Duffy D C, McDonald J C, Schueller O J, Whitesides G M
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138.
Anal Chem. 1998 Dec 1;70(23):4974-84. doi: 10.1021/ac980656z.
This paper describes a procedure that makes it possible to design and fabricate (including sealing) microfluidic systems in an elastomeric material [Formula: see text] poly(dimethylsiloxane) (PDMS) [Formula: see text] in less than 24 h. A network of microfluidic channels (with width >20 μm) is designed in a CAD program. This design is converted into a transparency by a high-resolution printer; this transparency is used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yields a polymeric replica containing a network of channels. The surface of this replica, and that of a flat slab of PDMS, are oxidized in an oxygen plasma. These oxidized surfaces seal tightly and irreversibly when brought into conformal contact. Oxidized PDMS also seals irreversibly to other materials used in microfluidic systems, such as glass, silicon, silicon oxide, and oxidized polystyrene; a number of substrates for devices are, therefore, practical options. Oxidation of the PDMS has the additional advantage that it yields channels whose walls are negatively charged when in contact with neutral and basic aqueous solutions; these channels support electroosmotic pumping and can be filled easily with liquids with high surface energies (especially water). The performance of microfluidic systems prepared using this rapid prototyping technique has been evaluated by fabricating a miniaturized capillary electrophoresis system. Amino acids, charge ladders of positively and negatively charged proteins, and DNA fragments were separated in aqueous solutions with this system with resolution comparable to that obtained using fused silica capillaries.
本文介绍了一种方法，该方法能够在不到24小时的时间内，用弹性体材料聚二甲基硅氧烷（PDMS）设计并制造（包括密封）微流控系统。在CAD程序中设计微流控通道网络（宽度>20μm）。该设计通过高分辨率打印机转换为透明片；此透明片用作光刻中的掩膜，以在正性光刻胶中制作母版。将PDMS浇铸在母版上，得到一个包含通道网络的聚合物复制品。该复制品的表面以及一块PDMS平板的表面在氧等离子体中被氧化。当这些氧化表面进行共形接触时，它们会紧密且不可逆地密封。氧化的PDMS还能与微流控系统中使用的其他材料，如玻璃、硅、氧化硅和氧化聚苯乙烯不可逆地密封；因此，许多用于器件的基板都是可行的选择。PDMS的氧化还有一个额外的优点，即它产生的通道在与中性和碱性水溶液接触时，其壁带负电荷；这些通道支持电渗泵浦，并且可以很容易地用具有高表面能的液体（特别是水）填充。通过制造一个小型化的毛细管电泳系统，对使用这种快速原型技术制备的微流控系统的性能进行了评估。使用该系统在水溶液中分离了氨基酸、带正电和负电蛋白质的电荷梯以及DNA片段，其分辨率与使用熔融石英毛细管获得的分辨率相当。
