1. Micro-Power Energy Harvester Using Piezoelectric for Acoustic Sound Wave Energy Harvesting

The advancement of portable electronic devices and the ever-increasing integrated functions which have become a necessity in smartphones, tablets and similar devices have prompted the industry to look for portable power supplies to enhance the lifetime and the usage of portable electronic devices. Therefore, harvesting free energy from the surroundings to provide usable electrical energy could be an interesting solution toward this requirement. In this paper, sound waves energy which is in the form of a pressure wave is investigated to be as a source of free energy which is abundant in our surroundings. The piezoelectric type called PZT 5A bimorph cantilever was introduced as a sound energy harvester during an experimental work. The piezoelectric was tested to extract sound energy produced by the loudspeaker at several predetermined distances from the loudspeaker. The result shows that the maximum voltage of 83 mV_peak was obtained with the sound intensity of 102.6 dB at a resonant frequency of 374 Hz, and the maximum power of 3.445 µW was produced at 1 kΩ of optimal load resistance.