A Liquid‐Metal–Elastomer Nanocomposite for Stretchable Dielectric Materials

Abstract

Stretchable high dielectric materials are crucial for electronic applications in emerging domains such as wearable computing and soft robotics. While previous efforts have shown promising materials architectures in the form of dielectric nano-/micro inclusions embedded in stretchable matrices, the limited mechanical compliance of these materials significantly limits their practical application as soft energy harvesting/storage transducers and actuators.Here, we present a class of liquid metal (LM)-elastomer nanocomposites with elastic and dielectric properties that make them uniquely suited for applications in soft-matter engineering. In particular, we examine the role of droplet size and find that embedding an elastomer with a polydisperse distribution of nanoscale LM inclusions can enhance its electrical permittivity without significantly degrading its elastic compliance, stretchability, or dielectric breakdown strength. In contrast, elastomers embedded with microscale droplets exhibit similar improvements in permittivity but a dramatic reduction in breakdown strength.The unique enabling properties and practicality of LM-elastomer nanocomposites for use in soft machines and electronics is demonstrated through enhancements in performance of a dielectric elastomer actuator and energy harvesting transducer.

Highly Stretchable Polymer Composite with Strain‐Enhanced Electromagnetic Interference Shielding Effectiveness

“…On the other hand, the unstretched 0–3 and 1–3 LM composites are essentially electrical insulators, owing to the isolation of the low dimensional LM inclusions in the polymer matrix and the presence of insulation Ga 2 O 3 layer on the surface of LMs 44,45. Our mechano–electrical modeling shows that the electrical current concentrates at the tips of the stretched LM inclusions and thus enhances the conductivity of the adjacent polymer matrix, offering an additional mechanism of strain‐enhanced conductivity in the 0–3 and 1–3 LM composites besides alignment and elongation of the LM inclusions (Figure S22, Supporting Information).…”

Liquid Metal–Based Soft Microfluidics

“…Furthermore, the composite exhibited a higher dielectric constant and low dielectric dissipation factor while the obtained tensile properties are superior to the properties obtained for conventional inorganic particles/elastomer composites (see Figure a–c) . In addition, Pan et al studied the effect of droplet size on dielectric materials (see Figure d,e). Regardless of the particle size, increasing the volume fraction of the liquid metal increases the dielectric constant of the composite.…”

“…Weibull dielectric breakdown strength and mechanical strain at break of LM‐elastomer composites with LM droplet size of f) 10 µm and g) 100 nm. Reproduced with permission . Copyright 2019, John Wiley and Sons.…”

Inner Surface Design of Functional Microchannels for Microscale Flow Control

“…Liquid metals such as gallium (Ga) and its alloys have attracted great attention in the construction of soft and stretchable electronic devices due to their fluidity and high conductivity . Confining the liquid metals in soft microchannels is one of the most common approaches for building soft electronics .…”