DocumentCode :
1019356
Title :
Hotplate-based monolithic CMOS microsystems for gas detection and material characterization for operating temperatures up to 500°C
Author :
Barrettino, Diego ; Graf, Markus ; Song, Wan Ho ; Kirstein, Kay-Uwe ; Hierlemann, Andreas ; Baltes, Henry
Author_Institution :
Phys. Electron. Lab., Swiss Fed. Inst. of Technol., Zurich, Switzerland
Volume :
39
Issue :
7
fYear :
2004
fDate :
7/1/2004 12:00:00 AM
Firstpage :
1202
Lastpage :
1207
Abstract :
Two monolithic CMOS microsystems for gas detection and material characterization fabricated in industrial 0.8-μm CMOS technology combined with post-CMOS micromachining are presented. The first microsystem comprises an array of three microhotplates, and three single-ended proportional temperature controllers (one controller per microhotplate), which regulate the microhotplate temperature up to 350°C using a polysilicon resistor as a temperature sensor on the microhotplate. The second microsystem comprises one microhotplate, and a fully differential proportional temperature controller, which regulates the microhotplate temperature up to 500°C using a platinum (Pt) resistor as a temperature sensor on the microhotplate. For gas sensing applications, the microhotplates were covered with tin dioxide (SnO2), which changes its conductivity upon exposure to gaseous analytes. Gas tests evidenced a detection limit of 0.2 ppm for carbon monoxide (CO). For material characterization, the microhotplates were covered with ammonium nitrate (NH4NO3), which exhibits a melting point of 169.6°C according to the CRC handbook of chemistry and physics. The measured melting point was 168±2°C. Temperature sensors, on- and off-membrane (near the circuitry), showed excellent thermal isolation between the heated membrane area and the circuitry area on the bulk chip (overall chip temperature rose by max 3°C at 500°C microhotplate temperature).
Keywords :
CMOS integrated circuits; calorimeters; gas sensors; temperature sensors; thermistors; 169.6 C; CMOS monolithic metal-oxide gas sensors; CMOS technology; NH4NO3; Pt; SnO2; bulk chip; circuitry area; conductivity; gas detection; gas sensing applications; heated membrane area; hotplate-based monolithic CMOS microsystems; material characterization; melting point; micro-calorimeters; microhotplates; platinum resistor; polysilicon resistor; post-CMOS micromachining; single-ended proportional temperature controllers; temperature control; temperature sensor; thermal isolation; CMOS technology; Circuits; Gas industry; Micromachining; Proportional control; Resistors; Sensor arrays; Temperature control; Temperature sensors; Textile industry; CMOS monolithic metal–oxide gas sensors; material characterization; microcalorimeters; microhotplate; temperature control;
fLanguage :
English
Journal_Title :
Solid-State Circuits, IEEE Journal of
Publisher :
ieee
ISSN :
0018-9200
Type :
jour
DOI :
10.1109/JSSC.2004.829929
Filename :
1308598
Link To Document :
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