Harvesting energy with zinc oxide bio-compatible piezoelectric material for powering cochlear implants

Efficient and uninterrupted operation of the implanted biomedical devices such as Cochlear implants demand integrated energy harvester. MEMS based piezoelectric energy harvesters are a potential solution. In a Cochlear implant the harvester has to be placed on the eardrum which vibrates as the sound waves enter the ear. If the frequency of the vibration of the eardrum matches with the resonant frequency of the energy harvester, it generates maximum voltage output which can be used to power the battery of the Cochlear implant. In this paper a novel energy harvester is designed with bio-compatible Zinc Oxide thin film (thickness 2 μm) as the piezoelectric material. The harvester is in the shape of a tapered cantilever beam with a proof mass to reduce the resonant frequency. Moreover, a perforation has been implemented on the cantilever beam in a suitable position to further reduce the resonant frequency and to increase the voltage output without increasing the length of the cantilever. The achieved resonant frequency of the final proposed structure is 126 Hz. The voltage obtained is 0.75 V at an acceleration of 0.1g at the resonant frequency. The proposed structure can be fitted easily on the eardrum and used to generate voltage from the vibration of the eardrum caused by incoming sound waves and can replace the need of recharging the battery in the Cochlear implants.