Biodegradable artificial muscles: Researchers in the field of soft robotics focus on sustainability

Artificial muscles are a future technology that could one day allow robots to function like living organisms. They open up many new possibilities for how robots positively impact the world around us, from devices we put on like clothes to help us in our daily lives or make us more mobile as we age, to rescue robots that navigate through rubble in search of missing people. How versatile the robots of the future will be is influenced by the artificial muscles they are built from – but that doesn't mean they have to have a big impact on the environment.

Thus, the topic of sustainability is coming more and more into focus in soft robotics too. Scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart, Johannes Kepler University (JKU) in Linz (Austria), and the University of Colorado (CU Boulder) in Boulder (USA) have developed a completely biodegradable, high-performance artificial muscle made of gelatine, oil, and bioplastic. In a research paper, the team shows how they have equipped a gripper arm with several such artificial muscles. If the muscles are damaged at some point or no longer function properly, they can be disposed of in the biowaste bin. Under controlled conditions, the artificial muscles break down completely within six months.

The research team calls the electrically powered artificial muscle HASEL. HASELs are plastic bags filled with oil and equipped with electrodes on both sides of the bag. When a high voltage is applied between the electrodes, the electrostatic forces cause the vegetable oil inside the bag to shift. As the oil is pushed back and forth, the bag contracts – like a real muscle. The most important prerequisite for the deformation of the HASELs to work is that all materials can withstand high electrical voltages.