Unlocking Directional Ultrasonic Wireless Power Transfer: Frequency Tuning and Energy Transfer Enhancement with Frequency Steerable Acoustic Transducers

Ultrasonic Wireless Power Transfer (UWPT) with Guided Waves (GWs) provides a suitable solution for energizing inaccessible sensor nodes preserving materials’ integrity in structural health monitoring (SHM) scenarios. This study explores the potential of directional piezoelectric devices called Frequency Steerable Acoustic Transducers (FSATs) for power transfer applications. More in detail, a frequency tuning was performed to define the optimal frequency for transmissions along the 0° direction and a receiving circuit made up of an impedance matching network (IMN) and a voltage rectifier was studied and tested. Experimental results carried out on a 1 mm thick aluminum plate with two FSATs bonded at a 50 cm distance proved that the proposed system can supply an ultra-low power device since a maximum received power value of 7.50 mW was measured at 71.6 kHz, with a 23 V peak-to-peak voltage in transmission and a parallel inductor IMN combined with a MOSFET-based rectifier in reception.