The motion of nano- and micro-scale particles can be controlled via chemical, electric, magnetic, acoustic, and temperature effects. Wavelength-sized particles can be guided with the help of light as can be seen in optical tweezer and optical tractor beam applications. Unfortunately, the complex environments in which these particles reside cause light scattering. Thus, it is unreliable to control particles simply through light.
Luckily, a process called thermophoretic drift can guide particles through a light-induced thermal effect. Propulsion occurs along the axis of a temperature gradient that has been induced by the heat generated from light absorption in the particle. Although thermophoretic drift is robust to scattering, the process has difficulty changing the direction of particles in motion. This technology addresses this challenge adding a multi-directional component to thermophoretic drift.