by Martin Kaltenbrunner, Florian Hartmann, Andreas Heiden and David Preninger
3D-printed vase deformed by human finger touch.
Future generations of robots will work very differently from those that assemble entire vehicles or solder electronics onto circuit boards at lightning speed on factory floors today. They will leave the factory halls and start working with people, handing them a tool at the right moment or assisting them in assembling heavy components. They will appear in agriculture, helping harvest the fields or process the fruits. And they will increasingly be found in living rooms, supporting and entertaining people there or simply making them feel less alone.
Of course, these robots will also look different from the enormous metallic contraptions found in today’s industrial plants. Their appearance will change along with their new functions. Whenever they come into contact with people, they will be gentle and soft so that they won’t hurt anyone – and “soft” here actually means that they are made of conformable materials; that their surface is elastic, flexible and stretchable. Of course, at the same time they are equipped with comprehensive sensor technology that immediately registers every touch and every approach, in order to be able to react appropriately. Today, the development of these soft electronics and robotics mostly relies on synthetic materials such as silicone elastomers – a rubber with very good elastic properties but of fossil origin. This also means that if soft robots become as omnipresent in the future as smartphones are today, the tech-waste grows substantially once again. This raises the question: Where are the biodegradable alternatives? And if they exist, how can we make truly empowering robots that move, sense, and react to their environment?
Martin Kaltenbrunner, head of the Soft Materials Laboratory at the Johannes Kepler University in Linz, Austria, investigates such sustainable alternatives for our future technologies. His team focuses on technologies that interface the human body and, therefore, are equally soft and conformable. Wearable electronics, stretchable energy supplies, and biomimetic robots are just a few examples. And by addressing sustainability, his team adds a new twist to these soft technologies.
The scientific breakthrough was achieved in 2020, when Kaltenbrunner and his team discovered a frugal way to make biodegradable gels (biogels) extremely resilient and durable but still vanish when disposed. Based on the abundant biopolymer gelatin, their material had similar properties and performance than the non-degradable silicone rubbers, paving the way for its use in soft robots.
Now, the doctoral students Andreas Heiden and David Preninger have built a system to 3D print this biogel into complex shapes. They have printed finger-like robots that use intricate sensor networks to sense their own deformation and also objects in their surroundings. Together with Florian Hartmann, materials engineer at EPFL, they have published their research in the renowned journal Science Robotics.
XYZ calibration cube and gummybear model printed from gelatin-based biogel ink.
Fully actuated 3-chamber actuator with integrated sensor network detects human finger touch.
