Ways fully compostable soft robotics are moving from silicon to soil

From Silicon to Soil: The Rise of Fully Compostable Soft Robotics
A new soft robot developed by South Korean scientists boasts a durability of one million cycles and, thanks to the use of elastomers, is fully compostable once decommissioned.
If current forecasts are anything to go by, the next technological revolution will take place at the intersection of robotics and artificial intelligence : machines capable of navigating real-world environments and carrying out complex physical tasks autonomously. However, from the perspective of Sustainability, the question remains: what happens to all that high-tech scrap? While recycling is the most intuitive solution, it is not without its hurdles.
To put this into perspective, a study by UNITAR, a UN agency, found that the world generated 62 million metric tonnes of electronic waste in 2022. A vast proportion of this ends up in landfill due to a lack of waste management infrastructure or the inherent difficulties of the recycling process .
Against this backdrop, an international team of researchers from Seoul National University in South Korea has unveiled a soft robotic system designed to be completely compostable . Crucially, they have achieved, for the first time, a level of durability that matches non-biodegradable soft devices.
Soft robotics represents an evolution of traditional engineering, replacing rigid structural frameworks with elastic, deformable materials such as elastomers or hydrogels. Inspired by the biomechanics of organisms like octopuses, this discipline allows for the creation of machines capable of adapting to irregular environments and handling delicate objects with a degree of safety that conventional robotics simply cannot offer.
The primary soft robotics technologies can be classified by their operating mechanism or by the type of materials used. Regarding the latter, the following types exist:
Synthetic elastomers and polymers. High-elasticity silicones and polyurethanes. These form the basis of pneumatic systems and are noted for their durability.
Hydrogels. Polymer networks with a high water content. Their structure most closely resembles biological tissue, as they react to changes in hydration or pH levels.
Shape-memory materials (SMM). Alloys and polymers that return to their original geometry after deformation. Activated by thermal or magnetic stimuli, they act as artificial muscles.
Variable viscosity fluids. Substances that alternate between liquid and solid states via electric or magnetic fields. These allow the robot to gain instantaneous structural rigidity.
Carbon and graphene composites. Materials used in flexible electronics. They allow for the integration of sensors and circuits that stretch and bend without losing electrical conductivity.
Recently, research has begun into soft robotics that is also biodegradable. In this vein, South Korean scientists have published a study in the journal Nature Sustainability introducing a robot with a structural framework made of polyglycerol sebacate (PGS) . Unlike other degradable materials used previously, PGS is an elastomer that contains no water, giving it superior chemical stability and mechanical strength similar to conventional rubber.
The choice of this material is a deciding factor in ensuring the device responds effectively to the demands of the working environment. While other organic compounds, such as hydrogels, tend to lose their properties when faced with variations in humidity or temperature, PGS maintains its structural integrity during active use. This allows the robot to perform precision tasks without the risk of premature degrading while still operational. As seen in the video below, the prototype was stored at room temperature for six months without these conditions affecting its performance:
The prototype developed features 21 integrated electronic components that allow it to function as a working robotic finger. The researchers strictly limited themselves to elements that can be absorbed by the environment, including biodegradable inorganic materials composed of magnesium and molybdenum—the latter used to manufacture semiconductors and sensors.
Integrating these elements into a soft structure has allowed the device to pass mechanical fatigue tests. According to the project leads, the robotic finger successfully completed  more than one million cycles  of bending and applying force. This figure represents a performance standard that makes its application in real-world automation environments viable, where long-term reliability is an indispensable requirement. After all, a compostable robot is of little use if it lacks practical functionality. But let us look at the process as it comes full circle.
The final phase of the study focused on the transition of the device from a technological object to organic waste. When processed in industrial composting systems, the robot began a decomposition process driven by microorganisms. Both the PGS body and the magnesium and silicon circuits disintegrated within a few months.
The compost resulting from the robots' degradation was used as a substrate to grow oats, and the plants flourished without showing any signs of toxicity.
And that is not all. To verify the safety of the process, the researchers conducted plant growth tests. The compost resulting from the degradation of the robots was used as a substrate to grow oats . The results showed that the seeds not only germinated normally but that the plants developed without showing any signs of toxicity. Finally, the metallic residues from the electronic components, present in minimal quantities and in natural oxidised forms, are consistent with the biological life cycle.
The viability of this system opens up research avenues in sectors where retrieving devices is complex and costly, or poses pollution risks. In precision agriculture, for instance, these sensors could be deployed to monitor crops and degrade in situ after harvest. They could also be used in forests and other ecologically sensitive environments. Likewise, in the healthcare sector, this type of biodegradable electronics paves the way for implants that the body can reabsorb once their function is complete.
This breakthrough proves that sustainability in robotics does not have to come at the expense of technical efficacy. The ability of these materials to offer stable performance over a million cycles opens up a horizon for devices designed for the era of the circular economy .
Alongside soft and biodegradable robots that return to nature as organic matter, there is also a new generation of machines inspired by it. We are referring, among others, to biomimetic robots inspired by marine creatures that allow for the exploration and monitoring of the oceans.
Source:
TechXplore
David is a journalist specializing in innovation . From his early days as a mobile technology analyst to his latest role as Country Manager at Terraview , an AI-driven startup focused on viticulture, he has always been closely linked to innovation and emerging technologies.
He contributes to El Confidencial and cultural outlets such as Frontera D and El Estado Mental , driven by the belief that the human and the technological can—and should—go hand in hand.
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