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04.09.2025 12:53

Paul Motzki receives one of Europe‘s most prestigious research grants to develop innovative cooling systems

Claudia Ehrlich Pressestelle der Universität des Saarlandes
Universität des Saarlandes

Ultra-flat, featherlight, and compact – these are the hallmarks of the next-generation cooling units being developed by Professor Paul Motzki at Saarland University. Backed by a prestigious ERC Starting Grant from the European Research Council, Motzki is pushing the boundaries of elastocaloric technology – a cutting-edge, climate-friendly method of cooling and heating – by combining two breakthrough smart material systems. This marks the third major success for Paul Motzki in just two years in the EU’s Horizon Europe research and innovation programme. He has already secured an EIC Pathfinder grant for visionary technologies and is also involved in a multimillion-euro EU cluster project.

Paul Motzki specializes in two distinct smart material technologies. The first involves shape memory materials – thin bundles of wire or sheets made from nickel-titanium alloy that contract or expand depending on the presence of an electrical current. These materials enable Paul Motzki and his team to build flexible actuators, such as lightweight robotic grippers. Because these alloys also absorb and release heat when they undergo deformation, they are central to another of the team’s core developments: elastocaloric cooling and heating – a climate-friendly and energy-efficient alternative to conventional systems.

The second type of smart material that Motzki and his team is exploring is a thin, highly flexible silicone film with remarkable capabilities. By adjusting the electrical voltage applied, these polymer films can be made to perform a wide range of movements – vibrating, tapping, pushing or pulling – making them ideal for creating lightweight, energy-saving mini motors. Paul Motzki’s team uses these polymer actuators to develop innovative pumps and valves. They also apply them to textiles to create wearable responsive interfaces that act as a haptic bridge between the body and digital systems. The films can also be used on smartphone displays to create dynamic buttons and haptic feedback.

Paul Motzki is a pioneer in this field and now, in a worldwide first, he is combining these two technologies – shape memory alloys and dielectric elastomer actuators – to take the emerging field of elastocaloric cooling a significant step forward. The European Research Council, Europe's largest funder of frontier research, is supporting this groundbreaking work with an ERC Starting Grant of approximately €1.5 million over five years.

Both technologies offer key advantages: they are lightweight and energy-efficient, and as environmentally clean as the electricity that powers them. Because of their ability to exert a substantial force in a confined space, they are often referred to as 'artificial muscles'. Motzki's goal is to combine these artificial muscles and mini motors made from smart materials to create cooling units that are extremely flat, compact and lightweight, and thus easy to integrate into other systems.

Motzki is also working to bring elastocaloric technology to market through another EU-funded project. In 2024, Paul Motzki and his team were part of a European consortium that won the European Innovation Council’s prestigious EIC Pathfinder Challenge, receiving €4 million in funding. He and his consortium partners are currently developing a prototype residential air conditioning system based on elastocaloric principles. The EIC Pathfinder award is given in recognition of ‘visionary, radical new technologies that have the potential to facilitate necessary societal transitions, tackle global challenges and establish new markets’. Motzki, who, in addition to holding a professorial position at Saarland University, is also Scientific Director/CEO at the Center for Mechatronics and Automation Technology in Saarbrücken, explains the difference between the two awards: ‘The EIC Pathfinder focuses on rapidly translating research into practical applications, while the ERC Starting Grant supports fundamental research aimed at expanding the scientific foundation of elastocaloric technology.’

For the EU to award a researcher with both the EIC Pathfinder and ERC Starting Grant is a rare achievement. Additional EU funding for Motzki’s research on the use of shape memory alloys in smart medical implants is being provided through the €21 million Horizon Europe project 'SmiLE – Smart implants for life enrichment', involving 25 leading institutions from 12 European countries.

Background

Elastocalorics

Elastocaloric cooling is a novel, climate-friendly and energy-efficient technology that operates without harmful refrigerants or fossil fuels. For years, Motzki and his doctoral advisor Stefan Seelecke have been developing this technology at Saarland University and at the Center for Mechatronics and Automation Technology in Saarbrücken through several multi-million-euro research initiatives. The European Commission has identified elastocaloric cooling as the most promising alternative to conventional methods, and the World Economic Forum listed it among the ‘Top Ten Emerging Technologies’ in 2024. The Saarbrücken team has already built a prototype mini refrigerator and is currently developing systems for vehicle cooling.

Elastocaloric cooling works by repeatedly stretching nickel-titanium wires or sheets and then letting them relax again, allowing heat to be absorbed in one location and then dissipated somewhere else. Whether using the system for cooling or heating, the team is able to achieve temperature differentials of around 20 °C. ‘This applies to a single-stage component,’ explains Motzki. ‘If we build multi-stage systems, we can achieve much greater temperature differences.’

The basis for all of the elastocaloric prototypes being developed in Saarbrücken is an unusual property of nickel-titanium alloy: shape memory. We all know that water can exist in three physical states or ‘phases’: solid (ice), liquid (water) and gas (water vapour). Nickel-titanium alloy has two phases. While both phases are solid, their crystal lattices have slightly different physical dimensions. The term ‘shape memory’ simply reflects the ability of nickel-titanium to revert to a previous state (crystal lattice structure) via a reversible phase transformation. When one of the phases transforms into the other, wires or sheets made from the shape-memory alloy (SMA) nickel-titanium will absorb heat; when that phase transforms back again, the material dissipates heat to its surroundings. So, air or liquid that flows over the nickel-titanium alloy as it undergoes a phase change will either cool down or heat up and this effect can be harnessed, for example, in heating or cooling systems. ‘Depending on the particular application, we use wires or thin sheets of the SMA, or we create 3D-printed components with complex geometries,’ explains Motzki.

The Saarbrücken researchers are developing practical cooling and heating systems by designing prototypes with clever mechanics that cyclically load and unload the shape memory components. The groundwork for this development work was laid in numerous research projects that examined how compact drive systems can be used to keep the SMA sheets or wires in constant motion.

The new prototypes currently under development will incorporate dielectric elastomer films as ultra-compact motors. ‘We’re using these dielectric elastomers to develop novel drive systems that do not need to be equipped with additional sensors,’ explains Paul Motzki. The films are coated on both sides with a highly flexible electrically conductive layer, which allows them to respond to voltage changes, enabling precise and energy-efficient motion. When the researchers apply an electric voltage to the polymer film, these electrically conducting layers attract each other, compressing the polymer and causing it to expand out sideways, thereby increasing its surface area. ‘By varying the applied electric field, we can control the motion of the film very precisely, and make it execute continuously variable flexing motions or make it vibrate at some desired frequency or amplitude. Essentially, we are creating an ultra-lightweight but efficient and energy-saving motor,' says Motzki.

Both the dielectric films and the shape memory wires are inherently able to provide feedback through changes in their electrical capacitance or resistance, completely eliminating the need for external sensors. ‘We can use these measured values to determine how the film or wires deform. Our technology is essentially self-sensing, as it has its own built-in position sensors,’ he adds. ‘We use artificial intelligence to map these electrical measurements to specific motion sequences, enabling us to very precisely control the motion of our actuators, drives or motors.'

Horizon Europe

Horizon Europe is the EU’s ninth research framework programme and the world’s largest single funding initiative for research and innovation. It aims to foster a knowledge- and innovation-based society and to build a competitive economy while promoting sustainable development.

ERC Starting Grants are awarded by the European Research Council (ERC) to support early-career researchers pursuing promising approaches in areas of basic research.

Prof. Dr. Paul Motzki

Paul Motzki is Professor of Smart Material Systems at Saarland University and Scientific Director at the Saarbrücken Center for Mechatronics and Automation Technology (ZeMA), where he heads the research division Smart Material Systems.
He studied mechatronics at Saarland University, where he received his doctorate in 2018 for research in the field of thermal shape memory alloys. In 2016, he took over as head of the Sensor and Actuator research group at ZeMA. After completing his doctorate in 2018, he was able to further expand his research group at ZeMA, which led to the creation of the Smart Material Systems research division. In 2022, Paul Motzki was appointed to a joint professorship at Saarland University (Department of Systems Engineering) and at ZeMA Smart Material Systems for Innovative Production (SMiP). Since 2023, Motzki has been chair of the VDI/VDE Technical Committee GMA 2.16: Smart Materials and Systems. He is also a member of the board of the smart3 network, director of the SMST board at ASM International, a member of the ASME SMASIS Senate, and co-founder of the International Elastocalorics Society (IES).

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Wissenschaftliche Ansprechpartner:

Prof. Dr. Paul Motzki, Smart Material Systems for Innovative Production (Saarland University and ZeMA)
Tel.: +49 (681) 85787-13; Email: paul.motzki@uni-saarland.de

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Weitere Informationen:

https://imsl.de/paul-motzki

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Paul Motzki is Professor of Smart Material Systems at Saarland University.
Quelle: Sophie Lessure
Copyright: Saarland University

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Professor Paul Motzki
Quelle: Oliver Dietze
Copyright: Saarland University

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