Nano Groove and Prism-Structured Triboelectric Nanogenerators

Abstract

Enhancing the output power of triboelectric nanogenerators (TENGs) requires the creation of micro or nano-features on polymeric triboelectric surfaces to increase the TENGs' effective contact area and, therefore, output power. We deploy a novel bench-top fabrication method called dynamic Scanning Probe Lithography (d-SPL) to fabricate massive arrays of uniform 1 cm long and 2.5 µm wide nano-features comprising a 600 nm deep groove (NG) and a 600 nm high triangular prism (NTP). The method creates both features simultaneously in the polymeric surface, thereby doubling the structured surface area. Six thousand pairs of NGs and NTPs were patterned on a 6×5 cm2 PMMA substrate. It was then used as a mold to structure the surface of a 200 µm thick Polydimethylsiloxane (PDMS) layer. We show that the output power of the nano-structured TENG is significantly more than that of a TENG using flat PDMS films, at 12.2 mW compared to 2.2 mW, under the same operating conditions (a base acceleration amplitude of 0.8 g).

Keywords: PDMS; nano features; nano groove and prism; triboelectric.

Figure 1

(a) The fabrication setup. (b) An array of 6000 NGs and NTPs on a $6\times 5$ cm${}^2$ area of a PMMA substrate. (c) Spin coating of PDMS onto the PMMA mold. (d) Curing of PDMS. (e) Peel off of the PDMS film from the mold. (f) A cross-sectional profile of the film obtained using AFM microscopy. The profile shows the NGs and NTPs.

Figure 2

(a) A microscopic image of an array made of 85 pairs of NGs and NTPs in a $4\times 3$ mm${}^2$ area. (b) A close-up microscopic image of a $750\times 565$ µm${}^2$ area. (c) AFM image of the NGs and NTPs in a $0.75\times 0.565$ mm${}^2$ area illustrating plastic deformation and material flow.

Figure 3

Triboelectric cyclic harvesting of mechanical energy.

Figure 4

The experimental setup mounts the TENG on electromagnetic shaker and uses a current amplifier and an oscilloscope to measure the output signal.

Figure 5

(a) The flat and (b) nano-structured molds used to cast the PDMS films. (c) Open-circuit voltage and (d) short-circuit current of the flat and nano-structured TENGs.

Figure 6

(a) A schematic illustrating measurement of the voltage and current generated by the TENG across a resistive load R. (b) Comparison of the output power of the nano-structured to the flat TENGs across R. (c) The measured voltage and current generated by the nano-structured TENG across R.

Figure 7

(a) A schematic of the TENG and its charging circuit comprising a capacitor and a bridge rectifier. (b) Measured capacitor voltage as a function of time for five capacitance values.

Figure 8

(a) A schematic of the TENG demonstration where they were deployed to power an array of series-connected red, white, yellow, and blue LEDs via a bridge rectifier. Images of an array of 180 LEDs while their power source, a nano-structured TENG, was (b) off and (c) on.