Feasibility of B-mode diagnostic ultrasonic energy transfer and telemetry to a cm2 sized deep-tissue implant

While radio-frequency based remote powering and back-telemetry is popular for many of the surface implants, like neural prosthesis or under-the-skin implanted batteries, it is not suitable for implants located deep inside the tissue. In this paper, we investigate the feasibility of using a commercial off-the-shelf (COTS), diagnostic ultrasound technology for delivering energy to a sub-cm² sized device implanted at depths more than 10cm away from the tissue surface. Using a COTS 3.5MHz ultrasound scanner we show how the B-mode interrogation protocol can be used to deliver energy to an encapsulated PZT transducer and how the B-mode video sequence can be parsed to retrieve the data from the transducer. In this paper we also discuss the limits of energy transfer at different implantation depths and we also discuss the energy requirements at the implant to achieve robust data transfer.