Understanding Cellular Energy Harvesting through Piezoelectric Polymers with Cellular Interfaces

Abstract

There is emerging interest in designing systems that are capable of harvesting energy from living tissue. These systems have potential applications in powering medical implants such as microdevices, actuators, and electronically active tissue engineering grafts. Specific attention has focused on the manipulation of system and substrate geometries to control biomimetic tasks using external electric fields1. To make these devices more feasible for in vivo usage without the need for external energy sources or stimuli, the concept of a cardiomyocyte pump has beendemonstrated using only chemical energy input to cells as a driver2. The current work describes advances in materials design and cellular integration to produce a piezoelectric system that is powered by mechanical cell contractions. Poly(vinylidene fluoride) (PVDF) is a piezoelectric material that will be driven by cardiomyocytes. Nanofibrous PVDF mats are fabricated with an electrospinning process. The chemical and electrical properties of piezoelectric PVDF films are characterized by FT-IR and voltage measurements under controlled deflection, respectively. Mimicking the highly oriented nature of human tissue and muscles may improve control/cell response; achievable with films of anisotropically aligned nanofibers. In addition to affecting the mechanical properties of such films, this macroscopic alignment has been shown to improve cell adhesion, proliferation and alignment. Anisotropic PVDF films are fabricated by modified electrospinning methods. Murine cardiomyocytes were differentiated on these films and the generated electrophysiological response of the cells was measured using a highly sensitive ammeter. This work demonstrates that aligned piezoelectric substrates are suitable for cell-based energy harvesting. These materials are conformal, can be potentially integrated with organ scale systems, and may be scaled to power microelectronic medical implants.1 Feinberg, A. et al., Science 317, 1366-1370 (2007).2 Tanaka, Y. et al., Lab on a chip 7, 207-212 (2007).