Dynamic time reversal acoustic focusing of ultrasound for biomedical applications

Time Reversal Acoustic (TRA) system provides effective focusing in inhomogeneous media that can be used in various biomedical applications including high intensity ultrasound treatment, ultrasound-assisted drug delivery, ultrasonic battery charging of implants, etc. In many cases the temporal variation of propagating media properties leads to a degradation of the focusing. The in situ adjustment of radiated TRA signal is required in order to restore focusing. We present the feedback algorithm with Tikhonov regularization that enables the refocusing of acoustic field based on the changes in the focused signal received by a beacon. Temporal and spatial quality of the feedback refocusing was characterized experimentally using hydrophone and compared with standard TRA focusing. Algorithm is applicable for power delivery to implantable wireless cardiac pacemakers, percutaneous devices and neuro-stimulators.