Abstract: A bi-directional photoacoustic gas sensor includes a first photoacoustic cell, where an electromagnetic radiation source emits radiation to interact with an external gas and generate pressure waves that are detected by a MEMS diaphragm. A second photoacoustic cell has an interior volume and acoustic compliance that corresponds to the interior volume and acoustic compliance of the first photoacoustic cell. Processing circuitry within a substrate uses a first acoustic signal, received by the first photoacoustic cell, and a second acoustic signal, received by the second photoacoustic cell, to determine a bi-directional response of the gas sensor to remove noise and improve the sensor's signal-to-noise ratio.

Abstract: A sensor including a micro-bridge structure, wherein the micro-bridge structure comprises a concave geometry, a first electrode on a surface of the micro-bridge structure, a second electrode on the surface of the micro-bridge structure, and a chemical sensing material coupled to the micro-bridge structure overlying the first electrode and the second electrode and exposed to an environment. The chemical sensing material overlays the first electrode and the second electrode and is within the concave geometry of the micro-bridge structure such that the chemical sensing material settles into the concave geometry of the micro-bridge structure during fabrication of the sensor, and wherein the chemical sensing material has an electrical resistance responsive to a concentration of gas in the environment.

Abstract: A gas sensor may include a plurality of elements that are responsive to particular gases based at least in part on the temperature of the temperature sensitive element. A first of the elements may be a gas detection element heated to a temperature at which it is responsive to a gas of interest. A plurality of additional elements may be configured in a reference element network and heated to a temperature at which they are not responsive to the gas of interest but are instead responsive to other effects such as humidity. The reference element network output may be used to remove the other effects (e.g., humidity) from the gas detection element output.

Abstract: A gas sensor may include a plurality of elements that are responsive to particular gases based at least in part on the temperature of the temperature sensitive element. A first of the elements may be a gas detection element heated to a temperature at which it is responsive to a gas of interest. A plurality of additional elements may be configured in a reference element network and heated to a temperature at which they are not responsive to the gas of interest but are instead responsive to other effects such as humidity. The reference element network output may be used to remove the other effects (e.g., humidity) from the gas detection element output.

Abstract: A pressure sensor includes a piezoelectric substrate having a generally planar structure and an anchor location fixing the piezoelectric substrate at the periphery of the planar structure of the piezoelectric substrate. The planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate. The second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is displaced relative to the neutral axis of the planar structure such that while undergoing bending the second region has either mostly compressive or mostly tensile stress.

Abstract: A pressure sensor includes a piezoelectric substrate having a generally planar structure and an anchor location fixing the piezoelectric substrate at the periphery of the planar structure of the piezoelectric substrate. The planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate. The second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is displaced relative to the neutral axis of the planar structure such that while undergoing bending the second region has either mostly compressive or mostly tensile stress.