Particle Manipulation Study Based On Laser-induced Thermo-optical Tweezers

Low-damage non-contact manipulation technology has epoch-making significance in the field of micro-manipulation of particles and cells,and is widely used in biomedicine,micro-assembly,chemical research and other fields.However,the traditional low-damage non-contact manipulation technology,such as optical,magnetic and acoustic tweezers,has many limitations,including but not limited to physical limitations,requirements for particle characteristics,small capture range and potential induction and damage to biological samples,which restrict the application and development of this technology.In order to solve these limitations,this paper proposes a new type of low-damage non-contact micromanipulation technology,thermo-optical tweezers technology,which combines thermoswimming,thermal convection and microfluidic technology.Based on the thermophoresis and thermal convection induced by photothermal effect,this technology absorbs the energy of 532 nm laser and causes the change of temperature gradient through the photothermal waveguide made by self-assembly with GR-261 photoinitiator.The change of temperature gradient will lead to the formation of thermophoresis and convection microflow fields,and then form an annular microflow potential well,which can realize the positioning and control of particles.In addition,by making photothermal waveguides with different structures,a variety of microfluidic states can be generated,and the custom manipulation of particles can be realized.This paper mainly carried out the following research contents:1.In this paper,the development and research status of low-damage non-contact manipulation technology are reviewed and discussed,and the particle manipulation technology based on laser-induced thermo-optical tweezers is proposed.Combined with the actual operation process,the principles of thermal swimming effect and thermal convection effect involved are analyzed,and the relevant mechanical formulas are derived,which lays the research foundation for the simulation calculation and experimental preparation of the full text.2.The circular capture of polystyrene beads and the near uniform transport along the Z-shaped path are realized by the single-focus laser acting on the dot-shaped photothermal waveguide and the double-track photothermal waveguide respectively.In addition,negative refractive index particles and irregular substances have been successfully captured and manipulated.In order to verify the feasibility of particle manipulation,the simulation calculation of thermal optical tweezers manipulating particles is carried out in this paper,and the distribution of capture force field is analyzed,which verifies the feasibility of manipulating particles.3.Dual-focus lasers with the same and different powers are used to act on the dual-track photothermal waveguide respectively,which realizes the manipulation and movement of various particles.Specifically,the capture and back-and-forth motion of polystyrene beads are realized at the midpoint of the connecting line of two focused lasers and on the connecting line respectively.In addition,the dual-focus laser with the same power acts on the dual-track photothermal waveguide and the single-track photothermal waveguide,which realizes the nearly uniform transport of particles in the track direction,as well as the lateral manipulation and lateral transport on the vertical line connecting the two focused lasers.