Design and analysis of a triple-axis thermal accelerometer

In this paper, the authors propose a triple-axis MEMS-based thermal accelerometer and analyze its sensitivity and response. Thermal accelerometers detect acceleration by measuring the deflection of a heat plume in a microchamber. Usually, the heat plume is created by a heater on the top of a microcavity. By the use of computational fluid dynamics, the measurement ability of the sensor was analyzed for different positions of the heater. The results showed that the conventional designs where the heater located at the cavity center could measure only two components of acceleration vector, since the large cross-sensitivity between vertical and horizontal measurements cannot be avoided. In contrast, in our novel design, the heater formed a wide loop rounding the cavity center so that the mutual effects of these measurements were significantly reduced. For instance, the cross sensitivities were less than 5 % for acceleration up to 10 g applied to any directions. Furthermore, with the new position of the heater a frequency bandwidth at 3 dB of 70 Hz was obtained with applying a sinusoidal acceleration.