Key Laboratory of Biorheological Science and Technology, Chongqing University, Chongqing 400030, China.
Anal Chim Acta. 2013 Aug 20;792:66-71. doi: 10.1016/j.aca.2013.07.009. Epub 2013 Jul 9.
A large number of microscale structures have been used to elaborate flowing control or complex biological and chemical reaction on microfluidic chips. However, it is still inconvenient to fabricate microstructures with different heights (or depths) on the same substrate. These kinds of microstructures can be fabricated by using the photolithography and wet-etching method step by step, but involves time-consuming design and fabrication process, as well as complicated alignment of different masters. In addition, few existing methods can be used to perform fabrication within enclosed microfluidic networks. It is also difficult to change or remove existing microstructures within these networks. In this study, a magnetic-beads-based approach is presented to build microstructures in enclosed microfluidic networks. Electromagnetic field generated by microfabricated conducting wires (coils) is used to manipulate and trap magnetic beads on the bottom surface of a microchannel. These trapped beads are accumulated to form a microscale pile with desired shape, which can adjust liquid flow, dock cells, modify surface, and do some other things as those fabricated microstructures. Once the electromagnetic field is changed, trapped beads may form new shapes or be removed by a liquid flow. Besides being used in microfabrication, this magnetic-beads-based method can be used for novel microfluidic manipulation. It has been validated by forming microscale dam structure for cell docking and modified surface for cell patterning, as well as guiding the growth of neurons.
大量的微结构被用于在微流控芯片上精心设计流动控制或复杂的生物和化学反应。然而，在同一基片上制造具有不同高度（或深度）的微结构仍然很不方便。这些微结构可以通过光刻和湿法刻蚀的方法逐步制造，但涉及到耗时的设计和制造过程，以及不同母版的复杂对准。此外，现有的几种方法都可以用于在封闭的微流控网络中进行制造。在这些网络中改变或去除现有的微结构也很困难。在本研究中，提出了一种基于磁珠的方法，用于在封闭的微流控网络中构建微结构。微制造的导电丝（线圈）产生的电磁场用于操纵和捕获微通道底部表面的磁珠。这些捕获的磁珠堆积在一起，形成具有所需形状的微尺度堆，从而可以调节液体流动、对接细胞、修饰表面等，这些都是那些制造的微结构所能完成的。一旦电磁场发生变化，捕获的磁珠可能会形成新的形状或被液体流移除。除了用于微制造之外，这种基于磁珠的方法还可以用于新型微流控操作。它已经通过形成用于细胞对接的微尺度挡水结构和用于细胞图案化的修饰表面以及引导神经元生长得到了验证。
