Neurostimulator
Methods and devices of stimulating nerves are disclosed. In one embodiment adapted for stimulating excitable tissue, the invention includes drive circuitry ( 12 ), an acoustic transducer ( 14 ) and a pair of electrodes ( 28 ).
1. An implantable neurostimulator comprising:
a first electrode electrically coupled to a first piezoelectric material;
a second electrode electrically coupled to the first piezoelectric material;
a third electrode electrically coupled to a second piezoelectric material;
a fourth electrode electrically coupled to the second piezoelectric material;
where the first piezoelectric material is configured to provide an electrical potential to biological tissue through the first and second electrodes in response to an ultrasound signal;
where the second piezoelectric material is configured to provide an electrical potential to biological tissue through the third and fourth electrodes in response to an ultrasound signal; and
where the first and second piezoelectric materials have different resonant frequencies.
2. The implantable neurostimulator of claim 1 , wherein the first and second piezoelectric materials are physically configured to facilitate insertion of the implantable neurostimulator into biological tissue.
3. The implantable neurostimulator of claim 2 , where the implantable neurostimulator is capable of being inserted into biological tissue using a 16 gauge needle.
4. The implantable neurostimulator of claim 1 , where the first and second piezoelectric materials are mechanically coupled.
5. The implantable neurostimulator of claim 1 , where the first piezoelectric material is made of a different composition than the second piezoelectric material.
6. The implantable neurostimulator of claim 1 , where the first and second piezoelectric materials have resonant frequencies that are sufficiently dissimilar such that when the implantable neurostimulator is subjected to an ultrasound signal having a frequency equal to the resonant frequency of the first piezoelectric material, the second piezoelectric material does not create a significant electrical potential.
7. The implantable neurostimulator of claim 6 , further comprising a third piezoelectric material having a resonant frequency different from the first and second piezoelectric materials.
8. The implantable neurostimulator of claim 1 , further comprising a third piezoelectric material electrically connected in series with the first piezoelectric material, where the third piezoelectric material has a resonant frequency having substantially the same as the resonant frequency as the first piezoelectric material.
9. The implantable neurostimulator of claim 8 , further comprising a fourth piezoelectric material electrically connected in series with the second piezoelectric material, where the fourth piezoelectric material has a resonant frequency substantially the same as the resonant frequency of the second piezoelectric material.