Wireless vibration sensor using frequency modulation technique

In recent years, wireless strain sensors have received attention as an efficient method to measure response of a structure in a remote location. Wireless sensors developed for remote measurement include RF wireless sensor modules and microstrip antenna-based sensors. In this paper, a simple wireless vibration sensor based on a piezoelectric sensor and the Frequency Modulation (FM) technique is developed for remote measurement of vibrating structures. The piezoelectric sensor can generate a voltage signal proportional to dynamic strain of the host structure. The voltage signal is then frequency modulated and transmitted wirelessly to a remote station by a simple FM transmitter circuit. Finally, the received signal is demodulated by a conventional FM radio circuit, and the vibration measurement data can be recovered. Since this type of wireless sensor employs a simple FM circuit, they do not require any wireless data transmission protocols allowing a low-cost wireless sensor in compact format. The proposed concept of the wireless vibration measurement is experimentally verified by measuring vibration of an aluminum cantilever beam. The proposed sensor could potentially be an efficient and cost effective method for measuring vibration of remote structures for dynamic testing or structural health monitoring.