Scalable Textile Manufacturing Methods for Fabricating Triboelectric Nanogenerators with Balanced Electrical and Wearable Properties

Abstract

Triboelectric nanogenerators (TENGs) are foreseen as a leading candidate to harvest mechanical energy from ambient sources such as human body movements. However, wearable TENGs, which are used for this purpose, require adequate wearability for long durations, in addition to sufficient electrical outputs. So far, it has been difficult to achieve this through the predominantly plastic-based wearable TENGs constructed using conventional nanogenerator fabrication methods. This Article evaluates the use of textile materials and scalable fabrication techniques to develop TENGs targeting balanced electrical and wearable properties. The fabrication process is conducted using yarn-coating, dip-coating, and screen-printing techniques, which are common textile manufacturing methods, and converted into fabrics using flat-bed knitting, resulting in TENGs with improved wearable and electrical performances. The electrical properties (open circuit voltage ( V oc ), short circuit current ( I sc ), and short circuit charge ( Q sc )) and wearable properties (air permeability, stretch and recovery, and moisture management) of these structures are evaluated, during which the yarn-coated TENG resulted in maximum electrical outputs recording V oc ≈ 35 V, I sc ≈ 60 nA, and Q sc ≈ 12 nC, under mild excitations. In terms of wearability, the yarn-coated TENG again performed exceptionally during the majority of tests providing the best moisture management, air permeability (101 cm 3 /cm 2 /s), and stretch (∼75%), thus proving its suitability for wearable TENG applications.

Advances in the Robustness of Wearable Electronic Textiles: Strategies, Stability, Washability and Perspective

“…It was observed that yarn-coated TENG outperforms other TENGs (i.e., screen printed and dip-coated fabric made of the same conductive yarn) in output due to higher triboelectric contact surface area. The electrical output of the yarncoated TENG (i.e., open circuit voltage (V OC ) ~34.5 V, short circuit current (I SC ) ~60 nA, short circuit charge (Q SC ) ~12 nC) was superior to that of other TENGs (screen printed; V OC ~17.3 V, I SC ~43 nA, Q SC ~5 nC and dip-coated; V OC ~4.9 V, I SC ~11 nA, Q SC ~2 nC) and showed better cyclic stability up to 3000 contact separation cycles [155]. Xiao et al developed cotton yarn-based sweat-activated batteries (CYSAB) by drop coating black carbon (cathode, 4 cm), a bare portion (salt bridge, 0.5 cm), and subsequently wrapped with Zn foil (anode, 1.0 cm) of the same pristine cotton yarn.…”

Recent Progresses in Wearable Triboelectric Nanogenerators

“…Reproduced with permission. [ 134 ] Copyright 2022, American Chemical Society. e) Method of conductive PA yarn and NPTY fabrication.…”

“…(Figure 7d). [ 134 ] Here, three samples were fabricated using common textile manufacturing methods. One of them was fabricated using the yarn coating technique by applying a PDMS coating to a silver‐coated yarn and then knitting a 1 × 1 rib fabric.…”

“…In one example, industrial yarn‐coating techniques were used to implement common textiles materials as triboelectric layers on regular textile yarns, thus creating core–shell triboelectric yarns. [ 134 ] The yarns were then converted into energy‐generating fabrics using well‐established flat knitting techniques, via rib knit structures. The structural characteristics of such knitted fabrics, containing inherent stretch‐recovery properties and conformal coverage of the body, have been predicted to improve TENGs electric performances.…”

“…Moreover, the use of textile‐based triboelectric materials (yarns, fabric strips) and fabrication techniques (braiding, knitting, weaving) for the development of accessory components such as belts and gloves may provide added advantage, as many of these materials and methods already contain the required durability and wearability characteristics. [ 12,134 ]…”