Design of resonant accelerometers based on DETF structure

Abstract

Motion sensors are widely used nowadays. They can easily be seen from the insertion into smart phones and gaming consoles such as iPhone and Wii's console. In this regard, studying in the design of sensor's primary components becomes a very hot topic. In this project, the characteristics and the functions of resonant accelerometer based on silicon structure are introduced. Two double-ended tuning forks are used as the force sensor to estimate the acceleration according to the change of resonant frequency caused by the inertial force acting on the forks. Sensing capacitor and driving capacitor with finger combs structure are designed to do the sensing process and resonating process in the accelerometer. The resonant push-pull differential accelerometer was fabricated by a silicon-on-insulator micromachining (SOIMUMPs) process, with resonant frequency 102.86 kHz which is confirmed by experimental value of 104.675 kHz. The sensor's sensitivity and quality factor are experimented by a set of equipment. The equipment includes two clampers, a ruler, a network analyzer (Range from 1 kHz to 8 MHz), a signal amplifying circuit and a vacuum chamber. The sensor's quality factor is analyzed through the experiment. Also, the sensitivity of the accelerometer shows a linear relationship between the frequency shifts of the sensor with the change of acceleration.