A 30nA quiescent 80nW-to-14mW power-range shock-optimized SECE-based piezoelectric harvesting interface with 420% harvested-energy improvement

Piezoelectric Energy Harvesters (PEHs) are usually used to convert mechanical energy (vibration, shocks) into electrical energy, in order to supply energy-autonomous sensor nodes in industrial, biomedical or domotic applications. Non-linear extraction strategies such as Synchronous Electrical Charge Extraction (SECE) [1,2], energy investing [3], and Synchronized Switch Harvesting on Inductor (SSHI) [4] have been developed to maximize the extracted energy from harmonic excitations. However, in most of today's applications, vibrations are not periodic and mechanical shocks occur at unpredictable rates [4]. SSHI interfaces naturally seem as the most appropriate candidates for harvesting shocks as they exhibit outstanding performance in periodic excitations [4]. However, the SSHI strategy presents inherent weaknesses while harvesting shocks, since the invested energy stored in the piezoelectric capacitance cannot be recovered.