摘要
Flow profiles are frequently engineered in microfluidic channels for enhanced mixing,reaction control,and material synthesis.Conventionally,flow profiles are engineered by inducing inertial secondary flow to redistribute the streams,which can hardly be reproduced in microfluidic environments with negligible inertial flow.The employed symmetric channel structures also limit the variety of achievable flow profiles.Moreover,each of the flow profiles specifically corresponds to a strictly defined flow condition and cannot be generalized to other flow environments.To address these issues,we present a systematic method to engineer the flow profile using inertialess secondary flow.The flow is manipulated in the Stokes regime by deploying a cascaded series of microsteps with various morphologies inside a microchannel to shape the flow profile.By tuning the shapes of the microsteps,arbitrary outflow profiles can be customized.A numerical profile-transformation program is developed for rapid prediction of the output profiles of arbitrary sequences of predefined microsteps.The proposed method allows the engineering of stable flow profiles,including asymmetric ones,over a wide range of flow conditions for complex microfluidic environmental prediction and design.
基金
This work was supported by the General Research Fund(17306315,17304017,and 17305518)and Research Impact Fund(R7072-18)from the Research Grants Council(RGC)of Hong Kong,China
the Excellent Young Scientists Fund(Hong Kong and Macao)(21922816)from the National Natural Science Foundation of China(NSFC)
the Seed Funding for Strategic Interdisciplinary Research Scheme 2017/18 from the University of Hong Kong
as well as the Sichuan Science and Technology Program(2018JZ0026).
