Dynamic characterization of bulk micromachined accelerometer using laser doppler vibrometer (LDV)

The paper reports dynamic characterization and performance evaluation of two out-of-plane (Z-axis) bulk micromachined piezoresistive accelerometers. Symmetric quad-beam structured bulk micromachined accelerometers with two different variations in beam length, i.e. 500 and 700 µm, keeping other parameters same, were fabricated using CMOS compatible 25 wt%. TMAH wet etching and deep reactive ion etching. Simulations for dynamic characterization were carried out using CoventorWare® and MEMS+® with MATLAB®. Furthermore, this paper reveals how a scanning laser doppler vibrometer, an instrument designed to measure vibrations of structures or objects, can be used in a non-traditional fashion to characterize MEMS accelerometer. From the frequency and transient response analysis, mode shape and resonant frequency, bandwidth, quality factor and settling time were evaluated experimentally. A comparison of simulated and experimental results is also presented, and the results are found to be in close agreement with each other.