| Since it was first demonstrated by A.Ashkin et al in 1986,optical tweezers technology has been widely used in biology,chemistry,colloid science and physics.Especially in biology,it has been used to manipulate cells,organelles,viruses,bacteria and DNA molecules,providing a powerful tool for studying these basic life units and understanding their biological functions.Fiber optic tweezers inherit the advantages of flexible fiber,small size and compact structure,and can reach the diseased tissue through the natural orifice of the human body,which is very good for in vivo medical treatment.In the research of fiber optical tweezers,it is a very important research topic to improve the maneuverability to achieve multi-dimensional operation,and people have done in-depth research in this aspect.Based on fiber optical tweezers,the multidimensional operation of cells was studied.We completed the capture,transport and ejection experiments of yeast cells,and carried out the theoretical calculation of cell rotation manipulation.In this paper,the background,technology development and current research status of optical fiber tweezers are summarized and reviewed.This paper mainly introduces the development and recent situation of optical tweezers based on special optical fiber,including optical tweezers based on annular core fiber,optical "light gun" based on coaxial double waveguide,“optical miniature hand” based on multi-core optical fiber,etc.Three kinds of optical trapping force calculation models are introduced.The calculation model based on electromagnetic theory and the moment calculation model are described emphatically.This paper presents two types of novel optical fiber tweezers:The one novel optic tweezers is a beak-shaped fiber optic tweezers with a curved cone.By artificially creating gradient thermal field,we improved the original taper drawing technology.The side can be used for two-dimensional cell capture,and the cells can be transported to the top of the optical tweezers,where they can be three-dimensional captured or ejected.In this paper,yeast cells were used for experiments,and it was proved that beak-shaped fiber optic tweezers can integrate two-dimensional capture,transport,three-dimensional capture,cell emission and other functions.The another novel tweezers is a cellular optical motor based on a multicore fiber that allows the cell to rotate in multiple directions.The optical motor system uses one or two coaxially aligned multicore optical fibers with their output light moving in the opposite direction.The opposite-aligned double optical fiber structure was only used for particle capture in earlier studies.This paper proposes a two-fiber optical tweezers based on seven core fiber,in which the central core is used for capture and the side core is used for rotation.Thus,the trapping beam and the rotating beam are independent of each other and can manipulate the particles freely.Furthermore,due to the presence of six side cores in our tweezers,multidimensional rotation of the cell can be achieved simply by controlling the optical power of the beam in each core without any additional mechanical manipulation.In this paper,two kinds of novel optical tweezers are analyzed in detail,including the trapping force analysis,the moment analysis and the motion trajectory dynamic analysis.Two new types of fiber optic tweezers are presented in this paper,which can be used in cytology,blood microflow and other fields. |
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