Characteristics Research On The Light-induced Rotating Micromotor

As a micron-sized energy conversion device,a micromotor can convert various forms of energy into mechanical energy.So far,micromotors have become an indispensable tool in many researches,and are widely used in the fields of drug delivery,acceleration of chemical reaction processes,and promotion of nerve growth.Micromotors that have been widely studied at present can be divided into the following two categories:The first type of micromotors are usually made of catalytic precious metals,which can catalyze the surrounding chemical fuels to generate common oxidation-reduction reactions to drive themselves,also known as internal-drive micro-motor;the second type of micro-motor can be made of a variety of materials,but requires external energy（such as magnetism,sound,electricity,light,etc.）to drive itself,and is also called an external-drive micro-motor.Compared with chemically driven micromotors,micromotors relying on external energy are popular because of their non-toxic and easy-to-control features.Among them,optical drive micromotors have also received more and more attention.However,most of the current research on optically driven micromotors is driven by light radiation pressure,and there are defects in the structure of the experimental device and the high requirements of the rotor preparation process.A small number of optical driving micromotors based on photophoretic or Marangoni effect There is also the disadvantage of low energy conversion efficiency.According to the research status of optically driven micromotors,this thesis uses absorbing material to design an optically driven micromotor driven by photophoretic in a liquid,and uses the classic optical tweezers experimental system to perform optical rotation operation on it,using the method of combining experiments,theory and simulation analyzes its motion characteristics in detail,and derives the force and torque expressions of the micromotor when it rotates.By changing the incident power of the laser,the relationship between the incident power and the rotation speed of the micromotor is explored.When the incident power of the laser is 50.58μW,the micromotor starts to rotate.When the incident power of the laser is78.16μW,the rotation speed of the micromotor reaches 769.23r/min,the experiment proves that the higher the incident power of the laser,the higher the rotation speed of the micromotor,and when the incident power is too high,the micromotor will break free from the shackles of the photophoretic due to the excessively fast rotation speed.The experiment is simulated and calculated,and the calculated results are consistent with the experimental results.This thesis explores the energy conversion efficiency of the micromotor when the numerical aperture of the objective lens is 1.25 and 0.75 by changing the objective lens of different magnification.It is concluded that the larger the numerical aperture of the objective lens,the higher the energy conversion efficiency of the micromotor.In addition,compared with the 10^-12-10^-9 energy conversion efficiency of the previous optically driven micromotor,the energy conversion efficiency of the micromotor designed in this thesis can be as high as 10^-7,an increase of 2-5 orders of magnitude.This thesis provides a non-contact,high-efficiency driving method for micro-motors made of absorptive materials,so that optically driven micro-motors may be used in a wider range of fields.