סמינר מחלקה של ג'אן לגרוואל - אלסטומרים של גביש נוזלי כמפעילים וחיישני מתח לא שגרתיים
School of Mechanical Engineering Seminar
Wednesday, December 7, 2022 at 14:00
ZOOM SEMINAR
Liquid crystal elastomers as unconventional actuators and strain sensors
Jan Lagerwall
Experimental Soft Matter Physics group, Department of Physics & Materials Science University of Luxembourg
A lively development in today’s materials science research is the creation of new ’smart’ materials that respond to specific stimuli by changing their appearance or shape. Importantly, this adaptive nature is inherent to the material, rather than arising from the interaction of multiple components. This allows single elements in a garment, a construction or any other artifact to be their own actuator or sensor, while at the same time filling the basic passive function that they were designed for. Liquid Crystal Elastomers (LCEs) constitute an exciting example of smart and adaptive materials. They can be designed to change their color in response to mechanical strain [1,2] (top figure) or, conversely, to change their shape—fully reversibly— in response to heat [3] (bottom figure), light, humidity or electric fields. Because the order that gives rise to their remarkable behavior develops by self-assembly in a liquid precursor, they can be made quickly and at low cost, in arbitrary shape, and the rubbery nature of their final state makes them easy to handle and integrate in a variety of structures.
The adaptive nature and versatile and easy processing of LCEs give them tremendous application potential across a variety of fields, from sun-powered kinetic building facades that autonomously adapt to daily and seasonal variations in temperature and humidity [4], saving energy and creating a better indoor climate for the building occupants, to garments that reveal the pressure they apply on the body as a function of location or illustrate the strains involved during motion [2]. In my talk, I will give a brief introduction to what LCEs are, how they work, and how they might be applied in the future, based on recent results from our group [1–3] and interdisciplinary collaborations [4].
[1] Rijeesh Kizhakidathazhath et al. Facile Anisotropic Deswelling Method for Realizing Large‐Area Cholesteric Liquid Crystal Elastomers with Uniform Structural Color and Broad‐Range Mechanochromic Response. Adv. Funct. Mater. 30, 1909537 (2020).
[2] Y. Geng, R. Kizhakidathazhath. & J. P. F. Lagerwall, Robust cholesteric liquid crystal elastomer fibres for mechanochromic textiles. Nat. Mater. (2022). DOI: 10.1038/s41563-022-01355-6.
[3] A. Sharma, A.M. Stoffel, & J.P.F. Lagerwall. Liquid crystal elastomer shells with topological defect-defined actuation: Complex shape morphing, opening/closing, and unidirectional rotation. J. Appl. Phys. 129, 174701 (2021).
[4] M. Schwartz & J.P.F. Lagerwall, Embedding intelligence in materials for responsive built environment: A topical review on Liquid Crystal Elastomer actuators and sensors. Building and Environment 226, 109714 (2022).
Jan Lagerwall (M.Sc. Physics 1997; Ph.D. Materials Science, 2002) is professor in physics at University of Luxembourg. His research focuses on soft matter physics, chemistry and materials science, connecting liquid crystals with many other fields, from fiber spinning and microfluidics to art, architecture, robotics and security. The motivation ranges from the scientific beauty to the diverse application opportunities arising through cross fertilization with other disciplines. He is a threefold ERC grant recipient (one CoG and two PoC grants). As postdoctoral researcher Jan worked with N.A. Clark (Boulder), G. Heppke (Berlin) and F. Giesselmann (Stuttgart). He previously held group leader positions at Martin Luther University Halle-Wittenberg (Germany) and Seoul National University (Korea). He is actively working to bring the fruits of his group’s academic research to use for society and industry through a multitude of collaborations and the foundation of spin-off companies.
This study shed light on the effects of pump configuration on the performance and risk of blood damage, indicating the roles of the hub shape and angular velocity as dominant parameter. These findings can be utilized to improve future designs of p-LVAD.
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