A system and method for tagging, tracking, locating and identifying people and vehicles transporting people using Perfluorocarbon tracers. An on-going problem faced by military as well as law enforcement personnel is that of friendly fire incidents. To prevent possible friendly-fire incidents, troops would separate the two layers of the uniform patch, thereby releasing a controlled release of the Perfluorocarbon vapors. Other “friendly” troops, equipped with sensors tuned to the specific perfluorocarbon characteristics would thus be able to literally view a plume around the tagged person or object. The system may conversely be used to tag enemies. Formulations of mixed perfluorocarbons may be used to provide coding of emissions.

Perfluorocarbons are generally non-toxic, safe, volatile, non-reactive, compounds, which are environmentally benign, especially when released on limited quantities. The ambient background concentrations of the five perfluorocarbons routinely used as tracers (PFTs) are in the range of parts per 1015 of air. The PFTs, by virtue of their high vapor pressure, provide the unique ability to permeate closed doors and windows, containers and luggage. On the other hand, PFTs can be optically or physically detected, and are impervious to electronic interference and other problems inherent with other tagging technologies. Once a location reaches steady state, the actively emitting tagged item will provide vapor traces that are detectable in the vicinity of the item (even temporarily following removal of the tagged item). By extending the detectable life of the perfluorocarbon tag materials, PFTs have been previously known to provide a unique tool for law enforcement in numerous applications including marking and tracking of currency and other non-invasive inspection scenarios when seeking various items of contraband under surveillance.
PFT technology has already been developed and utilized in various applications including: (1) detection of leaks in underground storage tanks; (2) detection of leaks in high-pressure, oil-filled electric transmission lines; (3) atmospheric tracing and air pollution dispersion studies; (4) building ventilation studies; (5) detection of tagged explosives (blasting caps) in airline luggage; (6) detection of leaks in natural gas pipelines; and (7) currency tracking in cases of kidnappings. It has also been proposed for early warning fire detection systems.
U.S. Pat. Nos. 3,991,680 and 4,256,038, expressly incorporated herein by reference, relate to methods of detecting small bombs to provide security against terrorist activities which can cause the destruction of civil aircraft in flight or detonate explosives in places where large groups of people congregate. These methods involve the tagging of explosive materials such as blasting caps with a so-called "vapor taggant" which can be "sniffed" and detected by suitable equipment. The vapor taggant disclosed in U.S. Pat. No. 3,991,680 is sulfur hexafluoride (SF.sub.6) absorbed in a fluoro-polymer. The vapor taggant disclosed in U.S. Pat. No. 4,256,038 is includes one or a plurality of the following compositions: perfluorocycloalkanes such as perfluorodimethylcyclobutane (PDCB), perfuoromethylcyclohexane (PMCH), and perfluorodimethylcyclohexane (PDCH); perfluoroaromatics such as hexafluorobenzene (HFB), octafluorotoluene (OFT), decafluorobiphenyl (DFBP), decafluoroxylene (DFX), octafluoronaphthalene (OFN), and pentafluoropyridene (PFP), perfluoroalkanes such as perfluorohexane (PFH), perfluoropentane (PFPT), and perfluorooctane (PFO), and perefluorocycloalkenes such as decafluorocyclohexene (DFCH) and octafluorocyclopentene (OFCP). Examples of elastomers which are compatible with several of these taggants are copolymers of vinylidene fluoride and hexafluoropropylene. The following PFT compositions are also particularly useful as taggants: pf-methylcyclopentane (PMCP); pf-1,2-dimethylcyclohexane (o-PDCH1); pf-1,3-dimethylcyclohexane (m-PDCH1); pf-1,4-dimethylcyclohexane (p-PDCH1), pf-trimethylcyclohexanes (PTCH), perfluorodecalin (Octadecafluorodecahydonaphthalene, PFD, CAS 306-94-5), and perfluoro(methyl)decalin (PFMD, CAS 306-92-3). These compositions may be combined, as desired, to form a specific "cocktail"; i.e., a taggant that can be selectively detected and discriminated with respect to other taggants.
As used herein. PFT's are intended to refer to a class of chemical entities which have at least one -CF2-CF2- portion, or otherwise has an optical spectral characteristics corresponding to those resulting from the highly electronegative fluorine substituents, such that the compound is spectrographically distinguishable at very low concentrations, i.e., less than ppm level, and preferably less than ppb levels, from environmentally common substances. In some cases, a non-perfluorinated fluorocarbons may also be suitable for use, and to the extent that these have similar or advantageous remote detection characteristics, have low toxicity, good environmental stability (but perhaps less so than the perfluorocarbons, to reduce detrimental long-term environmental persistence and global warming potential), and appropriate volatility and dispersion in air, these may also be included with the scope of PFTs as encompassed herein.
Taggant use involves the detection of gaseous vapors (in minor tracer quantities) that are emitted over time. As there are a plurality of separate usable tracers in the PFT family, each with its own "fingerprint", the PFTs can be combined in a range of combinations and concentrations, yielding thousands of discrete "signatures". This allows discrimination between various compositions and enables the individual detection of multiple products, or the tracking of individually tagged products to provide exact identification and location.
The PFT technology is the most sensitive of all tracer technologies because the ambient background levels of the routinely used PFTs are extremely low (in the range of parts per quadrillion-ppq), and PFTs can be measured down to those levels.
It is the physical and chemical inertness of the PFTs that not only prevents their loss in the atmosphere, but also helps in their separation and analysis from less stable interfering compounds and makes them biologically inactive; and thus safe to use. Their limited industrial use not only results in low ambient background concentration, but also limits the possibility of numerous higher local concentrations that might confuse detection capability.
John H. Heiser and Arthur J. Sedlacek, "Using LIDAR to Measure Perfluorocarbon Tracers for the Verification and Monitoring of Cap and Cover Systems", Brookhaven National Laboratory (2005), http<://>www.ecd.bnl.gov/pubs/BNL-75583-2006-JA.pdf, expressly incorporated herein by reference, teaches the use of LIDAR to detect PMCH, a perfluorocarbon.
Mason K Harrup, "Use of Custom Polyphosphazenes as Tunable Matrices for the Controlled Release of PFTs" (White Paper), expressly incorporated herein by reference, discloses a "tuned" polyphosphazene matrix, having a balance of perfluoronated pendant groups designed to hold the PFT tightly, providing slow release, and polar pendant groups designed to be incompatible with the PFT, providing fast release, to thereby control the observed PFT release rate.
U.S. Pat. No. 6,025,200, expressly incorporated herein by reference, relates to remote optical detection of PFTs. According to U.S. Pat. No. 6,025,200, cyclodextrins, liposomes, and synthetic polymer systems can be used in the development of encapsulated PFTs. As a group, these technologies provide a menu of tracer devices which can be tailored to meet a specific need. Cyclodextrin-PFT complexes can be formulated as a dispersion, true solution, or as solid crystalline powder.
The cyclodextrin-PFT complexes can be made in water or mixed solvent systems and isolated as a free-flowing powder by spray drying or filtration from the mother liquor. The complex can be formulated in its mother liquor or used as a true solution or dispersion.
U.S. Pat. No. 6,214,624, expressly incorporated herein by reference discloses the use of PFTs to track hydrocarbon liquids. U.S. Pat. No. 5,409,839, expressly incorporated herein by reference, is entitled and describes a method for the tagging and detection of drugs, crops, chemical compounds and currency with perfluorocarbon tracers. U.S. Pat. No. 6,617,591, expressly incorporated herein by reference, relates to remote detect ion of explosives, for example, buried mines. See also, U.S. Pat. Nos. 4,520,109, 5,173,298, 5,362,568, 5,585,112, 5,853,752, 6,071,495, and 6,196,056, expressly incorporated herein by reference.
DESCRIPTION OF THE INVENTION According to one embodiment of the invention, a method is provided for using Perfluorocarbon Tracers to Identify Personnel (Friend or Foe) on the Battlefield, e.g., traditional or urban. For example, an encapsulation formula of Perfluorocarbon tracers can be impregnated into one or both of the layers of separable patch, which prior to separation, has a minimal rate of PFT release, and after separation, has a steady rate of release sufficient to allow remote detection. The patch, for example, may be a tear-away Velcro patch adapted to be affixed to soldiers in a war zone. To prevent possible friendly-fire incidents, troops would separate the layers of the patch, thereby initiating a controlled release of the PFT vapors. Other "friendly" troops on the field of battle, equipped with sensors for the PFT emissions, which may operate passively by detecting absorption or fluorescent emission from normal light sources, or actively by stimulating optical emissions and/or measuring specific absorption. At night, for example, illuminators tuned to the fluorescent wavelength of the Perfluorocarbon gases and specially designed, wavelength-matched vision devices would thus be able to literally "visible" as a cloud that might surround or emanate directly from the friendly troops. Likewise, an automated system could be provided to automatically block fire against friendly troops, bypassing the user's discretion, and perhaps acting with faster response and accuracy.
Alternately, a tag may be placed on personnel or objects, to assist in tracking them. For example, a patch, liquid, or powder, may be surreptitiously applied to an enemy vehicle, which could then be tracked to its destination. In this case, the tag may also be used to guide munitions, rather than inhibit them.
In a normal scenario, multiple taggant compositions and combinations may be employed, for various purposes. Thus, even if an enemy were to gain control over a set of tags, it would have to know the encoding, which could change periodically, in order to effectively use them as a false defense or offensive tool.
Likewise, the detector may be provided which requires authentication, such as biometric, token, security code, or the like, which would impede unauthorized use. This technique is especially useful where the PFTs themselves are dynamically encoded, and therefore without certain secret knowledge, the output of the detector would be difficult to interpret at any given time. For example, according to one embodiment, the PFTs release a time coded coded plume, which may alternately indicate friend, foe, or other identification Likewise, release of dummy PFTs may be employed, to obscure particularly encoded releases, and thus requiring a sophisticated detector.
It is noted that a sophisticated adversary might seek to develop measures to track a reading device, and thus a passive (relying on ambient illumination) or remotely operable illuminator is preferred in such circumstances. Likewise, it is preferred that the reader incorporate at least one sophisticated and difficult to obtain critical technology, to impede unauthorized recreation.
It is also useful to provide an interrogator detection system, in the event that unauthorized devices are or become available, so that the badge wearers can take immediate action to avoid personal or other risk, when an unauthorized interrogator is detected. For example, authorized interrogators may produce a cryptographically encoded emission, the authenticity of which is determinable by an authentication device. Even in the event that an authentic device is diverted, the encoding may be device-specific, permitting individual detection and countermeasures to be employed, without requiring all authorized devices to be modified. For example, if an interrogator includes a laser illuminator, the laser itself, or an associated signal, may be individually modulated corresponding to an encoded signal. In the event of an unencoded, unauthorized, or deauthorized encoding in an illuminator suitable for detecting PFTs, users can immediately detect this illuminator when targeted by it, and take countermeasures, such as targeting the illuminator for destruction, and removing the PFT emitting devices from their person or vehicles. The detectors may also be protected by code or biometrics, to prevent their unauthorized use.
It is noted that since there are a number of usable compounds which are perfluorocarbons, or are closely related to perfluorocarbons, a large number of "recipes" are available. Therefore, it is preferred that the reader or interrogator permit individual detection of the various usable compounds, as well as distinguishing the components of a mixture and/or quantitatively determine ratios thereof. Typically, this detection will employ a laser illuminator to determine a specific spectrographic and/or fluorescence optical response of each PFT employed.
The reader or interrogator will typically employ a narrow bandwidth directional illumination source. The specific absorption wavelengths for perfluorocarbons and related compounds are in the UV range. Thus, a suitable illuminator would be a filtered broadband lamp, UV LED, LED (or other source) excited photon capture UV fluorescent emitter, a laser, or other emission source. Typically, a high efficiency design is preferred, since a low efficiency illuminator would emit heat and have high power demands, limiting portability and duration of battery life. Thus, a preferred design employs an LED excited emitter, or electroluminescent design, to provide a significant battery life and a low level of undesired emissions.
The detector is typically a spectrophotometric-type detector, capable of distinguishing specific PFT signatures from interfering emissions or absorptions. It is also preferably battery operated and small. The detector may also be provided as a broadband sensitive detector with one or more specific filters.
The PFT emitting device itself is, for example, a flat sheet-like patch, for example 1-25 square inches, composed of two sheets which are impermeable to perfluorocarbon vapors. These may be, for example, metallized or aluminized Mylar® Biaxially-oriented polyethylene terephthalate (boPET) polyester film, or other suitable material. A base sheet preferably has a removable attachment means, such as Velcro®, snaps, magnets, or other suitable method for removable attachment, e.g., to a uniform or object. Between the sheets is a controlled release perfluorocarbon material. For example, a polyphosphazine matrix, wax, or other material impregnanted with PFT's, or microencapsulated PFT's in a matrix, is provided, which selectively adheres to the base sheet. The controlled release perfluorocarbon material is covered during storage with a cover sheet which is removable, and which easily releases from the controlled release perfluorocarbon material. For example, an adhesive or heat-generated seal is formed around the periphery junction of the two sheets, which is frangible when subjected to a peeling force.
While a relatively homogeneous material (i.e., homogeneous matrix or embedded microcapsule matrix) is preferred, a macroscopic barrier or atomizer may also be used to control release of PFT. In the later case, a pump, MEMS device, piezoelectric device, bubble jet, or other electrically operated device may be operated to release PFT. Such a device could have an electronic control, capable of arbitrary release profile generation, and remote activation/deactivation. Likewise, the device could employ separate control over a plurality of tracers, each with a separate release profile. Thus, an authorized device could have a predefined but secret temporal release profile (for example defined by a cryptographic function), allowing authentication of PFT releasing devices. The device could further have RF-ID attributes and/or a wireless receiver for remote controllability. Advantageously, an electronic embodiment employs a zinc air battery, activated by unsealing, and thus storage stable and activated along with the release of PFTs. Indeed, a film battery technology may permit formation of the battery together with the film forming the barrier to contain the PFT prior to intended release. Typically, a seal is provided for storage, since even low levels of unintended leakage over time will deplete the device and potentially pollute the atmosphere, making specific detection more difficult.
During storage, the sheets thus prevent release of PFT, while when the cover sheet is removed, the PFT is continually or controllably released over an extended period. It is preferred that, in a passive device, the release be at a relatively constant rate. Various known methods for temporally controlling release rates, such as employed in conjunction with pharmaceuticals, may also be employed. See, e.g., Temporal Control of Drug Delivery, Hrushesky, Langer, & Theeuwes, Eds., NY Acad. Sci 618 (1991), expressly incorporated herein by reference, and especially, Langer, Robert & Kost, Joseph, "Real Time Response Polymeric Delivery Systems", pp. 330-334.
Preferably, the PFT is not a single material, but at least two different materials, which are combined such that they are both released in detectable quantities. This combination permits coding of the patches, and makes counterfeiting more difficult. It likewise facilitates detection, since the composite spectral signature will have more features available for analysis. It is noted that, in the case of a combination release, it is possible to employ a different composition entirely, for example one that is not a PFT. Preferably, the detection system for the plural compositions will include substantial common elements, although this is not required.
Another aspect of the invention provides a method of using tracers to identify "friendly" vehicles, e.g., on the battlefield. For example, an encapsulated formulation, either in the form of a patch, or aerosolized by an aerosolizing apparatus, can used in conjunction with a vehicle, for example, tanks, HUMVEES, personnel carriers, Jeeps, etc. The vehicle will this emit a distinguishable plume, which can be remotely detected by its characteristic fluorescent pattern, can be used to identify various "friendly" vehicles. The detector can be used as part of a manual weapons targeting system, or as part of an automated trigger inhibition or fusing system.
On the other hand, such a plume may also be used to target or track vehicles (e.g., enemy or suspect) or other objects, especially where it is not the vehicle, but its future contents, which are of interest, since tagging the vehicle will generally require intimate contact.
A further aspect of the invention provides a method and composition for tracking, detecting and/or identifying suspected terrorists or criminals by ingestion, or for tracking potential kidnap or abduction risks. It has been determined that following exposure to perfluorocarbon materials that a human subject will emit a detectable chemical signal of perfluorocarbon for a period of up to one month, or longer depending upon individual metabolism and exposure dosage. The perfluorocarbons are emitted through bodily pores, excreted bodily fluids, and/or exhalation.
It is thus known that perfluorocarbons can be retained in the human body for extended periods of time. This is particularly obvious in the presence of technologies such as the DSITMS which provides very low detection levels in real-time. In the course of preparing for the demonstrations described below, it was noted that perfluorocarbon could be detected from one of the researchers at the Oak Ridge National Laboratory (breath, skin, urine) for three days after limited contact with a wax crayon formulation. Perfluorocarbons are nonmetabolizable, however, they do induce hepatic metabolizing enzymes. PFD given to rats was shown to induce cytochrome P-450 in a manner similar to phenobarbital. As with Phenobarbital induction, the activities of cytrochrome P-450 IIA1 and IIA2 (a.k.a. cytochrome P450b and cytochrome P450e) were increased approximately two-fold following PFD treatment. Likewise, the activities of benzphetamine-N-demethylase and aldrin-epoxidase were increased. The activities of cytochrome P-450 IA1and IA1 (induced by 3- methylcholanthrene-type inducers) and cytochrome P450 IV (induced by fatty acids and perfluoronated fatty acids) were unaffected. Although the perfluorocarbons are sequestered in the fat and later transferred to the liver, over time they are eliminated from the body via the lungs by exhalation. See, Final Report for CRADA Number ORNL99-0562, under funding from Tracer Detection Technology Corp. under contract of the National Institute of Justice, Jul. 26, 2000.
By incorporating encapsulated Perfluorocarbon tracers into food stuffs or other supplies or provisions anticipated to be delivered to, being transported to the hideouts of, or ingested by mammals of interest, the location, even if hidden, can be remotely detected. In this embodiment, preferably a pure form of PFT, or an encapsulation formulation thereof, in which the PFT can be mixed with food, other ingestible items or other supplies which are ultimately ingested, will emit a plume of the vapor taggant that can be detected through various means of sensing. Alternately, the PFT is released or volatilized during cooking, and thus the location of a "hideout" may be determined by searching for an associated plume from this release. Therefore, the PFT may be absorbed in, or placed in conjunction with, a food which requires cooking, such as rice.
The present invention further encompasses a method of using PFTs to track, detect and identify suspected terrorists or criminals, or hideouts of terrorists or criminals, by marking vehicles suspected of traveling to terrorist or criminal hideouts or other objects which are carried to these locations.
Effective inspection of large containers and trucks for controlled substances and narcotics is essential for the success of drug interdiction efforts. A significant fraction of drugs are smuggled through this avenue. Without prior knowledge provided through intelligence activities, the chances for drug detection are very slim. A successful drug interdiction program therefore requires efficient, rapid and cost-effective inspection techniques for large objects. The current technique used to thoroughly inspect containers is manual, highly labor intensive and can hardly be expanded to meet the challenge of abating the flow of illicit drugs from one country to another. Hence, an efficient way to meet the goal of an effective counter-drug effort is to provide a rapid, automatic, non-intrusive inspection system to inspect shipments and cargo containers without removing all of the contents for manual inspection. Thus, if a shipment can be tagged near its point of origin, it may be tracked using PFTs to distribution, permitting an entire chain to be tracked, without seizing the contraband at an intermediate stage.
In order for PFT tagging to function effectively, the release should be of sufficient concentration as to enable unambiguous identification, and also should be sufficiently long-lasting as to fulfill various usage parameters. Thus, in order to provide a sustained release of PFTs, a matrix is provided which provides a desired release profile. One type of matrix is a paraffin wax matrix or one based on large molecule inclusion complexes, however, such matrices may be difficult to control.
Polyphosphazenes are a class of polymers with backbones consisting of alternating phosphorus and nitrogen atoms. A repeating unit in polyphosphazenes is shown below, where the side groups G can be organic, inorganic or organometallic, and need not be the same. Interest in these polymers relies on the fact that, compared to various other biodegradable polymer materials, polyphosphazenes are easier to manipulate with different side groups. In addition, their physical and chemical properties are greatly affected by the nature of the side groups. Therefore, polymers with a wide range of properties can be obtained by appropriately choosing side chain groups. The possibility of obtaining polyorganophosphazene with different tunable properties makes those polymers potentially useful in many fields, ranging from pharmaceutical, industrial to agricultural applications. See, Shan Cheng, Stimuli-Responsive Polyphosphazenes as Controlled Drug Delivery Matrix Materials (2001), http<://>dspace.library.drexel.edu/retrieve/963/end.pdf.

Two different fundamental routes to synthesize substituted polyphosphazenes are generally used. A first method one starts from substitution reactions of the chlorine atoms on hexachlorocyclotriphosphazene to prepare phosphazene cyclic trimers with different side groups. By ring-opening polymerization of these small cyclic trimers, polyphosphazenes with different substituents can be obtained.
Many new materials have been prepared through this direct synthesis. However, the steric hindrance effect greatly limits the variety and the amount of the substituent on polymer chains.
To solve this problem Allcock and his co-workers developed a synthesis route which involves the preparation of poly(dichlorophosphazene) and a sequential substitution reaction of chlorine atoms. In the first step, poly(dichlorophosphazene) as highly reactive macromolecular intermediate, can be prepared by several different methods. The most effective route to high molecular weight poly(dichlorophosphazene) is via the ring-opening polymerization of the cyclic trimer, hexachlorocyclotriphosphazene at 250° C. in the molten phase or in solution. This reaction gives a polymer with a broad molecular weight distribution, but with an Mw near 2,000,000, which corresponds to approximately 15,000 repeating units per chain. More recently, a room-temperature, living cationic condensation polymerization of Me3SiN=PC13 method has also been developed. This reaction yields narrow molecular weight distribution polymers, with excellent control of the molecular weight and access to block copolymers.
The second step in the synthesis involves the replacement of the chlorine atoms by reactions with different organic or organometallic groups. Typically, an average of 30,000 chlorine atoms per molecule could be replaced at this stage as the result of high reactivity of the P-Cl bond. Based on this macromolecular substitution reaction, several hundred different polyorganophosphazenes have been synthesized. Most of the current industrial important polyphosphazenes are made by this method.
As a relatively new biodegradable polymer, polyphosphazene as drug delivery material has been widely studied. Compared with other drug delivery matrix materials, polyphosphazene shows particular advantages because it has an inorganic backbone that is biocompatible over time and that degrades to harmless small molecule products: ammonia, phosphate, and water. The system can be tailored to respond to different physiological environmental conditions by appropriate choice of substituted side chains. Many results show that the delivery systems designed with this material can accommodate a large variety of drugs including small drugs and macromolecules. Release study has been explored with both hydrophobic and hydrophilic polyphosphazene. The former ones are usually studied for polymer matrix erosion and diffusion release systems, while the latter ones are used to prepare hydrogel matrices after being crosslinked.
With respect to perfluorocarbons, it is well known that they have a high self-affinity, and this a fluorinated alkyl or perfluorinated substituent will be compatible with the PFT, thus leading to a high loading capacity and slowed release. Likewise, PFTs are incompatible with polar substituents, leading to lower loading capacity and higher release rates. As is known, the properties of a matrix may be tailored by balancing the proportions of the various substituents.
An alternate method for controlling release rate of PFTs is to provide a mechanical barrier, such as a perforated sheet, which allows volatilization dependent on the perforated area. In this case, the release rate is decoupled from the PFT holding capacity, though the mechanical structure is somewhat more complex and the composite structure will be more sensitive to mechanical treatment during use.
Indeed, both a matrix and a barrier technique may be combined, for example as shown in FIGS. 1A and 1B. FIG. 1 shows a representative cross section of a perfluorocarbon tracer having taggant microcapsules within a matrix, on a carrier layer, before and after release of a cover layer. The taggant capsules provide a relatively high bulk storage capacity, while the matrix provides release profile control. Typically, the matrix will be saturated with taggant, with the capsules providing a replenishing source. The release rate will be dependent on the surface area and an air-matrix release coefficient for the taggant, which in turn will be dependent on the vapor pressure of the taggant and the affinity of the matrix for the taggant.
The present invention therefore provides a system and method for identifying and tracking persons and objects, comprising use of a controlled taggant release device which has a very low rate of release prior to activation, and has an extended duration consistent rate of release after activation, which may be conveniently applied to persons or objects.
The present invention also provides a system for detection of taggant release device, comprising remote optical detection system which employs an illuminator emitting an optical wavelength for exciting a fluorescent emission from a taggant, and an imaging detector for sensing and/or imaging the excited fluorescence. This detector is preferably battery operated, portable by a human. The device may operate independently, but is preferably integrated with a fusing or triggering mechanism for munitions. The device is further preferably configured as part of an "identify friend or foe" (IFF) system, which may be manually or automatically operable. In one embodiment, the detector or imager is mounted on an unmanned vehicle, such as an unmanned aerial vehicle (UAV).
It is therefore an object of the invention to provide a method of using volatile perfluorocarbons to identify personnel, comprising the steps of applying a selectively activatable controlled release perfluorocarbon to a person. Preferably, the controlled release mechanism employs a substituted polyphosphazene matrix. The PFT is preferably one or more perfluorocarbons selected from the group of PMCH, PMCP, o-PDCH', m-PDCH', p-PDCH' and PTCH. The controlled release is preferably initiated by removal of a barrier, such as a confining film. Preferably, the controlled release continues after initiation for 4-48 hours, and thereafter occurs at only a low level. Longer duration formulations may also be provided. The PFT matrix may be provided as an aerosol, paint or powder. The PFT is preferably released from a substituted polyphosphazene matrix, formulated to control a capacity and release profile of the PFT from the matrix.
The volatile perfluorocarbons may also be used to identify land vehicles. Thus, according to another embodiment, it is an object of the invention to provide a method of using perfluorocarbon tracers to identify vehicles, comprising of the steps of applying a formulation of perfluorocarbon tracers in a paint or aerosol spray to a vehicle, and detecting the vehicle remotely based on perfluorocarbon emissions.
According to a further embodiment of the invention, a PFT is provided as a part of a food or liquid product, for human ingestion. Preferably, the PFT is provided in a PFT-polyphosphazene matrix, in such form as it will not release until heated or otherwise changed chemically. The PFT can be detected by urinalysis, breath testing, of other body fluid testing. Vapor emissions may be used to detect the location of a tagged individual.
The numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Methods and articles for identifying objects using encapsulated perflurocarbon tracers


A film frame aligner for automatically aligning a film frame includes a film frame support, a film frame pusher for pushing the film frame, and a film frame location mechanism for locating at least one notch in the film frame.

1. Technical Field
The present invention relates to film frames as used in semiconductor and microelectronics manufacturing, and more specifically a device for ensuring the proper concentricity and square-ness of a film frame in relation to the process used to optically inspect the product on the film frame.
2. Background Information
Over the past several decades, the semiconductor has exponentially grown in use and popularity. The semiconductor has in effect revolutionized society by introducing computers, electronic advances, and generally revolutionizing many previously difficult, expensive and/or time consuming mechanical processes into simplistic and quick electronic processes. This boom in semiconductors has been fueled by an insatiable desire by business and individuals for computers and electronics, and more particularly, faster, more advanced computers and electronics whether it be on an assembly line, on test equipment in a lab, on the personal computer at one's desk, or in the home electronics and toys.
The manufacturers of semiconductors have made vast improvements in end product quality, speed and performance as well as in manufacturing process quality, speed and performance. However, there continues to be demand for faster, more reliable and higher performing semiconductors.
Processors who are building semiconductors and like microelectronics must handle the substrate that holds the semiconductor or like microelectronics. This handling process often involves the need to align, and more specifically, as to film frames, a film frame aligner is needed to ensure the proper concentricity and square-ness of a film frame in relation to the process used to optically inspect the product on the film frame. It is known that the act of aligning the film frame speeds up the optical inspection process and ultimately leads to less time to inspect, and thus it is desirable to perform film frame alignment and more importantly to improve upon the current systems and process. It is also known that aligning the film frames ensures that they will insert smoothly back into the film frame cassette preventing a damaging collision.


An additive suited to use in combination with heat transfer media comprises a chemically stabilized nano-particle size powder. Suitable powders include those of copper, beryllium, titanium, nickel, iron, alloys or blends thereof, and carbon. The surface of the powder is modified by surface complexation or physical adsorption with a chemical agent. The additive, when mixed with a heat transfer medium, forms a colloidal dispersion which exhibits enhanced heat transfer capacity and thermal conductivity, stable chemical composition, faster heat transfer rates, dispersion maintenance which are beneficial to most heat transfer systems.

1. Field of the Invention
The present invention relates to additives for heat transfer media and refrigerants, and in particular to the use of stabilized nano-particle size metal powders to enhance the thermal capacity and thermal conductivity of refrigerant and heat transfer media.
2. Description of the Prior Art
Heat transfer media have applications in both heating and cooling, including refrigeration, air conditioning, computer processors, thermal storage systems, heating pipes, fuel cells, and hot water and steam systems. Heat transfer media include a wide range of liquid or phase change materials, including water, aqueous brines, alcohols, glycols, ammonia, hydrocarbons, ethers, and various halogen derivatives of these materials, such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and the like. These have been used alone or in combination with additives, such as refrigerant oil additives for lubrication and composites of fluids to affect boiling or freezing temperature. Such media are used to transfer heat from one body to another, typically from a heat source (e.g., an vehicle engine, boiler, computer chip, or refrigerator), to a heat sink, to effect cooling of the heat source, heating of the heat sink, or to remove unwanted heat generated by the heat source. The heat transfer medium provides a thermal path between the heat source and the heat sink, and may be circulated through a loop system or other flow system to improve heat flow.
Several criteria have been used for selecting heat transfer media for specific applications. Exemplary criteria include the influence of temperature on heat transfer capacity and viscosity, and the energy required to pump the medium through a heat transfer system. Specific parameters describing the comparative performance of a heat transfer medium are density, thermal conductivity, specific heat, and kinematic viscosity. The maximization of the heat transfer capability of any heat transfer system is important to the overall energy efficiency, material resource minimization, and system costs. There are numerous improvements in heat transfer systems that are further enhanced by increased thermal capacity. One example is the utilization of secondary loop or multiple stage refrigeration systems. A secondary loop refrigeration system is more compact in design, has a reduced charge of refrigerant, requires a reduced system horsepower, and has lower implementation costs.
Other factors that affect the feasibility and performance of heat transfer media include environmental impact, toxicity, flammability, physical state at normal operating temperature, and corrosive nature.
A variety of liquids can be use d as heat transfer media in systems where heat transfer efficiency is to be maximized and fluid transport energy minimized. Such media can benefit from enhanced thermal conductivity. The heat transfer media may include a filler material that is thermally conductive to enhance the thermal conductivity of the heat transfer medium. Nanoparticle size copper oxide has been used in a water heat transfer fluid in a secondary loop. However, high surface area metal powders in an aqueous environment tend to experience corrosion, even so-called inert metals.
The present invention provides a new and improved additive for heat transfer media and method of use.
In accordance with one aspect of the present invention, a heat transfer composition is provided. The composition includes a heat transfer medium, and an additive comprising a powder, the powder having a corrosion inhibitive coating or dispersion enhancing coating thereon.
In accordance with another aspect of the present invention, an additive for a heat transfer medium is provided. The additive includes a nano-particle size powder formed from one of the group consisting of a metal, an alloy, a metal compound, and carbon, the powder being chemically stabilized with an azole.
In accordance with another aspect of the present invention, a process for transferring heat between a heat source and a heat sink is provided. The process includes transferring heat between the heat source and the heat sink with a heat transfer composition which includes a powder. The powder has a surface thereof coated with a chemical agent which provides the powder with improved corrosion resistance or dispersion characteristics as compared with an uncoated powder.
As used herein, the term heat transfer is used to imply the transfer of heat from a heat source to a heat sink, and applies to both heating and cooling (e.g., refrigeration) systems.
The term xe2x80x9cprimary loopxe2x80x9d refers to the heat transfer method used in a primary refrigeration system, boiler system, or any other system that is directly affected by an energy transfer mechanism. This includes a compressor in a refrigeration system, combustion source in a boiler system, or a heat transfer fluid in an absorption system.
The term xe2x80x9csecondary loopxe2x80x9d refers to the path over which a heat transfer medium travels while it is being cycled between a heat source and a primary system, boiler system, or any other system that is indirectly affected by an energy transfer mechanism. This includes a shell and tube or plate heat exchanger in a refrigeration system or in a boiler system. The loop refers to the path over which the heat transfer medium travels while it is being cycled between the heat source and the primary system. Thus, for example, a secondary loop refrigeration system uses a heat transfer medium to transport energy from a heat source to a primary refrigeration system.
The term xe2x80x9cheat transfer fluid,xe2x80x9d or xe2x80x9cheat transfer medium,xe2x80x9d as used herein, includes liquids, viscous materials, vapor and gaseous heat transfer materials which flow at the operating temperature of a heat transfer system, and includes materials which may be solid at room temperature, but that are flowable at the operating temperature of the system.
The term xe2x80x9cnano-sized particle,xe2x80x9d or similar terms, as used herein, includes particles which have an average size of up to 2000 nm.
One advantage of the present invention is that the thermal conductivity, thermal capacity, and energy efficiency of a host heat transfer medium are increased.
Another advantage of the present invention is that pump energy requirements may be reduced.
Yet another advantage of the present invention is that the additive is readily dispersed in the heat transfer medium.
A further advantage of the present invention derives from stabilization and passivation of the additive, enabling direct immersion into corrosive environments.
A yet further advantage of the invention is that the additive may maintain a mobile colloidal dispersion within the heat transfer fluid, enabling the additive to be utilized without the use of dispersion enhancement devices in a host heat transfer system.
A still further advantage of the present invention is that effects on the boiling and freezing temperatures of the host heat transfer fluid are minimized.
Other advantages of the present invention derive from the enhanced thermal capacity of the heat transfer composition, which results in energy consumption reductions by reducing the incoming fluid temperature (in a cooling system) needed to achieve a targeted fluid leaving temperature. Reductions in fluid velocities may also be achieved, thereby reducing friction losses and pressure losses within a circulation pump.
A further advantage of the present invention is that by enabling stabilizing pure metals or their alloys to be used in a heat transfer system, heat transfer compositions with higher thermal transfer properties may be achieved as compared with compositions using oxidized forms of the metals or alloys.
Yet another advantage of the present invention is that the heat transfer additive is compatible with a wide range of heat transfer media, including, but not limited to media for applications ranging from engine cooling, heating, air conditioning, refrigeration, thermal storage, and in heat pipes, fuel cells, battery systems, hot water and steam systems, and microprocessor cooling systems.
Additional features and advantages of the present invention are described in and will be apparent from the detailed description of the presently preferred embodiments. It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.
An additive is provided for use in thermal transfer media which enhances the thermal capacity of the heat transfer media. A thermal transfer medium in combination with the additive, forms a composition which, when used in a heat transfer system, has a number of advantages, including increased thermal capacity increased heat transfer rate, while minimizing pump energy requirements and providing long and stable additive performance.
The heat transfer additive is a material that improves the thermal transfer properties of the fluid and preferably comprises a powder which is thermally conductive. The powder may be a finely ground or otherwise comminuted solid or a crystalline solid. For example, ball milling or other suitable process may be used to form a fine powder.
The preferred particle size is influenced by a number of factors, including cost effectiveness, dispersion and settling characteristics (smaller particles tend to settle more slowly and re-disperse more quickly). Preferred powders have an average particle size (expressed in terms of the number average value of the largest dimension perpendicular to the longest dimension of the particle) of from about 1 nanometer and 100 microns. More preferred powders have a particle size of from about 10 nanometers to about 2000 nm. Particularly preferred powders have a particle size of from about 25 nanometers to about 1000 nm. Above about 1000 nm, the particles tend to maintain a dispersion for shorter time than may be desirable for some applications. Within the preferred range, some of the particles may form aggregates or clusters having an average width of from about 50 nm to 1000 nm.
Preferred materials for forming the powder have a high heat transfer coefficient and high thermal conductivity per unit weight of the material. The powder may be a powdered metal, powdered alloy, powdered compound of a metal, powdered carbon, powdered carbon compound, or a combination thereof. Exemplary metal-based powders include, for example, those of copper, aluminum, titanium, nickel, beryllium, silver, gold, or iron, alloys or blends, or compounds thereof. Copper and beryllium are particularly preferred metals for forming the powder, copper metal being particularly preferred. Exemplary carbon-based powders include those of graphite, carbon nanotubes, diamond, fullerene carbons of the general formula C2n, where n is an integer of at least 30, or blends thereof.
The powder is chemically or physically altered by association with a chemical agent, for example, by surface complexation or physical adsorption of a chemical agent on the surface of the powder particles. The chemical agent is preferably one which stabilizes and/or passivates the powder, providing corrosion resistance. This provides stabilization and passivation of the additive over a wide temperature range and in a wide variety of potentially corrosive environments. Improved redispersion, increased settling time, reduced clumping, and long term stability of the host powder, may also result from the presence of the chemical agent, as compared with a similar powder without the chemical agent. While the exact cause of some of these improvements is not fully understood, it is speculated that the chemical agent controls hydrophobic, hydrophilic, and molecular polarity properties of the powder, thus affecting settling time and redispersion time. The chemical agent also allows the use of pure, or relatively pure metals which are usually prone to corrosion, rather than their oxides. Thus, copper metal powder may be used in place of copper oxide, resulting in enhanced thermal conductivity.
The chemical agent preferably acts as a coating for the particles, residing primarily on the surface of the particles. It will be appreciated that the coating comprising the chemical agent of the present invention is not merely an oxidized layer of the metal powder, such as a layer of copper oxide on a copper powder formed by oxidation of the copper surface.
For the chemical agent, corrosion inhibitors and/or metal film coatings may be used. Exemplary chemical agents include azoles and their substituted derivatives, particularly aromatic azoles (including diazoles, triazoles, and tetrazoles), such as benzotriazole, tolyltriazole, 2,5-(aminopentyl)benzimidazole, alkoxybenzotriazole, imidazoles, such as oleyl imidazoline, thiazoles, such as mercaptobenzothiazole, 1-phenyl-5-mercaptotetrazole, thiodiazoles, halogen-resistant azoles, and combinations thereof. Examples of halogen-resistant azoles include 5,6-dimethyl-benzotriazole; 5,6-diphenylbenzotriazole; 5-benzoyl-benzotriazole; 5-benzyl-benzotriazole and 5-phenyl-benzotriazole. Alkyl-substituted aromatic trazoles, such as tolyltriazole are particularly preferred. Azoles are particularly useful with copper-containing powders, such as pure copper or copper alloys, e.g. brass, but also have application with other metal-based powders, such as those formed from aluminum, steel, silver, and their alloys.
Other suitable chemical agents include inorganic corrosion inhibitors, including, but not limited to water-soluble amine salts, phosphates, and salts of transition elements, such as chromate salts. These chemical agents may also be used in combination with other corrosion inhibitors, such as azoles, to provide a xe2x80x9cself healxe2x80x9d function. Lignin-based chemical agents may also be used, in particular with carbon-based powders.
Ethylene oxide/propylene oxide (EO/PO) block copolymers may also be used as chemical agents. Surfactants, such as anionic and nonionic surfactants, may also be used as chemical agents, particularly for carbon. Exemplary anionic surfactants include calcium salts of alkylbenzenesulfonates. Exemplary nonionic surfactants include polyoxyalkylene alkyl ethers and polyoxyethylene/polyoxypropylene polymers.
Tolyltriazole is a particularly effective chemical agent for copper. One preferred additive includes copper powder to which tolyltriazole is applied at from about 1-5% by weight. For aluminum and its alloys, cerium-based chemical agents may be used. For example, an aqueous cerium non-halide solution is first applied to the powder, followed by contacting the treated surface with an aqueous cerium halide solution. For copper and silver particles, in particular, thiodiazoles substituted on the ring by a mercapto group and/or an amino group and triazoles substituted by a mercapto group and/or an amino group are effective. These compounds form a film on the particles. Oleyl imidazoline is particularly effective for steel. Ferrous and copper alloys can benefit from chemical agent corrosion inhibitors sold under the tradename TRIM(trademark), available from Master Chemical Corporation of Toledo, Ohio which include triethanolamine and monoethanolamine.
Combinations of two or more azoles may be particularly effective, such as a combination of alkoxybenzotriazole, mercaptobenzothiazole, tolyltriazole, benzotriazole, a substituted benzotriazole, and/or 1-phenyl-5-mercaptotetrazole. Another combination which is particularly effective for metallic surfaces is a mixture of a pentane-soluble imidazoline, a pentane-soluble amide, a pyridine-based compound, a pentane-soluble dispersant, and a solvent.
Other corrosion inhibitors/passivating agents may be used which result in passivation of the powder and/or achieve a desirable effect on dispersion and redispersion.
For carbon-containing powders, such as graphite, nanotubes of carbon, or blends of these carbon derivatives, suitable chemical agents, include lignin and its derivatives. In the paper-making industry, lignin may be recovered as a by-product of the cellulose product. Depending on conditions under which the lignin is precipitated, the precipitated lignin may be either in the form of free acid lignin or a lignin salt. A monovalent salt of lignin, such as an alkali metal salt or an ammonium salt, is soluble in water, whereas free acid lignin and polyvalent metal salts of lignin are insoluble in water. In the case of carbon-based powders, the chemical additive tends to act as a dispersant, rather than as a corrosion inhibitor/passivation agent.
Other chemical agents particularly useful with carbon-based powders include alkali metal salts, alkali earth metal salts, ammonium salts, alkyl ether phosphates, solvents, butyl ether and other surfactants, and the like.
The lignin-based compounds may be used alone or in combination with other chemical agents. Lignin sulfonic acid, alkali metal salts of lignin sulfonic acid, alkaline earth metal salts of lignin sulfonic acid, and ammonium salts of lignin sulfonic acid act as an anionic, surfactant-like component.
Such lignin-based compounds can be present in the chemical agent either individually or in the form of mixtures of two or more compounds. For example, lignin sulfonic acid and/or alkali metal, alkaline earth metal and/or ammonium salts and one or more alkyl ether phosphates are effective chemical agents for carbon-based powders. Storage stable, low viscosity dispersants can also be made by replacing 10-25% of the submicron lignin with either an acrylic resin, a rosin resin, a styrene-maleic anhydride copolymer resin, or a combination thereof. These are effective chemical agents for carbon-based powders, in particular. For example, the chemical agent may include a lignin sulfonic acid and/or an alkali metal, alkaline earth metal, or ammonium salt. Other suitable combinations include a mixture of aminoethylated lignin and a sulfonated lignin.
While not fully understood, it is thought that lignin-based compounds reduce the interfacial tension between the carbon particles and the aqueous phase in order to wet the surface of the carbon particles.
As is apparent, the choice of a preferred chemical agent may depend not only on the material from which the powder is formed, but also on the chemical environment, for example, whether the heat transfer medium is generally hydrophobic or hydrophilic, the desirability of reducing friction losses in the operating system in which the composition is to be used, and the desirability of maintaining a long term dispersion within the heat transfer composition.
For example, in compositions where a high chemical resistance is desired, a neutral or alkaline azole, such as 2,5-(aminopentyl) benzimidazole may be used as the chemical agent. Hydrophobic additives tend to maintain superior dispersions when the heat transfer fluid composition is significantly hydrophobic. Hydrophilic additives tend to maintain superior dispersions when the heat transfer fluid compositions is either water or significantly hydrophilic.
While the exact process by which dispersion is improved and maintained by the chemical agent is not known, it is thought that organic corrosion inhibitors, such as heterocyclics react with the metal powder surface to form an organometallic complex. This takes the form of at least one, preferably several monolayers on the surface of the particle. The corrosion inhibitive action of such chemical agents upon the metal powder is manifest even at molecular layer dimensions, while unexpectedly achieving enhanced dispersion of the additive in the heat transfer medium. While aromatic azoles are believed to bond directly to the metal surface to produce an inhibiting complex, other surface interactions which result in a modification of the surface resulting in improved dispersion and/or passivation are also contemplated.
One or more of such heat transfer additives may be used in combination with a heat transfer medium.
In addition to a chemical agent, a suitable solvent may also be used. Common solvents may be used for this purpose.
The composition may further include a prestabilized filler to further enhance the effectiveness of the surface modification. For example a material that will inhibit oxidation of the particle, for example, a noble metal, such as gold or silver, with or without a fatty acid may be used as a prestabilized filler in combination with powder particles treated with one of the chemical agents described above.
One or more of such fillers may be used in combination with a heat transfer medium.
The treated powder formed by treating the powder with a chemical agent as described above may include an optional further functionalization agent, such as a treatment with polytetrafluoroethylene (PTFE, sold under the trade name Teflon by E. I. Du Pont de Nemours and Co., Wilmington, Del.). Such funtionalization may be carried out by solvent polymerization of copolymers containing monomer units useful as coating additives. The tolyltriazole, or other azole used as the chemical agent, may be functionalized prior to mixing with the powder. Such PTFE-functionalized azoles are commercially available.
Such functionalization agents tend to reduce the coefficient of friction associated with the treated powder. Less polar fluids, such as alcohols and alkylglycols, which add hydrophobic characteristics that enhance the additive""s dispersion within the fluid may also be used as functionalization agents. Functionalization agents may also be used to accelerate the re-dispersion time of the additive in the heat transfer composition. Fuctionalization agents which provide surface modification or functional group substitution may also be used. Other benefits of certain functionalization agents include a reduction or elimination of mechanical dispersal mechanisms and lower pressure drops that enable reduced pumping energy and smaller pump horsepower. The functionalized treated powder may enable the reduction of refrigerant oils to enhance further the efficiency of a heat exchanger.
Other functionalization agents may be used to increase control of hydrophobic, hydrophilic, and molecular polarity qualities associated with treated metal powders.
The heat transfer composition may further comprise other additives, such as surfactants to reduce further the interfacial tension between the components. The interface between components typically contains voids and airspace that detracts from higher heat transfer coefficients. For example, co-corrosion inhibitors selected from the group of aromatic acids and naphthenic acids, which acids have the free acid form or the alkaline, alkaline earth, ammonium and/or amine salt form may be used. Sodium benzoate, however, is generally not suitable.
The composition may further include anti-oxidants to improve the long-term stability of the composition, while maintaining the superior thermal characteristics of metals as compared to their metal oxide counterparts. The composition may further include other additives, such as traditional dispersants to maintain superior dispersions within the heat transfer fluid. For example, a low molecular weight dispersant may be applied as a coating to the powder and having a polar group with an affinity for the heat transfer media. Hydrophobic dispersants will maintain superior dispersions when the heat transfer media is significantly hydrophobic. Hydrophilic dispersants will maintain superior dispersions when the heat transfer media is either water or significantly hydrophilic. The composition may further include materials which reduce the surface friction between the metal additives and any surfaces in the heat exchanger or pump surfaces. Abrasion prevention agents, antifoaming agents, and lubricating oils may also be used to enhance the overall performance of heat transfer compositions, such as refrigerants in achieving optimal heat transfer.
The stabilized nano-particle to micron-particle size powder provides increased operational energy efficiencies to the thermal transfer fluid through its enhanced thermal capacity. The additive also reduces the need for dispersal mechanisms in the heat transfer system. The additive exhibits slow settling and soft settling characteristics and maintains a colloidal dispersion, as compared with conventional additives. This enables heat transfer systems to operate with higher energy efficiencies through simple addition of the additive to an existing heat transfer medium.
The heat transfer medium preferably has a high heat transfer capacity, high thermal loading capacity, and long-term thermal and chemical stability throughout the range over which the composition is to be operated. Suitable heat transfer media include fluids, such as liquids, gases, pressurized gases (i.e., fluids which are gaseous under atmospheric pressure but are liquid or semi-liquid under the operating conditions used), viscous fluids, and phase change materials. Phase change materials are those which change from one phase, such as a solid, to a flowable material, such as a liquid or viscous fluid, at the operating temperature of the composition. The additive may be used in combination with a variety of heat transfer media, suitable media including water and other aqueous systems, such as, for example, aqueous brines (e.g., sodium or potassium chloride solution, sodium or potassium bromide solution, and the like), and mixtures of water with alcohols, glycols, ammonia, and the like. The additive may also be used in organic-based systems, suitable media for these applications including materials such as hydrocarbons, mineral oils, natural and synthetic oils, fats, waxes, ethers, esters, glycols, and various halogen derivatives of these materials, such as CFCs, hydrochlorofluorocarbons (HCFCs), and the like. These heat transfer media may be used alone or in combination. Mixed organic and aqueous heat transfer media may also be used, such as a mixture of water and ethylene glycol. One preferred mixed heat transfer media includes ethylene glycol and water in a volume ratio of from about 5:1 to about 1:5.
In secondary loop systems, preferred heat transfer media include glycols, such as ethylene glycol, water, poly-xcex1-olefins, silicate esters, chlorofluoro carbon liquids sold under the tradename Fluorinert, such as FC-70, manufactured by the 3M Company. Polyaromatic compounds may also be used, such as biphenyl, diphenyl oxide, 1,1 diphenyl ethane, hydrogenated terphenylquatraphenyl compounds, and mixtures thereof, and dibenzyl toluene. Eutectic mixtures of two or more compounds may also be used, such as a eutectic mixture sold under the tradename Dowtherm A by Dow Chemical Co., which includes 73% diphenyl oxide and 27% biphenyl. Other preferred heat transfer media for secondary loop systems include mineral oils and waxes, such as naphthenic and paraffinic oils and waxes, particularly those specified for high temperature applications, natural fats an oils, such as tallow and castor oils, synthetic oils, such as polyol esters, polyolefin oils, polyether oils, and the like.
For primary loop systems, suitable heat transfer media include water, aqueous solutions, salts, CFCs, HCFCs, perfluorinated hydrofluorocarbons (PFCs), highly fluorinated hydrofluorocarbons (HFCs), hydrofluorocarbon ethers (HFEs), and combinations thereof. Azeotropic mixtures of heat transfer media may be used. Propane and other natural gases are also useful in some applications.
Exemplary primary loop media include salt-hydrates, organic eutectics, clathrate-hydrates, paraffins, hydrocarbons, Fischer-Tropsch hard waxes, and inorganic eutectic mixtures. Examples of these primary loop media include inorganic and organic salts, preferably ammonium and alkali and alkali earth metal salts, such as sulfates, halides, nitrates, hydrides, acetates, acetamides, perborates, phosphates, hydroxides, and carbonates of magnesium, potassium, sodium, and calcium, both hydrated and unhydrated, alone or in combination with these or other media components. Examples of these include potassium sulfate, potassium chloride, sodium sulfate, sodium chloride, sodium metaborate, sodium acetate, disodium hydrogen phosphate dodecahydrate, sodium hydroxide, sodium carbonate decahydrate, hydrated disodium phosphate, ammonium chloride, magnesium chloride, calcium chloride, calcium bromide hexahydrate, perlite embedded with hydrogenated calcium chloride, lithium hydride, and lithium nitrate trihydrate. Other suitable primary loop media include acetamide, methyl fumarate, myristic acid, Glauber""s salt, paraffin wax, fatty acids, methyl-esters, methyl palmitate, methyl stearate, mixtures of short-chain acids, capric and lauric acid, commercial coconut fatty acids, propane and methane and the like.
Propylene glycol, mineral oil, other oils, petroleum derivatives, ammonia, and the like may also be used.
The selection of a preferred heat transfer medium is in part dependent on the operating temperature range, heat transfer effectiveness, cost, viscosity within the operating temperature range, and environmental impact if the material is likely to leave the system.
The heat transfer additive is particularly useful in combination with heat transfer media which tend to be corrosive, such as aqueous brines.
The heat transfer additive is combined with the heat transfer medium to form an effective heat transfer composition which comprises a dispersion of the additive in the heat transfer medium. The heat transfer additive may be supplied in powder form for addition to a heat transfer medium or to a heat transfer system in which a heat transfer medium or fluid is already present. Other additives may be added directly to the heat transfer medium, or combined with the heat transfer additive.
Alternatively, the heat transfer additive may be combined as a blend, solution, or other mixture (azeotropic or otherwise) with one or more other materials. Such other materials may include other heat transfer additives and substances used to alter the freezing, melting, and/or boiling temperature of the heat transfer fluid.
In yet another embodiment, the heat transfer additive is supplied in concentrated form, together with one or more of the components of a heat transfer fluid, for later combination with the remaining components. For example, all of the components of a heat transfer fluid, including the heat transfer additive, but with the exception of water or other bulk fluid, are combined and supplied as a concentrate. When needed, the concentrate is mixed or otherwise combined with water, other bulk fluid, or added to an existing system in which the additive and/or other components of the heat transfer fluid have become depleted over time.
For example, the chemical additive may be first combined with a suitable solvent in which the chemical additive is soluble. Heat may be applied, if desired, to effect solubilization. The powder is then added to the mixture and allowed to contact the powder and interact to form the treated powder. Other additives, such as functionalizing agents and surfactants may also be added to the mixture. Excess chemical additive may be removed by filtering the treated powder then washing the treated filtered powder in a suitable solvent, which may be the same solvent used to dissolve the chemical additive, or a different solvent. The washed or unwashed treated powder is then dried, either by air drying or in an oven at a sufficient temperature to remove the solvent without deleteriously affecting the properties of the additive. Alternatively, for example, where the solvent is useful in the heat transfer media, the drying step may be avoided. In another alternative embodiment, the treated powder is filtered to remove the solvent and/or excess chemical additive.
In yet another alternative embodiment, the chemical agent is added to a mixture of the heat transfer medium and the powder. In this embodiment the chemical agent still contacts the powder surface and modifies the surface properties, either by chemically modifying the surface, physical adsorption or some other form of interaction.
The optimal amount of the additive used depends on the particular application, the composition of the additive, and the host heat transfer medium""s ability to maintain the additive as a dispersion in the heat transfer composition. The cost to benefit ratio in terms of increased energy efficiency may also be a factor in determining the preferred concentration. The additive may be present in the heat transfer composition at a concentration of from about 1 to 99% by weight, more preferably from about 3-20% by weight, and most preferably, around 10% by weight.
Preferably, the chemical agent is present in a stoichiometric excess. By this, it is meant that the chemical agent is present in sufficient amount to provide at least a monolayer of coverage over the available surface of the particles.
Additives formed according to the present invention preferably maintain a colloidal dispersion, are not prone to gas phase change, and have a high heat transfer capacity with low viscosity over the entire intendedoperating range. Preferred additives are also nonflammable, environmentally friendly, non-toxic, and chemically stable. The additive exhibits compatibility with a wide range of heat transfer media and applications over a wide range of operating conditions. Additives formed according to the present invention exhibit effectiveness within both primary and secondary loop heat transfer media as dispersion and closed loop re-circulation is achieved in non-phase change and phase change processes. The heat transfer media additive may be used in a variety of applications, including engine cooling, air conditioning, refrigeration, thermal storage, heat pipes, fuel cells, and hot water and steam systems.
The heat transfer composition has application in a wide variety of heat transfer applications including, but not limited to heating and cooling, including refrigeration, air conditioning, computer processors, thermal storage systems, heating pipes, fuel cells, and hot water and steam systems. The enhanced thermal capacity heat transfer composition may be utilized in primary and or secondary loop heat transfer systems.
In primary loop systems the heat transfer composition transfers heat between an energy source and a heat transfer medium by transferring energy from the energy source to the heat transfer composition.
In secondary loop systems, the heat transfer composition transfers heat in a secondary loop, between a heat source and a heat sink by transferring heat from the heat source to the heat transfer composition and transferring the heat from the heat transfer medium to the heat sink.
Without intending to limit the scope of the invention, the following example describes a method of forming and using the heat transfer compositions of the present invention.

Refrigerant and heat transfer fluid additive


A one piece osteotomy guide and method of use, for making a bi plane chevron cut in an osteotomy surgery, such as bunion surgery where accurate redirection of a bone or joint is required. This guide is used to mark a first cut and then placed in the cut. The guide is then used to direct the second cut. Use of the guide allows these cuts to match perfectly, thus speeding the healing process.

The present invention relates to an improvement in the methods used to perform chevron osteotomy procedures that are commonly employed in bunion correction surgery. More specifically, to the design of a device that will aid orthopedic surgeons in making the precise bone cuts that are necessary for the successful completion of a biplane chevron osteotomy procedure and the treatment of a hallux valgus or bunion deformities.
A hallux valgus deformity is a very common foot disorder that results in the formation of a bunion on a patient""s foot which can be a source of pain and embarrassment. The deformity is a result of a static subluxation of the first metatarsalphalangeal joint (herein after referred to as the MTP joint) with a lateral deviation of the big toe and a medial deviation of the first metatarsal. More specifically, the word hallux is the medical term for the big toe and valgus is an anatomical term which refers to a deformity that is oriented in a direction away from the midline of the body. That is to say, the term hallux valgus describes a big toe that, from its tip to its base, is deformed in an outward manner in relation to the body of the foot. The condition can also be medically described in terms of the first metatarsal bone as metatarsus primus varus which refers to the orientation of the first metatarsal from its tip to its base being pointed towards the midline of the foot.
The result of this skeletal deformity is very often a large protruding bump on the outside base of the big toe that can be very sensitive to any pressure created by contact. Additionally, the condition is self-perpetuating in that the pressure it creates against the patient""s footwear causes the metatarsal bone at the point of contact to thicken. This thickening at the head of the metatarsal increases the size of the resulting bunion which adds to the pressure at the point of contact which in turn increases the severity of the condition and the associated discomfort to the patient.
The most common cause of a hallux valgus condition is the prolonged deformity of a foot which is most commonly associated with the long term wearing of improperly fitting footwear coupled with some sort of preexisting susceptibility resulting from such things as genetic factors or prior trauma. The footwear connection to the disorder is supported by the fact that it is much more common in women who are prone to wearing high heel shoes having a constricted forefoot area. This tends to force the big toe into an abnormal position which can cause the associated muscles to migrate laterally. Once this migration of the muscles passes outside of the line of the MTP joint the resulting hallux valgus condition tends to reenforce itself and continually worsen.
The first step taken in the medical diagnosis and treatment of a hallux valgus condition is to accurately define a number of critical measurements through the use of a series of X-rays taken of the foot""s bone structure. One of these is the intermetatarsal angle (herein after referred to as the IM angle) which is defined by the relationship of the first metatarsal shaft compared to the line of the second metatarsal shaft and generally in normal circumstances is between 6 and 9 degrees of deviation.
Another of the measurements taken is the determination of the hallux valgus angle (herein after referred to as the HV angle) which defines the angle of the line created at the MTP joint between the first metatarsal bone shaft and the first phalangeal bone shaft. This angle is generally considered to be within the normal range at 9 to 10 degrees and any HV angle that measures greater than 12 degrees is considered to be in the abnormal range requiring some sort of corrective action to be taken. Additionally, the distal metatarsal articular angle (herein after referred to as the DMAA) can also be measured which quantifies the angle created between the line if the first metatarsal shaft and the metatarsal head""s contact surface at the MTP joint.
Finally, the preliminary examination will also include an evaluation of the condition of the MTP joint to determine whether there has been a lateral subluxation of the joint. The combined evaluation of these and other factors will determine the course of action to be taken and in general terms a patient with a congruent MTP joint (a joint with no lateral subluxation), an IM angle of less than 15 degrees, and a HV angle of less than 30 degrees is a candidate for chevron osteotomy corrective surgery. For those patients who""s hallux valgus condition does not fall within these parameters there are other corrective procedures available.
The chevron osteotomy procedure for the correction of a hallux valgus condition has been around for a long time so it is quite natural that there exists numerous devices that are intended to aid a surgeon in the performance of a chevron osteotomy. An example of this type of device is illustrated in U.S. Pat. No. 5,843,085 issued to Graser 1998. The Graser patent describes a device which is intended to be used as a cutting guide in three different types of osteotomy procedures and consists of a two piece jig having multiple cutting slots and which may also require the use of more than one KIRSCHNER wire. While the device performs its desired functions, the fact that it is designed to perform multiple functions means that it is inherently complex and cumbersome to use which increases the risks of error when compared to a hypothetical design for a single use device.
Therefor, from the forgoing discussion it can be seen that it would be desirable to provide a device that would aid a surgeon in performing a biplane chevron osteotomy procedure for the correction of a hallux valgus condition. Additionally, that it would be advantageous to provide such a device that would be simple to use and that would allow the surgeon to make the complex bone cuts involved time after time with a high degree of accuracy.
It is the primary objective of the present invention to provide a means by which a surgeon can use a device that will aid him in making the V-shaped biplane cuts in the first metatarsal bone of a human foot that are necessary to perform a biplane chevron osteotomy procedure to correct a hallux valgus or bunion deformity.
It is an additional objective of the present invention to provide such a device that will allow a surgeon to precisely mark the forward end of the first metatarsal bone in such a manner that will provide a clear guide in making the subsequent primary superior and inferior osteotomy cuts through the stem of the first metatarsal.
It is an additional object of the present invention to provide such a device that will allow for the making of such cuts in the precise location on the metatarsal that is desired and also at the exact 67 degree angle, or formed so as to measure any other angle as desired in the procedure between the superior and inferior components of the primary osteotomy cut in the chevron procedure.
It is an additional objective of the present invention to provide such a device in which the initial marking portion (the primary guide body) is designed in such a way that the forward marking portion will slip into the primary superior and inferior cuts allowing the most forward surface of the secondary guide body to fit tightly against the distal surface of the capital fragment of the metatarsal.
It is a further objective of the present invention to provide such a device that has a secondary guide body formed in a such a manner so that its sides are precisely angled to provide the surgeon with guiding surfaces to aid in the making of the secondary superior and inferior cuts necessary to complete the bone cutting stages of the biplane chevron osteotomy.
It is a still further objective of the present invention to provide such a device to aid a surgeon in the performance of a biplane chevron osteotomy that can be easily manufactured in an inexpensive manner which will facilitate its wide distribution and thus improve the quality of the hallux valgus repair procedures taking place and therefor improve the quality of the patient""s life.
These objectives are accomplished by the use of a cutting jig apparatus used in biplane chevron osteotomy surgery for the correction of a hallux valgus (or bunion condition) in which the redirection of the joint between the first metatarsal and the first phalangeal bone is performed. The purpose of the chevron osteotomy is to remove a wedge of bone from the forward portion of the first metatarsal which allows these bones to be realigned in a manner that lessens or completely corrects the patient""s hallux valgus deformity.
In the past these cuts were typically made by hand in order that the wedge of bone be removed. The problem with this method is that the procedure requires that two cuts be made at precise angles in order for the remaining bone surfaces to match properly so that the osteotomy will heal adequately. While the first of these cuts is relatively easy to make, the second can be very difficult to make without a precise cutting guide. Therefore, the use of freehand techniques of the past led to problems in the length of time the surgical procedure took and often resulted in and errors made during the cutting process which could lead to healing problems.
The first step in the use of the present invention is to remove the medial eminence from the distal head of the first metatarsal. This procedure removes a significant portion of the protruding bone surface that created the problem and leaves a relatively flat surface to work with. Once this has been completed, a perpendicular KIRSCHNER wire (herein after referred to as a K-wire) is inserted into this surface at the center of the metatarsal head. The K-wire then provides a device which allows the present invention to be precisely positioned on the distal surface of the first metatarsal.
The positioning of the present invention is accomplished by slipping the body of the invention over the K-wire by the use of the K-wire hole that longitudinally spans the length of the secondary guide body of the invention. The use of the K-wire in this function serves two purposes. First, it places the invention in a perpendicular orientation to the surface of the metatarsal from which it can be rotated into the proper orientation for bone marking purposes and second, it serves to hold the invention in place during the metatarsal marking operation ensuring that the primary Chevron cuts will be made properly. It should also be stated that other means of holding the device may be possible.
With the V-shaped cutting edge of the present invention in the proper location, the upper surface of the invention is tapped with a hammer which forces the V-shaped cutting edge into the surface of the metatarsal bone leaving a V-shaped mark opening away from the metatarsal head. This mark is then used as a guide, after the removal of the present invention, by a surgeon for making the primary superior and inferior chevron cuts into the body of the metatarsal. After the completion of these cuts, the most forward portion (or the primary guide body) of the present invention is placed within the gap created by the cuts in a manner that places the forward surface of the secondary guide body against the surface of the metatarsal bone. This allows the surgeon to use the outer surfaces of the secondary guide body as guides to make the secondary superior and inferior chevron cuts at angles that will match up perfectly with surfaces of the primary cuts.
The completion of the secondary cuts separates a wedge of bone from the body of the first metatarsal and the present invention is removed from the cuts. The wedge of bone is then removed which leaves an open V-shaped chevron biplane cut having all of the inside cut edges matching perfectly which allows the stem and capital fragments of the first metatarsal to be inwardly realigned in relation to one another to close the gap created by the removal of the bone wedge. This realignment allows the capital fragment of the first metatarsal to be shifted laterally and oriented out of valgus, thus correcting the abnormal shape in the foot created by the long standing valgus drift due to increased DMAA and thereby alleviating the bunion condition. The stem and capital fragments of the first metatarsal are then generally held in place during the healing process by the use of a pin, screw, or other similar device and the healing of the bone will then allow the patient normal use of the foot.
For a better understanding of the present invention reference should be made to the drawings and the description in which there are illustrated and described preferred embodiments of the present invention.

Device for the repair of a hallux valgus deformity


The object of the present invention is to propose an apparatus for determining a physical variable of a medium (2) in which the formation of deposits or buildups of the medium (2) on a subelement (4) of the apparatus (1) which comes into contact with the medium (2) is reduced or avoided.

The invention relates to an apparatus for determining a physical variable of a liquid or solid medium in a container or in a vessel.
A wide variety of types of sensors are used for determining physical measured variables. In applications in which at least a subelement of the sensor is in direct or indirect contact with the medium to be measured, there is the risk of build-ups forming on the corresponding sensor element. These build-ups impair the measuring accuracy or the function of the sensor in some cases quite considerably.
The invention is based on the object of proposing an apparatus in which the formation of build-ups on the sensor is reduced.
The object is achieved by the apparatus comprising a plurality of subelements, at least one subelement coming indirectly or directly into contact with the liquid or solid medium, and the at least one subelement having a microstructured surface layer. The microstructured surface layer prevents or reduces the formation of deposits on the sensor. Furthermore, a surface film is prevented from forming on the corresponding subelement of the sensor where there is contact with a viscous medium, for example honey.
The reason for the low formation of deposits is to be seen in the great reduction in the forces of adhesion between the sensor element and the medium due to the surface roughness of the sensor element. Even if a deposit forms, it can be easily removed again subsequently on account of the low forces of adhesion. In addition to the consistently good measuring accuracy, an important side-effect of this, as it were, self-cleaning surface structure is the increased service life of the sensor. Consequently, in addition to the (self) cleaning function, the microstructured surface also assumes a protective function.
According to an advantageous development of the apparatus according to the invention, the microstructured lay applied as a surface coating to the at least one subelement. It is preferred here, because of the simplicity of application, for the surface coating to be a layer of varnish or paint which has been applied to the least one subelement. It is also possible, however, to apply the surface layer by a different production technique. As an example, mention may be made here of vapor deposition.
One advantageous embodiment of the apparatus according to the invention proposes that the microstructured surface has elevations and depressions, the distance between the elevations lying in the range from 5 to 200 xcexcm and the height of the elevations lying in the range from 5 to 100 xcexcm. EP 0 772 514 B1 discloses in detail how the microstructured surface may be formed.
The apparatus according to the invention can preferably be used in the field of continuous level measurement or limit-level measurement. Used here are measuring systems which measure different physical variables and derive the desired information on the filling level from the variables measured. In addition to mechanical feelers, capacitive, conductive or hydrostatic measuring probes are used, as well as detectors which operate on the basis of ultrasound or microwaves. Less critical of course are sensors which do not come into direct contact with the product, although contaminations may also occur on microwave antennas for example, which are arranged above the product to be measured. In the case of other types of sensor which are immersed into the product for the purpose of measured value acquisition, the formation of deposits is usually particularly critical.
The formation of deposits is, however, problematical in any event in the case of capacitive sensors and TDR sensors. An arrangement for the capacitive level measurement of a medium arranged in a non-conductive container is disclosed for example by DE 38 24 231 C2. As a further example of capacitive sensors, mention may be made of the MULTICAP level sensors, produced and sold by the applicant. When there are deposits or build-ups on the probe, that is to say the subelement which is in direct contact with the product, the measuring accuracy is affected considerably. Measuring errors of the order of approximately 5% occur.
In many fields of application, for example petrochemistry, chemistry and the food industry, highly accurate measurements of the level of liquids or bulk materials in containers (tanks, silos, etc.) are required. Therefore, use is made here increasingly of TDR sensors, in which short electromagnetic high-frequency pulses or continuous microwaves are injected into a conducting rope or rod probe and introduced by means of the probe into the container in which the product is stored. Incidentally, TDR stands as an abbreviation for Time Domain Reflectometry. Seen in physical terms, this measuring method utilizes the effect that part of the guided high-frequency pulse or of the guided microwave is reflected at the boundary layer between two different media, for example air and oil or air and water, because of the abrupt change (discontinuity) in the dielectric constants of the two media, and is returned via the probe into the receiving device. The reflected component is all the greater here the greater the difference in the dielectric constants of the two media. The distance from the boundary layer can be determined on the basis of the delay time of the reflected component of the high-frequency pulse or microwave. With knowledge of the distance when the container is empty, the filling level of the product in the container can be calculated.
It has been found that the measuring accuracy of TDR sensors is reduced relatively greatly by the formation of deposits. Consequently, measuring errors of up to approximately 5% also occur here. Incidentally, a TDR sensor which can be used in connection with the apparatus according to the invention is described in U.S. Pat. No. 5,361,070. As a further example, mention may be made of the TDR sensor LEVELFLEX, produced and sold by the applicant.
The level sensor may, however, also be a vibration sensor. For the purpose of level measurement, here the detuning of the resonant frequency of the vibration sensor which occurs as soon as the vibration rods of the vibration sensor come into contact with the product is used for the purpose of level measurement.
The formation of deposits is always critical in the case of vibration sensors when the build-ups do not form symmetrically on the two vibration rods. As an example of vibration measuring systems, mention may be made of the LIQIPHANT or SOLIPHANT, likewise produced and sold by the applicant.
It goes without sayingxe2x80x94as already described elsewherexe2x80x94that the microstructured surface is also advantageous in connection with an antenna which transmits sound, ultrasound or electromagnetic waves in the direction of the surface of the medium.
Seen quite generally, however, the apparatus according to the invention is not only suitable for measuring the filling level of a product in a container but also can be used in connection with any type of sensor which can measure any desired physical variables of a liquid or solid medium and comes into contact with the medium or is exposed indirectly to the influence of the medium during the measuring operation. The physical variables mentioned above may be, for example, the pressure, temperature, humidity, throughflow or mass throughflow of a medium. The microstructured surface of the sensor element which comes into indirect or direct contact with the medium has the effect of effectively avoiding or reducing adherence of the medium to the corresponding subelement of the sensor.

Apparatus for determining a physical variable of a liquid or solid medium

Abstract: For this purpose, at least the subelement (4) is provided with a microstructured surface layer (7).