The Study Of Light-driven Micro/nanomotors And Micropumps

Motion is very important for the life system.The kinetic energy of myosin in an organism is provided by the energy released by the biomolecule motor to hydrolyze ATP,which carries the movement of the material required by the cell and performs life activities at the designated location.Inspired by the organism,scientists have put a lot of effort into the research of the movement of tiny devices.These devices range in size from nanometers to micrometers,and their primary function is to absorb external energy to propel their own motion.The external driving forces mainly include physical drive,chemical drive,biological drive and hybrid drive.Among them,the study of light energy as the source of energy in physical drive has become a hot spot in recent years.Because of the pollution-free advantages of light energy,the application range of micromotors of optical drive is more extensive.Micro/nanomotors are mainly divided into the following two categories.One type is micro/nanomotors,which absorb external energy into kinetic energy to promote their own movement,and the other is micropumps,which generate a certain flow behavior of the surrounding fluid through external stimulus response.Their application areas are mainly in the process of pollution control,fixed-point delivery,and drug treatment.However,it is difficult to accurately manipulate the direction of motion of the micromotor,which hinders the application of artificial micromotors.In addition,single-component nanomotors with dual phototaxis are rare.Based on the above scientific problems,the main work of our research is to solve the problem of accurately controlling the bidirectional phototaxis of micro/nanomotors and the bidirectional pumping behavior of micropumps based on the structure of simple structure.Therefore,in order to solve these problems,we divide the research work into the following three parts:1.In the first part of the work,we first synthesized porphyrin iron nanomotors of various sizes by one-step precipitation method.The porphyrin iron nanomotor can move toward the light source,but as the light intensity increases slowly,the moving direction of the nanomotor changes from the original direction to the light source to a direction away from the light source.And its speed of motion will increase.We also found that the motion behavior of collective nanomotors also has a certain relationship with the angle of illumination.When the illumination angle is 0 degrees,a plurality of nanomotors at a small light intensity move in parallel toward the direction of the light source,and when the illumination intensity increases,the nanomotor moves in a direction away from the light source.When the light intensity is 45 degree,the collective behavior of the nanomotor at a low light intensity is aggregated toward one side of the light source.When the light intensity is increased,the nanomotor also moves away from the light source.2.In the second part of the work,we studied a positive phototaxis micromotor using water as fuel.We used the emulsion method to make micromotors based on iron phthalocyanine.In the measurement,we found that these micromotors are microspheres.Under illumination,the micromotor based phthalocyanine iron can move toward the light source.We believe that this motion behavior is based on the self-diffusion mechanism.In addition,we combine the motion behavior of micromotors with the excellent photocatalytic activity and find that it can improve the degradation efficiency of organic pollutants in solution,which may realize the application of micromotors in environmental treatment.3.We synthesized a micropump with controllable pumping direction by electrospinning.The micropump contains two materials,namely photoresist and surfactant.Micropumps are mainly pumped by light and have different pumping directions under different intensity illumination,i.e.pumping outwards and pumping inwards.When the light intensity is low,the surfactant in the micropump can be released,so that the solute buoyancy causes the fluid to move outward,and when the light intensity increases,the photoresist in the micropump absorbs more heat to form a thermal gradient,causing inward pumping behavior.More interestingly,the magnitude of the force between the two mechanisms of motion leads to a unique heartbeat.