Thermomagnetic Microactuators and Generators (TMG)
PI: Dr. Joel Joseph [Contact]
We are developing microactuators using the ferromagnetic transition in soft-magnetic materials as well as corresponding devices for energy generation at miniature scales. Thermomagnetic and shape memory microactuators provide high work density and efficient energy utilization, making them particularly attractive for microactuation concepts. Energy Harvesting gains increasing interest as a potential energy source for sensors and sensor networks currently under development, such as structural health monitoring systems, wireless sensor networks, or medical devices. Due to the compact form factor of the harvesting devices, the power density is increased, enabling an even higher power output through the parallel operation of multiple devices.
Our research contributes to the research program 3: "Materials Systems Engineering" (MSE), Topic 1: "Functionality by Information-Guided Design: From Molecular Concepts to Materials", in the research field „Information“ as defined by the Helmholtz Association. Link to MSE website.
Research Areas
- Thermomagnetic microactuators
- Thermomagnetic generators
- Piezoelectric conversion of thermal energy
- EU network “Heat4Energy”
Publications
- Wischnewski, M., Joseph, J., Ohtsuka, M., Miki, H., and Kohl, M. (2024). A Multilayer Piezoelectric Thermo-Magnetic Film Generator. Proceedings of the 2nd International Electronic Conference on Actuator Technology, 4–6 November 2024 (MDPI: Basel, Switzerland)
- Joseph, J. (2023). Power Generation by Resonant Self-Actuation. Dissertation, Karlsruher Institut für Technologie (KIT), Fakultät für Maschinenbau (MACH), doi:10.5445/IR/1000162553.
- Joseph, J., Ohtsuka, M., Miki, H., and Kohl, M. (2023). Resonant Self-Actuation Based on Bistable Microswitching. Actuators 12, 245, doi:10.3390/act12060245.
- Joseph, J., Fontana, E., Devillers, T., Dempsey, N.M., and Kohl, M. (2023). A Gd‐Film Thermomagnetic Generator in Resonant Self‐Actuation Mode. Adv Funct Ma-ter, 2301250. doi:10.1002/adfm.202301250.
- Joseph, J., Ohtsuka, M., Miki, H., and Kohl, M. (2022). Thermal processes of miniature thermomagnetic generators in resonant self-actuation mode. iScience 25, doi:104569.10.1016/j.isci.2022.104569.
- Kohl, M., Joseph, J., and Seigner, L. (2022). Energy Harvesting Using Magnetic Shape Memory Alloys. In: Encyclopedia of Smart Materials (Elsevier), pp. 96-103. doi:10.1016/B978-0-12-815732-9.00040-1.
- Joseph, J., Wehr, M., Miki, H., Ohtsuka, M., and Kohl, M. (2021). Coupling Effects in Parallel Thermomagnetic Generators Based on Resonant Self-Actuation. In: 2021 21st International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers) (IEEE), pp. 463–466. doi:10.1109/Trans-ducers50396.2021.9495569.
- Joseph, J., Ohtsuka, M., Miki, H., and Kohl, M. (2021). Lumped Element Model for Thermomagnetic Generators Based on Magnetic SMA Films. Materials 14, 1234. doi:10.3390/ma14051234.
- Joseph, J., Ohtsuka, M., Miki, H., and Kohl, M. (2020). Upscaling of Thermomagnetic Generators Based on Heusler Alloy Films. Joule 4, 2718–2732. doi:10.1016/j.joule.2020.10.019.
Thermomagnetic generators are based on novel alloys that exhibit strongly temperature-dependent magnetic properties near room temperature. The change of magnetization induces an electrical current in an applied pick-up coil. The required temperature changes are only a few degrees Celsius. A possible field of applications are microgenerators, for instance, to power sensors in hardly accessible places or to energize electronic components in order to operate them without batteries. In the next four years, researchers of the EU doctoral network HEAT4ENERGY will advance this technology and implement first functional prototypes. Among the partners is the spin-off company memetis GmbH (https://www.memetis.com) found in 2017 by three former PhD student at IMT that specializes on innovative actuator technologies.
More (in German)
With five award winners, the IMT was extremely successful at the KIT President's Evening of Honour: Dr. S. Lehmkuhl becomes a Emmy-Noether fellow, Prof. U.W. Paetzold acquired an ERC-Consolidator Grant, Dr. J. Xu got a Nexus-funding from Carl-Zeiss Stiftung to build up a young investigator group, Dr. G. Huang was honored with the IU35 award as most brilliant innovator under 35 and Dr. J. Joseph received the HGF doctoral award for his excellent PhD thesis.
On April 29, Joel Joseph received this prestigious award from Prof. Dr. Otmar Wiestler, President of the Helmholtz Association (HGF). As part of his doctorate in Prof. Dr. Manfred Kohl's working group, Joel Joseph investigated the innovative use of thermomagnetic thin-film drives to develop thermal energy harvesters with very high power per footprint. The development efforts resulted in a 340 percent increase in power per footprint compared over the first prototype. With his research results, Dr. Joel Joseph is making an important contribution to satisfying the enormous demand for local, distributed energy generation. These are particularly needed in connected devices specifically designed to accurately sense environmental conditions.
Researchers at KIT and Tohoku University (Japan) succeeded in significantly enhancing the electrical power of thermomagnetic generators with respect to footprint. This research is the front topic of the December 2020 Issue of the Energy Journal ‘Joule’.
Original Publication: Joel Joseph, Makoto Ohtsuka, Hiroyuki Miki, and Manfred Kohl: Upscaling of Thermomagnetic Generators Based on Heusler Alloy Films. Joule, 2020.
DOI: 10.1016/j.joule.2020.10.019