A MEMS gas sensor includes a photoacoustic sensor including a thermal emitter and an acoustic transducer, the thermal emitter and the acoustic transducer being inside a mutual measurement cavity. The thermal emitter includes a semiconductor substrate and a heating structure supported by the semiconductor substrate. The heating structure includes a heating element. The MEMS gas sensor further includes a chemical sensor thermally coupled to the heating element, and the chemical sensor including a gas adsorbing layer.

The present invention discloses a multi-channel aerosol scattering absorption measuring instrument, comprising a light path device, a detection device and a gas path device. The light path device supplies three different wavelengths of laser entering the detection device in sequence; the detection device is provided with photoelectric detectors at multiple angles for measurement, so as to reduce the measurement error of aerosol scattering coefficient; the gas path device comprises a sample loading unit, a calibration unit and a sample discharging unit; and a light source from the light path device and a gas flow from the gas path device enter the photoacoustic cavity of the detection device respectively and are detected by a control unit. The aerosol scattering absorption measuring instrument of the present invention is characterized by multi-channel, multi-angular, full-scale and direct measurement of scattering phase function and absorption coefficient of aerosol particles, combines the function of synchronously acquiring the optical parameters of an aerosol (such as scattering coefficient, extinction coefficient, visibility, transmittance, single scattering albedo, etc.), and achieves the integrated on-line detection of different optical parameters of an aerosol with high automation degree and good stability.

Laser-based spectroscopy systems and methods including a laser source that emits a beam of radiation, an optical resonant cavity having at least two cavity mirrors, and at least one beam filtering element positioned along a path of the beam external to the cavity and having a front surface, wherein the front surface is oriented such that an intersection of the beam and the surface is at an angle, such as the Brewster's angle or a pseudo-Brewster's, that reduces or eliminates reflection of a predominant polarization component of the beam by the filtering element.

A photoacoustic gas sensor device for deter-mining a value indicative of a presence or a concentration of a component in a gas comprises a substrate and a measurement cell body, the substrate and the measurement cell body defining a measurement cell enclosing a measurement volume. A reflective shield divides the measurement volume into a first volume and a second volume. An opening in the measurement cell is provided for a gas to enter the measurement volume. In the first volume and on a front side of the substrate are arranged: An electromagnetic radiation source for emitting electromagnetic radiation through an aperture in the reflective shield into the second volume; and a pressure transducer communicatively coupled to the second volume for measuring a sound wave generated by the component in response to an absorption of electromagnetic radiation by the component. At least a portion of a surface of the reflective shield facing the second volume is made of a material reflecting electromagnetic radiation.

Gas detection apparatus for the detection of a target gas in a gas mixture, having a radiation source, a first measurement chamber and a second measurement chamber, as well as a first and second measurement detector. A first gas mixture flows through the first measurement chamber, and a second gas mixture flows through the second measurement chamber. Electromagnetic radiation emitted by the radiation source passes initially through the first measurement chamber and subsequently through the second measurement chamber. The first measurement detector registers a physical effect in the first measurement chamber, this physical effect correlating with the intensity of the radiation passing through the first measurement chamber, and generates a first signal correlating with the physical effect. The second measurement detector is correspondingly configured for the second measurement chamber. A second measurement point is thus provided without requiring a second radiation source.

The present invention belongs to the field of trace gas detection technology and provides a multi-cavity superimposed non-resonant photoacoustic cell and gas detection system. The multi-cavity superimposed non-resonant photoacoustic cell includes a cylindrical metal shell, a plurality of non-resonant photoacoustic cavities, a sensitive diaphragm of the fiber-optic Fabry-Perot acoustic sensor, an optical glass window, an air inlet and an air outlet. The circular sensitive diaphragm of the fiber-optic Fabry-Perot acoustic sensor is fixed on one side of the cylindrical metal shell, and the other side of the cylindrical metal shell is sealed by an optical glass window. The gas to be measured enters through the inlet, diffuses into a plurality of non-resonant photoacoustic cavities, and exits through the outlet on the other side.

The technology relates to devices and methods thereof for the detection of one or more biomarkers from a user's exhaled breath. In one embodiment, the present invention provides a device comprising a metered dose inhaler, and a sensor that detects one or more biomarkers comprising HFA, CO.sub.2, and NO. In another embodiment, the device detects HFA, CO.sub.2 and NO simultaneously by photoacoustic spectroscopy. In another embodiment, the device may be used as part of an overall treatment regimen for asthma or COPD.

A device for detecting gases or particles includes a light source capable of emitting a light beam, an interaction cavity including first and second reflective walls substantially parallel with each other, a plurality of monomode optical waveguides each having a first end of width l1 optically coupled to the light source and a second end of width l2, greater than the width l1, optically coupled to a first end of the interaction cavity, each optical waveguide including in its second end of width l2 a diffraction grating having a pitch P in particular chosen as a function of a concentration C and a parameter α of interaction with the light beam of a type of gas or particle to detect; and a detector coupled to a second end of the interaction cavity.

Systems and methods for measuring the isotope ratio of one or more gaseous oxides produced during combustion of drugs, pharmaceuticals, or medicines aiming to detect counterfeit drugs, pharmaceuticals, or medicines based on comparison of the isotopic composition of the tested drugs, pharmaceuticals, or medicines with the isotopic composition of the authentic products.

In an embodiment an electro-thermal device includes a heater, a readout circuit, a digital controller having a first input coupled to a first output of the readout circuit and a digital sigma-delta modulator having a first input coupled to an output of the digital controller and an output coupled to the heater.