Comb-shaped electrode-based triboelectric nanogenerators for bi-directional mechanical energy harvesting

Triboelectric nanogenerators (TENGs), which utilize coupling of contact electrification and electric induction to effectively harvest the mechanical energy around us, have attracted much attention due to their advantages such as simple design and high accessibility. Herein, we report new types of TENGs containing comb-shaped electrode, which are fabricated with a simple thermal nanoimprinting process where a commercially-available metal mesh was used as a stamp to simply impart microtopography on the TENGs to increase electrical output performance. The fabricated TENG with the comb-shaped electrode enables to harvest bi-directional mechanical energy (including both lateral and vertical contact/separation), which can be a new strategy to efficiently harvest the energy from complex real mechanical motions. The TENG with the comb-shaped electrode generates a short circuit current (I-SC) of 85 nA and an open circuit voltage (V-OC) of 6.4 V under the lateral contact/separation, which are increased up to 850% and 1600%, respectively, compared to the TENGs with the conventional rectangular electrode. The TENG with comb-shaped electrode is also found to harvest energy of I-SC of 339 nA and V-OC, of 31 Vat a pressing frequency of 0.5 Hz and force of 58.8 N under the vertical contact/separation without significant loss of electrical output performance compared with the TENG with the conventional rectangular electrode. The results indicate that the comb-shaped electrode would be a powerful (potential) candidate of electrode shape of the TENG to harvest the energy from real mechanical motions. (C) 2017 Elsevier B.V. All rights reserved.