Deposition of Vertically Aligned Ag/Ag2 S Nanoflakes on EGaIn Particles for Humidity Sensing

Ligand Mediation for Tunable and Oxide Suppressed Surface Gold-Decorated Liquid Metal Nanoparticles

Gallium-based liquid metal systems hold vast potential in materials science. However, maximizing their possibilities is hindered by gallium's native oxide and interfacial functionalization. In this study, small-molecule ligands are adopted as surfactants to modify the surface of eutectic gallium indium (EGaIn) nanoparticles and suppress oxidation. Different p-aniline derivatives are explored. Next, the reduction of chloroanric acid (HAuCl4 ) onto these p-aniline ligand modified EGaIn nanoparticles is investigated to produce gold-decorated EGaIn nanosystems. It is found that by altering the concentrations of HAuCl4 or the p-aniline ligand, the formation of gold nanoparticles (AuNPs) on EGaIn can be manipulated. The reduction of interfacial oxidation and presence of AuNPs enhances electrical conductivity, plasmonic performance, wettability, stability, and photothermal performance of all the p-aniline derivative modified EGaIn. Of these, EGaIn nanoparticles covered with the ligand of p-aminobenzoic acid offer the most evenly distributed AuNPs decoration and perfect elimination of gallium oxides, resulting in the augmented electrical conductivity, and highest wettability suitable for patterning, enhanced aqueous stability, and favorable photothermal properties. The proof-of-concept application in photothermal therapy of cancer cells demonstrates significantly enhanced photothermal conversion performance along with good biocompatibility. Due to such unique characteristics, the developed gold-decorated EGaIn nanodroplets are expected to offer significant potential in precise medicine.

Enabling High-Performance Pressure and Proximity Dual-Mode Sensing with EGaIn/Ag/ZnO Egg-Shell Ternary Composite Particles

Eutectic gallium-indium alloy (EGaIn) is a biocompatible liquid metal, promising for wearable electronics. Through functionalization and formation of composites, EGaIn-based materials have shown potential in multifunctional sensing devices. Here, egg-shell EGaIn/Ag/ZnO ternary composite particles were prepared through an ultrasound-assisted displacement reaction combined with room-temperature hydrolysis. The composite was further constructed as a wearable sensor capable of both pressure and proximity detection. For pressure sensing, due to the decrease in the Young's modulus of the egg-shell structure and the presence of the electrical double layers between Ag and ZnO, which enriched surface charges, the sensor showed excellent sensitivity at low pressures (2.17 KPa-1, <0.4 KPa) and thus the ability to sense body movements. For proximity sensing, the composite sensor was able to detect approaching objects that were up to 20 cm away. By combining and fitting the sensing curves for both the touchless and touching modes, the extracted parameters were used to create fingerprints for different objects, demonstrating the great potential of our sensor in the differentiation and identification of unknown objects for future robotics and artificial intelligence.