On The Experiments Of Additive Manufacturing For Typical Microfluidic Components

Various components(microfluids,thin films,microcavities,microelectrodes,etc.)of the microfluidic system exhibit three-dimensional(3D)geometric features,especially for 3D stacked structures.However,it is difficult to manufacture 3D complex structures and the integration of multi-function components for traditional MEMS fabrication process.In view of the manufacturing precision-efficiency reconciliation problem,additive manufacturing technology has been shown potential application in the fabrication of 3D micro/nano structures.Therefore,a novel principle and method of additive manufacturing at micro/nano-scale was provided to fabricate 3D microfluidic structures.The manufacturing and integration of microfluidic components such as 3D microfluidic channels,movable film-microcavity microvalves and microelectrodes were investigated,and the applications of these components were explored in the fields of biomedicine,flexible sensing and detection.The main works of the thesis are as follows:An experimental platform of nanofiber self-consistent additive manufacturing based on EHD printing was constructed.A multi-mode(such as electrospinning,electrostatic printing,direct writing,etc.)integrated 3D printer was designed and developed.The behaviors of PDMS construction fluids and nanofibers printing process were studied,and the printing rules and process parameters were mastered,which laid a platform and process fundamental for the subsequent manufacture of diverse microfluidic devices.The tree-like branch-spiral 3D interconnected microfluidic concentration gradient device was fabricated for various anti-tumor drug combination screenings by photocurable 3D printing.Based on the principle of concentration dilution,36 kinds of combination drugs with different concentration ratios were formed using four drugs,and 36 different concentrations of combination drugs for human lung cancer cell A549 tests were analyzed.The 3D interconnected structure is easy to produce multi-drug combination,which improves the efficiency of drug screening.A new principle and method for the fabrication of nanofiber self-consistent microfluidic devices based on the principle of EHD printing is proposed.In this paper,the interaction between PDMS solution and nanofiber membrane was innovatively utilized to construct a nanofiber self-consistent microfluidic device.Based on the principle of the process,a nanofiber-based microfluidic valve was fabricated and tested The experimental results show that the control pressure of the valve is greater than 35 kPa,the response time is 52.6 ms,and the valve can still work after more than 200 cycles,which can provide a new technical approach for the fabrication of micro-structure units such as movable film-cavities and long microchannelsA method for direct-writing liquid metal electrode on nanofibers membrane was proposed.The application and integration of liquid metal electrodes in microfluidics were investigated.The performance of tensile and bending of liquid metal electrodes was investigated,which showed a good stability.The liquid metal electrode was integrated into the microfluidic component to manufacture a microfluidic electrostatic actuator.Results showed that the microfluidic valve has the characteristics of turn-off when the control voltage is 8 kV.Finally,a low cost and high sensitivity SERS sensing system with liquid metal nanograss structure electrode was also proposed for the SERS active site.The additive manufacturing process of several typical microfluidic basic components is investigated in this paper.The 3D interconnected network micro-channel,movable film-microcavity,micro-electrode and other complex structures are realized This study has a very good promotion for the large-scale manufacturing and integration of microfluidic basic components.