A measuring device for determining a gas concentration includes a gas-sensitive element, a sensing device, a stimulation unit, and a processing unit. The gas-sensitive element is configured to absorb a gas. The sensing device is configured to determine a parameter of the gas-sensitive element in a predetermined time period, where the parameter depends on an absorbed quantity of the gas. The stimulation unit is configured to stimulate the gas-sensitive element and accelerate desorption of the gas out of the gas-sensitive element. The processing unit is configured to determine a rate of change of the parameter, to control the stimulation such that a concentration of the gas in the gas-sensitive element lies outside of an equilibrium state, and to determine the gas concentration based on the rate of change.

A gas analyzer uses continuous sonic signals through a conduit to determine the composition of a gas in the conduit. A transmitting transducer drives sonic signals at a fixed frequency and a second transducer receives the sonic signals. The phase shift between two signals corresponds to the speed of sound through the gas and is related to the composition of the gas. The electronic versions of these signals are processed by lowering, or dividing, the fixed frequency which expands the range of phase shift measurement and allows the determination of an expanded range for the gas composition. In an ozone generation system, the gas analyzer is highly suitable for determining the composition of gases derived from air as a gas of known composition and a calibration point.

According to an embodiment, a sensor arrangement comprises a first micropump, e.g. a microfluidic or peristaltic pump, having a normally closed (NC) safety valve, e.g. at the micropump output, a second micropump, e.g. microfluidic or peristaltic pump, having a normally closed (NC) safety valve, e.g. at the micropump output, and a sensor having a sensor chamber, e.g. a sensor cavity or sensor volume, with a sensor element, e.g. an active sensitive region or layer, in the sensor chamber, wherein the sensor is configured to provide a sensor output signal based on a condition of the fluid, e.g. a gas or liquid, in the sensor chamber. The sensor chamber of the sensor is fluidically coupled between the first and second micropump, and the first and second micropump are configured to provide a defined operation mode of the sensor arrangement based on the respective activation or operation condition of the first and second micropump for providing (1.) a defined negative fluid pressure in the sensor chamber, (2.) a defined positive fluid pressure in the sensor chamber or (3.) a defined fluid flow, e.g. fluid throughput, through the sensor chamber.

A measurement apparatus includes: a number concentration measurement device configured to measure a number concentration of particles in a air; a humidity measurement device configured to measure a humidity of the air; and a air concentration measurement device configured to measure a concentration of a specific air in the air, wherein a mass concentration of the particles in the air is calculated based on a measured number concentration, a measured humidity, a measured concentration of the specific air, and a predetermined correlation between the number concentration, the humidity, and the concentration of the specific air, and the mass concentration of the particles in the air.

A system for determining ozone concentration in ice includes at least one emitter and first and second detectors. The emitter can be a light source including visible and UV light components, or the emitter can be a first emitter for emitting UV light and a second emitter for emitting visible light. The UV and visible light components can be directed through a sample of ice. The transmitted UV and visible light components can be detected by UV and visible light detectors. The amount of UV and visible light received by the detectors can be compared to levels of UV and visible light emitted by the emitter(s) can be used to determine the concentration of a dissolved gas (e.g., ozone) in the sample of ice.

A method of spectroscopically assessing the chemical composition of a bubble while the bubble constrains a gas within the interior of the bubble by passing light passing through the bubble and comparing properties of the light before and after the light has passed through the bubble. The bubble is located, preferably compressed between a first plate and a second plate providing a compressed bubble with relatively flat first polar end wall portion adjacent the first plate in a relatively flat second polar end wall portion adjacent a second plate and directing the light to pass through the bubble via the first and second polar end wall portions.

An apparatus includes an emitter, the emitter comprising an ultraviolet light emitting diode (UV-LED) and being disposed on a first end of a bounded volume suitable for holding a liquid. The liquid may have a negative Langelier saturation index (LSI). The bounded volume can be a chamber, a tank, or the like. The apparatus includes a detector, the detector comprising an ultraviolet light sensor (UV sensor) and being disposed on a second end of the bounded volume, the second end being opposite the first end, wherein the UV-LED comprises a point source, and wherein the emitter generates a parallel beam of light.

A resistive metal oxide gas sensor comprises a support structure and a porous sensing layer (1) arranged on the support structure or partly housed therein. Electrodes (2) are in electrical communication with the porous sensing layer (1), and a heater (3) is in thermal communication with the porous sensing layer (1). The heater (3) can be operated to heat the porous sensing layer (1) to a target temperature for allowing a determination of the presence or the concentration of a target gas, i.e., ozone, based on a sensing signal supplied via the electrodes (2). The porous sensing layer (1) comprises a network of interconnected monocrystalline metal oxide nanoparticles (14) and a gas-selective coating (12) of the network. A thickness (t1) of the porous sensing layer (1) is at most 10 pm. The coating (12) comprises one or more of silicon oxide and silicon nitride, and is of a thickness (t12) of less than 5 nm.

Embodiments of the present invention relate to an apparatus for detecting ozone in ambient air, including an absorption cell with a bounded chamber for receiving air sample for analysis, a light source positioned to transmit light through absorption cell, a detector positioned to measure the attenuation of light passing through absorption cell, a pumping system for transporting ambient air into chamber and then reversing direction to transport ozone-free air into the absorption cell for purging the chamber, a scrubber positioned downstream from outlet port of the absorption cell to remove ozone from sample air exiting the absorption cell, a relative humidity (RH) equalizer for controlling humidity of sample air exiting absorption cell such that the sample entering scrubber has relatively the same humidity as ambient air, and a data system for digitizing and processing output from detector.

A method of measuring a gas concentration is described. The method comprises illuminating, with a light source, a volume of space that includes a gas and measuring, with a detector, a first illumination level of the volume of space. The method further comprises determining, via a processor, a gas concentration in the volume of space based on the measured first illumination level, where the volume of space is configured to be in fluid communication with a gas recirculation flow path including a catalyst, the catalyst configured to substantially remove the gas from the volume of space.