Kerr noise L-shaped beam MEMS MEMS accelerometer MEMS sensors MEMS technology MEMS-IMU MEMS-IMU accelerometer Taguchi method WiFi-RSSI radio map acceleration accelerometer activity monitoring angular-rate sensing auto-encoder body sensor network built-in self-test capacitive accelerometer capacitive transduction cathode tips array classification of horse gaits dance classification deep learning delaying mechanism digital resonator electromechanical delta-sigma electrostatic stiffness fault tolerant field emission frequency