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Introduction: Artificial Muscles and Their Environmental Impact
Sustainability in Soft Robotics: A Collaborative Effort
Designing a Biodegradable Artificial Muscle: HASEL
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Introduction: Artificial Muscles and Their Environmental Impact
Artificial muscles are an advancing technology that could potentially make robots function like living organisms. These muscles offer new possibilities for how robots can interact with the world, from enhancing physical abilities in older individuals to aiding in search-and-rescue operations. However, it’s important to consider the environmental impact of using artificial muscles.
Sustainability in Soft Robotics: A Collaborative Effort
A team of international researchers from the Max Planck Institute for Intelligent Systems (MPI-IS), Johannes Kepler University (JKU), and the University of Colorado (CU Boulder) has brought the topic of sustainability in soft robotics into focus. Their collaboration led to the development of a fully biodegradable artificial muscle made of gelatin, oil, and bioplastics. This innovative technology was used to create a robotic gripper, which has potential applications in single-use scenarios like waste collection. Importantly, these artificial muscles can be disposed of in municipal compost bins and fully biodegrade within six months.
“We recognize the need for sustainable materials in the field of soft robotics. Biodegradable parts could offer a sustainable solution, especially for single-use applications such as medical operations, search-and-rescue missions, and handling hazardous substances. Instead of ending up in landfills, robots of the future could become compost for future plant growth,” says Ellen Rumley, a visiting scientist from CU Boulder who worked on the project.
Designing a Biodegradable Artificial Muscle: HASEL
The research team developed a biodegradable artificial muscle called HASEL, which is driven by electricity. HASELs are essentially oil-filled plastic pouches with electrodes on either side. When a high voltage is applied, charges build up on the electrodes, causing the oil to move away and resulting in the contraction of the pouch, mimicking the movement of a real muscle. The key to HASELs’ functionality is using electrical insulators for the materials composing the pouch and the oil to withstand the high electrical stresses generated by the charged electrodes.
One of the challenges faced by the team was creating a conductive, soft, and fully biodegradable electrode. The researchers at Johannes Kepler University developed a recipe using a mixture of gelatin and salts, which could be directly cast onto the HASEL muscles. This formulation is easily integrated into various types of electrically driven systems and serves as a foundation for future biodegradable applications.
Finding suitable biodegradable plastics was another crucial step. The engineers focused on properties like degradation rate and mechanical strength, but also had to ensure electrical insulation, a requirement for HASELs operating at high voltage levels. Fortunately, some bioplastics displayed good material compatibility with gelatin electrodes and provided sufficient electrical insulation. HASELs made from a specific material combination even demonstrated durability through 100,000 actuation cycles at several thousand Volts without any sign of electrical failure or performance loss. These biodegradable muscles are comparable in performance to non-biodegradable alternatives, a significant development in promoting sustainability in artificial muscle technology.
“Our outstanding results with this new material system will incentivize the robotics community to consider biodegradable materials when building robots. Hopefully, our success with bio-plastics will inspire other material scientists to develop new materials with optimized electrical performance,” adds Ellen Rumley.
The research project undertaken by the team represents a significant step towards a paradigm shift in soft robotics. Using biodegradable materials for artificial muscles is just the beginning of a sustainable future for robotic technology.