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Calorimetric gas sensor

United States Patent

5,834,627
November 10, 1998
View the Complete Patent at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
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.
Ricco; Antonio J. (Albuquerque, NM), Hughes; Robert C. (Cedar Crest, NM), Smith; James H. (Albuquerque, NM), Moreno; Daniel J. (Albuquerque, NM), Manginell; Ronald P. (Albuquerque, NM), Senturia; Stephen D. (Brookline, MA), Huber; Robert J. (Bountiful, UT)
Sandia Corporation (Albuquerque, NM)
08/ 766,142
December 17, 1996
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with Government support under Contract DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.