Experiments On The High-viscosity Solution Pumping Based On Microscale Weissenberg Effect

In the manufacturing process of polymer-based micro/nano structures,the problems of nozzle clogging,slow response rate and resistance to the pumping of a high-viscosity solution at the picoliter level.To address these challenges,a generalizable method is presented to pump a highly viscous solution at the picoliter level using the microscale Weissenberg effect(MWE).The liquid supply system and the micro-nozzle are effectively combined to constitute a rotary micro-nozzle,which solve the above problems and transport trace high viscosity polymer rapidly and stably.The performance of direct writing based on MWE and its application of microfluidic channel chip and helical fibers fabrication are explored.The principle of liquid supply based on MWE is analyzed,and through analysis the effect of rotation speed,steel capillary diameter and solution viscosity on the rod-climbing effect,the feasibility and stability of the MWE for solution transport is explored.The influence of two steel capillary spacing,rotation speed and solution viscosity on the solution transport is analyzed.The performance of micro-channel transportation solution based on MWE was explored.The minimum liquid supply speed can reach 167pL/s,which lays the foundation for the continuous and steady direct writing of narrow line width.A direct writing device based on MWE was constructed,and the direct writing behavior was studied systematically and deeply.The effect of collecting moving speed,rotation speed,solution concentration and collection distance on the liquid film line morphology was analyzed.The response and recovery characteristics of the liquid supply based on MWE were analyzed.The response time of the liquid supply was less than 0.5s,which was far less than the 58s of the squeezed liquid supply.Patterned 2D,3D and microfluidic chip were written directly,which demonstrates the stability and rapid response of MWE in the direct writing of trace high viscosity fluids.The fabrication process of microfluidic chip with channels of variable diameter was studied,and the manufacturing process of helical micro-nano optical fiber(polymethyl methacrylate,PMMA)has been innovatively proposed.The influence of the rotation speed,the length of the rotation rod tip extending out of the steel capillary and the collection distance on the starting voltage and maintaining voltage were analyzed.The influence of the moving speed,the rotation speed of and the collection distance on the helical fiber diameter and the spiral period are investigated.Transmission optical power varies with coupling length was tested,and the helical fiber sensitivity to temperature and fluorescence are studied,the minimum detectable fluorescence molecular concentration is 10-10mol/L,which is 2 orders of magnitude smaller than that of a non helix optical fiber.