Stretchable Conductive Adhesives with Superior Electrical Stability as Printable Interconnects in Washable Textile Electronics

Abstract

As practical interest in stretchable electronics increases for future applications in wearables, healthcare, and robotics, the demand for electrical interconnects with high electrical conductivity, durability, printability, and adhesion is growing. Despite the high electrical conductivity and stretchability of most previous interconnects, they lack stable conductivity against strain and adhesion to stretchable substrates, leading to a limitation for their practical applications. Herein, we propose a stretchable conductive adhesive consisting of silver particles with carbon nanotube as an auxiliary filler in silicone adhesives. The conductive adhesive exhibits a high initial conductivity of 6450 S cm–1. They show little change in conductivity over 3000 stretching cycles at 50% strain, currently the highest stability reported for elastic conductors. Based on strong adhesion to stretchable substrates, the gel-free, dry adhesives printed on an elastic bandage for electrocardiography monitoring exhibit an extremely stable performance upon movement of the subject, even after several cycles of detachment–reattachment and machine washing.

Textile Electronics–Prospects, Advances, Challenges and Opportunities

“…The MWCNT were oxidized, mixed with silicone rubber, the Ag particles were added and then the compound was mixed. The resulting paste exhibited 6450 S cm-1 conductivity, which showed great stability even after 3000 stretching cycles at 50% strain [23]. Another method involving CNTs utilized the properties of natural silk, like biocompatibility and mechanical strength, to create sheathed CNT wires.…”

Stretchable anisotropic conductive film (S-ACF) for electrical interfacing in high-resolution stretchable circuits

“…However, in the stretchable devices, the large mismatch in elastic modulus between stretchable circuit lines and the rigid or flexible electrodes causes delamination and fracture during repeated stretching cycles (28)(29)(30)(31)(32). Although weak electrical interface is the main cause of device failure in the stretchable electronics and the lowresolution interface is the bottleneck of miniaturized stretchable devices, a small number of the related researches have been carried out for low-resolution interfacing (11,(33)(34)(35)(36) and high-resolution interfacing has not yet been successful.…”

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature

“…Among them, the newly developed waterborne adhesive has a wider range of applications, while the oxidation and short circuit problems caused by water vapor need more attention [29][30][31]. In addition to the above two types of conductive interconnecting materials, researchers have also tried to develop various dry adhesives [32,33]. Carbon nanotubes (CNTs) with hierarchical structures can provide an outstanding and stable adhesion for thermal and/or electric management [34,35].…”