| Microfluidics is the science and technology of systems that process or manipulate small(10-9 to 10-18 litres) amounts of fluids,using channels with dimensions of tens to hundreds of micrometres.Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology,which has attracted great interests of scientists from many disciplines.It is totally a focus topic that fabricating microfluidic chips with non-oxide ceramic materials via a preceramic polymer route.There are many disvantages of ordinary heat curing in preceramic route for the fabrication of microceramic structures.In this paper,lots of efforts were spent on the synthesis and applications of UV curable preceramic polymers,which were quite good for the developing of microfluidic chips with novel materials.During the experiments,six halids(MBMA,EBC,AC,CC,BPMA,and CPA) and three isocyanates(BEI,IEM,and IDBI) were selected as candidates for the chemical reactions with PVSZ.Finally,four modified preceramic polymer(m-PVSZ,e-PVSZ, b-PVSZ,i-PVSZ) with excellent UV curing properties were selected for the fabricating of non-oxide ceramic microstructures.The results pointed out that the synthesis of m-PVSZ and e-PVSZ were both carried out by a substitutional mechanism between the allyl bromine of MBMA or EBC and the secondary amine of PVSZ with the same byproduct HBr.However,the synthesis of b-PVSZ and i-PVSZ were both carried out by a linkage mechanism between the isocyanate group of BEI and secondary amine of PVSZ,at the same time it was some kind of "clean" chemical reaction without any byproduct.The UV sensitivity of PVSZ was dramatically increased by chemical modification,the peak heat flow of b-PVSZ was as high as 9.0 W/g,as those were 2.4 W/g,1.18 W/g and 3.3 W/g for m-PVSZ,e-PVSZ and i-PVSZ,respectivelyAfter then,microstructures for microfluidics,such as two dimensional patterns, three dimensional micro structures and microreactors,were fabricated with the as-synthesized polymers by several kinds of photolithography techniques.Many patterns were fabricated by UV photolithography and the factors which affected the reliability of the patterns were discussed.μ-imprinting UV lithography was a new method developed by this paper,which has combined both the advantages of a molding process and UV lithography.It is possibile to control the feature size of a pattern exactly by a proper design of a mold.On the other hand,the adherence between PDMSO mold and patterns were dramatically decreased because of the fast curing of b-PVSZ,and then the reliability of patterns was increased,it was easily to fabricate patterns within the size of dozens of nanometers.A 3D wood pile structure with the size of 10μm×10μm was fabricated by a two-photon absorption process.It remained a good shape even after pyrolysizd at 600℃,and the maximum shrinkage was about 15%. Several types of microreactors were fabricated by UV curing techniques.During the fabricating process,the novel curing properties of b-PVSZ had played a very important role.The probability of successfully bonding a cover to microchannel had increased up to 80%by using b-PVSZ,which had greatly increased the efficiency of fabricating microreactors.Laminar flow and capillarity phenomena were observed by the as-fabricated microreactors.
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