Stroboscopic sampling moiré microscope (SSMM) for investigating full field in-plane vibration of MEMS mechanical transducers

Abstract

Precise analysis of the full-field in-plane vibration of microelectromechanical system (MEMS) transducers is crucial for assessing their device functionality and performance. As an example, in the context of frequency/amplitude modulation of Quartz Tuning Fork (QTF)-based atomic force microscopy (AFM) systems, understanding QTF’s in-plane vibration can significantly enhance accurate evaluation of tip-sample forces. Current methods, such as analytical and numerical approaches, have limitations when it comes to providing accurate measurements. To address these limitations, we proposed an experimental approach that combines stroboscopic and sampling moiré (SM) techniques. This method focuses on investigating the in-plane vibration of a QTF and utilizes the obtained results to measure the sensor’s dynamic properties such as vibration mode shape, resonance frequency ($f_0$), and quality factor ($Q$). Nanometer-scale light pulses, generated using a custom-designed stroboscope, are synchronized with the QTF’s excitation voltage to freeze the vibration effectively, enabling imaging using a standard CCD camera. Subsequently, SM analysis is employed to extract the surface vibration profile, facilitating the measurement of vibration mode shape, $f_0$, and $Q$. This technique shows promise for analyzing the dynamic behavior of various micro-devices compatible with the sample preparation process.