Enhancing the Performance of Stretchable Conductors for E‐Textiles by Controlled Ink Permeation

Abstract

Delivery of electronic functionality to the human body using e-textiles is important for realizing the future of wearable electronics. Printing is a promising process for large scale manufacturing of e-textile since it enables arbitrary patterns using a simple and inexpensive process. However, conductive inks printed atop of textile are vulnerable to cracking because of the deformable and porous structure of textiles. The authors develop a mechanically and electrically robust wiring by controlling ink permeation in the structure of textile. This is done by adjusting the ink's solvent. The use of butyl carbitol acetate, with its low vapor pressure and boiling point, enables deep permeation into the textile. The sheet resistance is initially 0.06 Ω sq , and the resistance increasing only 70 times after stretching to 450% strain. Finally, a four-channel electromyogram (EMG) monitoring garment is demonstrated to show the potential of a large-scale e-textile device for health care and sports.

Electronic Component Mounting for Durable E-Textiles: Direct Soldering of Components onto Textile-Based Deeply Permeated Conductive Patterns

“…The deep permeation of patterns prevents the peeling and stress concentration by soldering. In addition, the proposed approach is compatible with other durability-enhancement methods, such as the formation of small rigid islands only at the connection point of components [23] and the gradual change in stiffness around the connection point which reduces the stress concentration. To verify the improvement in durability by deep permeation, a type of surface mount component was soldered on printed patterns with different permeation depths, and the durability of the samples was evaluated by measuring the variations in resistance due to mechanical deformation.…”

“…In recent years, electronic textiles (e-textiles) have attracted significant research attention with respect to the development of new biological information monitoring systems [1][2][3][4][5][6], human interface systems [7,8], and fashions [9,10], among other schemes [11][12][13][14][15][16][17][18]. At present, only conductive tracks and pads and several types of sensors can be formed on a textile by weaving, knitting, and stitching of conductive yarns on the textile [9,[19][20][21], or by printing of conductive inks on the textiles [3,22,23]. Moreover, various types of electronic components such as transistors, batteries, and microprocessors cannot be directly fabricated on a textile by the weaving, knitting, and stitching, as well as printing processes.…”

“…Therefore, it is necessary to mount the components on the textile circuit, which are fabricated by other processes, to improve the performance and function of e-textiles. In previous studies, to mount the components on textile circuits, the following two types of mounting methods were used: stitching of conductive yarns on the component electrodes [9,[19][20][21] and adhesion of the components on the electrodes printed on a textile by conductive adhesives [23][24][25][26]. With respect to previous methods, small electronic components such as surface mount devices cannot be mounted.…”

Strategies for Designing Stretchable Strain Sensors and Conductors

“…Alternative techniques have been developed to fabricate conductive textiles, such as integrating metal filaments with yarns, coating fibers with a thin layer of conductive materials (metal nanoparticles/nanowires, carbon nanotubes, graphene, etc. ), or direct patterning of conducting polymers, and inkjet/stencil/screen/nozzle printing of conductive materials onto textiles ( Figure ) . The inclusion of metal wires in the yarns would increase the stiffness of the textiles and thereby decrease the wear comfort.…”

A Moss‐Inspired Electroless Gold‐Coating Strategy Toward Stretchable Fiber Conductors by Dry Spinning

“…[8][9][10][11][12][13][14][15][16][17] However, the mixing method requires high volume ratio of conductive filler in the elastic substrate, which usually reduces elasticity; [10,12] whereas, the coating method often raises concerns of delamination due to Young's modulus mismatch between elastomeric polymers and active materials. Stretchable fiber conductors usually consist of elastic fiber substrates and conductive fillers, and mixing and coating methods are two main approaches to combine elastic substrates and conductive fillers.…”