Where 𝐶𝐶 is a coefficient whose value depends upon the interparticle distance and 𝛼𝛼 refers to the Clausius-Mosotti function. The incorporation of PEDOT into non-conductive composites has been shown to drastically increase not just the overall conductivity but also the dielectric permittivity of the resulting materials. Indeed, optical microscopy and electrooptical measurements of MIL-101(Cr)PEDOT show significantly higher polarizability and E-field response in terms of particle chaining and subsequent chain alignment compared to MIL-101(Cr). To carry out these studies, sample cells constructed using two ITO-covered glass slides and a spacer well were filled with suspensions of MIL-101(Cr)PEDOT or MIL-101(Cr) and the suspensions exposed to an alternating applied potential. The cells were placed on an optical microscope equipped with a photodetector to measure changes in the degree of light transmission upon the application of the E-field (Scheme 2). Without an applied voltage, the particles are randomly distributed, blocking light transmission through the sample. Once the vertical E-field is turned on, the MIL-101(Cr)PEDOT particles chain along the E-field, allowing increased light transmission. For easier visualization of chain formation, horizontal E-fields were applied, and microscope images are included in Scheme 2b as insets. However, the less polarizable MIL-101(Cr) exhibited limited chaining and no detectable changes in the light transmission when the E-field was switched on. (Scheme 2c). Such differences in polarizability and conductivities explain the differing E-field assisted deposition patterns of MIL-101(Cr) versus MIL-101(Cr)PEDOT onto the IDEs. An additional advantage of the conductivity conferred by the incorporation of PEDOT is that when conductive MIL-101(Cr)PEDOT particles attach to the electrode edges, they effectively enhance the E-field intensity at the tips of the particles, attracting other particles to the tips in a chain growth process that leads to particle chains spanning the electrode gaps, as previously observed by others in the case of gold nanoparticles. The MIL-101(Cr)PEDOT deposits were investigated via Linear Sweep Voltammetry in order to study the current-voltage characteristics (I-V curve) and the corresponding electrical conductivity of aligned and unaligned MIL-101(Cr)PEDOT samples, denoted as MIL-101(Cr)PEDOT-A and MIL-101(Cr)PEDOT-UA, are calculated (Table ). Generally, the electrical conductivity of aligned MIL-101(Cr)PEDOT-A is higher than that of the unaligned MIL-101(Cr) PEDOT-UA, which is attributed to better contact between particles and the selective positioning of MIL-101(Cr)PEDOT between the electrodes (Figure ). Drop-casting in the absence of an E-field, however, leads the particles to being randomly distributed and significantly lower overall conductivity due to limited percolating pathways in the deposited materials. To investigate the impact of the spatioselective MOF deposition on the electrical response in potential sensing applications, humidity sensing was tested as a proof-of-concept demonstration under a range of different relative humidity levels (RH 10% to 90%) at a fixed temperature (25 °C). As demonstrated in previous reports of other MOFs for humidity sensing, as RH% increases, water sorption by MIL-101(Cr)PEDOT increases, thereby enhancing the proton conduction pathways and overall charge transport through the MOF chains, thus increasing their overall conductivity. The initial study shows that, as expected, the conductivity of MIL-101(Cr)PEDOT samples increases gradually upon the increase of humidity levels. On average, MIL-101(Cr)PEDOT-A shows about 200 times higher conductivity, than the MIL-101(Cr)PEDOT-UA sample with a higher difference at 50% relative humidity (Table ). In addition, the differences in conductivity upon change of humidity is significantly larger in the aligned samples, particularly once reaching 50% RH. The abrupt rise of conductivity at 50% RH followed by a slower but steady increase from 60% RH to 90% RH matches the water sorption isotherm of MIL-101(Cr) where most of the water intake is observed at 50% RH (Figure ). The maximum increase of conductivity (∆C/C10) reaches 40 times for the unaligned samples and more than 230 times when aligned, thus, offering better sensing accuracy (Figure ). In contrast, recorded conductivities of PEDOT on IDE showed no increase at RH% ranging from 10% to 90% (Figure ) proving the importance of both components of the MIL-101(Cr)PEDOT system: unloaded MIL-101(Cr) conductivity being too poor and unstable to act as a humidity sensor and PEDOT showing no change in conductivity depending on the RH%. The enhanced performance in conductivity MIL-101(Cr)PEDOT illustrates that the overall behavior of the system is promising for sensing applications. To get more insight into the sensing performance of aligned materials over unaligned systems, electrochemical impedance spectroscopy (EIS) analysis was conducted. MIL-101(Cr)PEDOT-A samples show typical semicircles, and the reduced diameters of semicircles upon increased humidity indicate the adsorption of water molecules decreases the impedance of the materials (Figure ). However, no complete semicircles can be observed in MIL-101(Cr)PEDOT-UA, indicating the large resistance present in the sample (Figure ). We further show that these samples can also be utilized for capacitive humidity sensing, a commonly utilized sensing technique in electrically transduced sensors, which offers the advantage of tuning the system sensitivity by controlling the frequency of the A.C. driving potential. It can be seen that at lower frequencies, such as 10 Hz, the change in capacitance is significantly enhanced (Figure ), therefore increasing the sensitivity of the system and the change in capacitance increases with relative humidity. For the unaligned system, no clear semicircle in the Nyquist plot is observed, hindering the determination of the capacitance values for humidity sensing (Figure ). This drastic difference in behavior between the aligned and unaligned samples again emphasizes the importance of precise spatioselective control over the MOF deposition on the IDEs.