Micro-nano Fiber Optical Tweezers Based On Evanescent Field

Near-field optical tweezers, for sub-contact, no damage, pollution-freemanipulation to particles, has become an important research tool in the field of cellbiology, micro-force measurement, micro and nano device fabrication, and so on.Especially in the biological field, near-field optical tweezers has been used to studythe cells, viruses, bacteria and DNA molecules. From the viewpoint of the resolutionand sensitivity, near-field optical tweezers is the most promising manipulation method.Therefore, the study to the near-field optical tweezers is crucial. This paper focuses onmicro and nano fiber near-field optical tweezers in-depth discussion and research.Deep analysis and research of micro-nano fiber optical tweezers is presented in thispaper.This paper introduces the development status of the near-field optical tweezersnearly four decades, and discusses the advantages and disadvantages of different typesof near-field optical tweezers. Meanwhile, the article from the light field radiationpressure and gradient force,explains the basic principle of optical tweezers, andestablishes corresponding computational model to three different sizes of particles.According to the function and application of the surfactant, an anionic surfactantis chosen as dispersant to polystyrene microspheres, which overcomes the problem ofclusters and instability for microspheres in solution. In addition, evanescent field ofmicro-nano fiber is simulated by COMSOL Multiphysics and MATLAB software.Meanwhile, the evanescent field intensity from different distances of the fiber surfaceis shown, which provides a theoretical basis for the experiment.In the end, micro-nano fiber optical tweezers with the core diameter of2μm istested.The article emphasizes several key details of the experiment of the selection oflaser source, the preparation of micro-nano fiber, dispersion of polystyrenemicrospheres and coupling efficiency.The results not only confirmed the balanceforces of light on microspheres, and microspheres are successfully captured andvelocity reaches5.3μm/salong the fiber. The research of micro-nano fibernear-field optical tweezersprovides an experimental basis to the application inbiological field.