U-shaped micro-nanochannels can generate significant flow disturbance as well as locally amplified electric field, which gives itself potential to be microfluidic mixers, electrokinetic pumps,and even cell lysis proce...U-shaped micro-nanochannels can generate significant flow disturbance as well as locally amplified electric field, which gives itself potential to be microfluidic mixers, electrokinetic pumps,and even cell lysis process. Numerical simulation is utilized in this work to study the hidden characteristics of the U-shaped micro-nanochannel system, and the effects of key controlling parameters(the external voltage and pressure) on the device output metrics(current, maximum values of electric field, shear stress and flow velocity) were evaluated. A large portion of current flowing through the whole system goes through the nanochannels, rather than the middle part of the microchannel, with its value increasing linearly with the increase of voltage. Due to the local ion depletion near micro-nanofluidic junction, significantly enhanced electric field(as much as 15 fold at V=1 V and P_0=0) as well as strong shear stress(leading to electrokinetic flow) is generated.With increasing external pressure, both electric field and shear stress can be increased initially(due to shortening of depletion region length), but are suppressed eventually at higher pressure due to the destruction of ion depletion layer. Insights gained from this study could be useful for designing nonlinear electrokinetic pumps and other systems.展开更多
实验研究了背压对U阀排料特性的影响,建立了可调节背压的立管-U阀实验平台,发现随背压增大,U阀排料速率明显减小,进气速率对排料速率的调控能力变弱,且背压波动时,孔口的高度越小,U阀的运行越稳定.针对本实验装置,背压小于7 k Pa时,U阀...实验研究了背压对U阀排料特性的影响,建立了可调节背压的立管-U阀实验平台,发现随背压增大,U阀排料速率明显减小,进气速率对排料速率的调控能力变弱,且背压波动时,孔口的高度越小,U阀的运行越稳定.针对本实验装置,背压小于7 k Pa时,U阀孔口高度小于0.11 m,背压大于13 k Pa时,孔口高度大于0.15 m,使U阀获得良好的排料特性.根据实验数据和理论分析建立了U阀排料速率与背压、进气速率和孔口高度之间的经验方程,计算值与实验值的平均相对误差为20.9%.展开更多
基金supported by the Intergovernmental International Science,Technology and Innovation Cooperation Key Project of the National Key R&D Programme(2016YFE0105900)the National Natural Science Foundation of China(21576130and 11372229)Kuwait Foundation for the Advancement of Sciences(Kuwait-MIT signature project,Project code:P31475EC01)
文摘U-shaped micro-nanochannels can generate significant flow disturbance as well as locally amplified electric field, which gives itself potential to be microfluidic mixers, electrokinetic pumps,and even cell lysis process. Numerical simulation is utilized in this work to study the hidden characteristics of the U-shaped micro-nanochannel system, and the effects of key controlling parameters(the external voltage and pressure) on the device output metrics(current, maximum values of electric field, shear stress and flow velocity) were evaluated. A large portion of current flowing through the whole system goes through the nanochannels, rather than the middle part of the microchannel, with its value increasing linearly with the increase of voltage. Due to the local ion depletion near micro-nanofluidic junction, significantly enhanced electric field(as much as 15 fold at V=1 V and P_0=0) as well as strong shear stress(leading to electrokinetic flow) is generated.With increasing external pressure, both electric field and shear stress can be increased initially(due to shortening of depletion region length), but are suppressed eventually at higher pressure due to the destruction of ion depletion layer. Insights gained from this study could be useful for designing nonlinear electrokinetic pumps and other systems.
文摘实验研究了背压对U阀排料特性的影响,建立了可调节背压的立管-U阀实验平台,发现随背压增大,U阀排料速率明显减小,进气速率对排料速率的调控能力变弱,且背压波动时,孔口的高度越小,U阀的运行越稳定.针对本实验装置,背压小于7 k Pa时,U阀孔口高度小于0.11 m,背压大于13 k Pa时,孔口高度大于0.15 m,使U阀获得良好的排料特性.根据实验数据和理论分析建立了U阀排料速率与背压、进气速率和孔口高度之间的经验方程,计算值与实验值的平均相对误差为20.9%.
