PROJECT SUMMARY Batteries for automatic implantable cardiac defibrillators (AICDs) typically need to be replaced every 5-7 years, whereas the average post-implantation longevity of AICD recipients with congestive heart failure (CHF) has increased to over 15 years. This mismatch poses a significant and ever-growing clinical and economic burden, since replacing the battery requires surgical intervention. Reducing the number of replacement surgeries will both prevent morbidity and lower costs. In the U.S. alone, AICD battery replacement costs billions of dollars each year, and reducing or eliminating these costs is clearly an imperative with health care reform. An innovative solution to increase AICD battery lifetimes is to harness the robust intrinsic energy of the heart and convert it to electrical power. Few successful studies on implantable energy generators have been reported however, and current piezoelectric generators are unsuitable for implantable applications due to low energy density or poor biocompatibility. In our preliminary studies, we have demonstrated that increasing the porosity of poly(vinylidene fluoride) (PVDF) structures increases their compressibility, resulting in higher piezoelectric efficiency. The hypothesis of this proposal is that flexible and conformable porous PVDF polymer films embedded inside AICD leads, or as stand-alone leads, can convert the mechanical motion of the heart into electrical energy by exploiting the high piezoelectricity efficiency of the PVDF film. In our specific aims, we will first develop flexible micro-power generators made of porous PVDF layers that can be interfaced with current AICD lead technology. Secondly, we will design computational models for porous PVDF structures and cardiac energy harvesting devices to allow for optimal design and power efficiency. In parallel, two types of bistable structures fabricated through strain engineering will be explored as energy harvesting devices, and their performance will be optimized using computer simulations. Thirdly, in vitro quantification and testing of the micro-power generator in an animal model of canine will be carried out to evaluate the clinical potential of our approach. Our research will support the development of a broad class of tunable porous nanomaterial networks capable of high efficient energy conversion, with potentially far-reaching applications in biomedical engineering.

PROJECT NARRATIVE Energy consumption and battery replacement are among the most challenging problems in the field of permanently implanted biomedical devices. Current piezoelectric generators are not suitable for implantable applications due to their low energy density or poor biocompatibility. The goal of this project is to design, characterize, optimize and test flexible porous polymer film power generators that convert cardiac motion into electrical power to recharge automatic implantable cardiac defibrillators (AICD).