A micromachined gas sensor based on a catalytic thick film/SnO2 thin film bilayer and thin film heater

Abstract

A micromachined gas sensor based on a catalytic thick film/SnO 2 thin film bilayer and a thin film heater was investigated for CH 4 sensing. The sensor demonstrated good sensitivity and high selectivity with low power consumption. The thin film heater and the SnO 2 thin film sensing layer were deposited on a Si micromachined structure having a silicon oxide-silicon nitride membrane. On the SnO 2 sensing layer, a Pd-Al 2 O 3 catalytic thick film was formed to oxidize interfering gases selectively. The sensor realized low power consumption and fast thermal response due to the low thermal conductance and the small heat capacity of the membrane. The power consumption at an operating temperature of approximately 450 • C was 30 mW. The sensitivity (R air /R gas ) to 2000 ppm CH 4 in air was greater than 5, while the sensitivity to H 2 , an interfering gas, was relatively low.

Optimization of power consumption for gas sensor nodes: A survey

“…At the same time, the sensor design guarantees more than 10 millions of heating cycles [33] that are enough for several years of operation.…”

“…The catalyst sensors have a dielectric support impregnated by Pt and Pd metals. The power consumption of these sensors during methane monitoring varies between 30 and 120 mW in continuous measurement mode [32] [33] . To the best of our knowledge the most energy efficient catalytic sensor is presented in Fig.…”

A high-temperaturein situcell with a large solid angle for fluorescence X-ray absorption fine structure measurement

“…Pt-doped SnO 2 (Pt-SnO 2 ) thin film deposited on the SnO 2 sensor film shows a high methane sensitivity with a low power consumption and this opens a new way to realize battery-driven gas sensors. [30][31][32][33] Using the fluorescence XAFS to study the local structure of Pt in this fresh Pt-doped SnO 2 film at room temperature, we found that the Pt took a solid solution structure, being located at the Sn position of the SnO 2 lattice. 34 In literatures, a Pt metal cluster is considered to be an active structure in the reaction.…”

Recent Developments in Modulation Spectroscopy for Methane Detection Based on Tunable Diode Laser

“…Therefore, a fast, accurate, and precise monitoring of trace greenhouse gas of CH 4 is essential. There are some methods for detecting methane, including chemical processes [3][4][5][6] and optical spectroscopy [7][8][9]. Optical spectroscopy for detecting gases is based on the Beer-Lambert law [10][11][12], in which the light attenuation is related to the effective length of the sample in an absorbing medium, and to the concentration of absorbing species, respectively.…”