ABSTRACT
Autonomous nano/microparticles are of great current interest due to their potential applications in cargo delivery, nanoscale assembly, robotics, fluidics, and chemical/biochemical sensing. Light provides a particularly useful means of manipulating motility since the stimulus can be applied remotely, patterned with a photomask, and readily translated to irradiate specified locations. A single particle generates a relatively small propulsive force and cannot be employed to transport a largo payload. As with social insects, such as ants, the solution lies in designing swarms of particles that can act cooperatively. Accordingly, the three outstanding challenges in the expanding field of autonomous nano/microparticle systems are: 1) to design fuel-free systems in which directed motion of nano/microparticle swarms can be powered solely by light, 2) to demonstrate function that can only be carried out by swarms, rather than by individual particles, and 3) to repeatedly pickup, transport, and deliver multiple cargo types. We will simultaneously showcase all three capabilities using titanium dioxide microparticle swarms. The swarms can be moved directionally using light. The swarms can collect and release a variety of inert cargo particles on demand. Moreover, the cargo particles of different sizes can be sorted and released sequentially.