Investigation Of Microfabricated Lab-on-a-Chip For Cell Separation Driven By Capillary Force

Microfluidics is considered to be the ideal tool for cell manipulation due to the similar size.There are many techniques for blood cell separation by microfluidic chip.But most of them need the necessary accessary equipment,which is not convenient the people in the area that is far away from hospital or that is lack for medical facility.To solve the problem,this thesis presented a portable microfluidic chip for fast blood separation which is drived by the capillary force.The channel in the microfluidic chip consists of a large number of micropost array,which supplys the power for capillary flow as a pump,and also separates the blood cells as a filter.The research contents in this thesis include:(1)The size of microposts in the channel will be determinated and optimized by simulation.The variety of the flow resistance under different structures of the microposts will be studied by COMSOL Multiphysics.The arrangement of microposts will be determinated by the results of simulation and the microposts are used for inducing capillary flow and separation.(2)Polydimethylsiloxane(PDMS)surface modification.The water contact angle of PDMS must be within 90° to form capillary flow while the native PDMS is hydrophobic.The corona treatment,O2 plasma treatment and surfactant can make the PDMS surface hydrophilic,which can contribute for the power-free microfluidic chip driven by capillary force.(3)Mask-free microfabrication technique.The UV laser is employed to directly expose the photoresist without photomask.The structure designed by computer will be directly fabricated,which enhances its flexibility.Compared to the convent photolithography,this technique saves cost and time without photomask fabrication.The microfluidic chip can be fabricated by the PDMS which replicates the structure and achieved the particle separation.