A system for measuring a gas concentration, the system including: a first oscillator including a first surface for placement in a sampling location, wherein the first oscillator oscillates at a frequency greater than 20,000 Hz but less than 300,000,000 Hz; a first counter to accumulate a count of oscillations of the first oscillator; and a comparator to calculate a difference between the accumulated counts of the first oscillator and a reference, wherein the difference calculated by the comparator is sampled at a frequency of less than 100 Hz.

Embodiments provide an odor identification system including an operation array unit including at least two or more sensors which interact with odor causative substances included in an odor factor of a gas sample, a sensor data processing unit processing data obtained by interaction with the odor factor in the operation array unit, an odor factor information storing unit storing information of the odor factor and the interaction pattern information of the odor factor in advance, and a pattern identification unit identifying the odor factor on the basis of an interaction pattern while referring to the pattern processed by the sensor data processing unit and the information of the odor factor information storing unit, and collating the interaction pattern with the known odor information, wherein the odor of the object to be measured is contained.

A method including providing an acoustic resonator having an absorption element with a surface portion, providing a sample fluid or a fluid mixture containing the sample fluid with at least one absorption fluid or particles such that the acoustic resonator is filled with the same, the surface portion of the absorption element being in contact with the sample fluid. Irradiating the surface portion of the absorption element with a first electromagnetic radiation such that the absorption element at least partly absorbs the first electromagnetic radiation in the region of the surface portion, or irradiating the fluid mixture with a first electromagnetic radiation such that the absorption fluid or the absorption particles at least partly absorb(s) the first electromagnetic radiation, and so, by way of the absorption, pressure energy is generated in the sample fluid or the fluid mixture, with the first electromagnetic radiation being amplitude modulated or frequency modulated with a modulation frequency. Measuring an acoustic response signal from the acoustic resonator. Determining at least one amplitude or phase of the acoustic response signal.

A respiratory assistance apparatus has a gases inlet configured to receive a supply of gases, a blower unit configured to generate a pressurised gases stream from the supply of gases; a humidification unit configured to heat and humidify the pressurised gases stream; and a gases outlet for the heated and humidified gases stream. A flow path for the gases stream extends through the respiratory device from the gases inlet through the blower unit and humidification unit to the gases outlet. A sensor assembly is provided in the flow path before the humidification unit. The sensor assembly has an ultrasound gas composition sensor system for sensing one or more gas concentrations within the gases stream.

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.

Embodiments provide an odor identification system including an operation array unit including at least two or more sensors which interact with odor causative substances included in an odor factor of a gas sample, a sensor data processing unit processing data obtained by interaction with the odor factor in the operation array unit, an odor factor information storing unit storing information of the odor factor and the interaction pattern information of the odor factor in advance, and a pattern identification unit identifying the odor factor on the basis of an interaction pattern while referring to the pattern processed by the sensor data processing unit and the information of the odor factor information storing unit, and collating the interaction pattern with the known odor information, wherein the odor of the object to be measured is contained.

A MEMS device for detecting particulate and gases in the air, comprising: a first semiconductor body; a second semiconductor body with a first surface facing a first surface of the first semiconductor body; and a first spacer element and a second spacer element, which extend between the first surfaces of the semiconductor bodies so as to arrange them at a distance apart from one another and define a first duct. The MEMS device further comprises at least one of the following: a first particulate sensor comprising a first emitter unit for generating acoustic waves in the first duct, and a first particulate-detection unit for detecting the particulate, the first emitter unit and the first particulate-detection unit facing one another through the first duct; and a first gas sensor, which faces the first duct and is configured to detect said gases in the air present in the first duct.

According to one embodiment, a molecular sensor contains a sensitive film in which a porous member and an ionic liquid coexist. The molecular sensor is capable of detecting a target molecule by measuring a change in physical quantity of the sensitive film due to adsorption of the target molecule to the sensitive film.

A dissipation-based sensor includes a single resonator with a nano-structured surface. The sensor exhibits improved sensitivity, up to about 2 orders of magnitude higher than a single resonator without a nano-structured surface. The sensor operates by measuring and estimating the fluid friction per oscillation cycle, operating in normal conditions without vacuum (e.g., in air or other ambient gas) at room temperature. The sensor can provide measurement data at a speed that is orders of magnitude faster than pre-existing resonance-based methods, as it is based on measurements from a few cycles only. The dissipation-based sensor may be utilized in a broad range of fast, inexpensive, hand-held measuring devices. Additionally, the sensor is capable of operating at standard temperature and pressure.

A method for determining properties of a hydrocarbon-containing gas mixture includes determining a thermal conductivity value, density measurement, viscosity measurement, and temperature and pressure. The method also includes determining a hydrogen content of the gas mixture on the basis of the thermal conductivity value and the temperature and pressure, determining a density measurement and associated temperature and pressure, and determining the mean molar mass or standard density on the basis of the density measurement and the temperature and pressure. The method further includes determining the mean molar mass or standard density of a hydrogen-free residual gas mixture based on the mean molar mass or standard density and the hydrogen fraction, determining the Wobbe index of the residual gas mixture based on the viscosity measurement and the temperature and pressure, and determining a calorific value based on the mean molar mass or standard density and the Wobbe index.