MEMS piezoresistive accelerometer sensor for gait analysis

Microelectromechanical Systems (MEMS) based accelerometers have been reported as one of the most popular applications in sensing methods. For establishing the microsystem technology, Finite Element Analysis (FEA) has been reported as the most time and cost effective way to build a model for simulation. Present work focuses on designs, analysis and simulations of MEMS piezoresistive accelerometer sensor for gait analysis of different size. The structure of the accelerometer is chosen to reduce the cross-axis sensitivity by selecting an appropriate material and suitable design parameters. The accelerometers are doped with p-type (boron diffused) silicon as their piezoresistor. A solid model has been simulated using COMSOL Multiphysics software to find von mises stress, displacement and sensitivity of the proposed designs. The designed accelerometers are based on the piezoresistive effect where the value of a resistor changes with applied mechanical stress. The changes in the resistors values are then converted to an output voltage using a Wheatstone bridge. The simulation shows that Design 1 has maximum value of spring constant and maximum displacement which is 91800N/m and 9.21x10-8 μm respectively. Design 2 has maximum value of Von mises stress which is 0.001684MPa while Design 3 has the lowest value of spring constant, 3400N/m.