Acoustic polarization for optimized implantable power transimittion

We present a fully-packaged acoustic power receiver which is implantable in the subcutaneous tissue to receive the acoustic energy generated from a compressive wave emitter on the skin. The implanted receiver is a piezoelectric acoustic transducer and is packaged by biocompatible cohesive gels. This specific package is soft enough to absorb the incident wave from the subcutaneous tissue. The receiver employs direct charging to convert the acoustic energy into the extractable electrical energy through piezoelectricity when exposed to the acoustic field. The effects of the scattering package shape and the stiffness ratio between the package and subcutaneous tissue are considered to design the receivers. The energy efficiency of the fabricated receiver is measured inside real streaky pork, which is used to simulate human subcutaneous tissue. The result indicates that the spherical package is more suitable than the cubic one when they are buried in the fatty layer. The maximum efficiency of the power transmission is found to be -40dB. © 2007 IEEE.