Abstract: In some embodiments, a method of operating a gas sensor includes setting power to a heater in contact with a MOx sensor to provide a temperature that is below a threshold temperature; holding the temperature below the threshold temperature for a period of time to reduce ozone concentration in a gas sample in contact with the MOx sensor; increasing power to the heater to increase the temperature of the MOx sensor to an operating temperature; acquiring resistance data from the MOx sensor at the operating temperature; and processing the resistance data to provide a result related the gas sample.

Abstract: An apparatus comprises a load resistance connectable in series with the electronic sensor to form a series resistance of the load resistance and the internal impedance of the electronic sensor; an excitation circuit configured to apply a predetermined voltage to a circuit element; and a measurement circuit configured to: initiate applying the predetermined voltage to the series resistance and determining the series resistance; initiate applying the predetermined voltage to the load resistance and determining the load resistance; and calculate the internal impedance of the sensor using the determined series resistance and the load resistance, and provide the calculated internal impedance to a user or process.

Abstract: An atmospheric pressure plasma system includes an atmospheric pressure plasma source that generates a glow discharge-type plasma. The atmospheric pressure plasma source comprises a plasma head and a gas sensor system. The plasma head includes a gas inlet, a gas passage surrounded by a dielectric liner, a radio frequency (RF) electrode and a ground electrode. The RF electrode and the ground electrode are arranged at opposite sides of an outer surface of a segment of the gas passage. The gas sensor system comprises a first pellistor that is exposed to a process gas entering the gas inlet and provides real-time monitoring of the presence and concentration of helium in the process gas entering the gas inlet during plasma operation.

Abstract: The embodiments provide a method making it possible to safely and inexpensively measure concentrations of combustible gases, such as methanol, at room temperature even in high concentration atmospheres, and also provide a sensor making it possible to carry out the above measurement method. The measurement method comprises: arranging a film containing nanoparticles of tungsten oxide and a pair of electrodes which are separated from each other and which individually keep in contact with said film in said atmosphere, exposing said film to light, measuring electric resistance change of said film before and after exposing said film to light, and determining said concentration based on said change.

Abstract: A ratiometric vapor sensor is described that includes a first sensor and a second sensor. The first sensor includes a first semiconductor component comprising a vapor-sensitive semiconducting organic compound, while the second sensor includes a second semiconductor component comprising a modified vapor-sensitive semiconducting organic compound including a modifying organic group. The ratiometric vapor sensor can be used to detect the presence of a vapor such as nitrogen dioxide, and determine the concentration of the vapor by comparing the outputs of electrodes connected to the first and second sensor.

Abstract: A method includes applying heat to a metal oxide sensing element of a gas sensor, varying the heat applied to the metal oxide sensing element for at least a time interval, and measuring an electrical resistance of the metal oxide sensing element versus variation of the heat for a time interval. The measurement of electrical resistance of the metal oxide sensing element versus variation of the heat applied to the metal oxide sensing element is compared to a set of corresponding reference measurements associated with a plurality of different target gases. A further sensor parameter versus the variation of electrical resistance and variation of the heat applied is measured to obtain a three-dimensional trajectory corresponding to variation of the sensor resistance, the variation of said heat and the variation of the further sensor parameter. This comparing includes comparing the trajectory in three dimensions to a set of reference three-dimensional objects.

Abstract: A gas detection device is provided. The device includes a substrate and a dielectric material applied to the substrate. A sensor material is applied to the dielectric film. The sensor material has a bottom, a side, and a top surface. An electrode material is at least partially applied to the dielectric film and at least partially applied to a portion of the side of the sensor material and a portion of the top surface of the sensor material to pin a portion of the sensor material to the dielectric material. The electrode material forms a vapor barrier upon the sensor material to facilitate preventing delamination between the sensor material and the electrode material over portions of the sensor material where the sensor material is not pinned to the dielectric material.

Abstract: In a sensor element for a limiting-current type gas sensor measuring concentration of NOx in a measurement gas, an inner pump electrode located to face a first internal space communicating, under predetermined diffusion resistance, with a gas inlet through which a measurement gas is introduced from an external space is made of a cermet of a Pt—Au alloy and zirconia, and includes a first portion located on a surface farther from a heater part and a second portion located on a surface closer to the heater part from among surfaces opposing each other in the first internal space, an Au content with respect to the Pt—Au alloy as a whole of the second portion is 0.3 wt % or more smaller than that of the first portion, and a total area of the first portion and the second portion is 10 mm2 to 25 mm2.

Abstract: Methods of the disclosed subject matter provide compensation for sensor drift in a hazard detection device having a plurality of sensors coupled to a processor to determine that a carbon monoxide sensor is drifting and to compensate for the drift by calculating a corrected carbon monoxide measurement value based on the ambient environmental conditions.

Abstract: A sensor structure is disclosed comprising at least four planar layers subsuming at least one cavity housed but not contained by overlapping apertures through at least two of the planar layers, wherein the at least one cavity comprises a plurality of chambers, and wherein at least one chamber of the plurality of chambers is configured to be in fluid coupling with at least one other chamber. The plurality of chambers may be defined by overlapping apertures through a plurality of the planar layers. The plurality of chambers may include a Gas Chromatograph (GC) column. The planar layers may be flexible flat glass. The planar layers may be fused together. The layers may be made with apertures through the layers disposed in a desired pattern to define complex structures by the apertures overlapping between abutting layers when the layers are stacked. The planar layers may be configured to admit ultraviolet light.

Abstract: A semiconductor substrate according to an embodiment includes a substrate having a first substrate surface, the substrate having a first outer diameter; a metal layer provided on the first substrate surface, the metal layer having a second outer diameter smaller than the first outer diameter; a first adhesive tape having a ring shape, the ring shape having a third outer diameter smaller than the first outer diameter and larger than the second outer diameter, the ring shape having a third inner diameter smaller than the second outer diameter, the first adhesive tape having a first base material, the first base material having a first surface and a second surface opposed to the first surface, the first adhesive tape having a first adhesive layer provided on the first surface, the first adhesive tape being attached to the first substrate surface and the metal layer through the first adhesive layer; and a second adhesive tape having a fourth outer diameter smaller than the first outer diameter and larger than the

Abstract: Ultrasensitive, decoupled thermodynamic sensing platforms for the detection of chemical compounds in the vapor phase at trace levels are disclosed, wherein the sensors have a heating resistor decoupled from a sensing resistor. Embodiments of the decoupled sensor comprise a metallic microheater resistor on one side of substrate, and a sensor resistor coupled to a catalyst on the other side of the substrate. A sensor array may be provided including a plurality of sensors each having a different catalyst that, when exposed to an analyte, each experience an endothermic reaction, an exothermic reaction, or no reaction. A comparison of the reaction results to data comprising previously obtained reaction results may be used to determine the presence and the identity of the analyte. Advantageously, the decoupled sensors utilize less power and provide greater sensitivity than other known systems, and may be used to detect and identify a single molecule of an analyte.

Abstract: The invention relates to a device and a method for cancer detection and screening, based on analysis of Volatile Organic Compounds emitted by certain cancerous tumors. The device and method provide high sensitivity and specificity analyses. The sample to be analysed may be e.g. blood or blood plasma. In one aspect, the invention is directed towards detection of or screening for gynaecological cancers, e.g. ovarian cancer. Particularly, the device comprises the following parts: a sample holder for a fluid or solid body sample; an air inlet; a detector tube comprising 4×4-16×4 sensors; optionally an individual potentiometer connected to each sensor of the detector tube; an analogue to digital signal converter; four control cards; a computer-based program for the registration and statistical calculation of results; and an electricity source.

Abstract: A sensing device including a transistor, at least one response electrode, and a selective membrane is provided. The transistor includes a gate end, a source end, a drain end, and a semiconductor layer, wherein the source end and the drain end are located on the semiconductor layer, and the gate end is located between the source end and the drain end. The at least one response electrode is disposed opposite to the gate end of the transistor and spaced apart from the transistor. The selective membrane is located on the at least one response electrode or on the transistor.

Abstract: A gas sensor includes: a semiconductor layer; a graphene film provided above the semiconductor layer and having at least a portion in contact with gas; and a barrier film between the semiconductor layer and the graphene film.

Abstract: A fluid sensor comprises a sensor material configured to come into contact at a surface region of same with a fluid and to obtain a first temporal change of a resistance value of the sensor material on the basis of the contact in a first sensor configuration and to obtain a second temporal change of the resistance value of the sensor material on the basis of the contact in a second sensor configuration. The fluid sensor comprises an output element configured to provide a sensor signal on the basis of the first and second temporal change of the resistance value.

Abstract: A gas sensor device has a crystalline film of copper(I) bromide, wherein a crystal surface of the copper(I) bromide is formed of a stepped terrace having a flat face and a steep slope.

Abstract: Embodiments of the present disclosure describe a gas sensor comprising a gas-sensing material including a metal-organic framework with fcu topology and a substrate with a pair of electrodes proximate to the gas-sensing material, wherein the gas sensor is configured to detect toxic gas. Embodiments of the present disclosure further describe a method of detecting gas comprising contacting a gas sensor including a metal-organic framework with fcu topology with a gas/vapour composition including at least one toxic gas, capturing the at least one toxic gas from the fluid composition, and measuring an electrical property to detect a presence of the at least one toxic gas.

Abstract: An oxidizing gas detection method and an apparatus thereof are provided for trace oxidizing gas detection. The detection method includes the following steps. First, perform an electroreduction reaction and a photoreduction reaction simultaneously to a metal oxide in which nanoconductors are distributed. Next, stop the electroreduction reaction and the photoreduction reaction, and read a resistance of the reduced metal oxide by applying a first pulse-width modulation signal. Next, provide an oxidizing gas to the reduced metal oxide, and photo-catalyze a redox reaction between the oxidizing gas and the reduced metal oxide. Next, read a resistance of the oxidized metal oxide by applying a second pulse-width modulation signal. Next, converse a concentration of the oxidizing gas according to a ratio of the resistance of the oxidized metal oxide and the resistance of the reduced metal oxide.

Abstract: A method of and system for detecting a gas or vapor includes providing a sensor comprising an electrode pair in electrical contact with a layer of porous material, the porous material layer having water adsorbed on its surface; contacting the sensor with a gas or vapor sample to be analysed; applying a voltage across the electrode pair of the sensor; and measuring a response, the response correlating to the presence of a target gas or vapor.

Abstract: A gas sensor device has a crystalline film of copper(I) bromide, wherein a crystal surface of the copper(I) bromide is formed of a stepped terrace having a flat face and a steep slope.

Abstract: A gas sensor device includes gas sensors and switches. The switches are connected to the respective gas sensors in series. The gas sensors each include: a first conductive layer; a second conductive layer; a metal oxide layer disposed between the first conductive layer and the second conductive layer; and an insulation layer covering the first conductive layer, the second conductive layer, and the metal oxide layer and having an opening from which a portion of the second conductive layer is exposed. The resistance of the gas sensor is decreased when a gas containing a hydrogen atom comes into contact with the second conductive layer.

Abstract: A MEMS IR sensor, with a cavity in a substrate underlapping an overlying layer and a temperature sensing component disposed in the overlying layer over the cavity, may be formed by forming an IR-absorbing sealing layer on the overlying layer so as to cover access holes to the cavity. The sealing layer is may include a photosensitive material, and the sealing layer may be patterned using a photolithographic process to form an IR-absorbing seal. Alternately, the sealing layer may be patterned using a mask and etch process to form the IR-absorbing seal.

Abstract: The invention relates to a measuring device and a method for determining mass and/or mechanical properties of a biological system.

Abstract: It is disclosed herein a semiconductor device and a method of manufacturing the semiconductor device. The semiconductor device is made using partly CMOS or CMOS based processing steps, and it includes a semiconductor substrate, a dielectric region over the semiconductor substrate, a heater within the dielectric region and a patterned layer of noble metal above the dielectric region. The method includes the deposition of a photoresist material over the dielectric region, and patterning the photo-resist material to form a patterned region over the dielectric region. The steps of depositing the photo-resist material and patterning the photo-resist material may be performed in sequence using similar photolithography and etching steps to those used in a CMOS process. The resulting semiconductor device is then subjected to further processing steps which ensure that a dielectric membrane and a metal structure within the membrane are formed in the patterned region over the dielectric region.

Abstract: Some embodiments of the present disclosure provide a gas sensor in an IOT. The gas sensor includes a substrate, a conductor disposed above the substrate, and a sensing film disposed over the conductor. The conductor has a top-view pattern including a plurality of openings, a minimal dimension of the opening being less than about 4 micrometer; and a perimeter enclosing the opening. Some embodiments of the present disclosure provide a method of manufacturing a gas sensor. The method includes receiving a substrate; forming a conductor, over the substrate; patterning the conductor to form a plurality of openings in the conductor by an etching operation, and forming a gas-sensing film over the conductor. The openings are arranged in a repeating pattern, and a minimal dimension of the opening being about 4 micrometer.

Abstract: In a gas sensor using a first FET-type sensor for a sensor unit, a gas density measurement unit measures a gas density of gas to be detected at a predetermined time on the basis of a first threshold change as a difference between a first threshold voltage applied to a first gate layer when a first source-drain current is a first threshold current while the gas to be detected is not present in the atmosphere and a second threshold voltage applied to the first gate layer when the first source-drain current is the first threshold current at the predetermined time while the gas to be detected is present in the atmosphere, and a temporal differentiation of the first threshold change.

Abstract: A gallium nitride-based sensor having a heater structure and a method of manufacturing the same are disclosed, the method including growing an n-type or p-type GaN layer on a substrate, growing a barrier layer on the n-type or p-type GaN layer, sequentially growing a u-GaN layer and a layer selected from among an AlxGa1-xN layer, an InxAl1-xN layer and an InxAlyGa1-x-yN layer on the barrier layer, patterning the n-type or p-type GaN layer to form an electrode, forming the electrode along the pattern formed on the n-type or p-type GaN layer, and forming a sensing material layer on the layer selected from among the AlxGa1-xN layer, the InxAl1-xN layer and the InxAlyGa1-x-yN layer, wherein a HEMT sensor or a Schottky diode sensor can be heated using an n-GaN (or p-GaN) layer, thus increasing the sensitivity of the sensor and reducing the restoration time.

Abstract: Embodiments of the invention include a fracture ring sensor and a method of using the same to detect out of tolerance forces. Aspects of the invention include a product having a defined an out of tolerance force, a fracture ring sensor, and a mounting assembly coupling the fracture ring sensor to the product. The fracture ring sensor is patterned with a conductive trace and is manufactured to break when subjected to a predetermined amount of force. The predetermined amount of force is substantially equal to a percentage of the out of tolerance force of the product.

Abstract: A processing and detection system for detecting presence of at least one gluten protein in a food sample comprises a food processor including: a reservoir containing a process liquid for processing the food sample; a body that comprises a chamber configured to receive the food sample; and a pressing surface configured to press on the reservoir to cause the process liquid to exit the reservoir and mix with the food sample, thereby generating a processed food liquid; and an exit port configured to conduct the processed food liquid out of the food processor; and a cartridge including: at least one sensor configured to receive the processed food liquid and to generate an electrical signal in response to interaction with the at least one gluten protein in the processed food liquid, and an analyzer in electrical communication with the at least one sensor for detecting the electrical signal and determining the presence of the at least one gluten protein in the food sample based on the detected electrical signal.

Abstract: A gas sensor includes a p-type semiconductor layer that contains copper or silver cations and contacts with detection target gas, a first electrode that is a Schottky electrode to the p-type semiconductor layer, a high-resistance layer that is provided between the p-type semiconductor layer and the first electrode such that the p-type semiconductor layer and the first electrode partly contact with each other and has resistance higher than that of each of the p-type semiconductor layer and the first electrode, and a second electrode that is an ohmic electrode to the p-type semiconductor layer.

Abstract: A micro heater includes a heater electrode formed on a first supporting portion. A micro sensor further includes a sensor electrode formed on the first supporting portion. In the micro heater and the micro sensor an anti-etching dam is formed on the supporting portion. The dam protects the shape of the first supporting portion during etching.

Abstract: A method of manufacturing an electrochemical sensing system is provided. The method includes forming a sensor with a first sensing element disposed on a sensor, the first sensing element configured to detect a target gas, disposing a second sensing element on the sensor, the second sensing element configured to detect the target gas, and coupling a protective feature to the second sensing element, the protective feature configured to prevent non-target gases from contacting the second sensing element. The sensor is configured such that if the first sensing element generates a current exceeding a first threshold current value and the second sensing element does not exceed a second threshold current value it is determined that the first sensing element is contaminated and a restoration protocol is performed on the first sensing element.

Abstract: Crystal lattice defects are generated in a horizontal surface portion of a semiconductor substrate and hydrogen-related donors are formed in the surface portion. Information is obtained about a cumulative dopant concentration of dopants, including the hydrogen-related donors, in the surface portion. Based on the information about the cumulative dopant concentration and a dissociation rate of the hydrogen-related donors, a main temperature profile is determined for dissociating a defined portion of the hydrogen-related donors. The semiconductor substrate is subjected to a main heat treatment applying the main temperature profile to obtain, in the surface portion, a final total dopant concentration deviating from a target dopant concentration by not more than 15%.

Abstract: A mobile device having a gas-sensing function including a case body, a backlight module and a gas sensor is provided. The case body has at least one through hole. The backlight module is disposed in the case body. The gas sensor is disposed in the case body. The gas sensor includes a gas-sensing material layer for sensing a gas. The gas-sensing material layer receives a visible light emitted from the backlight module and is activated by the visible light.

Abstract: A gas sensor for measuring a concentration of carbon dioxide in a gas environment (GE) is provided. The gas sensor includes a graphene layer having a side facing towards the gas environment (GE), an electrode layer including a plurality of electrodes electrically connected to the graphene layer, and a chalcogenide layer covering at least a part of the side of the graphene layer facing towards the gas environment (GE).

Abstract: A semiconductor device is capable of accurately sensing a temperature of a semiconductor element incorporated in a semiconductor substrate. The semiconductor device includes a temperature sensor. The temperature sensor includes a first nitride semiconductor layer of p-type, a first sense electrode, and a second sense electrode. The first sense electrode and the second sense electrode are located to be capable of passing an electric current between the first sense electrode and the second sense electrode through the first nitride semiconductor layer.

Abstract: In general, this disclosure is directed to a flexible or stretchable sensor and a method of detecting a substance and/or electromagnetic radiation using said sensor. The sensor comprises a flexible or stretchable substrate, a pair of terminal electrodes disposed on the flexible or stretchable substrate in mutually spaced apart and opposing relation, and a sensing element applied to the flexible or stretchable substrate, between and in electrical contact with the pair of terminal electrodes, wherein the sensing element is responsive to a substance and/or electromagnetic radiation impinging thereon, and wherein when a voltage is applied across the sensor, an electrical signal is generated that is proportional to a resistance value corresponding to a sensing of the substance and/or electromagnetic radiation impinging on the sensing element.

Abstract: A semiconductor gas sensor device includes a substrate, a conductive layer supported by the substrate, a non-suitable seed layer, and a porous gas sensing layer portion. The non-suitable seed layer is formed from a first material and includes a first support portion supported by the conductive layer, a second support portion supported by the conductive layer, and a suspended seed portion extending from the first support portion to the second support portion and suspended above the conductive layer. The porous gas sensing layer portion is formed from a second material and is supported directly by the non-suitable seed layer in electrical communication with the conductive layer. The first material and the second material form a non-suitable pair of materials.

Abstract: Analyte filter arrays and methods for making an analyte filter array are provided. The arrays are formed using a dispersion of filter particles having selected moieties attached to the surface of the particles and a microarray having complementary moieties formed in an array on a substrate, such that each filter particle is attached to a selected region of the microarray. The moiety on the substrate may be RNA or DNA or other molecule. The substrate may be a surface of a detector array, a membrane that may be placed in registration with the detector array or a stamp used to transfer the filter array to a detector array.

Abstract: Methods, systems, and devices are disclosed for implementing molecular sensors. In one aspect, an ion-gas sensor device includes a pre-concentration module to collect and concentrate a gas-phase chemical for analysis; a piezoelectric fan to produce an air-flow through acoustic streaming to drive the gas-phase chemical released by the pre-concentration module to one or more downstream modules; an ionizer downstream from the piezoelectric fan to ionize the gas-phase chemical; and a gas sensor downstream from the piezoelectric fan and the ionizer to detect the ionized gas-phase chemical driven by the piezoelectric fan. The piezoelectric fan can include a stack of thin-film layers that includes a thin-film piezoelectric layer. The ion-gas sensor device is made into an ultra-portable package capable of integration with mobile communication devices, such as PDA devices or smart phones.

Abstract: A processing and detection system for detecting presence of at least one gluten protein in a food sample comprises a food processor including: a reservoir containing a process liquid for processing the food sample; a body that comprises a chamber configured to receive the food sample; and a pressing surface configured to press on the reservoir to cause the process liquid to exit the reservoir and mix with the food sample, thereby generating a processed food liquid; and an exit port configured to conduct the processed food liquid out of the food processor; and a cartridge including: at least one sensor configured to receive the processed food liquid and to generate an electrical signal in response to interaction with the at least one gluten protein in the processed food liquid, and an analyzer in electrical communication with the at least one sensor for detecting the electrical signal and determining the presence of the at least one gluten protein in the food sample based on the detected electrical signal.

Abstract: A sensor for sensing gaseous chemicals includes a substrate, a variable resistance nanocrystalline ITO thin film formed on the substrate, and electrodes electrically coupled to the thin film. A sensor array assembly includes a sensor slide and a perforated interface circuit. The interface circuit abuts and electrically couples the sensor slide. The sensor slide includes several spaced apart ITO film strips formed on a slide substrate. A common electrode is electrically coupled to a common portion of each ITO film strip providing an electrically conductive path across the common portions of each of the plurality of spaced apart ITO film strips. A discrete electrode is electrically coupled to a discrete portion of each ITO film strip. The interface circuit is configured to abut and electrically couple to the sensor slide. A conductive discrete electrode pad electrically couples each of the plurality of discrete electrodes of the sensor slide to discrete terminals on the interface circuit.

Abstract: A gas cleaning system for removing gaseous pollutants from a hot process gas comprises a vessel for bringing the hot process gas into contact with an absorbent material, and a separating device for separating at least a portion of the absorbent material from the hot process gas to form a separated dust material. The gas cleaning system further comprises a measuring device for measuring, directly or indirectly, a dust parameter such as a density, and/or a friction, and/or a hygroscopicity, and/or an electrical property of the separated dust material, to obtain a measurement, and a control system for controlling at least one operating parameter of the gas cleaning system based on the measurement of the measured dust parameter.

Abstract: A biological gas detection apparatus of an embodiment of the present invention includes: a sensor unit including plural types of gas sensors; a control unit of the sensor unit; a data recording unit; and a data analyzing unit, wherein the data recording unit includes a database on properties of sensitivities of the gas sensors for a single body of a desired gas component, a single body of an interference gas component, and a mixed gas of these that are included in the biological gas, and the data analyzing unit calculates concentration of the desired gas component based on sensitivities of the gas sensors output when detecting the biological gas and the database.

Abstract: A gas detecting system, device and method use a variable pulse voltage waveform to increase the temperature of a detecting unit of the gas detecting system so it reacts with gas molecules from a particular space, and outputs a sensing signal. A processing unit of the gas detecting system then performs calculations on the sensing signal, such that an analysis unit may determine the presence of a target gas in the particular space, and further the composition and concentration of the target gas within the particular space, thus providing a detection that is accurate, rapid and convenient.

Abstract: Technologies are generally described for an air monitoring device, a method for forming an air monitoring device, and methods and systems for monitoring air using an air monitoring device. A method of forming an air monitor device may include placing a sorbent membrane on a material of n type conductivity. The method may further include placing an electrode on the membrane and placing a thermoelectric heater in thermal communication with the membrane. The method may further include placing the membrane, material, and electrode in a sealed container including a valve to form the air monitor device. The valve may be effective to selectively expose the membrane to an environment outside of the container.

Abstract: A combination sensor and corresponding method of measuring a plurality of environmental parameters uses a pressure sensor disposed on an integrated circuit die; a humidity sensor disposed on the integrated circuit die; and a circuit coupled to and shared by the pressure sensor and the humidity sensor to facilitate pressure and humidity sensing.

Abstract: A sensor device comprises a sensitive element (1) and a support (2) for the sensitive element, the support having a surface (3) with an access opening (4) to the sensitive element (1). A layer of adhesive material (5) covers at least parts of the surface (3). A venting medium (6) extends over the entire surface (3) of the support (2) and the access opening (4) and is attached to the support (2) by the layer of adhesive material (5).

Abstract: The application describes methods and apparatus for chemical sensing, e.g. gas sensing, which have high sensitivity but low power operation. A sensor is described having a flexible membrane comprising a III/N heterojunction structure configured so as to form a two dimensional electron gas within said structure. A sensing material is disposed on at least part of the flexible membrane, the sensing material being sensitive to one or more target chemicals so as to undergo a change in physical properties in the presence of said one or more target chemicals. The sensing material is coupled to said heterojunction structure such that said change in physical properties of the sensing material imparts a change in stress within the heterojunction structure which modulates the resistivity of the two dimensional electron gas.