Improved energy harvesting from a clamped–clamped micro beam with cavity

Abstract

This paper presents modelling and numerical evaluation of a piezo electrically excited clamped–clamped micro beam (CCMB) with cavity as a vibrational energy harvester. The harvester micro beam is made to vibrate at resonance by piezoelectric excitation to resemble the ambient vibration conditions. The generated voltage from the CCMB with cavity is found to be higher when compared to a similar CCMB without cavity. An analytical expression for the output voltage is derived for a particular actuation voltage at resonance and further analysis is also carried out by varying the position and thickness of the cavity to extract maximum output voltage from the CCMB harvester with and without cavity. The analytical results are well supported by numerical simulation results that are carried out in COMSOL Multiphysics FEM tool. The introduction of cavity in CCMB increases the generated peak output voltage when compared with CCMB without cavity. The proposed CCMB harvester design with cavity can also be replaced by bridge resonators in various MEMS/NEMS based sensors with piezoelectric excitation and detection.