Research On Laser-induced Surface Tension Driving Method At Gas-liquid Interface

Micromanipulation technology plays an important role in the fields of micro/nano manufacturing technology,physical science and biomedical engineering.Laser-induced surface tension driving method has many advantages,such as high accuracy,simple control,no pollution to liquid,which has broad application prospects in micro-operation.However,the current research is still mainly on the experimental level,lacking in-depth understanding of its driving mechanism and related influencing factors and influencing laws.In this paper,the driving mechanism of laser-induced surface tension on the gas/liquid interface of micro-objects is studied combining the National Natural Science Foundation of China(NSFC).Firstly,the mechanical analysis of micro-objects is carried out.Based on Newton mechanics equation and Young-Laplace equation,the static model of liquid surface micro-object is established,and the dynamic model of liquid surface object under laser irradiation is established based on the relationship between surface tension and temperature.Aiming at the problem of poor accuracy of single laser beam driving,which is widely used in laser-induced surface tension driving at present,the operation method of multi-laser beam driving is proposed,and the motion process of micro-object irradiated by two and three laser beams is analyzed.Secondly,in order to clarify the driving mechanism of laser-induced surface tension and its influencing factors,a finite element simulation method is proposed.Laser is equivalent to the Gauss heat source model,and the simulation model of temperature field variation of floating object irradiated by laser is established.The influence of laser parameters,such as laser power,spot size,laser irradiation position,and the change of material,shape and size on the temperature field distribution is analyzed.Then,the influence of these parameters on the motion law of the object is analyzed by using the mechanical model of the micro-object.For the multi-laser beam driving method,the influence of spot spacing,laser layout and laser moving speed on the motion process of the object is analyzed,which provides a parameter basis for the subsequent experimental research.Lastly,the experimental platform of laser-induced surface tension driving is established.The experiments of different laser parameters,object materials,size parameters,spot spacing,the influence of laser moving speed on object trajectory under single laser irradiation and multi-laser irradiation are carried out.The experiments of complex trajectory such as circular liquid surface object,shape assembly and indirect operation under multi-laser irradiation are also carried out.The analysis results are compared to verify the correctness of the theoretical analysis method.