High contact surface area enhanced Al/PDMS triboelectric nanogenerator using novel overlapped microneedle arrays and its application to lighting and self-powered devices

One key to enhance the output performance of triboelectric nanogenerators (TENG) is how to increase the effective contact area that strongly depends on the feature morphology and pattern density. Conventional morphologies of TENG including pyramids, cubes, lines, pillars, and domes with insufficient feature surface area are generally fabricated using an expensive-and-time-consuming lithography and etching process. Here, we propose a novel morphology of overlapped microneedles (OL-MN) arrays for high total contact surface area to enhance the output performance of aluminium/polydimethylsiloxane (Al/PDMS) TENG under low operation frequencies using hand tapping. Two kinds of separate low-density and high-density microneedles arrays, namely LD-MN and HD-MN, are comparatively studied. The integrated process of low-cost CO2 laser ablation and PDMS casting is used for rapid prototyping. The OL-MN has the highest total contact surface area compared to the LD-MN and HD-MN at the constant laser power and scanning speed. The output performance of open-circuit voltage (V-oc) and short-circuit current (I-sc) of OL-MN-TENG are 123 V and 109.7 mu A those are 3.66 and 3.71 times the V-oc and I-sc of LD-MN-TENG, respectively. The excellent OL-MN-TENG can light on 103 LEDs connected in series and store energy in capacitors for application to various self-powered devices.