A Versatile Triboelectric Nanogenerator Using a Flexible\nPoly(vinyl alcohol)/Polyethylene Glycol/Chinese Ink Hydrogel

Stretchable conductive hydrogels\nexhibit promising potential as\nportable electronic devices and strain sensors. However, they suffer\nfrom intricate preparation procedures and inadequate mechanical properties\nfor constructing triboelectric nanogenerators (TENGs). Herein, we\npropose a borax-cross-linked poly(vinyl alcohol) (PVA)/polyethylene\nglycol (PEG)/Chinese ink (C) carbon nanoparticle composite hydrogel,\nwhich boasts a simple fabrication method and environmental friendliness.\nThe dispersion of carbon nanoparticles throughout the polymer network\nbolsters the mechanical strength of the hydrogel and also imparts\n good electrical conductivity. The incorporation of PEG improves the\nmechanical properties of the hydrogel, while the dynamic bonding between\nborate ions and PVA confers excellent self-recovery properties. Upon\ncutting and reuniting the fractured surfaces for 30 s, the two segments\nof the hydrogel underwent spontaneous healing without external stimuli.\nThe mended incisions of the hydrogel nearly vanished and withstood\nstretching to three times their original length without fracturing,\nshowing a remarkable self-healing capability and stretchability. Finally,\nTENGs were prepared using the PVA/PEG/C hydrogel, and the output voltage\nwas approximately 2.9 V across all frequencies. The PVA/PEG/C-TENG\ndemonstrated a rapid response at 180° of bending, reacting to\nthe stimulation in a mere 0.256 s and returning to its original state\nwithin 0.511 s after the stimulus was removed. The PVA/PEG/C hydrogel\nshows versatility in applications such as wearable motion monitoring,\nprecise stroke recognition, and efficient mechanical energy harvesting.