Optimized Design of the MEMS-Based Three-Axis Thermal Accelerometer for Its Better Performance in a Wide Measurement Range

A new design of the three-axis thermal accelerometer with a set of temperature sensing elements (thermistors) in the direction of each axis located on a thin-film SiO2 membrane is proposed. Finite-element study of the accelerometer with the selected design shows that the temperature difference between the symmetrically placed thermistors linearly increases with acceleration in the range from 1g to 10g. At the same time, with increasing their distance from the central heater the sensitivity of thermistors reaches a maximum value, and then gradually drops to zero near the edge of the membrane. It was also found that in order to achieve the maximum thermal sensitivity when detecting acceleration in the lateral direction, thermistors should be asymmetrically placed relative to the heater along the corresponding axis, and the asymmetry of their optimal location on the membrane increases with acceleration. The results obtained can be used to improve the design of MEMS (Micro-Electro-Mechanical-System) accelerometers based on thermal effects.