| Fluid mixing at micro-scales is an important topic of microfluidics and microreactor technologies.It is also a key process involved in chemical synthesis,bio-chemical analysis and medical diagnostics.With the miniaturization of fluidic devices,the fluid viscosity becomes dominant in the flow.The lack of turbulence and reduced inertial effects raise the difficulties of fluid mixing.To solve this problem,so far there have been many reports,but mostly focusing on in-line micromixers for continuous flows.In comparison,the fluid mixing in microchambers has been less discussed.Relevant study is still of significance as it is widely applied in biomedical fields.In this work,chaotic advection is applied for fluid mixing in microchambers.A chaotic mixing strategy is proposed.The key factors that influence the mixing efficiency are investigated through numerical and experimental methods.Its application for PCT(procalcitonin)measurement is also examined.The main work and results are summarized below:(1)A mathematical model for chaotic advection is built based on two interacting intermittent rotating flows.The occurrence of chaotic advection and the influencing factors are analyzed.Results show that mixing efficiency is influenced by the angular velocity,disturbing frequency,and the distance between the centers of the rotating flows.(2)Based on the simulation results,a chaotic micromixer is designed for fluid mixing in small chambers.Using a gas-solid-liquid coupling structure,flow-induced vibration of an elastic membrane is produced which is utilized for fluid agitation.Chaotic mixing is produced through alternate fluid agitations.The influences of the perturbing frequency,driving pressure,and fluid viscosity are examined.After optimization,50μl liquids of viscosity of 1-15 c P can be completely mixed within 10-75 s.(3)The application of current chaotic mixer for PCT measurement is studied.Results show that through mixing enhancement,a high binding efficiency of PCT antigen and antibody can be achieved,the accuracy of PCT concentration is around 0.02ng/ml,showing the potential application of current mixing system for PCT detection. |
