No abstract

A polymer based energy harvester with wide bandwidth is designed, fabricated and tested in this work. A polymer based structure has a lower resonance frequency compared to a silicon based structure with the same dimensions due to the much lower stiffness of polymeric materials. Therefore, a polymeric energy harvester is more useful for situations with lower ambient vibration frequencies. Aluminum nitride pads are fabricated on an SU-8 membrane to convert mechanical vibration of the membrane to electrical voltage. A new and scalable microfabrication process flow is proposed to properly fabricate piezoelectric layers on SU-8 structures. The nonlinear stiffness due to the stretching strain in the membrane provides a wider harvestable frequency bandwidth than conventional linear oscillators. Wideband energy harvesters are more useful for practical applications due to uncontrollable ambient vibration frequency. The load-deflection equation of the device is calculated using finite element simulation. This equation is then used in an analytical solution to estimate the nonlinear effect of the structure. A bandwidth of ~146 Hz is obtained for the fabricated device and a maximum open circuit voltage of 1.42 V, maximum power of 1.37 µW, and power density of 3.81 µW cm−2 were measured at terminal load of 357.4 kΩ under an excitation acceleration of 4 g. A power output of 10.1 µW and power density of 28.1 µW cm−2 was estimated using a synchronized switch harvesting on interface (SSHI) electrical interface with electrical quality factor of 5. In addition, the lumped element model has been employed to investigate the scaling effect on a polymeric circular diaphragm.

No abstract

No abstract

No abstract