Design and simulation of a two-axis thermal MEMS accelerometer with optimized sensitivity

In this paper a micro-accelerometer with a simple design, low fabrication cost, low volume and weight as well as sensitive to very small accelerations with acceleration measurement capability in two axes has been designed. In the proposed design, thermal-convection method has been used to measure the acceleration. This microsensor consists of a heater and two pairs detectors. By applying acceleration along the X or Y axis, a temperature change occurs in the detectors that is proportional to the acceleration applied to the system. Two stages of simulation and optimization of the micro-sensor were performed using finite element method and Taguchi method, respectively. Sensitivity is one of the most important output factors of the thermal accelerometers that geometric parameters and thermal conditions have huge effect on that. So effects of different levels of geometric and temperature variables have been studied and optimized for achieving the maximum sensitivity by analyzing the signal to noise ratio in Taguchi experimental design method. The sensitivity was improved 12.77 times compared to the average value of the simulations results, by adjusting the variables on the optimal levels. As a result, the sensitivity of 0.23 [˚c/g] for air-filled package and 0.70 [˚c/g] for CO2-filled package was obtained in this research.