This disclosure presents a process to determine characteristics of a subterranean formation proximate a borehole. Borehole material can be typically pumped from the borehole, though borehole material can be used within the borehole as well. Extracted material of interest can be collected from the borehole material and prepared for analyzation. Typically, the preparation can utilize various processes, for example, separation, filtering, moisture removal, pressure control, cleaning, and other preparation processes. The prepared extracted material can be placed in a photoacoustic device where measurements can be taken, such as a photoacoustic imager or a photoacoustic spectroscopy device. A photoacoustic analyzer can generate results utilizing the measurements, where the results of the extracted material can include one or more of fracture parameters, fracture plane parameters, permeability parameters, porosity parameters, and composition parameters. The results can be communicated to other systems and processes to be used as inputs.

An apparatus for capturing a target analyte in advance of performing spectroscopic analysis to determine the existence of the target analyte from a source contacted with a collection substrate. The collection substrate is fabricated of a material selected to have an affinity for the target analyte, sufficiently transparent in a spectral region of interest and capable of immobilizing the target analyte thereon in a manner that limits scattering sufficient to obscure spectral analysis. The collection substrate may be coated with a material selected to react with, bind to, or absorb the target analyte. The target analyte may be captured to the collection substrate by one or more of wiping, dabbing or swabbing a target analyte carrier with the collection substrate.

A gas sensing device includes a photoacoustic spectrometry device, including a radiator for emitting light, a gas detection chamber for exposing a mixture of gases to the light, a microphone for detecting sound in the detection chamber, which is caused by exposing the mixture of gases to the light, and wherein the photoacoustic spectrometry device generates signal samples corresponding to a concentration of the gas in the mixture of gases based on the sound detected by the microphone, and a computing device for receiving the signal samples. The computing device includes a feature extraction block including a trained model algorithm block.

A photoacoustic gas sensor device is proposed for determining a value indicative of a presence or a concentration of a component in a gas. The photoacoustic gas sensor device comprises a substrate, and a measurement cell body arranged on a first side of the substrate. The substrate and the measurement cell body define a measurement cell enclosing a measurement volume. The measurement cell comprises an aperture for a gas to enter the measurement volume. The device further comprises an electromagnetic radiation source for emitting electromagnetic radiation, and a microphone for measuring a sound wave generated by the component in response to an absorption of electromagnetic radiation by the component. The electromagnetic radiation source and the microphone are arranged on the first side of the substrate and in the measurement volume. The microphone has a bottom port facing the substrate, and the measurement volume is communicatively coupled to the bottom port.

The present disclosure relates to the technical field of fiber-optic gas sensing and laser photoacoustic spectroscopy, and reliability of a gas detection system is improved by actively selecting a working frequency of low noise interference combined with an optical fiber photoacoustic sensing probe capable of isolating high-frequency noise. A gas enters a photoacoustic microcavity through gaps on a sound-sensitive diaphragm after diffusing into a miniature air chamber through a plurality of micropores. Photoacoustic excitation light is incident into the photoacoustic microcavity through a fiber-optic collimator and then excited to generate a photoacoustic pressure wave to cause the sound-sensitive diaphragm to vibrate periodically. An end face of a single-mode optical fiber and the sound-sensitive diaphragm constitutes a fiber-optic Fabry-Perot interferometer. The interferometer measures a deflection of the diaphragm and inverts a concentration of the to-be-measured gas.

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 detector cell for a photoacoustic gas sensor comprises a first layer structure, a second layer structure arranged at the first layer structure and comprising a membrane structure, and a third layer structure arranged at the second layer structure. The first layer structure and the third layer structure hermetically enclose a cavity, wherein the membrane structure is arranged in the cavity.

In a first aspect, the invention relates to a method for detecting aerosol particles in ambient air by means of a photoacoustic gas sensor, wherein an analysis volume is present in the beam path of a modulable emitter such that the emitter can use modulable radiation to excite aerosol particles in the analysis volume to form sound pressure waves which are detectable by means of the sensor. Using the modulable emitter, the analysis volume is irradiated with the modulated radiation to generate sound pressure waves. The generated sound pressure waves are measured by means of the sensor, whereby the presence and/or concentration of the aerosol particles in the ambient air is determined on the basis of the measurement results. Particularly preferably, the aerosol particles are bioaerosols, preferably pollen, spores, bacteria and viruses. In a further aspect, the invention preferably relates to a photoacoustic gas sensor suitable for carrying out the method.

The invention relates, in a first aspect, to a photoacoustic spectroscope for analyzing gas, comprising an infrared emitter (3), which can be modulated, an analysis volume (1), which can be filled with gas, and a sound pressure detector. The sound pressure detector comprises a structure (5) capable of vibrating, an actuator and a measurement unit, wherein the actuator is configured to actively excite vibration of the structure (5) capable of vibrating and the measurement unit can measure the vibration properties of the structure (5) capable of vibrating, which measurement depends on the formation of the sound pressure waves.

In an additional aspect, the invention relates to a method for analyzing gas, comprising the provision of a photoacoustic spectroscope for analyzing gas, irradiating the gas with infrared radiation, modulated by a modulation frequency, to generate sound pressure waves, exciting the structure (5) capable of vibrating at an excitation frequency, measuring the vibration properties of the structure (5) capable of vibrating, which measurement depends on the sound pressure, and determining the sound pressure of the gas based on the measured vibration properties.

The invention relates to a modulatable infrared emitter comprising an aperture structure, a structured micro-heating element, and an actuator, wherein the aperture structure and the structured micro-heating element are movable relative to each other in parallel planes by means of the actuator to modulate the intensity of emitted infrared radiation. The invention further relates to methods of manufacturing the infrared emitter, a method of modulating emission of infrared radiation using the infrared emitter, and preferred uses of the infrared emitter. In further aspects the invention relates to a system comprising the infrared emitter and a control device for regulating the actuator.