Research On High Efficiency Femtosecond Laser Integration Of Functional Microfluidic Chips

Microfluidic chip technology is considered to be one of the significant technology in the 21st century.It has a variety of advantages than conventional methods,such as low reagent consumption,low cost,fast detection,high integration,portability and so on.The design and manufacture of the microfluidic chips are important parts of this technology.The traditional ways for chips fabrication are dependent on MEMS processing technology.It can only fabricate 2D microfluidic chips while it is difficult to produce 3D microfluidic devices with high performances.Therefore,it is highly desirable to develop a new processing technology to fabricate and integrate the functional 3D microchips.Due to its distinct advantages such as 3D processing capability,high resolution,low thermal effect and diverse processing materials,femtosecond laser two-photon polymerization(TPP)has been widely researched.But the traditional femtosecond laser integration of 3D microfluidic devices is based on single-point writing scheme,the processing efficiency is low and it can not be widely used in the industrial application.Multifoci parallel scanning technology based on spatial light modulator can greatly reduce the processing time,improve the efficiency of processing structure,and makes it possible to endow the new functions of microfluidic chips by integrating 3D microdevices.This dissertation combines femtosecond laser TPP and multifoci technology based on spatial light modulator(SLM),and proposed a new technology called multifoci parallel integration of 3D microfluidic chips based on spatial light modulator which greatly improves the speed of fabricating 3D microfluidic devices;In order to endow more excellent functions into microfluidic chips,we have designed various 3D microstructures with high-performances by utilizing the 3D processing capacity of femtosecond laser TPP.This dissertation first analyzes the technology of spatial light modulation,elaborates phase-type and amplitude-type spatial light modulator(SLM),and analyzes the operating principle of the phase-type spatial light modulator.Then two multifoci shaping algorithms is explained which can be used for following chip processing.Also,in preparation for the subsequent processing 3D device in the microchip,we compare the two algorithms in uniformity of multifoci power and rates of convergence.After that,we have precisely shaped the single beam into target multifoci pattern and successfully realized high efficient integration of 3D microstructures inside a microfluidic chip.Then,we have further optimized the chip processing technology which provides a reference for subsequent processing of 3D microdevices.3D micro-filters were also fabricated inside a given microchannel and the filtering performances of the filters were characterized in filtering particles and cells.The conventional micropore membranes suffer from two major issues:one is clogging,the otheris that most of the micropore membranes have a limited capability that only the particles smaller than a specific size can be filtered.In order to deal with these problems,we have designed a new type of arch-like microsorter.Through designing of different sizes of grid structures,we can successfully achieve multimode particles sorting:high-capture sorting mode(large particles capture),band-capture sorting mode(median particles capture)and low-capture sorting mode(small size particles capture).Also,through fluid simulation to assist in design,we can finally greatly improve the clogging of the microsorters.By using the above-mentioned fabrication method:femtosecond laser multifoci parallel fabrication,the processing time decreases greatly(It's five times less).Finally,the new microsorters are used for multi-size particle separation and cancer cells separation from human's blood.The present methods for particles or cell capturing have a lot of disadvantages:low capture efficiency,poor selectivity,difficulty in single-trap and complexity in a controllable way to trapping particle-clusters.To solve these problems,we have proposed a new trapping method called real-time two-photon lithography in a controlled flow.We systematically investigate and optimize the processing condition of the technology,and successfully capture single particles with different sizes,shapes and compositions.In addition,we also achieve the controllable capture of particle-clusters which can be used for high-quality imaging.Finally,preliminary experiments prove that we can realize the single capture of yeast cells,and cultivate the trapped yeast cells,proving the potential applications of this new technology in the field of single cell analysis.