Research On Disposable And Multifunctional Microfluidic Chips Integrated With Cell Electrical Impedance Detection

The maturity of microfluidic technology and single-cell impedance detection technology has led researchers paying more attention to the application of microfluidic chips integrated with micro-electrodes to clinical point-of-care testing(POCT)instruments.However,the costeffective manufacture and mass production of microfluidic chips has run into the bottleneck due to the expensive machine and complicated processing craft needed.Based on the laser cutting technology and existing single-cell impedance detection platform in our laboratory,lowcost polymer-film microfluidic chips integrating particle focusing module,separating module and micro-electrodes are studied.Detailed information about this research is listed as follows:(1)Microfluidic chips containing inertial focusing module,separation module and liquid sensing electrodes are studied in this thesis.Spiral microfluidic channels enabling inertial focusing,separation and single-cell direct current impedance detection were designed.The flow rate range within which particle and cell suspension could be focused and separated was obtained using this microfluidic chip.The performance of this laser-cut microfluidic chip was studied on the single-cell impedance detection platform.Micro-electrodes were made of Ag/AgCl,with KCl solution as the feeding liquid.The impedance signals of detection region were obtained by the ion exchange principle.By the experiments results,the optimum flow rate of feeding liquid into the electrode cavity was obtained.The impedance peak values of microbeads of various diameters show strict linear relation with their volume.Inertial focusing,separation and single-cell impedance detection were integrated.Target microbeads was inertial focused,separated and counted in the detection region.This type of microfluidic chip realized high throughput and coulter counting.(2)Microfluidic chips integrating viscoelastic focusing,separation and electroplated 3D electrodes were studied.Polymer film chips containing straight converging-diverging microchannels and electroplated electrodes were designed.The performance of particle focusing and separation in hyaluronic acid(HA)solutions of different mass friction was studied.The results show that 0.1% HA solution leads to the optimum particle focusing and separation performance.The processing craft of electroplated Cu electrodes was also explored and the technological parameters were obtained.It was found that electroplating Au on the surface of Cu electrodes could overcome the problem of the oxidation of Cu electrodes.Compared to coplanar ITO electrodes,electroplated 3D Cu electrodes generate stronger and more uniform electric fields.The integration of viscoelastic focusing,separation and cell impedance detection was realized.(3)Microfluidic chips integrating straight converging-diverging micro-channels and liquid metal electrodes were studied.Polymer film microfluidic chips in which upper structure is in a converging-diverging form.Compared to common straight channel,this structure could realize particle 3D focusing.Using this chip,3D focusing of MCF-7,Hela and PC-3 cells were observed.The processing craft of liquid metal electrodes was explored.The performance of the microfluidic chip was studied on the single-cell impedance detection platform.It was found that this liquid metal electrodes could be qualified to DC impedance detection and AC impedance detection at the same time.Integration of high throughput focusing and coulter counting was realized.