These "picosprings" have remarkably large and tuneable compliancy and can be controlled remotely through magnetic fields (even deep within the human body) allowing articulated motion in microrobots as well as micromanipulations well beyond the state of the art.
Moreover, the extension of the picosprings can also be used visually to measure forces, for example propulsion or grasping forces, in interaction with other objects like cells. For example, these picosprings have been used to measure the locomotive propulsion force of sperm cells. The publication showcases these capabilities by demonstrating several microbots (including a micropenguin) containing picosprings at multiple locations that can do these tasks at cellular scales: propel themselves, grasp and release cells and measure the minute forces needed to do this safely. Figures 1 and 2 show two of these novel spring-loaded structures – a microgripper and a micropenguin extracted from the publication [https://doi.org/10.1038/s41565-023-01567-0].
Dr. Haifeng Yu, first author of the study and group leader at the Chinese Academy of Sciences in Shenzhen (China), says: "Programmable elasticity at the micrometer scale offers a feasible strategy for producing 3D devices and finely structured 'micro-surgeons' capable of performing complex medical tasks".
Dr. Mariana Medina-Sanchez, group leader at the Leibniz IFW and BCUBE- TU Dresden, co-author and co-supervisor of this work, adds: "These picospring-based micromachines with programmable elasticity and magnetism, crafted through monolithic fabrication, open numerous possibilities for localized force sensing and actuation in low Reynolds number environments. This versatility underscores their significance across a spectrum of biomedical applications".
Prof. Oliver Schmidt, who is last author of the paper and supervised this work, sees this as another important step in the transition towards life-ready soft and smart modular microrobotics. "Remotely controlled microdevices using magnetic fields form a particularly promising technology for non-invasive medical applications – and now this extends to mechanical mechanisms inside these remote microdevices", says Schmidt.
"Being able to incorporate designer springs will also add a new tool to the growing capability at TU Chemnitz towards microelectronic morphogenesis and artificial life," adds Prof. John McCaskill, co-author of the study, member of the Research Center MAIN, and Founding Director of the European Centre for Living Technology. The topic "Microelectronic Morphogenesis" was covered in a recent press release.
This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreements No 835268, and No. 853609).
Publication: 3D nanofabricated soft microrobots with super-compliant picoforce springs as onboard sensors and actuators, Haifeng Xu, Song Wu, Yuan Liu, Xiaopu Wang, Artem K. Efremov, Lei Wang, John S. McCaskill, Mariana Medina-Sánchez, Oliver G. Schmidt. Nature Nanotechnology (2024).
DOI: https://doi.org/10.1038/s41565-023-01567-0
