Multimodal Deformation of Liquid Metal Multimaterial Composites as Stretchable, Dielectric Materials for Capacitive Pressure Sensing

Abstract

Traditional electronic devices are composed of rigid materials and components that tend to be unsuitable for soft robotic and stretchable electronic applications, such as wearable or continuous pressure sensing. However, deformable materials have the potential to improve upon traditional devices through enhanced sensitivity and responsiveness, better conformability and biocompatibility at the human–machine interface, and greater durability. This work presents deformable composite materials composed of the gallium–indium–tin alloy galinstan (GaInSn) that combines the conductivity of a metal and the intrinsic deformability of a liquid. Dispersing galinstan in an elastomer allows for the formation of deformable dielectric materials that have tunable mechanical and electrical behavior, for example, modulus and relative permittivity. Galinstan composites have been shown previously to have a minimal modulus impact on the elastomer but concurrently achieve impressive dielectric performance. However, galinstan dispersions can be costly and face challenges of mechanical and electrical reliability. Thereby, this work investigates multimaterial composites composed of galinstan and a rigid filler, either iron or barium titanate, with respect to morphology, mechanical behavior, dielectric behavior, and pressure sensing performance for the purpose of achieving a balance between a low modulus and superior electrical performance. By combining galinstan and rigid fillers, it was found that the mechanical and electrical properties, such as modulus, permittivity, loss behavior, sensitivity, and linearity of the multimaterial composites can be improved by tuning filler formulation. This suggests that these dielectric materials can be used for sensing applications that can be precisely calibrated to specific material properties and the needs of the user. These deformable multimaterial composites, found to be stretchable and highly responsive in sensing applications, will expand the current mechanical abilities of deformable dielectric materials to improve soft robotic and stretchable electronic devices.

Dielectric Elastomers with Liquid Metal and Polydopamine-Coated Graphene Oxide Inclusions

“…With PDA-GO added, the LM droplets appear smaller, and this may due to PDA-GO/ LM/PDMS having a higher viscosity that results in smaller LM droplets, which is consistent with previous studies. 59,60 Figure 5c shows that the PDA-GO/LM/PDMS composites can stretch to strains on the order of ∼80%, similar to that of the unfilled elastomer. Following an initial loading cycle, the PDA-GO/LM/PDMS composites exhibit very low mechanical hysteresis when comparing subsequent loading and unloading curves (Figure 5d).…”

Integrated Bending Actuation and the Self‐Sensing Capability of Poly(Vinyl Chloride) Gels with Ionic Liquids

“…[ 4,5 ] Even though some integration of actuation and sensing has been achieved in the dielectric elastomer [ 6–9 ] and piezoelectric materials, [ 10,11 ] the development of EAPs with integration of actuation and sensing still have a big challenge for simultaneously achieving high‐pressure sensitivity and high actuation performances. For example, the strategies of improving elastomers conductivity of elastomers are usually beneficial for improving pressure‐sensing performance, [ 12,13 ] however are unfavorable for improving actuation performances. [ 14 ]…”

“…conductivity of elastomers are usually beneficial for improving pressure-sensing performance, [12,13] however are unfavorable for improving actuation performances. [14] The dielectric polymer gel (DPG) is an electronic type of electroactive elastomers which has many advantages than dielectric elastomers due to low modulus and high dielectrics such as lower driving voltage, degree of various actuation freedoms and high actuation strain etc.…”

A micro-vibration-driven direct ink write printing method of gallium–indium alloys

“…Experiment results demonstrated the superiority of the method in terms of Ga-In alloys extrusion control. With this method, the printability of the liquid metals is enhanced.Gallium-based alloys, which are liquid metals with low melting points, are commonly used in flexible electronics 1,2 , materials synthesis 3,4 , stretchable electronics 5,6 , sensors 7,8 , and other areas due to their unique physical properties. The molding capabilities of Ga-In alloys are improved by combining 3D printing technology.…”

“…Gallium-based alloys, which are liquid metals with low melting points, are commonly used in flexible electronics 1,2 , materials synthesis 3,4 , stretchable electronics 5,6 , sensors 7,8 , and other areas due to their unique physical properties. The molding capabilities of Ga-In alloys are improved by combining 3D printing technology.…”