When looking at the animate world around us, and in particular at the “building blocks” that we are made of, we will find that nature has developed intricate ways to unite a wide range of antagonistic materials into highly sophisticated “hybrid soft robots”. From hard and resilient as bones teeth, elastic and tough as muscles and tendons all the way to soft and squishy as the brain – seamless interfaces between soft and hard are found everywhere in and around us. At the beginning of GEL-SYS, we took this intricacy as inspiration for our quest to develop the soft electronic and robotic systems of the future. We developed a method for instant tough bonding of hydrogels to a wide variety of materials spanning hard and brittle to soft and stretchable in a frugal and effective way using dispersions of quickly reacting synthetic glues. This enabled us to employ tough and stretchy hydrogels to create a variety of soft systems, from electronic sensor skins all the way to stretchable batteries as power supply. While pursuing the goal of GEL-SYS of developing technologies that ever more intimately and seamlessly integrate in our daily lives, we inevitably arrived at a key question: Can we develop advanced technologies in a sustainable way? Facing ever-growing amounts of e-waste – 50 million tons of it in 2019 alone – sustainability must become a driving principle of research. New trends, from bio-inspired robotics to personalized healthcare and monitoring, create undreamt-of possibilities for a worthwhile future. Here, innovation that is sustainable is innovation that lasts. Within GEL-SYS, we contributed to this overarching goal by developing a new class of resilient yet bioderived and biodegradable hydrogels that closes the gap between sustainability and performance. Based on the biopolymer gelatin, this biogel is highly durable with outstanding elastic characteristics, yet degrades fully when disposed. It self-adheres, is rapidly healable and derived entirely from natural and food-safe constituents. What’s more, these gels can be readily 3D printed for dexterous soft grippers that are proprio-and exteroceptive. The team’s efforts culminated in the development of the first high-power stretchable and biodegradable batteries, an essential step towards autonomous and sustainable soft devices. Future robots will benefit from lightweight, efficient and fast “muscles” that are readily controllable. Polymer-based electrostatic actuators are promising here, within GEL-SYS we developed their first biodegradable embodiments that do not compromise in performance, but are compostable once no longer needed. By merging materials innovations with scalable, low cost fabrication methods, GEL-SYS is a step towards durable, life-like soft robotic and electronic systems that are sustainable and closely mimic their natural antetypes. The numerous achievements of the project have so far led to 30 peer reviewed journal publications and the foundation of a startup company. They were disseminated by the team at the major conferences in the field, as well as through wide press coverage in public media and outreach activities such as at the ARS Electronica media arts festival.
