Method of manufacturing implantable wireless acoustic stimulators with high energy conversion efficiencies
Receiver-stimulator with folded or rolled up assembly of piezoelectric components, causing the receiver-stimulator to operate with a high degree of isotropy are disclosed. The receiver-stimulator comprises piezoelectric components, rectifier circuitry, and at least two stimulation electrodes. Isotropy allows the receiver-stimulator to be implanted with less concern regarding the orientation relative the transmitted acoustic field from an acoustic energy source.
1. A method for manufacturing an implantable receiver-stimulator for converting an acoustic field to electrical power comprising the steps of:
forming an insulating layer on an electrically conductive sheet;
forming a circuit pattern on the insulating layer; electrically connecting a first plurality of acoustic piezoelectric components to the circuit pattern on the sheet;
electrically connecting a plurality of individual rectifier circuits to the circuit pattern on the sheet, the rectifier circuits configured to convert electrical power output from the piezoelectric components to a biologically stimulating electrical output;
electrically connecting the biologically stimulating electrical output to a pair of stimulation electrodes; and folding the sheet into an octagonal or otherwise substantially cylindrical can structure, thereby arranging the acoustic piezoelectric components such that acoustic energy is harvested efficiently from any direction of the propagating acoustic field.
2. The method of claim 1 , wherein the acoustic piezoelectric components are composed of a piezoelectric material, optionally wherein the piezoelectric material is one of a poly crystalline ceramic piezoelectric material or a single crystal piezoelectric material.
3. The method of claim 2 , wherein the piezoelectric components are in the shape of a cuboid, wherein one of the faces of the cuboid is mounted to the circuit pattern on the sheet.
4. The method of claim 1 , wherein the rectifier circuitry comprises one or more rectifiers connected in parallel and protection circuitry to protect the rectifiers from damage due to voltages above approximately 4V.
5. The method of claim 4 , wherein the protection circuitry comprises a Zener diode or a series of GaAs Schottky diodes.
6. The method of claim 1 , further comprising: affixing an end cap to the can structure, the end cap having a second plurality of acoustic piezoelectric components composed of a piezoelectric material, wherein the second plurality of piezoelectric components has a piezoelectric axis that is substantially perpendicular to that of the first plurality of piezoelectric components.