Liquid Metal Patterned Stretchable and Soft Capacitive Sensor with Enhanced Dielectric Property Enabled by Graphite Nanofiber Fillers

Abstract

In this work, we introduce liquid metal patterned stretchable and soft capacitive sensor with enhanced dielectric properties enabled by graphite nanofiber (GNF) fillers dispersed in polydimethylsiloxane (PDMS) substrate. We oxidized gallium-based liquid metal that exhibited excellent wetting behavior on the surface of the composites to enable patterning of the electrodes by a facile stencil printing. The fluidic behavior of the liquid metal electrode and modulated dielectric properties of the composite (k = 6.41 ± 0.092@6 wt % at 1 kHz) was utilized to fabricate stretchable and soft capacitive sensor with ability to distinguish various hand motions.

Liquid-Metal-Coated Magnetic Particles toward Writable, Nonwettable, Stretchable Circuit Boards, and Directly Assembled Liquid Metal-Elastomer Conductors

“…Liquid metal (gallium and its alloys) is a compelling material for applications in soft and stretchable electronics due to its ability to maintain metallic conductivity even when deformed . Upon exposure to oxygen, liquid metal spontaneously forms a passivating thin oxide layer (∼3 nm) on its surface. , This oxide layer can promote the adhesion of the liquid metal onto various substrates and helps the metal be patterned into the desired geometries through injection, − vacuum-assisted filling, three-dimensional (3D) printing, , direct writing, , molding using elastomeric stamps, − and forced wetting. , As liquid metal is a well-known supercooled metal, it remains in liquid state below its freezing point. However, the metal can be solidified by providing a nucleation point to initiate phase transition. ,, Under the oxide layer, highly ordered nanoscopic features of the liquid metal alloy can emerge at the alloy surface during solidification, which involves surface-catalyzed heterogeneous nucleation, not bulk solidification in the interior region …”

“…1,2 This oxide layer can promote the adhesion of the liquid metal onto various substrates and helps the metal be patterned into the desired geometries through injection, 3−5 vacuum-assisted filling, 6 three-dimensional (3D) printing, 7,8 direct writing, 9,10 molding using elastomeric stamps, 11−13 and forced wetting. 14,15 As liquid metal is a well-known supercooled metal, it remains in liquid state below its freezing point. However, the metal can be solidified by providing a nucleation point to initiate phase transition.…”

Dielectric properties and dielectric relaxation process of polymethylphenylsiloxane/silicon dioxide nanocomposites

“…Bhuyan et al dispersed graphitic nanofibers in a PDMS matrix, which enhanced the dielectric properties of the material. They fabricated a stretchable soft capacitive sensor that was capable of discriminating various hand movements 18 . Chen et al used a solution method to synthesize polyphenol nanoparticle‐modified multiwalled carbon nanotubes (PNs@MWCNT) with PDMS to prepare a DE actuator that had excellent electromechanical properties 19 .…”

Soft and Stretchable Liquid Metal–Elastomer Composite for Wearable Electronics

“…Gallium-based (Ga-based) LMs not only have nontoxic and liquid features at room temperature but also have excellent thermal conductivity and electrical properties, which can be used to prepare soft robots, wearable electronics devices, and even self-healing electronic products. − Shu et al injected Ga-based LMs into elastic fibers prepared from triblock copolymer polystyrene- b -(ethylene- co -butene)- b [styrene] resin, which can achieve 800% strain . LM particles (LMPs) with high ε r (up to 60) are soft and easily dispersed in elastomers, leading to liquid metal embedded elastomers (LMEEs) with higher sensitivity and high deformability .…”