Selective Receiver Charging using Acoustic Vibration Modes

Unlike other wireless power transfer methods that use electromagnetic waves, acoustic vibrational waves can be used to transfer power through metal structures without being shielded, which is useful for applications such as pipeline structural health monitoring, wireless sensor networks, and UAV recharging platforms. In this paper, we demonstrate, for the first time, the unique ability of acoustic power transfer to selectively charge receivers attached at different locations on a metal structure by exciting different Lamb wave vibration modes using a transmitter array. Efficiency ratios (efficiency of the targeted receiver divided by the efficiency of the untargeted receiver) as high as 55000 could be achieved, with 33% efficiency achieved at 28 kHz when transferred along a 30 inch steel tube. Finite element modeling was also used to visualize the standing wave vibration modes.