Graphene oxide-incorporated PVA/sodium alginate composite hydrogel-based flexible and sensitive single-electrode TENGs for efficient energy harvesting and smart security applications

Conductive hydrogels have attracted significant attention in the field of flexible and wearable electronics owing to their exceptional flexibility, electrical conductivity, and mechanical properties. However, balancing among mechanical strength, flexibility, and electrical output in conductive hydrogels remains a challenging task. In this study, we develop a flexible and sensitive single-electrode triboelectric nanogenerator (SE-TENG) using graphene oxide (GO)-incorporated poly(vinyl alcohol)/sodium alginate conductive composite hydrogels (PVA/SA@GO CCHs), which are subsequently soaked in an ionic solution. The effects of SA and GO concentrations on the electrical output performance of the SE-TENG are systematically investigated. Additionally, the electrical conductivities, mechanical properties, and electrical output performances of the SE-TENG are evaluated. An optimized PVA/SA@GO-3 (0.75 wt% GO) CCH-based SE-TENG demonstrates superior electrical output performance, with output voltage, current, charge density, and power density values of ∼ 495 V, ∼ 22 μA, ∼ 125 μC/m², and ∼ 4.2 W/m², respectively. The robustness of the SE-TENG is further investigated under different environmental conditions, which indicates its exceptional mechanical properties, stable electrical output, and potential for wide applications. The SE-TENG is successfully demonstrated as a touch sensor that can harvest mechanical energy from human body movements as well as for powering portable electronic devices. Finally, the proposed keypad SE-TENG array is integrated with an Arduino microcontroller unit for real-time smart security sensing systems. The PVA/SA@GO CCH-based SE-TENG harvests biomechanical energy to power portable electronics and is employed as a self-powered sensor for smart home/bank locker security alert applications.