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.

An apparatus comprising: a void; an interferometer detector; and light guide means for guiding a light signal along a light path to the interferometer detector wherein the light path comprises a cantilever light guide that is supported such that a free-end can move within the void and the interferometer detector is configured to detect a deflection of the free-end of the cantilever light guide; and a reflector, wherein the cantilever light guide comprises a light outcoupler configured to out-couple the light signal to extend the light path from the cantilever light guide to the reflector.

A system for measuring gas concentration includes a package having a cavity and a port, a photoacoustic gas sensor device within the package, and a Micro Electro Mechanical System (MEMS) valve separate from the photoacoustic gas sensor device placed over the port of the package and to allow ambient gas diffusion into the cavity in a first mode of operation, and to prevent ambient gas diffusion into the cavity and to acoustically isolate the cavity in a second mode of operation.

Methods include treating a portion of a sample composition to be tested for presence of an analyte by depleting or blocking the target analyte. The treated composition may be used to equilibrate an acoustic wave sensor prior to exposing the sensor to the untreated sample composition for analysis. By using the treated sample composition, in which the analyte is depleted or blocked, to equilibrate the sensor, the sensor may be equilibrated with a composition having a similar viscosity and non-specific binding characteristics to the untreated sample composition, which should result in improved accuracy when analyzing the analyte in the untreated sample composition.

A photoacoustic sensor device may include a housing and first and second ceramic cavity packages disposed in the housing. The first ceramic cavity package may include a first sidewall having a first set of electrical contact elements, a first cavity structure, and a light source electrically coupled to the first set of electrical contact elements. The second ceramic cavity package may include a second sidewall having a second set of electrical contact elements, a second cavity structure, and a photoacoustic detector electrically coupled to the second set of electrical contact elements. The first and second ceramic cavity packages may be arranged such that the light source and the photoacoustic detector face one another, and oriented such that the first and second sets of electrical contact elements align with electrical contact points of a PCB when the photoacoustic sensor device is positioned over the PCB for coupling to the PCB.

According to a first aspect of the present invention, there is provided a method for transmitting and/or receiving an optical signal through a fluid, the method comprising: using a pressure wave to cause a change in refractive index in the fluid, the change in refractive index causing a waveguide to be formed; and transmitting and/or receiving the optical signal through the waveguide.

A photoacoustic sensor comprises an emitter for emitting electromagnetic radiation at a first wavelength and electromagnetic radiation at a second wavelength, wherein the first wavelength is for photoacoustically detecting particulate matter in a measurement cavity and the second wavelength is for photoacoustically detecting the particulate matter and at least one target gas in the measurement cavity. The photoacoustic sensor further comprises an acoustic transducer for transducing a first acoustic signal into a first sensor signal depending on an interaction of the electromagnetic radiation at the first wavelength and the particulate matter, and for transducing a second acoustic signal into a second sensor signal depending on an interaction of the electromagnetic radiation at the second wavelength with the particulate matter and the at least one target gas.

A photoacoustic device for detecting gas includes a photoacoustic cavity having a side wall extending between a first end and a second end and having an outer surface; a light source suitable for emitting a modulated light radiation, and coupled to the first end; a microphone coupled to the side wall, the photoacoustic cavity being made of a material transparent to the light radiation of the light source; a mirror being arranged on at least one portion of the outer surface of the side wall; and the side wall having a thickness chosen as a function of the depth of penetration of a thermal wave coming from the mirror into the transparent material.

A photo-acoustic gas sensor may include a detector component. The detector component includes a package that defines a reference volume. The reference volume houses a reference gas. The detector component includes a pressure sensing element to measure an amount of pressure in the reference volume. The amount of pressure in the reference volume depends on absorption of a wavelength of light by the reference gas in the reference volume. A sensitivity of the pressure sensing element when measuring the amount of pressure in the reference volume depends on a length of a reference path associated with the reference volume. The detector component includes a reference path structure that causes the length of the reference path to be less than or equal to 0.5 millimeters.

A photoacoustic gas analyzer, including: a gas chamber to receive a gas to be analyzed; a radiation source that emits into the gas chamber electromagnetic radiation with a time-varying intensity to excite gas molecules of N mutually different gas types the concentrations of which are to be determined in the received gas, wherein the radiation source is operable in N mutually different modes, each mode having a unique emission spectrum different from the emission spectra of the other N-1 modes; an acoustic-wave sensor that detects acoustic waves generated by the electromagnetic radiation emitted into the gas to be analyzed; and a control unit to operate the radiation source in the different modes respectively to emit electromagnetic radiation with a time-varying intensity; to receive in each mode from the acoustic-wave sensor signals; and to determine from the signals received in each mode the concentrations of the N mutually different gas types.