Minimal-cost, high-accuracy, and portable devices used to detect the presence of insects at all stages of life, including in the egg stage, in stored products by sensing gas phase markers such as volatile pheromones, semiochemicals, and kairomones. The methods, devices, and systems disclosed herein utilize a sensor array configured to simultaneously measure a plurality of target markers and filter background gases while remaining compact, highly accurate, and easy to operate.

An apparatus for calculating a thermal conductivity of a gaseous substance is provided. The apparatus includes a substrate; a cover member disposed on the substrate, wherein the cover member comprises a flow tunnel for the gaseous substance; a flow sensing element disposed on the substrate, wherein the flow sensing element is exposed to the gaseous substance in the flow tunnel; and a pressure sensing element disposed on the substrate, wherein the pressure sensing element is exposed to the gaseous substance in the flow tunnel.

A monolithic gas-sensing chip assembly for sensing a gas analyte includes a sensing material to detect the gas analyte, a sensing system including a resistor-capacitor electrical circuit, and a heating element. A sensing circuit measures an electrical response of the sensing system to an alternating electrical current applied to the sensing system at (a) one or more different frequencies, or (b) one or more different resistor-capacitor configurations of the system. One or more processors control a low detection range of the system to the gas, a high detection range of the system to the gas, a linearity of a response of the system to the gas, a dynamic range of measurements of the gas by the system, a rejection of interfering gas analytes by the system, a correction for aging or poisoning of the system, or a rejection of ambient interferences that may affect the electrical response of the system.

The present disclosure provides a gas sensor comprising a gas sensing layer fabricated based on a solution-processed, template-free synthesis method that achieves controllable ZnO nanostructured morphologies. The method is based on promotion and suppression of growth at specific crystallographic dimensions by tuning the polarity of the solvent. The gas sensing layer with the ZnO nanostructures exhibits high response, excellent selectivity and rapid recovery time.

A method of identifying a gas is provided. The method includes providing a gas sensor device comprising at least two stacked metal oxide layers, wherein a change in conductance of the gas sensor device in a presence of a gas varies with a temperature of the stacked metal oxide layers. The method includes bringing the gas into proximity with the stacked metal oxide layers. The method also includes measuring the conductance of the gas sensor device when the gas is in proximity with the stacked layers at multiple temperatures to generate a temperature-conductance profile. The method also includes identifying a gas of interest based on the temperature-conductance profile.

A gas sensing method and a gas sensing system are provided. The gas sensing method includes using a gas sensing device to sense a target gas, the gas sensing device having a self-heating region capable of producing a change in resistance in response to the target gas being sensed by the gas sensing device, and controlling a change in supply of current or voltage to the gas sensing device according to the change in resistance, so that the gas sensing device is substantially maintained operating at a predetermined temperature for sensing the target gas.

Minimal-cost, high-accuracy, and portable devices used to detect the presence of insect larvae and adult insects in stored products by sensing gas phase markers such as volatile pheromones, semiochemicals, and kairomones. The methods, devices, and systems disclosed herein utilize a sensor array configured to simultaneously measure a plurality of target markers and filter background gases while remaining compact, highly accurate, and easy to operate.

In an embodiment a sensor system includes a carrier implemented as one of a ceramic carrier, a printed circuit board or a transistor outline header, a measuring area semiconductor body implemented as a first micromechanical component, a gas sensor implemented as a second micromechanical component and including an electrode assembly, a sensitive layer and a sensor membrane that spans a recess, wherein the measuring area semiconductor body and the gas sensor are connected to each other, a further sensor with a further electrode assembly and a further sensitive layer, wherein the further sensor is a further gas sensor or a humidity sensor, and a measuring area filled by the gas sample and arranged between the measuring area semiconductor body and the gas sensor, wherein the gas in the measuring area is in contact with the gas sensor and the further sensor.

A microhotplate comprising a membrane suspended over a substrate by a plurality of tethers connected between the substrate and the membrane. The membrane comprises a resistive heater comprising an electrically conductive material having a varying width from a peripheral portion of the membrane to a center of the membrane. The electrically conductive material comprises a first portion spiraling in a first direction and a second portion spiraling in a second direction and in electrical communication with the first portion at the center of the membrane. The microhotplate further comprises a first electrically conductive trace extending over a first tether and in electrical contact with a bond pad on the substrate and the first portion and a second electrically conductive trace extending over another tether and in electrical contact with another bond pad on the substrate and the second portion. Related chemical sensors and related methods of detecting at least one analyte are also disclosed.

A gas detector uses a MEMS gas sensor having: a substrate provided with a cavity and an insulating film over the cavity; a metal oxide semiconductor and a heater both provided on the insulating film. A drive circuit operates the heater with a predetermined period for a predetermined pulse duration in order to heat the metal oxide semiconductor. The drive circuit halts operation of the heater or elongates the period when a humidity sensor detects that the atmosphere is humid.