Biomimetic microstructure design for ultrasensitive piezoionic mechanoreceptors in multimodal object recognition.

The challenge of achieving high recognition accuracy in artificial mechanoreceptors arises from the trade-off between sensitivity and stability in the sensing unit. Inspired by human skin, we developed a biomimetic approach that involves structural and engineering enhancements for ionic-conducting polyvinyl alcohol/Ti3C2Tx (PVA/MXene) composite hydrogel microneedles (HM) to enhance the sensitivity. By integrating the HM with a polyethylene terephthalate/indium tin oxide (PET/ITO) film, we create a non-faradaic junction that ensures stable electrical output without transmission loss under stimulation. Furthermore, the significant alteration in nanosheet spacing facilitates proton transport along the MXene microchannels, increasing the plasmonic gradient between the junction and the hydrogel's center, thereby boosting piezoionic efficiency. Consequently, the biomimetic sensing unit achieves a high power density of 165.6 mW m-2 and exceptional sensing stability over 10,000 cycles. When combined with vertical memristor units, this system effectively captures and transforms characteristic signals from various objects, achieving a recognition accuracy of 90%.