This artificial hand comes directly from the 3D printer. What makes it so special is that its artificial muscles, which look like small, wrinkled balls, can be controlled using compressed air.
In bionics, a branch of robotics, scientists try to imitate natural mechanisms. While some areas have been mimicked with great success, recreating the structure and function of muscle fibers remains a challenge. One of the reasons for this is that muscle strands in nature have to meet a large number of different requirements. There are muscle groups that can contract particularly quickly or strongly, but there are also those that only perform small but very precise movements, such as muscles in the human face that are responsible for facial expressions. Special arrangements of muscle groups can also ensure that something rotates, bends or moves back and forth.
Before such complex movements can be realized in robotics, it first needs an artificial muscle structure that is able to meet the requirements for strength and precision. Corrado De Pascali from the Italian Institute of Technology in Genoa and his team have now presented a structure that could deliver this. It is a kind of sphere with folds that can expand or contract under pneumatic influence - similar to a muscle fiber. The so-called GRACEs (GeometRy-based Actuators able to Contract and Elongate) can be produced with a commercially available 3D printer and integrated directly into more complex structures.
Depending on the area of application, the GRACEs can be variably scaled. "Their size is only limited by the manufacturing method," explains De Pascali. "In addition, we can vary their performance with different techniques, i.e. adjust how well they can deform and how much force they apply." In order to change the characteristics of the GRACEs, the scientists use different materials with different elasticity properties, for example. But the thickness of the membrane, i.e. the outer skin of the pneumatic components, also plays a role. In this way, the researchers can on the one hand change the pressure required for the expansion and on the other hand change the force that the GRACEs exert in the process. Depending on the material, the spheres can then lift more than a thousand times their own weight.
To demonstrate a potential use for their artificial muscle, De Pascali and his team 3D printed a human hand. The scale model shown here weighs around 100 grams and has 18 GRACEs installed. The individual fingers can be bent and stretched over these. Thanks to the special arrangement, the scientists are also able to bend the palm of the hand and turn the artificial wrist using the four spheres integrated into it.
In the future, such pneumatic muscle analogs could help to find robotic solutions that would otherwise be difficult to implement. One of their advantages is that the structures can be produced by a standard 3D printer and can also be integrated directly into a complex arrangement. In addition, the production costs of the imitation muscle fibers are very low, which means that they could also be of interest for industrial solutions.