Fabrication And Motion Control Of Micro And Nanorobots Based On Electron Beam Lithography

With the development and progress of nanotechnology,the prospect of using micro and nanorobots to achieve targeted drug delivery becomes possible.Although nanorobots can potentially improve nano-drug delivery systems,one of the main challenges is the use of micro and nanorobots for in vivo drug delivery,that the biological tissue fluid environment limits the application of larger-scale robots,but most of the current research are focused on the preparation and functional development of micrometer and millimeterscale robots.In order to solve this problem and promote the application of micro and nanorobots in vivo,this study uses electron beam lithography technology to fabricate achiral L-shape micro and nanorobots.The minimal planar geometry of the L-shape micro and nanorobots enable the use of nano-lithographic techniques to fabricate robots down to 400 nm.In this study,a two-dimensional L-shaped achiral structure was used to prepare the magnetic nanorobot,which met the swimming shape requirements of the robot.In order to optimize the swimming performance of the micro and nanorobots,the parameters in the fabrication process will be carefully studied to ensure the characteristics of consistency and repeatability.This study used a fabrication protocol that combines electron beam lithography,electron beam evaporation,and ICP etching technology to create two-dimensional achiral L-shape micro and nanorobots.A custom built magnetic control system was used to control the motion of the achiral L-shape micro and nanorobots.The micro and nanorobots were actuated using a rotating magnetic field.Furthermore,the swimming posture of the micro and nanorobots can be controlled.A tracking algorithm was used to study and analysis the motion of the micro and nanorobots.The 3D motion control of the achiral L-shape micro and nano robot was carried out by controlling the direction of the rotating field's plane of rotation.This research focuses on the preparation process of the achiral L-shape micro and nanorobots and their motion control under a rotating magnetic field.The findings of this work are as follow:(1)Using the planar achiral geometry,micro and nanorobots with minimum side length of 400 nm has been successfully fabricated.The fabrication parameters is summarized in this report which include the use of sodium hydroxide in the stripping process to adjust the p H value of the hydrogen peroxide solution in order to successfully release the L-shape micro and nanorobots;(2)Combined with a high-power microscope and the magnetic controller,the movement postures of the L-shape micro and nanorobots was manipulated and analyzed;this is useful in determining the movement state of the L-shape micro and nanorobots which in turn helps controlling their velocity;(3)The 3D motion control of the micro-nano robot under the rotating magnetic field was performed and analyzed.The results herein will serve as a foundation for the future research on swarm control of micro and nanorobots in a simulated in vivo environment.The innovation of this research is as follow: the use of electron beam lithography technology to overcome the size limitation of magnetic microrobots.Compared with other preparation methods in the field,such as ultraviolet lithography,laser direct writing,or chemical synthesis,e-beam lithography offers high precision and high throughput fabrication at the nanoscale which is essential to drug delivery.This preparation method can prepare a micro-nano robot with a size that matches the movement in the living body.In this study,by preparing a simple two-dimensional achiral L-shape micro and nanorobots,three-dimensional motion can be achieved in a rotating magnetic field.The results of this work will enable the use of micro-nano robots to complete in vitro drug delivery,which is an important step towards a practical drug delivery system.