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

Stretchable conductive hydrogels exhibit promising potential as portable electronic devices and strain sensors. However, they suffer from intricate preparation procedures and inadequate mechanical properties for constructing triboelectric nanogenerators (TENGs). Herein, we propose a borax-cross-linked poly(vinyl alcohol) (PVA)/polyethylene glycol (PEG)/Chinese ink (C) carbon nanoparticle composite hydrogel, which boasts a simple fabrication method and environmental friendliness. The dispersion of carbon nanoparticles throughout the polymer network bolsters the mechanical strength of the hydrogel and also imparts good electrical conductivity. The incorporation of PEG improves the mechanical properties of the hydrogel, while the dynamic bonding between borate ions and PVA confers excellent self-recovery properties. Upon cutting and reuniting the fractured surfaces for 30 s, the two segments of the hydrogel underwent spontaneous healing without external stimuli. The mended incisions of the hydrogel nearly vanished and withstood stretching to three times their original length without fracturing, showing a remarkable self-healing capability and stretchability. Finally, TENGs were prepared using the PVA/PEG/C hydrogel, and the output voltage was approximately 2.9 V across all frequencies. The PVA/PEG/C-TENG demonstrated a rapid response at 180 degrees of bending, reacting to the stimulation in a mere 0.256 s and returning to its original state within 0.511 s after the stimulus was removed. The PVA/PEG/C hydrogel shows versatility in applications such as wearable motion monitoring, precise stroke recognition, and efficient mechanical energy harvesting.