Publication

Gas pressure measurement device

Ian Michael Rousseau, Pirouz Sohi
2019
Patents

Abstract

The present invention concerns vacuum pressure gauge or gas pressure measurement device comprising a polar semiconductor structure, at least one light source for illuminating a surface of the polar semiconductor structure, measurement means configured to measure a value representing a gas adsorption rate or a change in gas adsorption rate on the surface of the polar semiconductor structure, comparison means configured to compare said measured value with at least one predetermined setpoint value representing a balance between photoinduced desorption and gas adsorption on the surface of the polar semiconductor structure and control means configured to change an optical output power of the light source to match or substantially match said measured value with said setpoint value.

Official source

https://infoscience.epfl.ch/entities/publication/3ba3fdec-935b-4145-ae92-f7fdadf25e53

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Ian Michael Rousseau, Pirouz Sohi
2019
Patents

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/3ba3fdec-935b-4145-ae92-f7fdadf25e53

About this result

Related concepts (13)

Adsorption

Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) is dissolved by or permeates a liquid or solid (the absorbent). Adsorption is a surface phenomenon and the adsorbate does not penetrate through the surface and into the bulk of the adsorbent, while absorption involves transfer of the absorbate into the volume of the material, although adsorption does often precede absorption.

Langmuir adsorption model

The Langmuir adsorption model explains adsorption by assuming an adsorbate behaves as an ideal gas at isothermal conditions. According to the model, adsorption and desorption are reversible processes. This model even explains the effect of pressure i.e. at these conditions the adsorbate's partial pressure, , is related to the volume of it, V, adsorbed onto a solid adsorbent. The adsorbent, as indicated in the figure, is assumed to be an ideal solid surface composed of a series of distinct sites capable of binding the adsorbate.

Pressure swing adsorption

Pressure swing adsorption (PSA) is a technique used to separate some gas species from a mixture of gases (typically air) under pressure according to the species' molecular characteristics and affinity for an adsorbent material. It operates at near-ambient temperature and significantly differs from the cryogenic distillation commonly used to separate gases. Selective adsorbent materials (e.g., zeolites, (aka molecular sieves), activated carbon, etc.) are used as trapping material, preferentially adsorbing the target gas species at high pressure.

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