Abstract: The present invention relates to the field of chemical detection. Specifically, the invention provides devices that respond quickly to various target chemical analytes present in the environment. Responses are based on a change in an electrical property (such as impedance or resistance) caused by adsorption or absorption of the target analyte(s) to or in a substrate-free chemical sensing element. The chemical sensing element is composed of a thin, electrically conductive polymer material (due to doping of structural polymer material(s) with electrically conductive particles and/or the use of electrically conductive polymer material(s)), which can allow vapors to pass through with little pressure drop. The chemical sensing material is either suspended in the environment, or emplaced adjacent to one or between two porous membranes, resulting in a sensing patch capable of high gas or vapor flux through the chemical sensing element.

Abstract: Apparatus, systems and methods are described for preconcentrators, chemical sensing systems and gas chromatographs. A preconcentrator is described that comprises a hollow enclosure containing a sorbent material. The enclosure may be a capillary tube that can be formed in to a desired shape and that may be heated. Heating may be accomplished by passing an electrical current through the capillary or other hollow enclosure form. The sorbent material can be a liquid, a solid, a porous ceramic material and/or a chemiselective polymer. The sorbent material can be coated to the inner wall of the enclosure. The hollow enclosure may be maintained in an insulated chamber. The preconcentrator acts to concentrate a vapor passed through the preconcentrator to a chemical sensing array that can detect chemicals present in the vapor. A gas passed through the hollow enclosure can provide a chemically concentrated input to a chromatographic column.

Abstract: The present invention relates to the field of chemical detection. Specifically, the invention provides devices that respond quickly to various target chemical analytes present in the environment. Responses are based on a change in an electrical property (such as impedance or resistance) caused by adsorption or absorption of the target analyte(s) to or in a substrate-free chemical sensing element. The chemical sensing element is composed of a thin, electrically conductive polymer material (due to doping of structural polymer material(s) with electrically conductive particles and/or the use of electrically conductive polymer material(s)), which can allow vapors to pass through with little pressure drop. The chemical sensing material is either suspended in the environment, or emplaced adjacent to one or between two porous membranes, resulting in a sensing patch capable of high gas or vapor flux through the chemical sensing element.

Abstract: Apparatus, systems and methods are described for preconcentrators, chemical sensing systems and gas chromatographs. A preconcentrator is described that comprises a hollow enclosure containing a sorbent material. The enclosure may be a capillary tube that can be formed in to a desired shape and that may be heated. Heating may be accomplished by passing an electrical current through the capillary or other hollow enclosure form. The sorbent material can be a liquid, a solid, a porous ceramic material and/or a chemiselective polymer. The sorbent material can be coated to the inner wall of the enclosure. The hollow enclosure may be maintained in an insulated chamber. The preconcentrator acts to concentrate a vapor passed through the preconcentrator to a chemical sensing array that can detect chemicals present in the vapor. A gas passed through the hollow enclosure can provide a chemically concentrated input to a chromatographic column.

Abstract: The present invention relates to the field of chemical detection. More specifically, the invention provides devices that can detect various target analytes (e.g., chemicals and/or biological materials) present in an environment by adsorption or absorption of the target analyte(s) to or in a chemical sensing material such that an electrical parameter (e.g., capacitance, resistance, etc.) of the chemical sensing material is altered in a manner detectable by circuitry associated with the sensing electrode pair coated with the chemical sensing material. Here, the sensing electrode pair(s) of the devices of the invention are suspended over an inert substrate via one or more posts used to space the electrodes from the substrate.

Abstract: A fixed parallel plate micro-mechanical systems (MEMS) based sensor is fabricated to allow a dissolved dielectric to flow through a porous top plate, coming to rest on a bottom plate. A post-deposition bake ensures further purity and uniformity of the dielectric layer. In one embodiment, the dielectric is a polymer. In one embodiment, a support layer is deposited onto the top plate for strengthening the sensor. In another embodiment, the bottom plate is dual-layered for a narrowed gap. Integrated circuit arrays of such sensors can be made, having multiple devices separated from each other by a physical barrier, such as a polycrystalline containment rim or trough, for preventing polymer material from one sensor from interfering with that of another.

Abstract: A fixed parallel plate micro-mechanical systems (MEMS) based sensor is fabricated to allow a dissolved dielectric to flow through a porous top plate, coming to rest on a bottom plate. A post-deposition bake ensures further purity and uniformity of the dielectric layer. In one embodiment the dielectric is a polymer. In one embodiment, a support layer is deposited onto the top plate for strengthening the sensor. In another embodiment, the bottom plate is dual-layered for a narrowed gap. Integrated circuit arrays of such sensors can be made, having multiple devices separated from each other by a physical barrier, such as a polycrystalline containment rim or trough, for preventing polymer material from one sensor from interfering with that of another.

Abstract: Apparatus, systems and methods are described for preconcentrators, chemical sensing systems and gas chromatographs. A preconcentrator is described that comprises a hollow enclosure containing a sorbent material. The enclosure may be a capillary tube that can be formed in to a desired shape and that may be heated. Heating may be accomplished by passing an electrical current through the capillary or other hollow enclosure form. The sorbent material can be a liquid, a solid, a porous ceramic material and/or a chemiselective polymer. The sorbent material can be coated to the inner wall of the enclosure. The hollow enclosure may be maintained in an insulated chamber. The preconcentrator acts to concentrate a vapor passed through the preconcentrator to a chemical sensing array that can detect chemicals present in the vapor. A gas passed through the hollow enclosure can provide a chemically concentrated input to a chromatographic column.

Abstract: A fixed parallel plate micro-mechanical systems (MEMS) based sensor is fabricated to allow a dissolved dielectric to flow through a porous top plate, coming to rest on a bottom plate. A post-deposition bake ensures further purity and uniformity of the dielectric layer. In one embodiment, the dielectric is a polymer. In one embodiment, a support layer is deposited onto the top plate for strengthening the sensor. In another embodiment, the bottom plate is dual-layered for a narrowed gap. Integrated circuit arrays of such sensors can be made, having multiple devices separated from each other by a physical barrier, such as a polycrystalline containment rim or trough, for preventing polymer material from one sensor from interfering with that of another.

Abstract: A sensor for determining the presence of an analyte is disclosed comprising a reactive layer disposed between a base plate and a movable plate. The reactive layer is configured to interact with an analyte effecting a change in capacitance between the base plate and movable plate. When the analyte has a polarity or overall Hildebrand solubility parameter that is similar to the reactive layer, the change in capacitance is caused by a swelling of the reactive layer as analyte is absorbed into the reactive layer. This results in a decrease in capacitance. When the analyte has a solubility parameter not near the reactive layer, the absorbed analyte causes the reactive layer's total polarity to increase, an effect that dominates swelling. This causes an increase in capacitance. A capacitive sensing circuit is included for measuring the change in capacitance which is indicative of the analyte exposed to the sensor.

Abstract: A chemical-sensing apparatus is formed from the combination of a chemical preconcentrator which sorbs and concentrates particular volatile organic chemicals (VOCs) and one or more chemiresistors that sense the VOCs after the preconcentrator has been triggered to release them in concentrated form. Use of the preconcentrator and chemiresistor(s) in combination allows the VOCs to be detected at lower concentration than would be possible using the chemiresistor(s) alone and further allows measurements to be made in a variety of fluids, including liquids (e.g. groundwater). Additionally, the apparatus provides a new mode of operation for sensing VOCs based on the measurement of decay time constants, and a method for background correction to improve measurement precision.

Abstract: A sensor for determining the presence of an analyte is disclosed comprising a reactive layer disposed between a base plate and a movable plate. The reactive layer is configured to interact with an analyte effecting a change in capacitance between the base plate and movable plate. When the analyte has a polarity or overall Hildebrand solubility parameter that is similar to the reactive layer, the change in capacitance is caused by a swelling of the reactive layer as analyte is absorbed into the reactive layer. This results in a decrease in capacitance. When the analyte has a solubility parameter not near the reactive layer, the absorbed analyte causes the reactive layer's total polarity to increase, an effect that dominates swelling. This causes an increase in capacitance. A capacitive sensing circuit is included for measuring the change in capacitance which is indicative of the analyte exposed to the sensor.

Abstract: A hot stage for a scanning probe microscope includes a substrate having a dielectric window region which is stress compensated to be held in mild tension at elevated temperatures. A heating element is supplied to heat a specimen deposited on the dielectric widow region and the scanning probe microscope is used to observe specimen characteristics at the elevated temperatures. The dielectric window region is configured to be thermally isolated from the rest of the hot stage allowing only a minimum amount of heat to be dissipated into the scanning probe microscope. Temperature sensing resistors are included for monitoring the temperature in the dielectric window region. Conductivity cell electrodes can also be included for sensing the conductivity and capacitance of the specimen. Furthermore, additional control and measurement hardware, such as a temperature sensor circuit, evaluation station, the ramp generator circuit, etc. can be included to provide additional system features.