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.

A sensor system includes a sensing element that includes a sensing material and electrodes configured to apply a first electrical stimuli to the sensing material at an electrical excitation frequency, a modifier assembly including one or more circuits configured to change an electrical impedance of the sensing element, and one or more processors configured to control the modifier assembly. Responsive to exposure of gas to the sensing element, the one or more processors change a linearity of a first electrical signal received from the sensing element by changing the electrical impedance of the sensing element and applying a second electrical stimuli to the sensing material at the electrical excitation frequency.

A sensor component and a mobile communication device including a sensor component are disclosed. In an embodiment a sensor component includes a subcomponent configured to sense a gas level including a resistive heater and a gas sensitive element disposed on the resistive heater; a package enclosing a cavity and accommodating the subcomponent, the package including a first opening in a position facing the gas sensitive element of the subcomponent and a second opening configured to allow a flow of gas to enter the package through the first opening and exit the package through the second opening; and an evaluation circuit configured to generate an output signal indicative of a speed of the flow of gas in response to electrical power to be supplied to the resistive heater.

A microelectromechanical sensor includes a base, a heater provided on the base, and a sensing electrode including a sensing portion. The heater includes a heating portion. The heater and the sensing electrode are provided at different layers in a stacking direction, and the sensing electrode is electrically insulated from the heater. On a reference plane in the stacking direction, a projection of the sensing portion of the sensing electrode is entirely covered by a projection of the heating portion of the heater.

A hydrogen sensor assembly includes a mounting portion; a sensor portion disposed adjacent to the mounting portion; and at least one pedestal connecting the sensor portion to the mounting portion, the sensor portion includes a metal oxide semiconductor having a hydrogen sensing surface and the hydrogen sensing surface includes a noble metal dopant.

Provided are: a gas sensor which is able to have improved gas detection performance, while being capable of suppressing variation in the output characteristics among individual gas sensors; a gas detection device; a gas detection method; and a device which is provided with a gas sensor or a gas detection device. This gas detection device (10) is provided with: a heat sensitive resistive element (2); a lead part (22b) which is connected to the heat sensitive resistive element (2) by welding, while having no material being interposed therebetween; a gas sensor (1) which is thermally coupled to the heat sensitive resistive element (2), while comprising a porous gas molecule adsorption material (3) from which specific gas molecules are desorbed by means of heating; and an electric power supply unit which supplies electric power to the heat sensitive resistive element (2), thereby heating the heat sensitive resistive element (2).

The invention is directed to a gas sensor that includes a hotplate, a support structure, a gas selective filter, and circuitry. The support structure is configured to define a cavity. The gas selective filter is held by the support structure and spans the cavity. Various components are connected to the circuitry, and may include a temperature sensor element, a gas sensing element, and a heater. The temperature sensor element is configured to sense a temperature T.sub.f of the filter. The gas sensing element is sensitive to a target gas in the cavity. The heater is in thermal communication with the gas sensing element. The circuitry is configured to operate the sensing element, estimate a temperature T.sub.f of the filter, and regulate the heater. The circuitry regulates an extent to which power is supplied to the heater based on the estimated temperature T.sub.f of the filter.

A gas detector includes metal-oxide semiconductor gas sensors and their driving circuit. The gas detector stores the ratio of initial gas sensor resistance in air and that in an atmosphere including Freon gas, for the gas sensors. The gas detector learns sensor resistance in air for a gas sensor in use and detects Freon gas by comparing the sensor resistance of the gas sensor in use with the learned resistance in air divided by the ratio. When the first gas sensor has been used for a predetermined period, both the first gas sensor and a second gas sensor are used for a learning period to continue detection of Freon by the first gas sensor and to learn the resistance in air of the second gas sensor. After completion of the learning period, Freon is detected by the second gas sensor.

A MEMS gas sensor is disclosed. In an embodiment a MEMS gas sensor includes a carrier having a recess, a gas sensitive element arranged in the recess and a shielding layer at least partially covering the recess.

Methods and systems are disclosed in which metal oxide composition electrical resistance is measured in a plurality of sensors to detect flammable or reducing compounds wherein at least one of the plurality of sensors is operated at a temperature or includes a metal oxide composition that is different than a respective temperature or metal oxide composition of another of the plurality of sensors.