[论文解读] Enhanced capillary pumping through evaporation assisted leaf-mimicking micropumps

Prasoon Kumar, Prasanna S. Gandhi+1 more|arXiv (Cornell University)|Jul 30, 2018

Microfluidic and Capillary Electrophoresis Applications参考文献 28被引用 5

一句话总结

本文提出了一种仿叶微泵，通过蒸发驱动的流体传输增强毛细泵吸作用，利用分支微通道网络和微多孔结构模仿叶脉和叶肉。该设计使体积泵送速率相比单毛细管系统提高了约6倍，实现了高效、无源的流体输送，适用于微流体和生物医学应用。

ABSTRACT

Pumping fluids without an aid of an external power source are desirable in a number of applications ranging from a cooling of microelectronic circuits to Micro Total Analysis Systems (micro-TAS). Although, several microfluidic pumps exist, yet passive micropumps demonstrate better energy efficiency while providing a better control over a pumping rate and its operation. The fluid pumping rate and their easy maneuverability are critical in some applications; therefore, in the current work, we have developed a leaf-mimicking micropump that demonstrated ~6 fold increase in a volumetric pumping rate as compared to the micropumps having a single capillary fluid delivery system. We have discussed a simple, scalable, yet inexpensive method to design and fabricate these leaf mimicking micopump. The microstructure of the micropumps were characterised through scanning electron microscopy and its pumping performance (volumetric pumping rate and pressure head sustainence) were assessed experimentally. The working principle of the proposed micropump is attributed to its structural elements; where branched-shaped microchannels deliver the fluid acting like veins of leaves while the connected microporous support resembles mesophyll cells matrix that instantaneously transfers the delivered fluid by a capillary action to multiple pores mimicking the stomata for evaporation. Such design of micropumps will enable an efficient delivery of the desired volume of a fluid to any 2D/3D micro/nanofluidic devices used in an engineering and biological applications.

研究动机与目标

• 开发一种用于微流体和生物医学应用的无源、节能微泵。
• 克服传统单毛细管微泵在流体输送速率和控制方面的局限性。
• 模仿自然叶片的分级流体传输机制，以增强毛细泵吸作用。
• 设计一种可扩展、低成本的制造方法，适用于二维/三维微/纳米流体系统的实际部署。

提出的方法

• 该微泵采用分支微通道网络，模仿叶脉以实现流体输送。
• 微多孔支撑结构复制了叶肉基质，实现流体向多个蒸发位点的快速毛细传输。
• 在类似气孔的孔隙位点发生蒸发，产生持续的毛细压力梯度，驱动流体流动。
• 该设计将毛细作用与蒸发诱导泵送相结合，以提高体积流量。
• 制造采用一种简单、可扩展且低成本的方法，适用于大规模生产。
• 通过扫描电子显微镜和泵送速率与压头的实验测量对性能进行了验证。

实验结果

研究问题

• RQ1 基于仿叶结构的生物微流体泵是否能显著提升毛细泵吸性能，超越单通道系统？
• RQ2 在多个孔隙位点的蒸发如何影响无源微泵中的体积流量？
• RQ3 分支微通道与多孔基质设计在多大程度上可提高微-TAS器件中的流体传输效率？
• RQ4 所提出的制造方法在实际微流体应用中的可扩展性和可重复性如何？

主要发现

• 仿叶微泵的体积泵送速率相比传统单毛细管微泵提高了约6倍。
• 该微泵维持了可测量的压头，证明了其可靠的流体输送能力。
• 扫描电子显微镜确认了分支微通道和微多孔支撑结构的结构保真度。
• 蒸发辅助机制实现了无需外部电源的连续流体输送。
• 所提出的结构设计具有可扩展性和成本效益，适用于集成到二维/三维微/纳米流体系统中。
• 该系统通过多个孔隙位点的蒸发增强毛细作用，实现了有效的流体输送。