Calorimetric gas sensor

Patent · Wed Dec 31 23:00:00 EST 1997

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 CORP
• 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

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