Ultrahigh Strain‐Insensitive Integrated Hybrid Electronics Using Highly Stretchable Bilayer Liquid Metal Based Conductor

Abstract

Human‐interfaced electronic systems require strain‐resilient circuits. However, present integrated stretchable electronics easily suffer from electrical deterioration and face challenges in forming robust multilayered soft‐rigid hybrid configurations. Here, a bilayer liquid‐solid conductor (b‐LSC) with amphiphilic properties is introduced to reliably interface with both rigid electronics and elastomeric substrates. The top liquid metal can self‐solder its interface with rigid electronics at a resistance 30% lower than the traditional tin‐soldered rigid interface. The bottom polar composite comprising liquid metal particles and polymers can not only reliably interface with elastomers but also help the b‐LSC heal after breakage. The b‐LSC can be scalably fabricated by printing and subsequent peeling strategies, showing ultra‐high strain‐insensitive conductivity (maximum 22 532 S cm−1), extreme stretchability (2260%), and negligible resistance change under ultra‐high strain (0.34 times increase under 1000% strain). It can act as stretchable vertical interconnect access for connecting multilayered layouts and can be scalably and universally fabricated on various substrates with a resolution of ≈200 µm. It is demonstrated that it can construct stretchable sensor arrays, multi‐layered stretchable displays, highly integrated haptic user‐interactive optoelectric E‐skins, visualized heaters, robot touch sensing systems, and wireless powering for wearable electronics.

Superstretchable Liquid-Metal Electrodes for Dielectric Elastomer Transducers and Flexible Circuits

“…The excellent comprehensive electromechanical performance of Supra-LMNs is particularly impressive as traditional stretchable conductors, which typically face challenges in maintaining stable resistance under large strains due to a trade-off between conductivity and stretchability. Compared to state-of-the-art stretchable conductors, ,,− ,,,,,− Supra-LMNs has outstanding performance in its extreme stretchability (>1500%) and negligible resistance change over strains (Δ R / R 0 = 1.34 @1600%), as shown in Figure h.…”

“…However, large amounts of rigid fillers normally render the "brittleness" of such composite material and hence decreased mechanical performance of DET. 19 Therefore, improving the conductivity and stability of electrodes without compromising their extensibility remains a major challenge.…”

Research Progress in Stretchable Circuits: Materials, Methods, and Applications

“…[24,25] Moreover, their ability to flow or change shape into various forms at room temperature has made them a promising material to resolve the electrical failure problem that occurs in conventional materials with conductive materials under stretching conditions. [26,27] While research on liquid metal originates from Hg, which have been eliminated due to its high toxicity and volatility, EGaIn (75.5 wt% Ga, and 24.5 wt% In) and Galinstan have been widely used in stretchable point circuit. Their conductivity is 3.4 × 10 6 and 3.5 × 10 6 S m −1 , respectively, which is 1/20th of copper's conductivity but greater than common stretchable conductive materials.…”

Programmable and Weldable Superelastic EGaIn/TPU Composite Fiber by Wet Spinning for Flexible Electronics

“…This demand has led to increased attention from researchers toward developing electronic devices that possess favorable properties, such as bendability, malleability, and facile functionalization. Numerous investigations have been conducted on flexible electronics, including electronic skins, , flexible sensors, − smart fabrics, − stretchable circuits, − and supercapacitors. , These studies have highlighted the vast potential of flexible electronics in various fields, such as health monitoring, − motion sensing, − and artificial intelligence. , …”