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Differential Thermal Conductivity CO2 Sensor

In this paper we present a novel MEMS technology for CO2 detection, based on differential thermal conductivity. Holes have been positioned across the thin-film dielectric membrane to induce an asymmetric temperature profile in conjunction with a centrally heated tungsten resistor, leading to distinct magnitudes of gas interaction across the sensor, all of which is substantiated by a numerical model. Differential readings are taken from four surrounding resistors and shown to correlate to CO2 concentration. The best resistor combination is investigated and is shown to provide a sensitivity of 0.05 mV/%CO2. Using separate heating and sensing elements greatly lowers the noise and a detection resolution of < 100 ppm is calculated. This proof-of-concept article introduces a device that could lead to low-cost, low-power, high-sensitivity, scalable gas detection.