Wireless Micromotor Drives By Twisting

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-11-26 11:39

Researchers from the Helmholtz-Zentrum Geesthacht and the Université de Bordeaux have presented an efficient micromotor and at the same time energy storage in the scientific journal Science. The simply constructed motor consists of a plastic microfiber, which is stiff at room temperature. When heated, the fiber becomes elastic and can be twisted - like a model airplane with a rubber band. Cooled down again, the fiber, unlike rubber, is to maintain its twisted state; until you reheat it on site. The three-phase voltage returns, the movable end begins to rotate and the "microfiber motor" can serve as a drive.

Higher torque with graphene oxide

In order to achieve a high energy density during storage, the researchers stiffen the plastic with tiny graphene oxide sheets. Lead author Jinkai Yuan, who does research at the Université de Bordeaux, explains: "The experiments showed that graphene oxide is superior to carbon nanotubes." Due to the favorable orientation of the nanosheets to the direction of deformation of the fiber and its own deformation, graphene oxide becomes higher Torque reached.

Rotations and temperature range can be predetermined

Prof. Andreas Lendlein, co-author and head of the HZG Institute for Biomaterial Research in Teltow, explains: "The number of rotations that the micro-fiber motor can make and the temperature range in which this movement is triggered can be predetermined." The so-called switching temperature up to which the three-phase voltage is maintained can be set within wide limits via the temperature at which the fiber was previously twisted. For the fiber material examined, polyvinyl alcohol, a programming temperature of 80 ° C has proven to be particularly favorable. 80% of the twists programmed by twisting the fibers should be able to be called up again here. For future medical applications, you can also work with a plastic that switches at body temperature.

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Important step towards application

"This result is an important step towards many applications - such as micro-robots or even autonomous systems in which programming could be done with wind power, for example," says Lendlein.

For many purposes, an electric motor is too weak, too big, not robust enough - and it requires power and control cables. In previous experiments with fibers, the rotation speed, torque and rotation angle were again too small. Above all, however, the weight-related energy density left something to be desired. With the microfiber motor, it is said to be 60 times higher than with natural skeletal muscles.

Electric motor