IMX Colloquium - Smart by Nature: Bio-Inspired sensors and actuators

Nature is the ultimate engineer. From squid beaks to citrus peels, living systems have evolved materials and structures perfectly adapted to their environment and requirements—lightweight yet tough, soft yet strong, protective yet flexible. Inspired by these designs, our research explores how we can translate nature’s strategies into soft, functional materials for stretchable electronics and soft robotics.
Inspired by the squid beak, we developed polyimide-polydimethylsiloxane (PI-PDMS) composites, that enables a single material with a seamless transition from hard to soft. These gradient materials offer great potential for stretchable electronics with built-in strain relief and anisotropic dielectric elastomer actuators. Complementary work on dynamic covalent silicone networks and super-soft inorganic elastomers enables even more precise control of stiffness and mechanical performance, providing versatile platforms for next-generation ultra-conformable soft devices. Foundational studies using a simple ball drop test provide an easy and cheap means for quantitative extraction of mechanical properties of soft materials such as dissipated energy, storage and loss modulus and Young’s modulus.
Taking cues from the damping properties of citrus peels, we created open-cell soft elastomer foams filled with carbon black. These are capable of absorbing impacts, sensing collisions, and, in combination with a pneumatic radial compression actuator, enable tailored energy dissipation. Further, we developed soft actuator concepts based on plant motions. A high-speed soft actuator with a response time of 4ms using mechanical instabilities triggered by temperature was inspired by the closing mechanism of the venus flytrap. The mimosa plant and its water-driven movements motivated phase transition actuators that enable untethered soft actuators for grippers, hinges and pumps. They can also easily be implemented in wearables.
By learning from nature, we can design soft machines that are smarter, more resilient, and more adaptable—capable of sensing, moving, and interacting with the world in ways previously only found in living organisms.

Bio: Ingrid Graz received her PhD in Physics from Johannes Kepler University Linz, Austria, where she focused on flexible ferroelectret pressure sensors for thin-film transistors. After a postdoctoral stay in Jena, Germany, she worked for three years on stretchable electronics in collaboration with Nokia at the Nanoscience Center, Department of Engineering, University of Cambridge. She then returned to Johannes Kepler University Linz, where she completed her habilitation on skin-inspired electronics and soft robotic and became an Associate Professor in Soft Matter Physics. From 2020 to 2024, she served as Head of the Christian Doppler Laboratory for Soft Structures for Vibration Damping and Impact Protection and currently leads a research group focused on Bioinspired soft Systems, affiliated with both the School of Education and the Institute for Biophysics. Recently she was elected Vice-Head of the BioMediCry Core Facility at Johannes Kepler University and serves as President of the EuroEAP Society.