Fabrication And Control Of Visible Light Driven Micro/Nano Robot

Micro-nano robots are functional devices that use external physical or chemical fields to achieve movement at the micrometer and nanometer scales.Micro-nano robots can perform complex tasks in liquid media.At present,it has been applied in many fields such as drug delivery,sewage treatment,and biopsy.In recent years,selfpropelled micro-nano robots have attracted more and more attention,but they also face challenges such as toxic driving fuel,difficult to control the direction of movement,and low efficiency of movement.The research object of this subject is the micro-nano robot with BiVO₄/Metal half-edge structure driven by visible light.The preparation and movement rules of the micro-nano robot and the performance under different conditions are investigated.This study is mainly divided into the following two parts.The first part is the preparation of BiVO₄/Metal Janus micro-nano robot.In the preparation of light-driven micro-nano robots,it is necessary to construct asymmetric geometric structures.In the synthesis and preparation of BiVO₄ microspheres,through multi-parameter design and control experiments,the optimized parameters of synthetic microspheres were obtained.When the p H of the solution is 4.6 and the reactant Bi/V ratio is 1:1,microspheres with uniform size,good morphology and stable crystal structure can be obtained.By comparing the hydrothermal method with low temperature precipitation,the size of microspheres synthesized by hydrothermal method was found to be larger than that obtained by low temperature precipitation.Electron beam vacuum evaporation method is used to coat a half of the microsphere with a layer of metal to form a half-sided Janus asymmetric structure.The photocatalytic degradation of methylene blue experiment confirmed that the photocatalytic efficiency of BiVO₄ microspheres with metal coating is higher than that of pure BiVO₄.The second part is about the motion behavior of BiVO₄/Metal Janus micro-nano robot driven by visible light.The principle is that the flow of photoprotons generated by the photocatalytic reaction drives the movement of the micro-nano robot.By adjusting the light ON/OFF,the stop-go motion of the BiVO₄/Pt Janus micro-nano robot was successfully achieved.During the experiment,after turning on light,the response time from random Brownian motion to directional motion is about 2 s.This repeatable light-driven principle is of great significance for the application of clustered micro-nano robots.In order to solve the dilemma of the micro-nano robot's excessive dependence on toxic fuels such as hydrogen peroxide during actuation,after testing various solutions such as glucose,urea,and pure water,it was found that the BiVO₄/Au Janus micro-nano robot can approximate the concentration of the human body Achieve higher speed movement in glucose and urea solution,which has positive significance for expanding the application of micro-nano robots.As the concentration of glucose solution rises,the movement speed of the micro-nano robot increases,and the maximum speed can reach 11.54 ?m/s.By changing the direction of the light,the directional movement of the micro-nano robot was realized,which confirmed the obvious phototaxis property.In addition,the movement behavior of the BiVO₄/Au micro-nano robot in the presence of glucose in the light was withdrawn.The effect of different coating metals and different sizes of micro-nano robots on the movement law was further explored.