On the controlled adhesive contact and electrical performance of vertical contact-separation mode triboelectric nanogenerators with micro-grooved surfaces

Highlights: • An exponential relationship between charge density and contact stress of TENG is proposed. • Numerical contact and electrical models of TENG with grooved surfaces are built. • Effects of alignment angle, applied pressure and loading time on the performance of TENG are studied. • Strategies for the output regulation of TENG with grooved surfaces without causing separation difficulty are given. The triboelectric nanogenerator (TENG) is a new energy technology to convert mechanical energy into electricity based on contact electrification and electrostatic induction. Altering the alignment state of TENG with two micro-grooved surfaces is a simple way to achieve controlled electrical output. To guide the output regulation of TENG with micro-grooved surfaces and avoid causing interface separation failure, comprehensive analysis based on adhesive contact mechanics is essential. In this paper, the relation between charge density and contact stress is measured. Numerical adhesive contact and electrical models of TENG with grooved surfaces considering the charge density-contact stress relation and material properties are established to quantitatively analyze the effects of alignment angle, applied pressure and loading time on adhesive contact and electrical performance. It is shown that there exists an exponential relation between charge density and contact stress. Alignment angle of grooved surfaces in TENG significantly affects the adhesive contact and electrical performance. Under low and high applied pressures, the variations of output voltage with alignment angle are 630.5% and 301.1%, respectively, while same pull-off force variation of 532.6% is exhibited. Large pull-off force usually comes along with high voltage output, except for alignment angle of 10°, at which relative high voltage and low pull-off force are exhibited. Strategies for the output regulation of TENG with grooved surfaces without causing interface separation difficulty are presented.