Research On The Key Devices And Integration Of The CD-like Microfluidic Platform

The CD (compack disk)-like microfluidic system is one type of simple andpractical microfluidic platforms. It has been widely used in point-of-care (POC)diagnostic, biology, food safety, pharmaceutics chemical synthesis and environmentalmonitoring. This thesis is focused on the process of manufacture and bonding formicrofluidic chips with high aspect ratio and complex structures, and the experimentalverification of the typical microfluidic devices, where the elastomeric mould basedhot embossing, laser ablation method and surface modification are used to achieve themulti-function integration, low-cost and massive production of the CD-likemicrofluidic chip, as well as the performance verification of the key microfluidicunits.The main contents of this thesis are listed as follows:Using the elastomeric mould based hot embossing, the problems on the high aspectratio and complex structures of the demoulding are solved effectively for thefabrication of microfluidic chip. Using this method, the surface-smooth, defect-freemicrofluidic chips can be obtained. The microstructure aspect ratio is up to3and thedeformation is less than5%. And through the solvent-assisted bonding method,bonding of microfluidic chips is achieved.The methods of self-assembly of nanoparticles, O2plasma treatment and surfacesilanization are used to carry out hydrophilic modification research. The modifiedsurfaces are characterized by Atomic force microscopy (AFM), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). And the modifiedmethod is verified by analyzing the mechanism of modification and the contact anglemeasurements. O2plasma treatment can achieve fast and efficient hydrophilicmodification of PMMA. After2-3minutes of O2plasma treatment, PMMA surfacecontact angle can be reduced to35o, and the contact angle remains45o after48hours.The passive micromixers designed using the layout optimization method areinvestigated experimentally. The designed micromixers are fabricated usingpolydimethylsiloxane soft photolithography techniques. The mixing performance isevaluated by stereoscopic and confocal microscopes. By comparing the mixingperformance of micromixers with layouts obtained using the layout optimizationmethod and that of micromixers without blocks, the effectiveness of the layoutoptimization method is verified in improving the mixing performance of micromixers.The reliability of the layout optimization method is confirmed by a comparison of thenumerical and experimental results.CO2laser ablation method is used to fabricate the CD-like microfluidic chip withthe PMMA substrate. On the basis of the formation mechanism of bulges, we apply acover layer on the top of PMMA to protect it during laser processing. And it is aneffective method to achieve a microfluidic chip without bulges at the rim of thechannels. Using the laminated design, the chip is layered according to the depth ofstructures. After the adhesive bonding process, rapid fabrication of the chip isachieved. Through the design and fabrication of detection chip, a fully integratedCD-like microfluidic system with multi functions is obtained. Through the wholeblood detection, we can verify the effectiveness of the manufactured CD-likemicrofluidic system which we design and fabricate.