Fabrication and characterization of Au–Fe/Ni/(Mo/Co) alloy microsphere motors (AMSM) based on physical vapor deposition

Abstract Au–Fe/Ni/(Mo/Co) alloy microsphere motors (AMSM), having an average diameter of 7 ~ 9 μm, were fabricated though a rapid and effortless method than the template direct electroplating (TDEP), which only requires physical vapor deposition (PVD) of inert metal coat on commercially available microspheres; thus, several kinds of AMSM with different alloy composition can be manufactured readily. Via co-catalytic decomposing reaction in the mixed fuel of hydrogen peroxide and hydrazine, the ejection of oxygen bubbles generated from the Fe/Ni/(Mo/Co) alloy hemisphere provides a powerful directional propulsion. The AMSM's moving ability closely depends upon the content of mixed fuel and the composition of alloy, especially the content of nickel. The AMSM can move as fast as 548.63 μm/s (ca. 64 body-lengths/s). Because of the permalloy composition, the AMSM also can be guided by the magnetic force besides controlled with the propelling force generated by the bubble thrust. Compared with the nanowire motor, the AMSM could facilitate different biomedical applications, such as targeted drug delivery in future research, because of its bigger specific surface area.