Gas sensors
US7242479B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 21, 2006 |
| Grant date | Jul 10, 2007 |
| Priority date | — |
| Expiry date | Apr 21, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/02872
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
Abstract
The present invention relates to a device for accomplishing noise reduction in a photoacoustic gas detector using a sound damping element and/or a background or reference microphone where a preferably larger external volume that acts as a sound damping element (SDE) is coupled to a smaller volume through which the gas diffuses. The coupling is accomplished in such a way that the externally generated sound waves incident upon the photoacoustic detector are adequately attenuated by the larger volume SDE without adversely affecting diffusion of the gaseous species of interest through the smaller volume for measurement by the detector. Preferably this is accomplished by coupling the larger SDE volume to the smaller gas diffusion volume by a long and thin pressure channel. Another photoacoustic detector includes a measuring system to measure the photoacoustic excitation of analyte gas entering the photoacoustic detector, a reference system to measure the effect of pressure waves in the environment, and a system for offsetting an output from the measuring system with an output from the reference system to reduce noise resulting from pressure waves in the environment in an output signal o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.