MEMS-based power generation system using contractile force generated by self-organized cardiomyocytes

This paper describes a novel hybrid mirco electro mechanical system (MEMS)-based power generation system that uses the contractile forces generated by self-organized cardiomyocytes. By directly seeding and culturing cardiomyocytes on a diaphragm made from single crystal lead magnesium niobate-lead titanate (PMN-PT), cell-driven electrical power generation can be easily realized: The mechanical stress induced by the contraction forces generated by self-beating cardiac cells is converted into electrical power by the piezoelectric effect. The PMN-PT materials are selected because not only of their highly favorable piezoelectric properties but also of their relatively low Young's modulus and biocompatibility. The low Young's modulus makes it possible for these materials to respond sensitively to external forces with a low frequency, and they are nontoxic for the culture of cardiac cells. The PMN-PT single crystal diaphragm used in this study is based on a one-sided, interdigitated, electrode design, which enables the use of a high piezoelectric d₃₃ coefficient and thereby allows effective energy conversion. Moreover, by adopting this design, electrodes can be isolated from the cell culture medium naturally and cardiac cell contraction can be observed under an inverted microscope through the gap between the electrodes. After four days of in vitro, the output voltage is measured to range from 1.48 to 4.19 mV. This proposed power generation mechanism is also proven to be feasible by the simulations of a multiphysics finite element model (FEM). In conclusion, we demonstrate our system to be a potentially useful micropower source either for micro/nano-robots or for micro-implantable devices. The same system can also be a useful test bed for the quantitative understanding of temporal cardiac cell dynamics.