Self-powered Wireless Health Monitoring Supplied by Synchronized Switch Harvesting (SSH) Method

Abstract

The development of autonomous wireless sensors and actuators in order to design advanced structural health monitoring (SHM) systems is an exciting challenge for both the industrial and the academic communities. Some studies have dealt with the implementation of wireless devices. Almost all the studies about so-called autonomous systems today still require power supply. It means that a fully self-powered system has not been achieved yet. The present study shows the design of self-powered wireless health monitoring system, for which the energy is supplied by the original method called the synchronized switch harvesting (SSH) method. The piezoelectric elements and electrical circuit, located on the vibrating structure, harvest electrical energy from the direct conversion of mechanical energy vibration. Lamb wave transmission is chosen for the SHM of a composite beam of length around 30 cm. Some piezoelectric elements, used for energy harvesting and signal transmission, are located on the beam. The energy required to wake-up the micro-controller and to achieve two complete transmission cycles is only 1.5mJ. This small amount of energy can be harvested in a short time period for reasonable beam displacement levels. The study details the different trade-off concerning such a self-powered health monitoring device.