gallium-based LM alloys such as EGaIn (eutectic gallium-indium) or galinstan (eutectic gallium-indium-tin) are typically selected as the liquid filler due to the combination of high electrical and thermal conductivity, low viscosity, and nontoxic characteristics. [4][5][6][7] By dispersing LM inclusions into elastomers, functional properties-including thermal conductivity, [8][9][10][11][12][13][14][15] dielectric constant, [16][17][18][19][20][21] and electrical conductivity, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] -can be improved with negligible changes in stiffness and extensibility of the host elastomer, even at high loading. LM embedded composites exhibit a unique combination of functional properties, low stiffness, and high strain limit that overcomes fundamental limitations of soft and deformable materials and offers great promise for emerging applications in soft robotics and wearable computing that require highly functional and elastically deformable materials. Despite the improved properties, both the density of Ga-based LMs (EGaIn: 6.25 g cm −3 ; galinstan: 6.44 g cm −3 ) and typically high loading (⩾85 wt%, or ⩾50 vol%) required to achieve the desired functional properties contribute to the high density of LM embedded composites, which can be problematic for largearea and weight-sensitive applications.Recently, researchers have shown that the properties of Gabased LMs can be enhanced through the addition of solid particles. Several LM mixtures have been studied to improve the thermo-mechanical properties [10,11,[40][41][42][43][44][45][46][47][48][49] , rheology and consistency, [50][51][52][53][54][55][56][57][58] and density [58,59] of LM. This has resulted in LM mixtures with high thermal conductivity >100 W m −1 K −1 , a fourfold increase as compared to pure LM, [43,44] LM pastes that can be easily spread on a surface, [40] and LM mixtures that can float on water. [59] However, LM mixtures that include metallic particles with fcc crystal structures, such as copper (Cu), silver (Ag), iron (Fe with fcc crystal structure), and nickel (Ni), tend to spontaneously react with LM and form intermetallics that solidify at low loading. [10] For LM mixtures with particles that do not form intermetallic species, the rheology and consistency of the mixtures are controlled by the fraction of solid particles that are added to the mixture, resulting in a transition from a liquid to paste-like rheology (⩽50% by volume) or liquid to powder at higher volume loading (>50%). [40,44,52,53,59] The viscosity of the Lightweight and elastically deformable soft materials that are thermally conductive are critical for emerging applications in wearable computing, soft robotics, and thermoregulatory garments. To overcome the fundamental heat transport limitations in soft materials, room temperature liquid metal (LM) has been dispersed in elastomer that results in soft and deformable materials with unprecedented thermal conductivity. However, the high density of LMs (>6 g cm −3 ) and the typical...