Researchers have developed a microrobot that measures a few micrometers across and resembles a paper bird made with origami. But unlike a paper structure, the robot moves without a visible force. It flaps its wings or bends its neck and retracts its head via magnetism.
The micromachine is made from materials that contain small nanomagnets, which can be programmed to assume a particular magnetic orientation. When the programmed nanomagnets are then exposed to a magnetic field, specific forces act on them. If these magnets are located in flexible components, the forces acting on them cause the components to move. The nanomagnets can be programmed repeatedly; this reprogramming results in different forces, and new movements result.
To construct the microrobot, the researchers fabricated arrays of cobalt magnets on thin sheets of silicon nitride. The “bird” constructed from this material could then perform various movements such as flapping, hovering, turning, or side-slipping. The movements take place within milliseconds; programming of the nanomagnets only takes a few nanoseconds. This makes it possible to program the different movements one after the other. The microrobot can first flap its wings, then slip to the side, and flap again. If needed, it could also hover in between.
The concept is an important step towards micro and nanorobots that not only store information to initiate a particular action but also can be reprogrammed to carry out different tasks. In the future, an autonomous micromachine could navigate through human blood vessels and perform biomedical tasks such as killing cancer cells. Other applications include flexible microelectronics or microlenses that change their optical properties and creating surfaces that can either be wetted by water or repel water.