Magnetic Control of Tubular Catalytic Microbots for the Transport, Assembly, and Delivery of Micro‐objects

Abstract

Recently a significant amount of attention has been paid towards the development of man‐made synthetic catalytic micro‐ and nanomotors that can mimic biological counterparts in terms of propulsion power, motion control, and speed. However, only a few applications of such self‐propelled vehicles have been described. Here the magnetic control of self‐propelled catalytic Ti/Fe/Pt rolled‐up microtubes (microbots) that can be used to perform various tasks such as the selective loading, transportation, and delivery of microscale objects in a fluid is shown; for instance, it is demonstrated for polystyrene particles and thin metallic films (“nanoplates”). Microbots self‐propel by ejecting microbubbles via a platinum catalytic decomposition of hydrogen peroxide into oxygen and water. The fuel and surfactant concentrations are optimized obtaining a maximum speed of 275 µm s−1 (5.5 body lengths per second) at 15% of peroxide fuel. The microbots exert a force of around 3.77 pN when transporting a single 5 µm diameter particle; evidencing a high propulsion power that allows for the transport of up to 60 microparticles. By the introduction of an Fe thin film into the rolled‐up microtubes, their motion can be fully controlled by an external magnetic field.