Energy harvesting from flexion motion using a flexible piezoelectric ring

In this study, we studied the performance of a ring-type energy harvester mounted on a finger flexion structure. We fabricated the harvester using a piezoelectric material, polyvinylidene fluoride, on a polydimethylsiloxane substrate. In addition, we used a finger flexion model composed of a 3D printed component and silicone (Ecoflex 00-30) to mimic the flexion motion of the human finger. We analyzed the relationship between the bending angle of the finger flexion structure and the electrical response of the ring-type energy harvester using visual results and voltage output measurements. Moreover, we conducted a parametric study to determine the effect of the design parameters of the harvester by changing the thickness and width of the piezoelectric material (polyvinylidene fluoride), the thickness of the silicone substrate (polydimethylsiloxane), and the notch orientation of the ring-shaped harvester. We found that the optimized dimensions of the ring-type energy harvester are the thickness and width of PVDF, the thickness of PDMS, and notch orientation of 28 μm, 15 mm, 1.5 mm, and 180°, respectively. Furthermore, a series of experiments were conducted under various bending angles and input frequencies, and the experimental and theoretical output powers were assessed and analyzed. We observed that the harvesting power was maximized at the matched load resistance to the impedance of the piezoelectric material and found a maximum harvesting power of approximately 230 nW.