Microfabricated thermal conductivity detector for the micro-ChemLab.
- University of California, Los Angeles, CA
This work describes the design, computational prototyping, fabrication, and characterization of a microfabricated thermal conductivity detector ({mu}TCD) to analyze the effluent from a micro-gas chromatograph column ({mu}GC) and to complement the detection efficacy of a surface acoustic wave detector in the micro-ChemLab{trademark} system. To maximize the detection sensitivity, we designed a four-filament Wheatstone bridge circuit where the resistors are suspended by a thin silicon nitride membrane in pyramidal or trapezoidal shaped flow cells. The geometry optimization was carried out by simulation of the heat transfer in the devices, utilizing a boundary element algorithm. Within microfabrication constraints, we determined and fabricated nine sensitivity-optimized geometries of the {mu}TCD. The nine optimal geometries were tested with two different flow patterns. We demonstrated that the perpendicular flow, where the gas directly impinged upon the membrane, yielded a sensitivity that is three times greater than the parallel flow, where the gas passed over the membrane. The functionality of the {mu}TCD was validated with the theoretical prediction and showed a consistent linear response to effluent concentrations, with a detection sensitivity of 1 ppm, utilizing less than 1 W of power.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 972450
- Report Number(s):
- SAND2005-4926J
- Journal Information:
- Proposed for publication in Sensors and Actuators B., Journal Name: Proposed for publication in Sensors and Actuators B.
- Country of Publication:
- United States
- Language:
- English
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