The development of artificial muscles is an advancing technology that has the potential to transform the way robots operate, making them more similar to living organisms. These muscles have the ability to revolutionize various fields, including the creation of wearable devices that can assist us in our daily lives as we age, as well as rescue robots that can navigate challenging terrains in search of survivors. However, it is crucial to consider the environmental impact of these artificial muscles after their use, despite their potential societal benefits.
A group of researchers from Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart, Johannes Kepler University (JKU) in Linz, and University of Colorado (CU Boulder) have highlighted the significance of sustainability in soft robotics. They have worked together to create a high-performing, fully biodegradable artificial muscle that is composed of gelatin, oil, and bioplastics. To demonstrate the feasibility of this biodegradable technology, they used it to power a robotic gripper, which could prove valuable in single-use applications like waste collection. At the end of its life cycle, the biodegradable muscles can be disposed of in municipal compost bins, where they degrade entirely within six months under controlled conditions. A Youtube video showcasing the robotic gripper has also been made available.
“We see an urgent need for sustainable materials in the accelerating field of soft robotics. Biodegradable parts could offer a sustainable solution especially for single-use applications, like for medical operations, search-and-rescue missions, and manipulation of hazardous substances. Instead of accumulating in landfills at the end of product life, the robots of the future could become compost for future plant growth,” says Ellen Rumley, a visiting scientist from CU Boulder working in the Robotic Materials Department at MPI-IS.
The upcoming publication, “Biodegradable electrohydraulic actuators for sustainable soft robots,” features Rumley as the co-first author. The research team created an electrically powered artificial muscle named HASEL, which stands for Hydraulically Amplified Self-healing Electrostatic Actuator. HASELs are essentially plastic pouches filled with oil and are partially covered by a pair of electrical conductors called electrodes. By applying a high voltage across the electrodes, opposing charges build up on them, leading to the creation of a force that pushes oil towards an electrode-free area of the pouch. This oil migration causes the pouch to contract, similar to the contraction of a real muscle.
To enable the deformation of HASELs, it is crucial that the materials composing the plastic pouch and oil are electrically insulating and can endure the high electrical stresses produced by the charged electrodes.
One of the main obstacles encountered during the project was the creation of a conductive, soft, and completely biodegradable electrode. Scientists from Johannes Kepler University have developed a solution using a blend of biopolymer gelatin and salts that can be directly poured onto HASEL actuators.
“It was important for us to make electrodes suitable for these high-performance applications, but with readily available components and an accessible fabrication strategy. Since our presented formulation can be easily integrated in various types of electrically driven systems, it serves as a building block for future biodegradable applications,” states David Preninger, co-first author for this project and a scientist at the Soft Matter Physics Division at JKU.
n the search for appropriate biodegradable plastics, engineers focused primarily on properties such as mechanical strength and degradation rate, rather than electrical insulation. This posed a challenge for HASELs, which require electrical insulation to operate effectively at high voltage levels.
However, some bioplastics demonstrated promising compatibility with gelatin electrodes and adequate electrical insulation. One particular combination of materials was even capable of enduring 100,000 actuation cycles at several thousand Volts without showing signs of electrical failure or performance degradation. This breakthrough confirms that biodegradable artificial muscles are just as competitive electromechanically as their non-biodegradable counterparts, representing an exciting development in sustainable artificial muscle technology.
“By showing the outstanding performance of this new materials system, we are giving an incentive for the robotics community to consider biodegradable materials as a viable material option for building robots,” Ellen Rumley continues. “The fact that we achieved such great results with bio-plastics hopefully also motivates other material scientists to create new materials with optimized electrical performance in mind.”
As eco-friendly technology continues to gain prominence, the team’s research project marks a significant milestone in the field of soft robotics. The use of biodegradable materials in the development of artificial muscles represents a critical step towards a future of sustainable robotic technology. However, this is just one aspect of a broader paradigm shift in the robotics industry towards eco-friendly and socially responsible technology. By incorporating sustainable design principles and materials in the development of robots and their components, we can create a future where robots not only benefit society but also leave a minimal environmental impact.
You might also be interested in reading, Breakthrough in Soft Robotics: Caterpillar-Like Robot Can Maneuver Through Narrow Spaces with Ease
