Multi-frequency MEMS sensor for single-point source localization in dispersive media using modal acoustic emission and wavelet transformation

The conventional method for one-dimensional acoustic emission (AE) source localization relies on two sensors to calculate the time-of-flight (TOF) and subsequently determine the source location given the wave speed. However, this method encounters inaccuracies when applied to dispersive mediums. To address this challenge, we suggest a novel method for single-sensor source localization. This method leverages multi-frequency Micro-Electro-Mechanical Systems (MEMS) equipped with sixteen resonators, each tuned to a specific frequency within the 100 kHz to 700 kHz range. By employing the wavelet transformation technique, we can determine the arrival times of these sixteen unique frequencies. By incorporating these arrival times with the dispersion curve, obtained from numerical simulation, it becomes possible to pinpoint the acoustic emission source location using just one AE sensor. Initial experimental validation conducted on a steel plate demonstrated the method's validity, achieving approximately 90% accuracy in source localization. This technique not only streamlines the process by eliminating the need for multiple sensors but also provides reliable source localization results in dispersive mediums.