Fabrication and Characterization of a Novel Micro-Thermal Conductivity Detector for Monitoring Small-Molecule Gases

Abstract

In this work, a novel micro-thermal conductivity detector (microTCD) with high sensitivity has been introduced, in which the two Pt-resistors on the same arm (reference arm or test arm) are arranged in parallel in the same thermal conductivity cell. The fabrication of the sensors is realized by micro-electro-mechanical system (MEMS) technology. A model of this microstructure is simulated in COMSOL that couples electrical and thermal physics together. Modeling results show that the temperature difference of this design between the platinum resistor ( ${T}_{f}$ ) and the thermal conductivity cell ( ${T}_{w}$ ) is maximum (more than 100 °C). Moreover, this configuration has good thermal isolation, improving the sensitivity of the sensor. Simultaneously, compared with the previous structure of two heat transfer cells with one platinum resistor in each arm, the two Pt-resistors on the same arm have more consistent resistance, reducing the baseline and improving the sensitive. The experimental results demonstrate that the fabricated microTCD can rapidly detect small molecular gas with detection limit of 5 ppm and quantitative repeatability of 0.82%.