Portable Energy-Logger Circuit For The Experimental Evaluation Of Energy Harvesting Solutions From Motion For Wearable Autonomous Sensors

In this paper, a portable battery-powered energy-logger circuit to monitor the energy harvested by different piezoelectric converters mounted on selected positions of the human body under typical daily activity is proposed. The circuit logs on an SD memory card both the rms value of the acceleration imparted to the Energy Harvesting ( EH) converter under test and the time intervals needed to achieve a predefined amount of energy stored on capacitors. The energy-logger circuit was tested with three different types of piezoelectric EH converters under different excitation conditions allowing to measure an effectiveness index given by the time necessary to accumulate the energy required to power one operating cycle of the autonomous sensor module representing the load. (C) 2014 Published by Elsevier Ltd.