Preparation Of Microfiuidic Chip Based On Special Wettability Surface

As a highly integrated and miniaturized detection technology with a variety of laboratory functions,microfluidic chip has the advantages of fast detection speed,low cost,and few samples required.The field attracts researchers'attention with its broad application prospects and high research value.However,the channel structure of the current microfluidic chip is mostly closed,which needs to drive the sample injection under the action of external force,which is limited in the application process.In view of this problem,this paper proposes the technology of making open microfluidic chips and conducting related research based on the principle of special wettability of solid surfaces.Firstly,this paper introduces the theory of solid surface wettability and analyzes the basic preparation principles of special surfaces.Secondly,the electroosmotic flow model is studied,and the two types of open and closed microchannels are established to analyze the effects of different parameters on the electroosmotic velocity.The simulation results show that the final stable values of the electroosmotic velocity of the open and closed microchannels are equal,but the time required for the open type to reach the steady state is almostly two times longer than the closed type.In addition,the influence of the solution concentration and applied electric field strength on the open type is the same as that of the closed type.The value change is affected while the settling time is not affected.Next,the superhydrophobic surface of the chip is prepared on the polymethyl methacrylate substrate by hot pressing and sandblasting-spraying.When using the hot pressing method,the micron aluminum template for hot pressing is first prepared by laser etching,and a layer of nanoparticles is attached to the etched template to form a micro-nano composite structure.Choose the best pressure 2.1Mpa for structural imprinting,and obtaining a super-hydrophobic surface with an average contact angle of 153°after fluorination.The sandblasting-spraying method method uses the impact of micron white corundum to form a micron structure on the surface of the substrate,and then sprays the configured nanoparticle suspension with a spray gun to form a micro-nano composite structure.After the selection of better sandblasting and spraying process parameters,the prepared surface contact angle is155°.On the basis of super-hydrophobic surface,laser etching technology was used to prepare super-hydrophilic transport channel.Observing the influence of laser parameters on the etching of microchannels,it is found that when the duty cycle and the number of printed layers are large,the inner wall of the channel is smoother and the depth is larger.Choosing appropriate parameters to etch the channel on the superhydrophobic surface and conducting a hydrophilicity test,it is found that the droplets can be injected without external forces.Finally,a self-made detection system was used with MES/His buffer solution to conduct electroosmotic flow test on the channel.The measured electroosmotic velocity was 7.44×10^-4m/s,which proves the feasibility of using special infiltration to prepare an open microfluidic chip.