Development of an energy harvesting device with a contactless plucking mechanism driven by a skeletal muscle

Abstract

We propose an energy harvesting device driven by the contraction of an electrically-stimulated skeletal muscle that can be used as an alternative to batteries for implantable medical devices. In order to realize a durable generator, this device has a contactless plucking mechanism comprising parallel leaf springs and magnets, with which the generator can be driven without friction. By utilizing this mechanism, the generator can be driven not only in the contraction phase of the muscle, but also during relaxation. For the design we optimized the stiffness of the springs, the gap between the magnets, and the magnetic circuit in order to maximize the power generated. The power generated by a prototype in a benchtop experiment was 35.8 μW, which is sufficient to drive an implantable medical device. Furthermore, we evaluated the power generated in an ex-vivo experiment in which the gastrocnemius muscle of a toad weighing 193.4 g was electrically stimulated to drive the mechanism. In this experiment, 18.1 μW of power was generated from a skeletal muscle weighing only 3.5 g. It was also confirmed that the power generated exceeded the power required to electrically stimulate the skeletal muscle. The results showed the feasibility of an energy harvesting system utilizing the proposed mechanism.