Process challenges of MEMS harvesters and their effect on harvester performance

In this paper we present process challenges for the fabrication of energy harvesters and how they affect the performance. For the piezo harvesters, improved etching recipes and packaging enables to reduce the variation in resonance frequency from 8 to 1.5%. Similar results were obtained for electrostatic harvesters. For thermal harvesters, we find that when reducing dimensions, the output voltage will increase, but also the contact resistance R_c. By optimizing the material stack, R_c has been reduced by two orders of magnitude, tripling the output power.