Bistable programmable origami based soft electricity generator with inter-well modulation

Abstract

Kresling origami features an axial compression and torsion coupled motion mechanism. The nonlinear stiffness is generated by this unique deformation mode, allowing Kresling origami to be employed in wave propagation control, mechanical storage devices, digital computing, and soft robotics. In this paper, a soft bistable electricity generator is developed based on Kresling origami. This soft electricity generator is capable of initiating inter-well motion for broadband energy harvesting at low frequency and low amplitude excitation based on delicately designed structural parameters, programmable bistable energy landscape and soft origami structure fabrication. Two asymmetric potential energy wells are obtained through combining the elastic potential energy of the origami structure with the gravitational potential energy of top mass. The prototype of the bistable Kresling origami structure is fabricated by a two-step mold procedure and the theoretical model is verified through quasi-static and dynamic experiments. The number of the stable states is tunable and the energy curve is programmable by varying the top mass, initial height hs and initial torsional angle. The nonlinear bistable origami has complex dynamic phenomena such as intra-well motion, inter-well motion and chaotic motion. Compared with intra-well motion, the harvested power of inter-well motion is increased by 18.5 times. The origami structure can be excited to the inter-well orbit under low intensity excitation of 0.19 m/s2 and low frequency of 2.5 Hz. An origami-based shoe pad is fabricated by integrating the origami generator into the shoe pad to not only harvest the energy but also measure the gait and motion information from the human motions. The proposed soft electricity generator of bistable programmable origami provides a competitive solution for broadband energy harvesting under low excitation acceleration and low frequency environment, i.e., human motion and bridge vibration, showing the great potential as power supply for wearable devices and bridge monitoring devices.