Research On Preparation Technology Of Microfluidic Chip Based On Near Field Direct Writing

With the rapid development of microanalysis systems,microfluidic chips have gradually become one of the important branches of the system.In the preparation of microfluidic chips,we usually prepare microchannels in the chip by certain means,building microchannel networks for fluid control and processing.And then,the controllable fluid is transported to each functional unit through the microchannel networks to realize various functions.Therefore,the manufacture of microfluidic channels is the key task of the preparation of microfluidic chips.The near field direct writing technology in electrospinning is considered to be one of the most likely industrialized micro-nano structure processing technologies in the field of additive manufacturing due to its low loss,high precision and simple processing method.Because it has met the high-quality and high-yield manufacturing requirements of microfluidic chips,the near field direct writing technology provides a promising development direction for the preparation of microfluidic chips.However,the preparation of microfluidic chips based on the near field direct writing technology is faced with scientific and technical problems such as the deformation of the template and the difficulty of demolding when the fiber template is used in the subsequent preparation of the microfluidic chip.This dissertation is mainly about the key issues in the process of preparing microfluidic chips based on near field direct writing,carrying out systematic and in-depth research on the mechanical properties of UV curable resin/PCL materials,the electric field influence mechanism of near field direct writing fiber deposition,and the use of fiber templates in the preparation of microfluidic chips.The main exploration directions and contributions of this study are introduced as follows:Firstly,regarding the materials used for the preparation of fiber templates,we mix the common materials(polycaprolactone)with a certain proportion of UV curable resin,and then tested the mechanical tensile properties and baseplate binding force to show that the fibers printed by the mixed materials successfully obtained the UV response capability.Meanwhile,we clarified the UV response characteristics of the UV curable resin/PCL fiber treated by a certain wavelength of UV light in the mechanical tensile properties and baseplate bonding force,which effectively improved the mechanical tensile properties of the fiber and the baseplate bonding force.Secondly,aiming at the near field direct writing process of UV curable resin/PCL materials,we conducted multi-domain single factor experiments to reveal the influence of multi-domain single factor on the diameter of UV curable resin/PCL fiber in the near field direct writing process,determining the relationship between the diameter of fiber and various factors with a preliminary relationship fitting curve.Then,we designed an orthogonal experiment scheme based on the results of the single-factor experiment,carrying out multifactor range and variance analysis through the data results obtained from the orthogonal experiment,which selected the core factors of multi-domain factors.In addition,the sensitivity of the diameter of fibers to various factors is arranged in order.Thirdly,we use COMSOL Multiphysics simulation software to build an electric field simulation analysis model with stacked fibers in the process of near field direct writing.By separately simulating the influence of the fiber wall stacked by fiber on the electric potential distribution and electric field intensity distribution in a specific space of the near field direct writing,we have clarified the electric field guiding effect of the fiber wall on the subsequent fiber deposition.In addition,the parameter sweep function is used to complete the simulation analysis of the electric field intensity above the adjacent fiber walls,we found that the electric field intensity above adjacent fiber walls will increase with the increase of the voltage difference from the tip of the needle to the baseplate,and will decrease with the increase of the distance from the tip of the needle to the baseplate,but the electric field intensity distribution trend still shows the three electric field intensity peaks.At the same time,the electric field intensity peaks caused by the fiber wall facing the needle are the maximum of the three peaks,which reveals the electric field influence mechanism by which the fibers can be stacked smoothly in the near field direct writing.Finally,for the fiber template prepared by near field direct writing of UV curable resin/PCL materials,through the thermal deformation treatment and structure transfer experiment of UV curable resin/PCL fiber,the results show that the addition of UV curable resin and its response to UV light are helpful for improvement of the fiber template's thermal stability and the bonding force between the fiber and the baseplate.Meanwhile,we realized the preparation of microfluidic devices based on UV curable resin/PCL templates,verifying the applicability of this microfluidic devices.