1 3 Microsyst Technol DOI 10.1007/s00542-014-2316-3 TECHNICAL PAPER Dynamic characterization of bulk micromachined accelerometer using laser doppler vibrometer (LDV) A. Sharma · R. Mukhiya · S. Santosh Kumar · R. Gopal · B. D. Pant Received: 23 August 2014 / Accepted: 28 August 2014 © Springer-Verlag Berlin Heidelberg 2014 1 Introduction With the evolution of emerging micro-electro-mechanical systems (MEMS)-based mechanical micro structures/sen- sors, it has become difficult to adopt conventional design, testing, and characterization methods, because of the reduc- tion of device structures to micrometer regime (Speller et al. 2002; Rinaldi et al. 2004). Another problem encountered during the characteriza- tion of MEMS devices is the decoupling of electrical and mechanical effects. Mechanical problems such as a spuri- ous resonance can be caused simply by the physical geom- etry of the structure. Likewise, an electrical spike in the output of the device can happen entirely by the electronic component of the device. These electrical and mechanical effects can easily be superimposed and masked by each other at the device and or system level (Speller et al. 2002; Rinaldi et al. 2004). Moreover, the problem can be further compounded when mechanical phenomena are stimulated by the electrical components of the device and vice versa. When the device measures a mechanical phenomenon and has an electrical output, it is difficult to determine the root cause of the observed behavior. In the present work, to evaluate the dynamic perfor- mance of bulk micromachined accelerometer sensor, laser doppler vibrometer (LDV) was used. To excite or actuate the accelerometer sensor, a piezoelectric disc was used. In order to eliminate the response from the piezo disc and to observe the accelerometer vibration, dual-beam meas- urements were performed. LDV technique offers many unique advantages for MEMS characterization and trouble- shooting. LDV measurements are electrically inert and do not introduce mechanical artifacts, they are ideally suited for dynamic characterization of the accelerometer sensor (Speller et al. 2002; Rinaldi et al. 2004). Abstract The paper reports dynamic characterization and performance evaluation of two out-of-plane (Z-axis) bulk micromachined piezoresistive accelerometers. Sym- metric quad-beam structured bulk micromachined acceler- ometers 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 Coventor- Ware ® 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 char- acterize MEMS accelerometer. From the frequency and transient response analysis, mode shape and resonant fre- quency, 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. A. Sharma · R. Mukhiya (*) · S. Santosh Kumar · R. Gopal · B. D. Pant MEMS and Microsensors Group, CSIR-Central Electronics Engineering Research Institute (CEERI), Pilani 333031, India e-mail: ravindramukhiya@rediffmail.com B. D. Pant e-mail: bdpant@ceeri.ernet.in R. Mukhiya · S. Santosh Kumar · R. Gopal · B. D. Pant Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India