Stimuli-responsive Polymerbased Micromotors And Micropumps

Inspired by the biological micromotors and micropumps,the man-made system with autonomous movement has achieved great developments in the past decade.The 2016 Nobel Prize in Chemistry was awarded to three scientists for the design and synthesis of molecular motors.Then,what's a micromotor?Briefly speaking,micromotor is a kind of device with size in micrometer scale that can make use of energy in the surrounding to maintain its self-motivation.For example,micromotor can realize self-propelling in the liquid,and micropump may induce the flow of fluid,both share the same operating mechanism at most time.Up to now,precisely controlling the motion of the micromotor and micropump is still a big problem,therefore the future research will focus on remote control in real time.According to previous researches,the methods of fabricating micromotor or micropump are very complicated and not suitable for mass production,which limits their potential applications.What we study was to precisely control the motion of the micromotor and micropump synthesized by scalable method.This thesis contains three parts.1.Use one-step electrospray method to fabricate hemisphere-like micromotors with uniform surface morphology in large scale.Intriguingly,the micromotor exhibited the controllable On/Off/On motion,which can be actuated by two different external stimuli(UV and NH3)in a reversible way.Moreover,the moving direction of the micromotor can be manipulated by the applied direction of UV and NH3,which is away from the stimuli.As a result,the motion accelerated when both stimuli were applied in the same direction and decelerated when the application direction was opposite.Besides,the dual stimuli responsive micromotor can be utilized as a reconfigurable logic gate with UV and NH3 as the input and the motion of the micromotor as the output.By controlling the direction of the external stimuli,OR and XOR dual logic functions can be realized.2.Use one-step electrospray method to fabricate cake-like microstructure,which can realize moving and pumping under the illumination of light.When we illuminated the sample from a tilted angle above the liquid,the moving and pumping behavior would be observed at the same time.While when we illuminated the sample with vertical light,only the pumping would be observed.Besides,when the sample was fixed under the water,by controlling the light irradiation intensity,the sample worked as a pump and its direction and speed can be controlled in a reversible way.More interestingly,by carefully adjusting the irradiation intensity,a 'heartbeat'(the appearance of the oscillating micropump behavior)can be observed.3.Use template synthesis method to fabricate tubular Ag/Gelation micromotors.The AgNPs would be deposited inside the wall of gelation tubes in a silver enhancer mixed solution,which catalyzed hydrogen peroxide decomposition to realize the self-propulsion based on bubble-driven mechanism.First,the fabrication process was simpler than rolled-up method and electrochemical deposition method.Second,the gelation was a natural biocompatible material,and the silver is not only cheaper than the platinum,but also can exert high-performance on catalyzing the hydrogen peroxide at low concentration.We have also studied some factors which influence the motion speed of the micromotor.