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The triboelectric nanogenerator (TENG), which converts mechanical energy to electrical output, is garnering attention owing to their application in low-energy electronic devices as a power source. To utilize the TENG as a power source, amplifying the electrical output and enhancing energy conversion efficiency are necessary. As the TENG generates electrical output through contact electrification and electrostatic charge induction, the electrical output can be amplified by enhancing the two mechanisms through the enlargement of the TENG area and the adoption of the pre-charge injected film (electret). In this regard, the fabrication of the large-scale electret is significant for amplifying the electrical output of the TENG. In this study, a corona charging system is proposed for the fabrication of the large-scale electret with a uniform charge-distributed area. Corona charging injects O2 ions into a dielectric film with an electric field generated between the pin electrode (PE) and ground electrode (GE). Through the utilization of a multi-PE (MPE) and conveyor belt-shaped GE (CBsGE) in the corona charging system, the O2 molecules near the pins can be ionized simultaneously while the CBsGE is rotating. Thus, the O2 ions can be injected uniformly into a wide area. About a voltage of 400 V and current of 45 μA can be generated by applying the fabricated electret to the TENG. As several electrets with various sizes can be fabricated simultaneously, the TENG with high electrical output can be batch fabricated to enhance its practicality significantly.

Piezoelectric sensors have been developed due to the self-powered sensing and flexibility and the promising potential applications in the electronic skin (e-skin) inspired by human skin. However, although the piezoelectric sensors have an excellent performance in detecting human movements, it is difficult to distinguish external mechanical stimuli such as tapping in a single structure, together. Here, we suggest a self-powered e-skin based on electrospun poly (vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), nanofiber hybrid triboelectric-piezoelectric sensor (E-HTPS), that can identify between human motions and external touch based on both triboelectric effect and piezoelectric effect. Triboelectric effect-based sensors have a good electrical output characteristic with various advantages of high-flexibility and simple working operation. Hence, the E-HTPS consists of two layers, triboelectric layer as a tactile sensor and piezoelectric layer as a human motion sensor. Therefore, we demonstrate that the E-HTPS can detect human movements and even finger touch with attached to the target body part. Consequently, the E-HTPS could provide an effective approach to designing the self-powered e-skin as an artificial sensory system for healthcare monitoring and soft robotics.