A thermal emitter includes a freestanding membrane supported by a substrate, wherein the freestanding membrane includes in a lateral extension a center section, a conductive intermediate section and a border section, wherein the conductive intermediate section laterally surrounds the center section and is electrically isolated from the center section, the conductive intermediate section including a conductive semiconductor material that is encapsulated in an insulating material, wherein the border section at least partially surrounds the intermediate section and is electrically isolated from the conductive intermediate section, and wherein a perforation is formed through the border section.

Microphones, microphone systems, and methods for capturing and processing sound are described. The microphones and microphone systems may adaptively change the direction from which sound is captured. The microphones and microphone systems avoid the need to provide arrays of microphones, while providing adaptive beamforming without a time delay between each channel of information, and multi-directional sound capture. A dependency between the frequency response and system size is also avoided.

A photoacoustic detector unit comprises a housing having an opening, and also a photoacoustic transducer designed to convert optical radiation into at least one from a pressure signal or a heat signal. The photoacoustic transducer covers the opening of the housing, such that the photoacoustic transducer and the housing form an acoustically tight cavity. A pressure pick-up is arranged in the acoustically tight cavity.

A gas detection device according to an embodiment of the present invention includes a casing and a plurality of sensor elements. The casing includes a gas introducing port, a first chamber that communicates with the introducing port, a second chamber that communicates with the first chamber, a flow limiter that limits a flow of gas from the first chamber to the second chamber, and a gas exhausting portion that communicates with the second chamber. The plurality of sensor elements are disposed within the second chamber and have different detection sensitivities depending on a gas type.

Disclosed are a photo-acoustic sensor device and a photo-acoustic sensing method of the same. The sensing method includes providing a source light in a subject and receiving an ultrasonic wave generated in the subject by the source light. The source light may have a wavelength of 1400 nm to 2500 nm in a near-infrared band.

A system for determining gas characteristics at high altitudes in embodiments of the present invention may have one or more of the following features: (a) a high-altitude balloon having one or more of the following features: (a) a balloon, (b) a balloonsat operably coupled to the balloon, (c) an air path chamber wherein gas at a high altitude can occupy the air path chamber, (d) a first speaker located on a substrate within the air path chamber, wherein the first speaker takes an electrical signal input and creates a first sound wave, and (e) a second speaker located on the substrate facing opposite of the first speaker located outside of the air path chamber, wherein the second speaker takes the electrical signal and creates a second sound wave.

The disclosure describes embodiments of an apparatus including a first gas chromatograph including a fluid inlet, a fluid outlet, and a first temperature control. A controller is coupled to the first temperature control and includes logic to apply a first temperature profile to the first temperature control to heat, cool, or both heat and cool the first gas chromatograph. Other embodiments are disclosed and claimed.

In quartz-enhanced photoacoustic spectroscopy (QEPAS), an analyte (typically in gas phase) generates a pressure wave in response to incident laser light. A quartz tuning fork (QTF) resonant at the frequency of the pressure wave transduces the pressure wave into an electrical signal. Pulsing the laser briefly reduces the amount of thermal chirp and increases the fraction of time that the laser emits at the wavelength(s) of interest. This increases the measurement efficiency. Pulsing the incident laser light with bursts of short pulses at the QTF resonant frequency increases signal strength. Exciting the sample with a two pulses at different laser wavelengths, separated by a half QTF period yields signal and background acoustic waves that partially cancel when integrated by the QTF, producing a differential measurement. Pulsing the incident laser light at a frequency faster than the gas response cut off frequency can improve the noise performance of a QEPAS measurement.

A gas sensor includes a piezoelectric substrate; a resonator in an electrode region on an upper surface of the piezoelectric substrate, the resonator including interdigital transducer (IDT) electrodes and IDT pads connected to the IDT electrodes, the IDT electrodes configured to generate a surface acoustic wave in a center region of the electrode region, the surface acoustic wave propagating in a first horizontal direction; a sensing film in the center region of the electrode region on the upper surface of the piezoelectric substrate, the sensing film including a sensing material that interacts with a target gas; and a heater in an edge region surrounding the electrode region on the upper surface of the piezoelectric substrate, the heater including heater electrodes configured to heat the sensing film and heater pads connected to the heater electrodes, the heater electrodes and the heater pads forming a closed conduction loop.

A sensor device comprises a quartz crystal microbalance (QCM) and a coating on at least a portion of a surface of the QCM, wherein the coating selectively reacts with radicals of a target gas and does not react with stable molecules of the target gas. The QCM is configured such that a resonant frequency of the QCM changes in response to reaction of the radicals of the target gas with the coating, wherein the change in the resonant frequency of the QCM correlates to an amount of the radicals of the target gas that have reacted with the coating.