Development of an Electrostatic Generator that Harnesses the Motion of a Living Body : Use of a Resonant Phenomenon

We aimed for permanently supplying the electrical energy to an apparatus for in vivo use such as a cardiac pacemaker and proposed and developed an electrostatic (ES) generator that harnesses the motion of the living body. The generating system consists of a battery as an initial charge supply (ICS), a variable capacitor (VC) in which mechanical energy is converted to electrical energy, a capacitor for energy storage and two rectifiers. In this study, an ES generator which does not consume electrical energy of the ICS was used. Since high frequency driving of the VC leads to large power generation, it is effective to introduce a resonant phenomenon. A honeycomb-type variable capacitor whose capacitance varies from approximately 32 to 200 [nF] was used as the VC. The resonator (resonant frequency 4.76 [Hz]) which consists of a honeycomb-type VC, tension coil springs and mass was made. It was possible to generate electrical power of 58 [muW] in case of the ICS with constant voltage of 24 [V] and a load with resistance of 1.0 [M Omega]. We found that use of resonant phenomenon was effective to increase generated power.