Multi-fuel Driven Micromotors:Synthesis And Their Applications

Micromotors are small devices that are self-propelled by energies converted from the surrounding chemical fuels. In recent years, micromotors have undergone rapid progresses with the continuous development of nano-science and techno logy. But, there are still many limitations in the field of micromotors. For example, existing conventional micromotors is still based on H2O2, I2, Br2 and hydrazine fuels, which not only contaminates the environment and but also hinders its application in biomedical fields. In addition, the micromotors can only be driven by single fuels instead of multiple fuels, which further hinders its potential applications.Based on the above problems, we study micromotors propelled by water and explore its applicatio n in the bactericidal field, detailed as follows:1. We fabricate the bimetallic Janus microsphere. By utilizing the thermal evaporation technique, we have coated a magnesium microsphere with a silver surface layer. Because of the Janus structure, this micromotor can be propelled in two different directions by the surface silver or magnesium ‘engine’ and hydrogen peroxide or water fuel. In addition, due to the bactericidal property of silver, this autonomous micromotor is capable of killing bacteria in solution. As compared to the static one, the micromotor is able to kill the bacteria at a much faster rate(about nine times of that of the static one), demonstrating the superiority of the motion one. We thus believe that the micromotor shown in the current study is potentially attractive for the environmental hygiene applications.2. We deposit a layer of metallic aluminum onto one side of the magnesium microsphere by thermal evaporator, resulting in the Mg/Al Janus micromotor. The Mg/Al Janus micromotor are propelled efficiently by the thrust from hydrogen bubbles generated by the reactions between Al coating and the strong alkaline solution. In addition, the micromotor can be self-propelled toward the opposite side based on the reactions between Mg and the acid or salt solution. Therefore, we have developed a micromotor that can function under different circumstances. Furthermore, since the speed of the Mg/Al Janus micromotor differs with the different pH, we anticipate the application of the current micromotor in the field of pH sensing.3. In this work, we report a micromotor which is fabricated by the template synthesis method, consisting of a gelatin shell with platinum nanoparticles decorating its inner surface. Pt nanoparticles catalyze the decomposition of hydrogen peroxide to generate O2 which provides the direct driving force for the autonomous movement. The current work provides a simple and efficient way to synthesize the tubular-shaped micromotors.