Piezoelectric Buckled Beam Array on a Pacemaker Lead for Energy Harvesting

Abstract

DOI: 10.1002/admt.201800335 in microfabrication and bioengineering allow for implantable pacemakers and AICDs at a small size with a satisfactory level of reliability. However, the typical estimated lifetime of the batteries used in those devices is only a few years.[3] The periodic surgeries to remove and replace the depleted lithium-based batteries of the implanted biomedical devices may cause health risks of serious complications for the patients (especially high risks for children and sicker patients), and certainly increase healthcare costs from the economic aspects. Therefore, energy consumption and battery replacement are key to the longevity and effectiveness of implantable biomedical devices. This work is essentially an effort toward the development of power solution for implanted biomedical devices such as cardiac pacemakers and AICDs. With the advances in low power consumption for implantable biomedical devices,[4–8] there is a growing interest to make them self-sustainable by having their own renewable power supply. Harvesting energy in the body has become increasingly attractive as a means to convert various in vivo energy sources into electrical power due to the sufficient powering ability.[9] Reported implantable energy harvesters have utilized the available energy from the pulsation of ascending aorta,[10] breathing,[11] legs’ motion,[12] and beating heart.[13–18] Among various in vivo energy sources in the body, the motion of the heart is particularly compelling, and is of interest for cardiac energy harvesting and further powering implantable biomedical devices. For example, implantable triboelectric nanogenerators (iTENG) have been employed to make use of heart beats to power wireless communication for real-time cardiac monitoring.[14] In another application, iTENG converted the mechanical energy from the contraction from breathing of a rat into electricity to further power a pacemaker.[19] Moreover, in vivo piezoelectric based energy harvesting devices have been conducted intensively to power implanted biomedical devices. For instance, a single crystalline (1 − x) Pb (Mg 1/3 Nb 2/3) O 3 − xPbTiO 3 (PMN-PT) was implanted into the heart of a live rat to show functional electrical stimulation of the heart.[15] Heartbeats of pigs were used to power wireless communication Self-sustainable energy generation represents a new frontier to significantly extend the lifetime and effectiveness of implantable biomedical devices. In this work, a piezoelectric energy harvester design is employed to utilize the bending of the lead of a cardiac pacemaker or defibrillator for generating electrical energy with minimal risk of interfering with cardiovascular functions. The proposed energy harvester combines flexible porous polyvinylidene fluoride–trifluoroethylene thin film with a buckled beam array design for potentially harvesting energy from cardiac motion. Systematic in vitro experimental evaluations are performed by considering complex parameters in practical implementations. Under various mechanical inputs and boundary conditions, the maximum electrical output of this energy harvester yields an open circuit voltage (peak to peak) of 4.5 V and a short circuit current (peak to peak) of 200 nA, and that energy is sufficient to self-power a typical pacemaker for 1 d. A peak power output of 49 nW is delivered at an optimal resistor load of 50 MΩ. The scalability of the design is also discussed, and the reported results demonstrate the energy harvester’s capability of providing significant electrical energy directly from the motions of pacemaker leads, suggesting a paradigm for biomedical energy harvesting in vivo.