A photoacoustic detector for detecting a gas which includes a resonant cavity having an inner wall capable of absorbing electromagnetic radiation and a passageway for circulating the gas through the resonant cavity. The detector also includes an electromagnetic source for generating an electromagnetic energy and an optical window associated with the electromagnetic source for introducing the electromagnetic energy into the resonant cavity towards the absorbing inner wall surface, thereby preventing the electromagnetic energy from radiating throughout the whole length of the resonant cavity. A pressure sensor is provided for detecting a pressure signal inside the resonant cavity which is representative of the gas being detected. A method is also provided for detecting a gas using the photoacoustic detector.

A gas sensing device includes a dielectric substrate, a heater integrated into a first side of the substrate and an insulating dielectric formed over the heater. A gas sensing layer is formed on a second side of the substrate opposite the first side. Contacts are formed on the gas sensing substrate. A noble material is formed on a portion of the gas sensing layer between the contacts to act as an ionizing catalyst such that, upon heating to a temperature, adsorption of a specific gas changes electronic properties of the gas sensing layer to permit detection of the gas.

A system for determining angular position includes a dipole magnet having an axis of rotation, wherein the dipole magnet produces a magnetic field. A first magnetic field sensor produces a first output signal and a second magnetic field sensor produces a second output signal in response to the magnetic field. The magnetic field sensors are operated in a saturation mode in which the magnetic field sensors are largely insensitive to the field strength of the magnetic field. Thus, the first output signal is indicative of a first direction of the magnetic field and the second output signal is indicative of a second direction of the magnetic field. Methodology performed by a processing circuit entails combining the first and second output signals to obtain a rotation angle value of the magnet in which angular error from a stray magnetic field is substantially cancelled.

Apparatuses for controlling gas flow are important components for delivering process gases for semiconductor fabrication. In one embodiment, a method of calibrating an apparatus for controlling gas flow is disclosed. Specifically, the apparatus may be calibrated on installation using a two-step process of measuring the volume of gas box downstream from the apparatus by flowing nitrogen gas into the gas box and measuring the resulting temperature and rate of pressure rise. Using the computed volume of the gas box, a sweep of several mass flow rates may be performed using the process gas and the gas map for the process gas. The apparatus is calibrated based on the measured temperature and pressure values, which allow calculation of the actual mass flow rate for the process gas as compared with the commanded mass flow rates.

Apparatuses for controlling gas flow are important components for delivering process gases for semiconductor fabrication. In one embodiment, a method of calibrating an apparatus for controlling gas flow is disclosed. Specifically, the apparatus may be calibrated on installation using a two-step process of measuring the volume of gas box downstream from the apparatus by flowing nitrogen gas into the gas box and measuring the resulting temperature and rate of pressure rise. Using the computed volume of the gas box, a sweep of several mass flow rates may be performed using the process gas and the gas map for the process gas. The apparatus is calibrated based on the measured temperature and pressure values, which allow calculation of the actual mass flow rate for the process gas as compared with the commanded mass flow rates.

A combustible gas sensor for detecting an analyte gas includes a first element including a first electric heating element, a first support structure on the first electric heating element and a first catalyst supported on the first support structure and electronic circuitry in electrical connection with the first element. The electronic circuitry is configured to operate in a first mode in which the first element is operated at a first temperature at which the first catalyst catalyzes combustion of the analyte gas, and in a second mode wherein the first element is operated at a second temperature which is below the temperature at which the first catalyst catalyzed combustion of the analyte gas but at which Joule heating of the first element occurs. The electronic circuitry is further configured to measure a variable in the second mode related to a mass of the first element.

A system for comparative pressure measurement includes a measuring chamber filled with a gas mixture having a gas pressure. A first sensor is arranged in the measuring chamber. The first sensor is adapted to measure the gas pressure independently of a type of the gas mixture. A second sensor is arranged in the measuring chamber. The second sensor is adapted to measure the gas pressure based on a known dependency from a type of the gas mixture. An evaluation unit determines a state of the gas mixture based on the gas pressure values measured by the first pressure sensor and the second pressure sensor at the same time.

A system for comparative pressure measurement includes a measuring chamber filled with a gas mixture having a gas pressure. A first sensor is arranged in the measuring chamber. The first sensor is adapted to measure the gas pressure independently of a type of the gas mixture. A second sensor is arranged in the measuring chamber. The second sensor is adapted to measure the gas pressure based on a known dependency from a type of the gas mixture. An evaluation unit determines a state of the gas mixture based on the gas pressure values measured by the first pressure sensor and the second pressure sensor at the same time.

A moisture detecting bleeder material includes a fiberglass material and a moisture absorption indicator material. The moisture absorption indicator material undergoes a color change from a first color to a second color when exposed to moisture. The color change thermally irreversible a temperature of 450 F.

Some implementations can include a computer-implemented method and/or system for medical gas inspection and electronic inspection report generation.