The femtosecond laser was used to manufacture a magnetically responsive "Janus Origami" robot, which realized the effective integration of various droplet manipulation functions

Recently, the reporter learned from the University of Science and Technology of China that Professor Hu Yanlei's team and his collaborators in the micro-nano Engineering Laboratory of the School of Engineering Science and Technology of the School have prepared a magnetic-responsive double-God origami robot that can be used for cross-scale droplet manipulation using femtosecond laser micro-nano manufacturing method, realizing the effective integration of diverse droplet manipulation functions. It includes droplet three-dimensional transport, merging, splitting, droplet distribution and on-demand release, stirring and remote heating. At the same time, the high stability of this control strategy gives it the ability to manipulate droplets across scales. The findings were published in Nature Communications.

The diverse manipulation of droplets across scales has important application prospects in the fields of fine chemistry and biomedical detection. From a practical point of view, effective droplet manipulation technology requires multi-functional integration and multi-scale applicability. However, how to further expand the function of magnetic response droplet manipulation and expand the diversified droplet manipulation from microliter scale to nanoliter scale remains a challenge.

According to the researchers, the upper and lower surfaces of the magnetic response Two-face origami robot have different wetting characteristics respectively. The upper surface of the robot is in a state of super-hydrophobic low droplet adhesion, while the lower surface is in a state of hydrophobic high droplet adhesion. At the same time, the upper surface of the robot is also designed with two creases, so that when the robot is in contact with the droplet, it can spontaneously wrap the droplet under the action of capillary force. The machining and modification of the robot's overall contour, crease and surface micro/nano functional structure are all made by second laser scanning. Driven by magnetic field, the robot can actively approach and wrap the water droplets by rolling, which can realize the controllable transport of water droplets.

In addition, the magnetically responsive Janus origami robot can also distribute child droplets from large droplets by directional tumbling and folding. The distributed droplet can be squeezed out of the robot by controlling the strength of the magnetic field. Using its specially designed superhydrophobic outer surface, the robot nudges the water droplets to achieve controlled release separation of the daughter droplets. The robot can also rotate under the action of a magnetic field to achieve a controlled mixing of liquids and, combined with its photothermal properties, remote heating.

The research shows that the magnetic response Janus origami robot can achieve stirring and heating functions similar to commercial magnetic mixers. In addition to the rapid mixing of water, the rapid mixing of high viscosity liquids (glycerin) can also be effectively achieved through the heating stirring function of the robot. The heating temperature can reach more than 80℃. On the basis of diversified droplet manipulation, the researchers made the magnetic response Janus origami robot can effectively integrate a variety of droplet manipulation functions to achieve continuous droplet manipulation goals, and this multifunctional droplet manipulation integration can also be effectively extended to nanoscale droplet. Finally, as a proof of concept, the researchers successfully achieved nucleic acid extraction and purification by surface modification of the magnetically responsive Janus origami robot, combined with its diverse droplet manipulation functions.

According to the researchers, the magnetically responsive Two-face origami robot can achieve cross-scale droplet manipulation, which is of great significance in fields such as fine chemical industry, medical diagnosis and microfluidics technology, which require accurate acquisition and addition of reagents, microdroplet pattern and rapid microdroplet reaction.

Source: Science and Technology Daily