Recently, Li Quan's team, dean and chief scientist of the Institute of Intelligent Materials and School of Chemistry and Chemical Engineering of Southeast University, has made important progress in the assembly and control of micro-colloid robots. The relevant results were published online in the Proceedings of the National Academy of Sciences (Proceedings of the National Academy of Sciences and United States of America, PNAS) under the title "Colloidal Tubular Microrobots for Cargo Transport and Compression".
Wang Xiaoyu, a doctoral student at Southeast University, is the first author, and Li Quan and young teacher Yang Tao are the co-corresponding authors.
Micro-nano robots refer to complex systems that can achieve controllable actuation and perception at the micro-nano scale, and ultimately achieve in vivo drug delivery and disease treatment. Inspired by swarms of bees and fish in nature, microrobot swarms have attracted increasing attention for their collaborative propulsion, delivery and signal transmission modes. As a new type of micro-robot system, the dynamic assembly of external field-responsive colloids can be used as an effective means for robot clusters. However, the existing colloidal robot assembly structures are limited to dense colloidal aggregates, which greatly limits its functionality. How to construct a complex colloidal assembly structure-function system and establish the corresponding structure-activity relationship is a challenge that needs to be overcome urgently.
Li Quan's team proposed a metastable colloidal structure assembly method. Through assembly path design, it was the first time to assemble complex three-dimensional hollow tubular structures from superparamagnetic colloidal microspheres. This method has a wide range of applications and can achieve repeated assembly of superparamagnetic colloidal particles from 200 nanometers to 30 microns in non-Newtonian fluids including blood. The assembled microtube robots can precisely control the three-dimensional trend, propulsion direction and speed through external magnetic fields. The internal hollow space enables these tubular microrobots to grab, transport and release goods according to instructions. In addition, two microtubule robots can be merged along the axis to form a new robot. Compared with other assembly structures, the metastable structure of the microtubule robot can maintain its radial repeated compression, so it can be used as microtweezers to squeeze internal red blood cells and other flexible cargo to achieve in-situ detection of target objects. This work provides new ideas for complex colloid assembly and microrobot manipulation.
This research work was funded by the Jiangsu Provincial “Double Entrepreneurship Team”, Jiangsu Provincial Natural Science Foundation and other projects.