This specification describes a leaf cell resonator sensor based on a geometry of Rhodonea conformal contours joined circumferentially in an eight-fold symmetry by central spoke electrode members. The resonator sensor may provide simultaneous and congruent measurement of fluid density and sound speed based on interaction of the leaf cell dynamics with self-formed Helmholtz cavity dilatational response of the fluid, and the associated changes in electrical admittance spectra in the sensor resulting from changes in fluid acoustic properties. A leaf cell resonator sensor may be capable of retrieving a density and sound speed measurement from fluid independent of the method of deployment, resulting from the principle of the self-formed Helmholtz resonant cavity feature that develops a standing acoustic wave pattern in the fluid without extraneous reflecting structure/hardware.

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).

A gas sensor includes a support structure with a cavity, a sensing element sensitive to a gas and arranged in the cavity, and a filter spanning the cavity. The filter is a size selective filter.

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 sulfurization detection resistor includes: a rectangle-shaped insulating substrate; pair of front electrodes formed at both ends facing each other on a surface of the insulating substrate; plurality of sulfurization detection conductors arranged in parallel between the paired front electrodes; plurality of resistors connected between the ends of each of the sulfurization detection conductors and the paired front electrodes; and sulfide gas impermeable protective film that covers all of the resistors and some of the sulfurization detection conductors, wherein each of the sulfurization detection conductors has a sulfurization detection unit exposed from a window hole in the protective film; and by covering the sulfurization detection units with different types of sulfurization rate adjustment layers formed of an acrylic resin, a silicon resin, and the like, timing of disconnection is set so as to vary in response to a cumulative amount of sulfurization in each of the sulfurization detection units.

A wearable CO.sub.2 monitor and stale air dosimeter comprising a power supply with rechargeable battery and battery charger, an accurate CO.sub.2 sensor, a fast-reacting CO.sub.2 sensor, programmable control circuitry, and a user interface for presenting results and indications. The accurate CO.sub.2 sensor provides CO.sub.2 levels which are used to compute staleness levels and further accumulated as a staleness dose. The fast-reacting CO.sub.2 sensor alerts the user to changes in CO.sub.2 levels and allows the accurate CO.sub.2 sensor to be powered down during periods when CO.sub.2 levels are stable.

A gas sensor includes: a first thermistor having a resistance value that changes according to a concentration of a first gas with a first sensitivity and changes according to a concentration of a second gas with a second sensitivity; a second thermistor connected in series to the first thermistor, the second thermistor having a resistance value that changes according to a concentration of the first gas with a third sensitivity that is lower than the first sensitivity and changes according to a concentration of the second gas with a fourth sensitivity that is different from the second sensitivity; and a correction resistor connected in parallel with the first or second thermistor.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.

A gas sensor includes a first electrode, a gas detecting layer disposed on the first electrode, and an electric-conduction enhanced electrode unit being electrically connected to the first electrode and the gas detecting layer. The electric-conduction enhanced electrode unit includes an electric-conduction enhancing layer and a second electrode electrically connected to the electric-conduction enhancing layer. The electric-conduction enhancing layer is electrically connected to the gas detecting layer and is made of an electrically conductive organic material.