High-performance triboelectric nanogenerator with enhanced energy density based on single-step fluorocarbon plasma treatment

Recently triboelectric nanogenerator (TENG) devices that transform environmental mechanical energy to electric power have been demonstrated as a renewable, clean and usable power source. However, the TENG output power still should be enhanced to better meet practical needs, and the working ability for practical applications should be further investigated. Here, we demonstrate a novel high-performance TENG by using a single-step fluorocarbon plasma treatment, which can significantly strengthen the TENG output performance. After the optimization of plasma treatment, the maximum instantaneous energy area density of the TENG with micro/nano hierarchical structures is enhanced by 278% to 4.85 mW/cm(2), with a peak output voltage of 265 V and current density of 18.3 mu A/cm(2). The reliability and stability of this single-step fluorocarbon plasma enhancement process were widely and deeply investigated by systematically comparative experiments. The density functional theory (DFT) is employed to analyze the chemical modification mechanism of this fluorocarbon plasma treatment, modeling for the first time the energy required for electron transfer for different friction materials at molecular level based on first-principle calculations. The ability of this TENG to work in the practical environmental, especially in the biomedical field, has been demonstrated by the investigation of the effect of the key environmental factor (i.e., humidity) on the TENG output performance, and a quantitative relation has been figured out. Based on this relation, humidity is established as a new consideration for future studies of TENG performance, and a novel self-powered humidity monitoring sensor is proposed. This high-output TENG is also successfully applied to drive an implantable microneedle electrode array to stimulate a frog's sciatic nerve. This represents the first application of a TENG for sustainably powering a biomedical microsystem implanted in real biological tissue, moving closer to practical biomedical applications of TENGs. (C) 2013 Elsevier Ltd.