Flexible hierarchical helical yarn with broad strain range for self-powered motion signal monitoring and human-machine interactive

To realize broad strain range and highly flexible self-sustainable intelligent wearable electronics, an ideal solution is integrating the structural diversity of flexible textiles with rapidly evolving energy harvesting technologies. Herein, a highly stretchable, flexible yarn with broad strain response range up to 120% is reported based on a multi-gradient hierarchical helical structure. The flexible hierarchical helical yarn (HHY) was obtained via coiling the conductive electrodes around a highly stretchable PU (the first helix layer) and super flexible silicon rubber (the second helix layer), respectively. The optimized HHY can operate within the strain range of 60%–120% and in the low-frequency scope of less than 2 Hz that matches human movement, the response ability of as-designed HHY to small strain range was also verified via harvesting the energy generated by body movement. Simultaneously, the generation of different current signals shows its distinct advantage in distinguishing joint-bending related human motion. Significantly, it was discovered that the harvested bioenergy can be directly applied to wirelessly control household devices without amplifying the signal. Furthermore, the HHY can be successfully served as a trigger switch to drive the electric piano and robotic arm synchronously when incorporating in a human-machine interactive system, indicating that the HHY has superior responsiveness to multiple synergy action mode. The paper shows that our HHY with a wide deformation range is a promising candidate for self-powered sensing and intelligent interaction.