Holocellulose nanofibrils biomimetic entrapment of liquid metal enable ultrastrong, tough, and lower-voltage-driven paper device.

Integrating liquid metal (LM) with wood fibers for flexible paper electronics is intriguing yet extremely challenging due to poor mechanical performance. Here, we disclose a hemicellulose trapping strategy to achieve exceptional ultrastrong and tough LM-based paper electronics. Holocellulose nanofibrils (HCNFs) with hemicellulose retention of approximately 20 % are found to effectively entrap nanoscale LM within the fibril network, analogous to spider silk capturing small water droplets. Phase separation of LM and coalescence of nanofibrils can be avoided during the fabrication process of sheet-like paper. The homogeneous distribution of nanoscale LM eliminates impairment and contributes to the dramatic enhancement of mechanical performance (tensile strength: 240 MPa; toughness: 16.5 MJ m). Further incorporating a small number of carbon nanotubes generates low-voltage-driven Joule heating performance with excellent heat generation capacity (200 °C at 4.0 V), surpassing LM-based elastomers, films, and textiles. Our study illuminates the remarkable potential of LM-based paper electronics and enables advanced flexible device applications.