Self-Powered Wireless Sensor by Collecting Electromagnetic Energy in Inhomogeneous Structure

This paper presents a new scheme of self-powered sensor by collecting electromagnetic energy. A unidirectional transducer group and an inhomogeneous piezoelectric structure are created inside the transducer while propagating the unidirectionality required for low loss and receiving the convergent acoustic wave with higher power output. The acoustic waves may be converged by modifying the angle of the slope boundary and the wavelength of the incident wave. Almost all energy in a wave period is converged and gathered in a flash. Therefore the peak power output in receiving IDT may be much larger than that in input UDT. The electromagnetic energy collected from antenna can be gathered and accumulated ceaselessly, then burst in short time, thus the sensor can be deployed in longer distance than that of ordinary passive SAW sensors. Simulation and measurement demonstrate that the maximum sensing distance of the self-powered sensor is more than that of ordinary passive sensors