Study On Microfluidic Fabrication And Characterization Of Magnetically Transportable Optical Core-shell Microstructures

Microfluidics is a specific term that describes the science and technology involved in the process of manipulating small amounts(nanoliter to picoliter)of fluids in microchannels.It is widely used in biological,chemical,medical,optical and other fields,for which has advantages of simple process,low cost,small size,short times for analysis and so on.The fusion of optics with microfluidics initiated a new research field of optofluidics,providing the possibility to generate,control,and process optical signals on chip.Mono-dispersed droplets(in single emulsion)and complex "core-shell"microstructure(in double emulsion)with controllable size can be generated by microfluidics.It is possible to endow such "core-shell" structures with diverse functions by incorporating appropriate component,resulting in novel multifunctional micro-optic devices.This thesis includes the fabrication of magnetically transportable optical core-shell structures based on glass-capillary microfluidics and the characterization of the microstructures,including the following aspects.1.By taking advantage of the immiscibility between oil and water,we fabricated the water-in-oil-in-water(W/O/W)double emulsions toward magnetically transportable microlasers.The dye doped cholesteric liquid crystal(DDCLC)mixture that forms the oil phase shell is responsible for band-edge laser emission.Water-dispersible Fe3O4 magnetic nanoparticles incorporated in the inner aqueous phase is responsible for the magnetically transportable ability.The influence of temperature and shell thickness on laser properties,such as wavelength,intensity and threshold,etc.,was studied by using a home-made inverted fluorescence microscope.Moreover,the manipulation of the DDCLC shells under a magnetic field was investigated on an electromagnetic platform.2.Magnetically transportable CLC core-shell structures and droplets with selective-light-reflection properties were fabricated by microfluidic technology.Under a polarized microscope,the mono-dispersed CLC microstructures generate tunable multi-colored patterns,known as the cross-communication phenomenon.The effect of the distance between the CLC microstructures on the light reflection from CLC droplets was investigated by a magnetic field.By the variation of temperature,the relationship between the helical pitch/the type of microstructures and the cross-coxmmunication behavior was revealed.Moreover,the osmotic pressure mediated control of shell geometries was discussed.And the arbitrary arrangement of microshells into designed arrays under a magnetic field was also demonstrated.3.Based on the properties of low loss and broad transparency of the UV-curable adhesive liquid material(NOA61),we fabricated the magnetically transportable dye doped UV-polymerized core-shell structures.To obtain the magnetically responsive ability,commercially available magnetofluid(EMG605)was added to the innermost aqueous phase.Compared with previously-used Fe3O4 magnetic solution,it leads to a faster response under a magnetic field.In addition,the whisper-gallery-mode(WGM)laser behaviors of dye(PM597)doped core-shell structures from polymerized NOA61 and the temperature dependent shift of resonant wavelength were analyzed.Meanwhile,we also measured the magnetically transportable performance of the NOA61 shells.