Saeed Abedini Shares Letter From Pres. Obama Admiring His 'Unyielding
- Pastor Saeed Abedini is sharing the personal letter he received from President Barack Obama, which is in response to a letter he sent to the White House to thank the president for his efforts to secure his release.
- In the name of love: Ten profound U2 lyrics about Christian faith
- Whatever your view of them however, it's hard to deny that they've made a massive contribution to popular music – and in more recent years thanks to the strong Christian faith of lead singer Bono, to wider and more important areas of our culture.
- Faith and Values: Politics shouldn't be distinct from Christian faith
- There are eight comments on this story ». Most recent City. new Suicide conference highlights Washington bill requiring awareness training for gun dealers; new North Idaho man sexually abused 102-year-old woman 2; Man jailed for allegedly causing ...
- Queen Elizabeth Says Devotion to Christian Faith Is Why She Won't Suport Gay
- Queen Elizabeth II opposed the legalization of same-sex marriage in England because of her deeply held Christian values, a close friend has reportedly told a London-based newspaper. The UK Daily Mail published a story Sunday which claimed that the ...
- Donald Trump suggests he was audited because of his 'strong Christian faith
- Whether it was businessman Donald Trump stating he was audited because he was a "strong Christian" or radio host Hugh Hewitt asking questions about religion-based tax exemptions, the issue of religion and taxes continues to gain much needed attention.
Great care has been taken to prepare the information on this page. Elements of the content come from factual and lexical knowledge databases, realmagick.com library and third-party sources. We appreciate your suggestions and comments on further improvements of the site.
Christian Faith Topics
Related searchesclan car clan clover
tipi construction
saddle bronc riding
carburetor power valve
sean combs early years
governor of jamaica
About - Contact - Advertising
© 2000 - 2016 Realmagick.com, All Rights Reserved.
© 2000 - 2016 Realmagick.com, All Rights Reserved.


text:
Courtyard by Marriott Bloomington by Mall of America - Bloomington
This hotel offers a restaurant, free self parking and a free airport shuttle. Go for a dip in the indoor pool during your stay. Guests wishing to enjoy a drink will surely want to visit the bar/lounge. Leisure facilities on offer include the fitness center and spa tub.
Multilingual staff are available at the front desk 24 hours-a-day and can provide express check-out. Free WiFi and high-speed (wired) Internet access is provided.
Courtyard by Marriott Bloomington by Mall of America - Bloomington
Hotel Info: 855-239-9399from $129
- Deluxe Suite
- Standard Room, 1 King Bed with Sofabed
- Standard Room
- Deluxe Room (Spa)
Also popular with travelers from the USA
At a glance
Key facts
Hotel size
- This hotel has 203 rooms
- This hotel is arranged over 7 floors
- Check-in time 3 PM-5:30 AM
- Check-out time is noon
- Express check-out
Required at check in
- Credit card deposit required
- Government-issued photo ID required
Travelling with others
- Pets not allowed
- Free WiFi and wired Internet access in public areas
- Free WiFi and wired Internet access in rooms
- Free airport shuttle (available 24 hours)
- Free self parking
- Extended parking
Other information
- Smoke-free property
In the hotel
- Buffet breakfast (surcharge)
- Restaurant
- Bar/lounge
- Room service (during limited hours)
- Coffee/tea in a common area
- Indoor pool
- Fitness facilities
- Spa tub
- Golfing nearby
- Hiking/biking trails nearby
- Cross-country skiing nearby
- Free use of nearby fitness center
- 24-hour business center
- Number of meeting rooms - 6
- Conference space
- Meeting rooms 6
- Conference space size (feet) - 2800
- Conference space size (meters) - 260
- 24-hour front desk
- Dry cleaning/laundry service
- Laundry facilities
- Free newspapers in lobby
- Multilingual staff
- Number of buildings/towers - 1
- Year Built 1998
- ATM/banking
- Safe-deposit box at front desk
- Terrace
- Accessible bathroom
- In-room accessibility
- Roll-in shower
In the room
- In-room climate control (air conditioning)
- Air conditioning
- Coffee/tea maker
- Iron/ironing board
- Premium bedding
- Separate sitting area
- Private bathroom
- Shower/tub combination
- Free toiletries
- Hair dryer
- Pay movies
- Premium TV channels
- Desk
- Free weekday newspaper
- Free WiFi
- Phone
- Refrigerator
- Daily housekeeping
- Connecting/adjoining rooms available
Courtyard by Marriott Bloomington by Mall of America - Bloomington's small print
Also known as
- Courtyard Marriott Minneapolis Bloomington
- Courtyard Minneapolis
- Courtyard Minneapolis Bloomington
- Marriott Courtyard Minneapolis Bloomington
- Courtyard Marriott Bloomington Mall America Hotel
- Courtyard Marriott Mall America Hotel
- Courtyard Marriott Bloomington Mall America
- Courtyard Marriott Mall America
The property has connecting/adjoining rooms, which are subject to availability and can be requested by contacting the property using the number on the booking confirmation.
Optional extras
Rollaway beds are available for an additional charge
Buffet breakfast is offered for an extra charge of USD 13 per person (approximately)
We have included all charges provided to us by this hotel. However, charges can vary, for example, based on length of stay or the room you book.


text:
Potters rally to nip CCHS
EAST LIVERPOOL – The East Liverpool Potters led only once after the first quarter, but they led when it mattered, as they claimed a pulsating 68-67 victory over Steubenville Catholic Central Friday night at Potter Fieldhouse.
Both teams are 7-4.
A steal by D.J. Austin was transformed into an up-and-under shot by Hayden Cunningham giving the Potters a 68-67 lead with just 22 seconds remaining in the game. Austin had pulled East Liverpool to within one, 67-66, with a basket following another steal at the 56-second mark.
The Crusaders had one final chance but Kade Reynolds and Aaron Long put the clamps on a lob from out of bounds with 4.7 seconds to claim the victory.
Cunningham paced the Potters with 21 points. Austin contributed 17 points and eight assists. Reynolds scored 15, while Owen Crawford pitched in nine points and pulled down eight rebounds.
"Hayden had a very strong first half," said East Liverpool head coach Nate Conley of Cunningham who tallied 16 in the first half. "They face-guarded him in the second half, which limited his touches. Kade had a tremendous second half and D.J. made things happen."
Ryan Fletcher drained 24 points for the Crusaders. Matt Martello and John Paul Dombrowski tallied 11 each.
East Liverpool found themselves trailing by 56-45 early in the fourth quarter before Austin and Reynolds erupted for a combined 19 points. Held scoreless in the first half, Austin tallied eight points in the third and nine in the fourth quarter. Reynolds hit two deep threes among his 10 fourth-quarter points.
"We had defensive breakdowns in the fourth quarter when the game was on the line," said Central head coach Sean Tucker. "We should be comfortable with six seniors in our rotation. Instead, we let No. 23 (Reynolds) get open and he hit three shots in the fourth quarter."
The Potters outscored Central 23-13 in the final quarter.
"It all boiled down to defense," said Conley. "Earlier Central was getting everything they wanted on their offensive end. Our defense was non-existent the first three quarters."
The Potters jumped out to an early 10-3 lead, before the Crusaders rallied to take an 13-10 lead. Four points by Cunningham and two by Long enabled East Liverpool to even the score at 16-16 at the end of quarter one. Cunningham netted 10 points in the first quarter.
Central led 32-26 with 46 seconds remaining in the first half. Drives by Cunningham and Crawford pulled East Liverpool to 32-30 at intermission.
Three three-pointers from deep in the corners by Fletcher allowed Central to move out to a 54-45 lead after three quarters.
Both teams are on the road tonight as the Potters travel to Cameron and Central visits Bridgeport.


text:
I work in the center of London, but I don't date girls there. First of all, it is just too expensive to date escorts in the center of London. Also, I find that a lot of the girls who present themselves as hot talented London babes, are not really that hot. The majority of them that I have met are a tad too posh for me, and are more concerned about their looks. That is another thing that puts me off as well. man of the girls that I have met at the agency have had enhancement work, and I have to say it puts me off. You don't get any of that with Hounslow escorts.
Hot talent at Hounslow escorts
Yes, it cheaper to date Hounslow escorts but that is not the main reason why I do it. Lots of my friends at work live on the outskirts of London, and stay behind in London after work, to date secy escorts. I really can't be bothered with that and prefer to go back home to Hounslow and date some hot Hounslow escorts. The girls at my local agency are just as hot and talented as many of the VIP girls in central London.
On top of that, the majority of Hounslow escorts do outcalls. They don't mind coming to your home after hours and I prefer that. The problem is that I finish work rather late, and I am simply not always in the mood to go out again. That doesn't mean that I am not in the mood for some hot and sexy actin, but I do prefer to get my action at home. It is more comfortable and afterwards I can always relax with a drink or two. It just isn't the same going to see an escort at her place.
Hot Blonde Action
I love hot blonde action, and I find that there are very few hot blonde escorts in the center of London. Here at Hounslow escorts, we have some really hot blonde action, and I have been able to get some favorite escorts that I like to see. All of the girls that I date on a regular basis, know what I need and they know what I am like. It is kind of cool when it is like that, and you get more of a chance to enjoy each others company at the same time.
Lots of the hot blondes babes at Hounslow ecorts, come from places like Poland. I know that lots of guys have a fetish about Polish escorts, and I am not any different. There is something truly special about these girls, and I just love being around them. All of the sexiest Hounslow escorts are from Poland, and sometimes, you may even find that your favorite bit of hot talent is not available for your pleasure. That tells you a little bit about the popularity of Hounslow escorts. Lots of gents, not only me, like to meet up with the hottest girls.
Services at Hounslow escorts
The services that Hounslow escorts offer is just as good as some of the hottest and most expensive escorts agencies in the center of London. I am sure that a lot of guys who date on a regular basis in the middle of London, are paying well over the odds for their dates. Here in Hounslow, I would get at least a couple of dates with Hounslow escorts, for the price of a date with a top London girl. Personally, I would rather date more not less, and that is what you are forced to do in London.
Hounslow escorts also offer things like fetish services and duo dating. I know one guy who has a serious foot fetish, and he says that all of his dates with Hounslow escorts have been amazing. This guy can really get kinky with feet, and he says that the girls that he sees at the local agency, don't mind his foot fetish at all. Also, the girls offer things like duo dating and escorts for couples. It is not for me, but I do know people who enjoy them. Well, with the girls here, they can make the most of them.
Swinging good time
I got into dating escorts after breaking up with my regular girlfriends. Some people enjoy swinging, and I am one of those. The problem was that my regular girlfriend did not enjoy swinging. In the end, we broke up, and I started to go swinging with a girl who worked for Hounslow escorts. We still go swinging, and we have a really good time together. If, you are into swinging but your girlfriend don't like, it could be a good idea to take a girl from an escorts service with you.
Some of the girls at Hounslow escorts are into swinging, but not all of them are. I have always been seriously turned on by swinging, but I do appreciate the fact that most regular girls are not. If, you don't get turned on by swinging, you shouldn't go. But recently I have noticed that swinging, seem to be getting more and more mainstream and more people are doing it. I sort of describe it as a pleasure for the soul and the body, a great release if you like.
Will I ever stop dating the girls at the Hounslow escort service? I am not so sure about. Having a regular girlfriend is okay, but the problem is that many of them are really demanding. On top of that, they are always after personal commitment, and I am not sure that I can always deliver that. Yes, it is fun to fall in love but having to spend lots of time with the same girl, is not for me. This is one of the many reasons that I date hot girls here in Hounslow and concentrate on enjoying myself instead. I am sure that many other guys my age are doing the same thing and feel the same.


text:
If the speculation is true, Toronto Maple Leafs GM Brian Burke may be able to save face by eliminating one unwanted player from his salary cap this offseason.
The NHL and the NHLPA will begin hammering out a new CBA (Collective Bargaining Agreement) following the conclusion of the playoffs, and speculation suggests that it may include an amnesty clause that would allow each team to remove one contract from their salary cap if they so choose.
The idea will remain just that until the terms of a new CBA are finalized, but even the rumors of an amnesty clause have NHL fans abuzz with dreams of contract relief and the possibilities that come with it.
The Leafs, in particular, have more than a few players on their current roster that are overpaid. So this news will come as music to the ears of many in Leafs Nation.
This list takes a quick looks at Toronto's top five candidates for amnesty.


text:
Cathy by Cathy Guisewite
- December 27, 2012
- From Beginning
- Previous feature
- Next feature
- Current
No Zoom
Comments (7) (Please sign in to comment)
Too real to be funny!
These two drive me crazy with their perfectionism/procrastination.
She didn't love the plant she received a couple of days ago.She gave it away, remember?
No need for thank you notes in my family. We say thank you in person or over the phone.
Hello everyone, hope the rest of your day is wonderful.
So, in other words . . . no "Thank You" of any kind for the beautiful poinsettia plant will EVER be given to the Brownes for their thoughtfulness. Figures!!!!! :-(
Hi, rgcviper!!!!!
lightenup: Hope you had a really wonderful birthday yesterday! When do you leave to see your mom and to go on your "secret mission"?
Hello to all my wonderful "Cathy Clan" friends! This is probably my favorite place in all the world to be whenever I'm on the internet . . . I just really love it here! The only thing that would make my happiness complete would be to have our dear friends, Aaron and Dr. Billy back here with us again!!!!!
Um … Cathy's mom? Have you completely lost your mind? I mean, I'm used to the nutjobbiness, but this is over the top even for HER.
HI, MOM! (And, Hello, Clan.)
Hi lightenup i'm sorry i missed you B.D. So Happy Belated Birthday hope you had the best birthday ever. Hi to the cathy clad come back Aaron & Billy we all miss and love you.
- Refresh Comments.
You must be signed in to make a comment.


text:
- Start
- Brief Description
- The Magnet-Gravitation Motor
- Chronicle of Events
- Physical Principles
- Contact
The international MAGRAV team is resolved to make its mark in the field of environmentally friendly drive technology using magnetism.
This basic approach is not new: The essential question revolves around the task of exploiting familiar physical phenomena to develop useful technologies – technologies which satisfy the needs and demands of politics, industry and users.
In the course of many years of research and development, the MAGRAV engineers have succeeded in demonstrating the efficiency of the magnet-gravitation motor, of which the second generation is already available. The next stage of development involves the construction of compatible magnet motors which can be implemented as, amongst other things, vehicle propulsion units or electricity generators.
At the moment, it is not possible to publish detailed technical information as the patent specifications have not yet been submitted. Therefore, the presentation is restricted to a sketch of the technical developments, which have been made to date, physical principles and possible applications.
For queries and further information, please, use the contact form.
andax Consulting & Management GmbH


text:
HOT SPRINGS, Ark. (AP) - Eleven people were killed Saturday when an amphibious tourist boat sank in a lake. Divers were searching for a 12th victim.
Police Cpl. Mike Buck said 20 people were aboard the Army-surplus boat, known as a duck because of its use on both land and water.
Lake Hamilton, south of this popular tourist town, was crowded with visitors enjoying a warm spring day when the boat took on water and sank suddenly.
Other boaters on the water helped try to rescue victims.
The ducks operate from several bases around Hot Springs, snaking their way from the downtown area to Lakes Hamilton and Catherine south and east of the city.
Coast Guard Lt. Bruce Fisher, chief of port operations at Memphis, Tenn., said the boat was owned by White & Yellow Duck Sightseeing Tours. The vehicles are generally World War II surplus property built for the Army to carry troops directly from land into the water, Fisher said.
The boats have three axles, six wheels and generally hold 25 or 26 people, including an operator who rides in the front.
"It's basically a boat hull on wheels," Fisher said.
The boats are inspected by the Coast Guard annually, usually in the late fall or winter when the tourist season is quiet.
The Coast Guard dispatched two investigators to the lake, Fisher said.
Other tourist-laden ducks appeared to continue operating after the accident.
© 2016. All Rights Reserved. | Contact Us


text:
A war of words erupted on The X Factor last night between judges Mel B and Natalie Bassingthwaighte.
The female judges had their biggest clash to date on Seven's reality talent search over 20-year-old dance teacher Briden-Starr Aspinall.
Aspinall's performance of Ricki-Lee Coulter's Raining Diamonds impressed Bassingthwaighte and male judges Ronan Keating and Guy Sebastian but Mel B was left underwhelmed.
"It all just rubbed me up the wrong way. I found it cheesy," the former Spice Girl said. "It was way too goody-two-shoes for me."
Scary Spice said she thought Aspinall's musical-theatre background could make it hard for her to be "edgy" and "international" enough to survive in the music business.
Bassingthwaighte hit back, saying: "There is nothing wrong with having a musical-theatre background. It only enhanced your performance."
Once the aspiring singer had left the stage, Bassingthwaighte accused Mel B of being "jealous" of Aspinall's talent, to which Mel flared up.
"No, I am not jealous, because I have done musical theatre too. I am not jealous," she said.
Aspinall told AAA she was shocked by the response to her audition and was left saddened by Mel B's opinion of her.
"There was definitely a little bit of a stir after my audition, I almost felt bad. I wanted to apologise to Mel," Aspinall said.
"It was a little bit hard to swallow but I see what she says. I was a little bit musical theatre."
However, after receiving the nod from Keating, Sebastian and Bassingthwaighte to make it through to Boot Camp, Aspinall said she would try a whole new approach to her next audition.


text:
HAMPTON BAYS - Investigators say criminality is not suspected after a man's body was found in a burning pickup truck on the East End.
The truck was found on a beach near North Road in Hampton Bays Saturday afternoon.
Police say the charred remains of the man were discovered on the driver's side seat.
The man has not been identified.
Anyone with information is urged to call Southampton Town Police at 631-702-2230.


text:
Next stop on slippery slope: Incest: Dr. Michael Brown warns Progressives push to "normalize" Incest
The push by progressives to make the immoral mainstream never stops. They are like a dog with a bone wanting to remake society and the culture. A few days ago I reported on how an upcoming MTV show, HappyLand, contains an incest storyline. A cast member of the show was quoted as saying, "Incest is hot! We're going to have some fun!" These are the tactics used by Liberals via the media to desensitize the public and change their views. It's a subtle form of indoctrination that has been very successful over the past 40 years.
MichaelBrown in WorldNet Daily
"Why any sexual acts committed by consenting adults should be considered a crime. After all, love is love, right?"
Gay activists constantly tell us that there's no such thing as a slippery moral slope and that the acceptance of homosexuality will not lead to the acceptance of other sexual practices, such as incest. The facts prove otherwise, and it is clear that we are rapidly sliding down the very slope whose existence they deny.
As I continually chart our society's moral free fall, the term that best describes our current condition is sexual anarchy, where men can have sex with men just as well with women, where sex outside of wedlock is just as acceptable as sex within wedlock, where marriage doesn't necessarily mean monogamy and where longstanding social taboos are cast off.
Already in 2007, Time magazine raised the question, "Should Incest Be Legal?" The article noted that critics of the Supreme Court's Lawrence v. Texas ruling in 2003, which struck down Texas' anti-sodomy law, argued that the ruling would lead to attempts to legalize same-sex "marriage" and polygamy. "It turns out," Time observed, "that the critics were right," adding that plaintiffs were now "using Lawrence to challenge laws against incest."
Not surprisingly, in December, 2010, when Columbia University professor David Epstein was arrested for a three-year, consensual affair with his adult daughter, his attorney said, "It's OK for homosexuals to do whatever they want in their own home. How is this so different? We have to figure out why some behavior is tolerated and some is not."
In keeping with the spirit of the age, some Columbia students asked why any sexual acts committed by consenting adults should be considered a crime. After all, love is love, right?
More here
Originally posted at The Last Tradition
Also see...
Even though my father, brother, uncles and grandfather were in the military, I seldom handled guns growing up. That's because unlike many of the other people in my family, I've...Read More
Samuel Gonzalez
Related Articles
Time For The First Military Tribunal
Time For The First Military Tribunal: Remember this ugly face? When last we heard from Ramzi Binalshibh, he was claiming
The Flight 93 Conspiracy
The Flight 93 Conspiracy: Like most tragic events of recent times, a myriad of conspiracy theories have sprung up about
W. And The Upside-Down Book
W. And The Upside-Down Book: I received an email today from RWN reader Doug Weinberg commenting on the doctored photo


text:
BMW suppliers excited about big announcementUPDATED 8:00 PM EDT Mar 27, 2014
BMW announcement expect Friday afternoonVideo Transcript
HEAR A COUPLE CLAPS A FUND OR MAYBE SOME THUNDERSTORMS WILL TALK MORE ABOUT THAT STORM SYSTEM A LITTLE BIT BMW'S BIG ANNOUNCEMENT... NO ONE IS TALKING. NOT BMW... NOT ECONOMIC DEVELOPMENT FOLKS... NOT EVEN SUPPLIERS. BUT... ALL OF THEM AND MORE SAY... WHAT'S GOOD FOR BMW... IS GOOD FOR THE UPSTATE AS WHOLE. IT MAY BE KNOWN AS THE ULTIMATE DRIVING MACHINE, BUT YOU CANT BUILD A BMW... WITHOUT SUPPLIERS... MANY OF THEM. obviously the jobs they create directly are important but the spill over effects into supplier types of jobs and things like that are enormous. and its not just suppliers you need more barbers to cut hair accountants to do taxes and things like that. TOM SMYTHE AN ECONOMIC PROFESSOR AT FURMAN UNIVERSITY SAYS THE SUPPLIER CHAIN FOR THE GERMAN AUTO MAKERS ONLY NORTH AMERICAN ASSEMBLY FACILITY IS HUGE. WE LOOKED AT THE NUMBERS... THE SPARTANBURG PLANT HAS ABOUT 40 SUPPLIERS IN THE STATE AND AROUND 170 THROUGHOUT NORTH AMERICA. SOURCES INCLUDING SENATOR LINDSEY GRAHAM.... SAY IT LOOKS LIKE BMW WILL ANNOUNCE A NEW LARGER SUV... THE X7... AT THE GREER PLANT. HERE IS WHAT HE TOLD US MONDAY. they could have put that product line anywhere in the world, BMW has a foot print all over the world they picked the greer plant because of the workforce and the way our economy is set up. this is a very business friendly state. WITH THAT NEW LINE... BMW WOULD HAVE TO CREATE A NEW PRODUCTION LINE... WHICH WILL ALSO MEAN NEW JOBS. you know the types of jobs BMW brings are higher paying those kinds of things so it helps lift the qulaity of life and the standard of living for a lot of folks in the upstate. THE BIG ANNOUNCEMENT FROM BMW... WILL BE TOMORROW AT 1. WE WILL
More Video
CommentsThe views expressed are not those of this site, this station or its affiliated companies. By posting your comments you agree to accept our terms of use. WYFF News 4 offers readers the ability to comment on stories with the understanding that these comments may be reprinted elsewhere on the site or used on WYFF News 4 newscasts. We ask that you refrain from profanity, hate speech, comments that don't relate to the story, and any personal remarks. THIS IS IMPORTANT: WYFF News 4 does not edit user submitted statements and we cannot promise that readers will not, at times, find offensive or inaccurate comments posted in the comments area. If you find a comment that is objectionable or offensive, click the flag that appears in the upper right corner when you hover over a comment. Flagged comments may be automatically hidden from comment threads. For comments to appear on the website and/or mobile app, email addresses must be verified through Disqus. We ask the community to monitor this forum with the knowledge that WYFF News 4 does not delete posts based on the content. We are glad to offer commenting on our site but we cannot be responsible for people who abuse the privilege.blog comments powered by Disqus
Latest from WYFF 4
Advertising4 Your Information


text:
HourlyHours to be determined
Start DateDecember 8, 2012
This is an on call position for a computer security researcher. Tasks will include help with navigating the Tor network, researching the latest computer security applications, products, and services. Must be familiar with counter-surveillance strategies. Most jobs will last only a few minutes, but could last for several hours. On rare occasions, jobs may last for days. Jobs will occur sporadically; sometimes once a month, sometimes once a day. This is a long term position. This job is not for those looking for a full time position. This job is not for you if you are unsure as to whether or not you have the skills. You must be certain beyond a reasonable doubt that you are capable of being an effective counselor and teacher. English must be superb.
We can work out a fixed rate for each task, since hours will be few. I pay well but I expect expert advice. Thank you for your time and consideration.
Skills: english, computer-hardware, computer-literacy, computer-technician, computer-science, remote-computer-repair, research
About the Client
United States
San Luis Obispo 06:06 PM
Jobs Posted
70% Hire Rate, 1 Open Job
Over $30,000
Total Spent
161 Hires, 6 Active
Avg Hourly Rate Paid
3,057 Hours