Evaluation of an Optical Energy Harvester for SHM Application

In this paper a preliminary study on an array configuration of rectified optical nanoantennas for energy harvesting (EH) application is proposed. Currently, the major impediments for the use of the rectenna device are the relatively low conversion efficiency and low power transfer to the load, both of them caused mainly by the mismatch between the impedance of the rectifier (several kilo ohms) and that of the antenna (hundreds of ohm). For this reason, the design of the array represents a crucial point to obtain the maximum energy transfer from the rectenna to the load, represented as a typical DC/DC boost power converter, and modeled by an equivalent input impedance. The novelty of this study confirms that it is possible to obtain dynamically an impedance matching between the array of optical rectennas and the load. According to this method, in the proposed rectenna array, N elements can be serially connected so to allow to the open circuit voltage to be increased and M elements can be parallel connected to give the degree of freedom needed to achieve the impedance matching with the load. Finally, a case study for Structural Health Monitoring (SHM) application is presented.