One of the main components of a factory is the robots that transport and assemble objects of varying shapes and sizes. When scaling down to the micro level, the steel and wiring that these robots are made of must be replaced by something else—one new idea is peanut-shaped particles that are propelled with light and steered by magnetic fields.
The light-activated docking system could provide the means to manipulate microscopic particles in a wide range of applications. The motion and cargo-carrying phenomena observed with the hematite dockers is based on osmotic/phoretic transport triggered by the photocatalytic properties of the hematite immersed in a reservoir of hydrogen peroxide. The light activation, photocatalysis, of the hematite triggers the activity and develops a concentration gradient of hydrogen peroxide, surrounding the particle. The hematite dockers themselves are made in bulk and are simple single-component particles, the team says.
The self-propelled colloidal hematite dockers can be steered to a small particle cargo many times its size, dock, transport the cargo to a remote location, and then release it. The self-propulsion and docking are reversible and activated by visible light. The docker can be steered either by a weak uniform magnetic field or by nanoscale tracks in a textured substrate. The light-activated motion and docking originate from osmotic/phoretic particle transport in a concentration gradient of fuel, hydrogen peroxide, induced by the photocatalytic activity of the hematite. The docking mechanism is versatile and can be applied to various materials and shapes. The hematite dockers are simple single-component particles and are synthesized in bulk quantities. This system opens up new possibilities for designing complex micrometer-size factories as well as new biomimetic systems.