Piezo Electric Energy Harvesting System

Background: Pacemakers and other similar implantable medical devices suffer from theshortcoming of limited battery life. When the useful life of the batteries powering thesedevices has expired, surgical procedures are usually necessary to replace them. Like allsurgeries, these procedures involve undesirable risk to the patient, patient discomfort, andutilization of healthcare resources that could be put to other uses. Therefore reducing oreliminating the need for performing these replacement procedures is desirable.  

Invention: This system allows for the harvesting of the body’s mechanical energy (e.g. fromthe heart cycle of contraction-relaxation) and subsequent conversion into electrical energyusing piezeoelectric materials. The piezoelectric materials are monolithically integratedwith rectifiers and millimeter-scale batteries, allowing for concurrent power generation andstorage of harvested electrical energy. The components of this system are coated in abiocompatible material with superior mechanical properties that allow for a uninhibitedorgan motion while avoiding delamination of the system. These Mechanical EnergyHarvesting (MEH) units are arranged in the body with other, identical units in order toincrease the power generation capability of the entire system. Results from bovine andovine models indicate that such a system is easily capable of generating enough power tooperate a cardiac pacemaker.

Application: This invention is capable of being used to power not only pacemakers, but alsoother implantable microelectronic devices such as heart rate monitors, cardioverter-defibrilators, neurostimulators, etc. The market and number of potential applications forthis invention is expected to grow as advances in the field of implantable microelectronicdevices increase the prevalence and types of said devices. Additionally, this invention mayalso be adapted for skin-mounted configurations, capable of producing power for not onlyhealth and wellness devices, but potentially non-biomedical devices, eliminating orreducing the need to replace the batteries of these devices as well.

Advantages: This invention has been shown to be superior to the state of the art in in vivoexperiments in bovine and ovine models.

•Output open-circuit voltages and short-circuit currents are 3 and 5 orders of magnitudegreater, respectively, than those achieved in previous in vivo experiments

•Piezoelectric material monolithically integrated with rectifiers and millimeter scalebatteries for simultaneous power generation and storage.

•Results indicate power production levels that are easily enough to power a cardiacpacemaker.

•Utilizes biocompatible materials with superior mechanical properties; also inducesnegligible constraints on motion of organs on which it is implanted – no detectable changesin cardiac conduction/epicardial motion even when affixed to the epicardium in in vivoresults.

•Mechanically and electrically stable device behavior over 20 million cycles ofbending/unbending in moist hydrogel environment.

•Maintains conformal contact with the heart, without delamination of the device, during theentire cycle of cardiac motion (contraction to relaxation).