Energy harvesting mechanism for medical devices
Embodiments of the invention provide apparatus, systems and methods for harvesting energy from bio-kinetic events to power various implanted medical devices. One embodiment provides an energy harvesting mechanism for a cardiac pacemaker comprising an energy converter and a signal path component. The energy converter is positionable inside a human body and configured to generate electric power signals in response to a bio-kinetic event of the human body such as a heart beat, respiration or arterial pulse. The converter can comprise a piezoelectric material which generates electricity in response to mechanical deformation of the converter. The converter can also have a power generation characteristic that is matched to the frequency of the bio-kinetic event. For heart beat powered applications, the power generation characteristic can be matched to the physiologic range of pulse rates.
1. An energy harvesting mechanism for a cardiac pacemaker, the mechanism comprising:
a deformable energy converter positionable inside a human body to generate electric power signals in response to a bio-kinetic event of the human body, a portion of the energy converter being at least partially formed by a material which directly converts mechanical deformation of the converter caused by the bio-kinetic event into the electric power signals, the energy converter having a stiffness/flexibility which varies over a length of the energy converter so that the energy converter provides a resonant frequency within a normal physiological range of the bio-kinetic event when the converter is deformed; and
a signal path component structured to enable the power signals to be carried from the energy converter to the cardiac pacemaker.
2. The mechanism of claim 1 , wherein the frequency is between 40 to 180 times per minute.
3. The mechanism of claim 1 , wherein the signal path component comprises a cable that provides a pace making signal to a heart.
4. The mechanism of claim 3 , wherein the energy converter is positioned within the cable.
5. The mechanism of claim 4 , wherein the cable is adapted to be positioned proximate to the heart wall in order to provide a pace making signal for the heart.
6. The mechanism of claim 4 , wherein the cable includes at least one wire that provides at least a portion of the signal path.
7. The mechanism of claim 4 , wherein the energy converter is coaxial with respect to the cable.
8. The mechanism of claim 4 , wherein the energy converter has a form factor which does not change the form factor of the cable without the energy converter.
9. The mechanism of claim 1 , wherein the energy converter is positioned to deform in response to the bio-kinetic event in order to generate the electric power signals.
10. The mechanism of claim 1 , wherein the energy converter comprises a piezo-electric material.
11. The mechanism of claim 1 , wherein the energy converter is shaped to be cylindrical when in a non-deformed state.
12. The mechanism of claim 1 , wherein the bio-kinetic event is a heartbeat, a respiration or an arterial pulse.
13. The mechanism of claim 1 , wherein the energy converter functions as a sensor to sense a property of a heart.
14. The mechanism of claim 13 , wherein the property is one of a heart rate, heart rhythm, arrhythmia, heart wall motion or heart wall motion abnormality.
15. The mechanism of claim 13 , wherein the energy converter generates one of a voltage or current wave form that is used to sense the property of the heart.
16. The mechanism of claim 1 , further comprising:
a rechargeable power supply coupled to the signal path component to receive electrical energy generated by the energy harvesting mechanism.
17. The mechanism of claim 16 , wherein the rechargeable power supply is a battery or a capacitor.
18. The mechanism of claim 1 , wherein the energy converter generates an AC signal.
19. The mechanism of claim 1 , further comprising:
a rectifying device to rectify an AC signal generated by the energy converter into a DC signal.
20. The mechanism of claim 1 , wherein the energy converter generates sufficient power to autonomously power the pacemaker from motion of a beating heart.
21. The mechanism of claim 1 , wherein the energy converter generates up to about 20 mW of power from motion of a beating heart.
22. The mechanism of claim 1 , wherein the energy converter includes a first energy converter positioned in a first location and a second energy converter positioned at a second location.
23. The mechanism of claim 22 , wherein the first energy converter is configured to generate energy during a first portion of the bio-kinetic event and the second energy converter is configured to generate energy during a second portion of the bio-kinetic event.
24. The mechanism of claim 23 , wherein the bio-kinetic event is a heartbeat, and the first portion of the event is systole and the second portion is diastole.