Emulsion Hydrogel Soft Motor Actuated by Thermal Stimulation

An emulsion hydrogel motor (E-H motor), constituted by low-boiling-point oil fuel and a hydrogel matrix, is prepared through a simple yet versatile oil-in-water (O/W) emulsion template method. The E-H motor can be efficiently propelled by the bubbles generated under a thermal stimulus. As thermally induced explosion occurs inside the E-H motor (diameter ∼4.0 mm and length ∼6.0 mm), the gas bubbles resulting from thermotropic phase transition are violently ejected from one side, leading to a fast speed of 14.78 ± 4.82 mm s^–1 in a 60 °C aqueous solution. Additionally, multiple water-insoluble organic solvents can serve as the fuel for self-propulsion, which demonstrates the favorable universality of the E-H motor. The magnetic navigation and near-infrared propulsion can be realized through incorporating hydrophilic iron oxide (Fe₃O₄) nanoparticles and graphene oxide (GO) into the aqueous phase. Moreover, the synchronous integration of GO and enrofloxacin bactericide can enable intelligent targeted cargo transportation and delivery. The attractive self-propulsion performance, precise locomotion control, and formidable integration ability of the emulsion hydrogel-based miniaturized soft motor hold great promise for numerous practical applications.