All living organisms operate far from thermodynamic equilibrium. Humans, for example, constantly consume energy, from food, sunlight, and other sources, to sustain movement, communication, and other daily functions in a dissipative manner. In materials science, responsive soft materials such as light-sensitive liquid crystal elastomers (LCEs) have been widely explored for applications ranging from switchable adhesion and microfluidics to energy damping and soft actuation. Recent advances have pushed these materials further from equilibrium, unlocking more complex behaviors.
One well-established approach to achieving non-equilibrium motion in LCEs is based on the self-shadowing effect. This involves deformation moduliting light absorption in order to generate cyclic motion under constant illumination. Although this principle has been studied for nearly two decades and applied to materials like hydrogels and bilayers, its use remains limited. However, this is not enough, says Zixuan Deng.
According to him, there are several fundamental limitations including: 1) Limited motion amplitudes and reliance on precise local irradiation; 2) Reciprocal actuation cycles, unsuitable for tasks such as fluid pumping in microfluidics; and 3) A disconnect between the material and its environment, hindering two-way interaction studies.
“A biologically inspired robotic material should be able to sense, actuate, make decisions, and interact with its environment, but without bulky electronics or complex computing. To achieve this, materials must operate out of equilibrium and become increasingly life-like, enabling autonomy, adaptability, and communication,’’ Deng explains.
His doctoral research addresses these challenges through three main directions: developing new actuation mechanisms that bypass self-shadowing, engineering symmetry-breaking strategies to unlock fluidic functionalities, and introducing sensing-like responses that allow materials to adapt to their surroundings. These advances broaden the design space for responsive soft matter and chart a path toward synthetic matter that merges non-equilibrium actuation and environmental adaptability.
Zixuan Deng is originally from China. He currently works as a doctoral researcher in the Smart Photonic Materials Group at Tampere University.
Public defence on Thursday 4 September
The doctoral dissertation of MSc (Tech) Zixuan Deng in the field of Chemistry titled Light-Fueled Self-Sustained Soft Robotics will be publicly examined at the Faculty of Faculty of Engineering and Natural Sciences at Tampere University at 12:00 on Thursday, 4 September 2025 at Hervanta campus, in Festia building, auditorium Pieni Sali 1 (Korkeakoulunkatu 8, Tampere).
The Opponent will be Professor Andreas Walther from University of Mainz, Germany. The Custos will be Professor Arri Priimägi from the Faculty of Engineering and Natural Sciences.