title: Prototyping of poly(dimethylsiloxane) interfaces for flow gating, reagent mixing, and tubing connection in capillary electrophoresis.
abstract: Integrated microfluidic systems coupled with electrophoretic separations have broad application in biologic and chemical analysis. Interfaces for the connection of various functional parts play a major role in the performance of a system. Here, we developed a rapid prototyping method to fabricate monolithic poly(dimethylsiloxane) (PDMS) interfaces for flow-gated injection, online reagent mixing, and tube-to-tube connection in an integrated capillary electrophoresis (CE) system. The basic idea was based on the properties of PDMS: elasticity, transparency, and suitability for prototyping. The molds for these interfaces were prepared by using commercially available stainless steel wires and nylon lines or silica capillaries. A steel wire was inserted through the diameter of a nylon line and a cross format was obtained as the mold for PDMS casting of flow gates and 4-way mixers. These interfaces accommodated tubing connection through PDMS elasticity and provided easy visual trouble shooting. The flow gate used smaller channel diameters, thus reducing flow rate by 25-fold for effective gating compared with mechanically machined counterparts. Both PDMS mixers and the tube-to-tube connectors could minimize the sample dead volume by using an appropriate capillary configuration. As a whole, the prototyped PDMS interfaces are reusable, inexpensive, convenient for connection, and robust when integrated with the CE detection system. Therefore, these interfaces could see potential applications in CE and CE-coupled systems.
authors: Department of Chemistry, Wichita State University, Wichita, Kansas, 67260, USA.
authors: Qiyang
authors: Q
authors: Zhang
authors: Department of Chemistry, Wichita State University, Wichita, Kansas, 67260, USA. Electronic address: maojun.gong@wichita.edu.
authors: Maojun
authors: M
authors: Gong
mesh_terms: D000596:Amino Acids / Q000302:isolation & purification; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000379:methods; D009757:Nylons / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D000596:Amino Acids; D004129:Dimethylpolysiloxanes; D009757:Nylons; C085707:poly(dimethylsiloxane)-polyamide copolymer; D012822:Silicon Dioxide
keywords: Capillary electrophoresis; Flow gate; Flow-gated injection; Interconnect; PDMS; Prototyping