Ultra‐robust stretchable electrode for e‐skin: In situ assembly using a nanofiber scaffold and liquid metal to mimic water‐to‐net interaction

Abstract

The development of stretchable electronics will thrive on the novel interface structure to solve the stretchability-conductivity dilemma, which is still a great challenge. Herein, we report a nano-liquid metal (LM)-based high-robust stretchable electrode (NHSE) with a self-adaptable interface that mimics water-tonet interaction. Based on in situ assembly of electrospun elastic nano bers scaffold and electrosprayed LM nanoparticles, the NHSE exhibits an extremely low sheet resistance of 52 mΩ/□. It is not only insensitive to a large degree of mechanical stretching (i.e., 350% electrical resistance change upon 570% elongation), but also immune to cyclic deformation (i.e., 5% electrical resistance increase after 100,000 stretching cycles with 100% elongation). These key properties are far more superior to the state-of-the-art reports. Its robustness and stability are veri ed under diverse circumstances, including long-term exposure in air (420 days), cyclic washing (30,000 times), and resilience against mechanical damages.The combination of conductivity, stretchability and durability makes the NHSE a promising conductor/electrode solution to exible/stretchable electronics for applications such as wearable onbody physiological signal detection.

Self-Patterning of Highly Stretchable and Electrically Conductive Liquid Metal Conductors by Direct-Write Super-Hydrophilic Laser-Induced Graphene and Electroless Copper Plating

“…It is observed that the resistance increases by 1.14, 3.41, and 7.95% under the strain of 100, 200, and 300%, respectively. In addition, Figure E shows LMs/SHL-LIG/Ecoflex has the lowest sheet resistance of 3.54 mΩ per square and second highest stretchability up to 480% compared with those of previously reported stretchable conductors. ,,− After 7000 stretching cycles under the strain of 300%, the resistance of LMs/SHL-LIG/Ecoflex shows excellent stability to quickly return back to its initial value after each stretching cycle (insets), as shown in Figure F. The very small resistance variation of ∼8% after each stretching cycle makes it the best among other existing stretchable conductors ,,− (Figure S3).…”

“…The excellent stretchability of Ecoflex enables the demonstration of a uniaxial tensile strain of ∼480% for the as-prepared LMs/SHL-LIG/Ecoflex sample with a size of 5 × 8 mm 2 (Figure B). Robustness and stability in the electrical resistance are important criteria for the performance of stretchable conductors. , …”

“…Previously, various stretchable electrodes have been reported, such as structurally stretchable conductors, stretchable conductive nanocomposites, and intrinsically stretchable conductors. − Other structurally stretchable conductors have utilized conductive materials of low stretchability with complex periodic microstructure designs for flexibility, such as three-dimensional helical structures, , scalable structures, and honeycomb structures. , These structure-based stretchable conductors are severely limited to work within a relatively small strain range of <50%. On the other hand, stretchable conductive nanocomposites have been demonstrated by embedding conductive nanofillers (e.g., metal nanostructures, ,, carbon nanotubes, , and graphene , ) into a highly extensible matrix.…”

Mechanical Gradients Enable Highly Stretchable Electronics Based on Nanofiber Substrates

“…Recently, fiber substrates have attracted attention due to their unique properties, and flexible electronic devices based on LM and fiber materials have also been widely reported . Further, our research and some other groups have shown that stretchable circuits with super-stretchability, high conductivity, stability, breathability, and safety can be obtained by printing LM on electrospun substrates. − However, these studies have mainly focused on the fabrication of stretchable electrodes, which do not possess the ability to directly fix rigid ICs. Therefore, it is of great value and significance to introduce rigid ICs into LM circuits (LMC) while maintaining device stretchability and reliability.…”

Flexible Wearable Pressure Sensor Based on Collagen Fiber Material

“…The recently developed triboelectric nanogenerator has provided ideas for the fabrication of self-powered wearable sensors [ 24 , 25 ]; moreover, selecting an appropriate detection position significantly improves the sensing signal strength. In addition, the wearability of sensors is also important for continuous wearable monitoring, which requires these sensors to be flexible and have low biotoxicity, and the dielectric layer material is the key for flexible stretchable sensors [ 26 , 27 ].…”