Highly stretchable energy harvester using piezoelectric helical structure for wearable applications

Proposed is a helical piezoelectric structure for a highly stretchable energy harvester to be applied on the human body. The proposed device consists of two counter-wound helical structures around a zcore structure made of an elastic fabric string. The inner fabric helix is used to separate the outer piezoelectric helix from the core to obtain a highly stretchable device. When stretched by 60% of its initial length, the device generates a maximum output voltage and power of 140 Vp-p and 0.6 mW, respectively, at an operation frequency of 4 Hz.