Calorimetric gas sensor

Patent · Thu Jan 01 00:00:00 EST 1998

OSTI ID:871967

Ricco, Antonio J ^[1]; Hughes, Robert C ^[2]; Smith, James H ^[1]; Moreno, Daniel J ^[1]; Manginell, Ronald P ^[1]; Senturia, Stephen D ^[3]; Huber, Robert J ^[4]

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1. Albuquerque, NM
2. Cedar Crest, NM
3. Brookline, MA
4. Bountiful, UT

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.

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-94AL85000
• Assignee: Sandia Corporation (Albuquerque, NM)
• Patent Number(s): US 5834627
• OSTI ID: 871967
• Country of Publication: United States
• Language: English

Related Subjects

calorimetric
gas
sensor
combustible
resistively
heated
noble
metal-coated
micromachined
polycrystalline
filament
calorimetrically
detect
presence
concentration
gases
filaments
tested
date
thick
times
10
wide
100
250
500
1000
m-long
overcoated
25
m-thick
protective
cvd
layer
catalytic
film
deposited
precursor
acac
microfilaments
approximately
degree
deposits
hot
constant-resistance-mode
feedback
circuit
pt-coated
operating
300
35
mw
input
power
respond
linearly
terms
change
supply
current
required
maintain
constant
resistance
temperature
concentrations
ppm
80
20
mixture
materials
combustible gases
feedback circuit
input power
noble metal
combustible gas
catalytic material
gas sensor
hot filament
resistively heated
catalytic materials
noble metal-coated
micromachined polycrystalline
maintain constant
filaments tested
calorimetrically detect
/73/422/