The Multiphysics Simulations And One-step Fabrication Research Of Microchannels Based On The Electrohydrodyanmic(EHD) Instabilities

In recent years, the lab-on-a-chip systems have great developments, and alsoattract much research attentions on them. Usually, the lab-chip systems integratemany functions, such as sample preparation, reaction, separation, detection, etc, withmany advantages including simple, high efficiency, low cost at the same time. So thelab-chip systems have been applied not only in the areas of bio and chemicalanalysis, disease detection, environment monitoring, but also a lot of other fieldsrelated with data memory, information security, fabrication, and so on. Therefore, theresearch of the lab-chip has been a vogue area at home and abroad. But so far, themain manufacture methods of the lab-chip are traditional lithography, etch, and softlithography, combined with the bounding process, which usually need multiplefabrication steps and are complicated. And the course inner surfaces have greatimpact on the liquid transmission. So, simpler fabrication method with smootherinner surface is of great meaning to the lab-chip systems. In the paper, we research anew liquid shaping technology, the electrostatic field assisted capillary (EFAC) toachieve one-step fabrication of microchannels with smoother inner surface. In orderto know more information about mechanics of the EFAC process, we studied from the followed aspects in the paper.Firstly, the electrohydrodynamic instabilities(EHDI) were studied. As a newmicrofabrication method, the EHDI don’t need the processes of exposure anddevelopment, and it uses electrostatic forces to drive the liquid film to formmicrostructures. The stability and evolution under the electrostatic field of the liquidfilm were researched. Referring to specific patterned masters, the evolutions of filmwere researched, and the conditions which the morphology perfectly replicates thestructures of master were studied.Secondly, the transient analysis model was built using the phase field method offinite element software, and factors such as the wetting angle, the initial thickness ofpolymer film, and the morphology of the master were studies. The results shown thatthe fine wetting property of the polymer is essential to the formation process of themicrochannels, otherwise the self-encapsulation can’t complete; but it doesn’t affectthe morphology of the final hollow microstructures obviously. The initial thicknessof the polymer film hardly impacts the microchannels formation, but can control themicrochannel size in an extent. The pattern of the master impact the formationprocess, and smoother structures are propitious to the microchannels formation.And lastly, the experiments researches were carried out. With the UV-LIGAtechnology and optimizing related parameters, fine nickel masters of the experimentswere manufactured. In experiments, PDMS was used, and the results validated theone-step fabrication method. After pre-cured, the wetting angle of polymer increased,and the results shown the essential impact of the wetting in the microchannelsformation. Furthermore, the microfabrication technology has shown greatadvantages in the manufacture of the hollow microcapsules, hollow microlens andother3D hollow microstructures.