We present a theoretical investigation of rotating electroosmotic flows(EOFs) in soft parallel plate microchannels. The soft microchannel, also called as the polyelectrolyte-grafted microchannel, is denoted as a rigid...We present a theoretical investigation of rotating electroosmotic flows(EOFs) in soft parallel plate microchannels. The soft microchannel, also called as the polyelectrolyte-grafted microchannel, is denoted as a rigid microchannel coated with a polyelectrolyte layer(PEL) on its surface. We compare the velocity in a soft microchannel with that in a rigid one for different rotating frequencies and find that the PEL has a trend to lower the velocities in both directions for a larger equivalent electrical double layer(EDL) thickness λFCL(λFCL = 0.3) and a smaller rotating frequency ω(ω < 5).However, for a larger rotating frequency ω(ω = 5), the main stream velocity u far away from the channel walls in a soft microchannel exceeds that in a rigid one. Inspired by the above results, we can control the EOF velocity in micro rotating systems by imparting PELs on the microchannel walls, which may be an interesting application in biomedical separation and chemical reaction.展开更多
Micro-flow channel is basic functional component of microfluidic chip,and every step-forward of its construction technique has been receiving concern all over the world.This article presents a not-complicated but flex...Micro-flow channel is basic functional component of microfluidic chip,and every step-forward of its construction technique has been receiving concern all over the world.This article presents a not-complicated but flexible method for fabrication of micro-flow channels.This method mainly utilizes the conventional molding capability of polydimethylsiloxane(PDMS) and widespread commercial microwires as templates.We have fabricated out some conventional types of microchannels with different topological shapes,as examples for the demonstration of this flexible fabrication route which was not dependent on the stringent demands of photolithographical or microelectromechanical system(MEMS) techniques.The smooth surface,high-intensity,and high flexibility of the wires made it possible to create many types of topological structures of the two-dimensional or three-dimensional microchannel or channel array.The geometric shape of the cross-section of thus forming microchannel in PDMS was the negative of that of embedded-in microwire,in high-fidelity if suitable measures were taken.More-over,such a microchannel fabrication process can easily integrate the conductivity and low resistivity of the metal wire to create micro-flow devices that are suitable for the electromagnetic control of liquid or the temperature regulation in the microchannel.Furthermore some preliminary optical analysis was provided for the observation of thus forming rounded microchannel.Based on this molding strategy,we even made some prototypes for functional microflow application,such as microsolenoids chip and temperature control gadgets.And an experiment of forming a droplet in the cross channel further confirmed the feasibility and applicability of this flexible microchannel forming technique.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.11772162 and11472140)the Inner Mongolia Autonomous Region Grassland Talent(No.12000-12102013)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2016MS0106)
文摘We present a theoretical investigation of rotating electroosmotic flows(EOFs) in soft parallel plate microchannels. The soft microchannel, also called as the polyelectrolyte-grafted microchannel, is denoted as a rigid microchannel coated with a polyelectrolyte layer(PEL) on its surface. We compare the velocity in a soft microchannel with that in a rigid one for different rotating frequencies and find that the PEL has a trend to lower the velocities in both directions for a larger equivalent electrical double layer(EDL) thickness λFCL(λFCL = 0.3) and a smaller rotating frequency ω(ω < 5).However, for a larger rotating frequency ω(ω = 5), the main stream velocity u far away from the channel walls in a soft microchannel exceeds that in a rigid one. Inspired by the above results, we can control the EOF velocity in micro rotating systems by imparting PELs on the microchannel walls, which may be an interesting application in biomedical separation and chemical reaction.
基金Supported by the Key Project for International Science and Technology Collaboration of the Ministry of Science & Technology (Grant No. 2005DFA00190)partially supported by "111 Project" (B06023)Chongqing University Post-graduates' Science and Innovation Fund (No.200707A1A0110248)
文摘Micro-flow channel is basic functional component of microfluidic chip,and every step-forward of its construction technique has been receiving concern all over the world.This article presents a not-complicated but flexible method for fabrication of micro-flow channels.This method mainly utilizes the conventional molding capability of polydimethylsiloxane(PDMS) and widespread commercial microwires as templates.We have fabricated out some conventional types of microchannels with different topological shapes,as examples for the demonstration of this flexible fabrication route which was not dependent on the stringent demands of photolithographical or microelectromechanical system(MEMS) techniques.The smooth surface,high-intensity,and high flexibility of the wires made it possible to create many types of topological structures of the two-dimensional or three-dimensional microchannel or channel array.The geometric shape of the cross-section of thus forming microchannel in PDMS was the negative of that of embedded-in microwire,in high-fidelity if suitable measures were taken.More-over,such a microchannel fabrication process can easily integrate the conductivity and low resistivity of the metal wire to create micro-flow devices that are suitable for the electromagnetic control of liquid or the temperature regulation in the microchannel.Furthermore some preliminary optical analysis was provided for the observation of thus forming rounded microchannel.Based on this molding strategy,we even made some prototypes for functional microflow application,such as microsolenoids chip and temperature control gadgets.And an experiment of forming a droplet in the cross channel further confirmed the feasibility and applicability of this flexible microchannel forming technique.
