Behavioral Investigations On The Surface And Interface And The Motion Of Micro/Nanorocket

Micro/nanorockets propelled by chemical energy have been proposed for practical applications by modifying the surface,such as drug delivery,sensor detection,environmental sustainability and micro/nanorobotics systems.At present,the research on the microrocket mainly focuses on the drag reduction,speed increase and motion control.Although bubble propulsion mechanism for microrocket has been proposed,the prediction of the velocity of cone shape microrocket remains inaccurate,which seriously affects the application of the microrocket.The relevant parameters of the microrocket motion model,such as the radius of bubble and the drag force of microrocket,are very important for the accuracy of microrocket velocity calculation.The anti-interference and the motion stability of the microrocket have not been reported.In addition,the driving process and the motion characteristics of nanorocket will change when the scale of microrocket is reduced from micrometers to nanometers.Therefore,hydrodynamic behavior on the surface and interface and the motion behavior of micro/nanorockets are investigated using thoeretical,experimental and computer simulation approaches.The topics of the research includes:In order to investigate the effect of the shape of the surface and interface of the microrocket on the drag force,the models of the drag force for a cone-frustum shape and a double truncated shape of microrockets are established by using low Reynolds number hydrodynamics method.The normalized drag coefficient of microrockets with different external configurations is proposed.The effect of the geometrical parameters of microrocket on the drag force is studied using numerical simulations,and the relation between the drag coefficient and the geometrical parameters of microrocket is obtained.In order to accurately predict the velocity of a microrocket propelled by bubble michanism,a mathematical models of the bubble growth and the detachment at the interface of the gas,solid and liquid phases are established,and the laws of the bubble detachment radius and the detachment frequency are obtained.By combining numerical simulations with experiments,the effects of the bubble detachment radius and the detachment frequency on the velocity of microrocket are analyzed.The relation between the microrocket velocity and bubble detachment radius,separation frequency can be used for the prediction of the mictocket velocity and the configuration design of the microrocket.To study the effect of the microstructure on the surface of the microrocket on the motion behavior,a microrocket with the stripe grooves has been designed and fabricated.A hydrodynamic model for the microrocket with stripe grooves microstructure is established using hydrodynamics method.The influence of the stripe grooves microstructure on the motion stability of microrocket is analyzed.The pressure center deviation is used as the measure of the microrocket stability,and the law of anti-interference of microrocket with the grooves microstructure is obtained.For the applications in the fields of biomedicine and biosensing,the fabrication method of the graphene/zinc(r GO/Zn)microrocket is studied.The process parameters for the fabrication of the graphene/zinc microrocket are obtained.The methods of drug loading on the graphene surface of microrocket are discussed.The motion behavior of the graphene/zinc microrocket is analyzed.The dynamics of a bilayer ultrastructure mesoporous nanorocket is analyzed based on the diffusiophoretic mechanism,and the motion model of the nanorocket is established.The block copolymer lithography is combined with an atomic layer deposition for fabrication of the Ti O2/Pt bilayer ultrastructure mesoporous nanorocket with length in 150 nm.The propulsion mechanism of the nanorocket based on diffusiophoresis is obtained using the combination of the finite element simulations and the experiments.In conclusion,the hydrodynamic behavior at the surface and interface and the motion behavior of chemically powered micro/nanorockets are investigated using thoeretical,experimental and computer simulation approache s.The reaseach reveals the role that surface and interface shape of the microrocket play in determining the drag force,the hydrodynamic behavior and the propulsion mechanism of bubble-propelled microrocket,the effect of the microstructure on the surface and interface of the microrocket on the motion stability,the motion law of the bilayer ultrastructure mesoporous nanorocket.The process parameters for fabrication graphene/zinc microrocket are obtained.The methods of drug loading on the graphene surface of microrocket are discussed.Micro/nanorockets can be used as drug transporter in the fields of biomedicine or biosensor.