Calorimetric gas sensor
US5834627A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1996 |
| Grant date | Nov 10, 1998 |
| Priority date | — |
| Expiry date | Dec 17, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/16
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A combustible gas sensor that uses a resistively heated, noble metal-coated, micromachined polycrystalline Si filament to calorimetrically detect the presence and concentration of combustible gases. The filaments tested to date are 2 .mu.m thick.times.10 .mu.m wide.times.100, 250, 500, or 1000 .mu.m-long polycrystalline Si; some are overcoated with a 0.25 .mu.m-thick protective CVD Si.sub.3 N.sub.4 layer. A thin catalytic Pt film was deposited by CVD from the precursor Pt(acac).sub.2 onto microfilaments resistively heated to approximately 500.degree. C.; Pt deposits only on the hot filament. Using a constant-resistance-mode feedback circuit, Pt-coated filaments operating at ca. 300.degree. C. (35 mW input power) respond linearly, in terms of the change in supply current required to maintain constant resistance (temperature), to H.sub.2 concentrations between 100 ppm and 1% in an 80/20 N.sub.2 /O.sub.2 mixture. Other catalytic materials can also be used.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.