Directed rotational motion of microscale objects using interfacial tension gradients continually generated via catalytic reactions

The controlled, continuous directed rotational motion of microscale objects can be achieved using spatially defined catalytic regions. SiO ₂ of 0.25μm was grown on n+ Si wafer and a seed metal layer consisting of 25 nm of chromium and 75 nm of gold was evaporated onto the oxide surface. A shipley 1827 positive photoresist was spun on the surface at 4000 rpm for 40 s, soft baked for 90 s at 110°C, was exposed through a mask for 3.5 s using a mercury lamp uv source calibrated to an exposure output of 12mWcm ^-2 on a Karl Suss MA-6 optical contact aligner. At the molecular scale, natural biological systems implement biomolecular motors, which acts as delivery vehicles and perform a wide variety of inter cellular functions. It was found that these motors are driven chemically through the catalytic hydrolysis of ATP, a chemical fuel present in the intercellular solution suspending these continuously operating motors.