The Study Of Propulsion,Control And Application Of Micromotor/Micropump

Micromotor can convert chemical or external energy into kinetic energy to realize its self-propulsion.On the other hand,the micropump can be obtained by simply immobilizing micromotor on the substrate.Micromotor and micropump share the similar propulsion mechanism and show great potentials in the field of precise medicine,construction of active materials,environmental remediation,etc.However,some urgent problems need to be solved for micromotor/micropump,for example,the bio-incompatibility of the constituent parts,the toxicity of the chemical fuels(H₂O₂),the weak control over the motion behavior and the limited applications.Aiming to address the above problems,the current thesis focuses on the propulsion(particularly the fuel-free propulsion)and motion control of the micromotor/micropump,and the exploration of new applications,which includes the following five parts:1.Mg/Al asymmetric micromotor driven by multi-fuels and its motion control.Heavy-metal-free micromotor is fabricated which consists of magnesium and aluminum.Due to the different chemical reactivity of magnesium and aluminum,the Mg/Al asymmetric micromotor can move toward Mg side in the presence of acid and salt solution,and move toward Al side in the presence of base solution,which are based on the bubble-propelled mechanism.Besides,the motion start and stop of the Mg/Al micromotor can be controlled by the addition of different fuels,indicating its great potential in the field of logic gates.Among others,when using different stimuli as the inputs and the micromotor motion as the output,the first micromotor with XOR and INHIBIT logic functions is achieved.2.Near infrared(NIR)light driven polypyrrole(PPy)based micromotor and its motion control.As a substitution of the chemical fuel driven propulsion,NIR is applied to drive the micromotor and its surrounding liquid flow.The underlying mechanism is based on the surface tension gradient around the micromotor caused by the p-doping process of PPy under light irradiation and the resulting increase of hydrophilicity.In addition,the motion behavior of the micromotor and the surrounding liquid flow can be precisely controlled by adjusting the incident angle of NIR,including translational motion alone,translational motion with outward water flow,and outward water flow alone.This unique property makes this PPy-based micromotor attractive in the field of cargo delivery and release.3.Visible-light-driven pentacene(PEN)based micromotor(Si O₂/Au/PEN)and its motion control.Under tilted irradiation,the micromotor shows positive phototactic moving behavior without adding any other chemical fuels,which relies on the self-eletrophoresis mechanism caused by the photocatalytic reaction of PEN.Interestingly,when the tilted irradiation is tuned to a vertical irradiation,the Si O₂/Au/PEN micromotors exhibit positive phototactic moving behavior at first,then stop immediately when approaching the irradiation center,forming an aggregate.Besides,the migration of micromotor aggregation can be well controlled by tuning the irradiation position.Based on the aggregation behavior,we have demonstrated their application in repairing the conductivity of the cracked circuit.4.White light driven PEN based micropump and the control over the pumping behavior.Micropump is the micromotor immobilized on the substrate.Visible light-driven micropump is achieved based on photocatalysis of PEN.Under irradiation,PEN micropump drives the surrounding fluid containing the tracer particles moving towards the pump along the substrate,which is attributed to the electro-osmosis mechanism.Besides,the inward pumping causes the agglomeration of the tracer particles on the surface of micropump.In addition,the position of this aggregation can be manipulated by moving the light between two adjacent micropumps.5.The application of the light driven PEN based micropump in the conductivity restoration of the flexible circuit.Based on the microparticle aggregation behavior enabled by the PEN-based micropump,a novel photowelding strategy for conductivity recovery is developed.When the conductive path is cracked,photochemical reactions of PEN will be activated near the cracked area under light illumination,causing the electro-osmosis phenomenon and propelling conductive microparticles to move toward the crack and aggregate near the crack.This method has good repeatability with the same crack being repaired for multiple times.When keeping other functional parts intact,both the size and location of the microparticle aggregation can be well controlled,allowing precise crack recovery with a resolution of 100?m.More interestingly,successful reparation of damaged circuits could be achieved even in the presence of an inert surface coating.The repeatability,precision and controllability of the photowelding strategy in this study may have great potential for conductivity restoration in flexible devices.