Integration of a torsion-based shear-mode energy harvester and energy management electronics for a sensor module

This work demonstrates the ability of a torsion-based shear-mode energy harvester to power a sensor module by integrating a temperature sensor circuit with a purpose developed piezoelectric energy harvester. A 10-cm ³ energy harvester was developed for this application and was found to produce over 200 µW of maximum power through an optimal load resistance under 0.25 g _pk acceleration excitation at its resonant frequency of 237 Hz. This harvester was then tested with two interface circuits: a standard interface diode bridge rectifier and a nonlinear synchronous electrical charge extraction circuit that were compared for their suitability in powering the sensor module. Through this, the synchronous electrical charge extraction nonlinear conditioning circuit was found to have superior performance when charging a capacitor and with DC loads at low voltages and was capable of providing a maximum power output of 37 µW under 0.25 g _pk acceleration at 237 Hz. This output power was then used to successfully power a temperature sensor module consisting of a temperature sensor, a microcontroller, and a radio-frequency identification memory chip at a sensing frequency of 0.5 Hz.