Piezoelectric energy harvesting for bio Mems applications

Abstract

This chapter presents an analysis of piezoelectric unimorph diaphragm energy harvesters as a potential tool for generating electrical energy for implantable biomedical devices. First the chapter discusses current and developing biomedical devices that require energy, and the need for capture of energy from the environment of the implant. Next, a general discussion of piezoelectric harvesters is presented, and a case is made for the use of 31 mode diaphragm harvesters for conversion of energy from blood pressure variations within the body. The chapter then presents derivations of available electrical energy for unimorph diaphragm harvesters, starting with general boundary conditions, and then proceeding to simply supported and clamped conditions of various piezoelectric and electrode coverage. Using these analytical results, the chapter ends with by presenting a brief set of numerical results illustrating the amount of power that could be harvested for a particular size of device, and how that power may be used as a source for a given implanted medical device. In summary, it is shown that the harvester could potencially provide enough power to operate a 10 mW device at reasonable intermittent rates. The relationships provided here may enable other optimal designs to be realized, for medical or for many other applications. © 2009 Springer US.