Rapid fabrication of a poly(dimethylsiloxane) microfluidic capillary gel electrophoresis system utilizing high precision machining
In this work, we demonstrate a rapid protocol to address one of the major barriers that exists in the fabrication of chip devices, creating the micron-sized structures in the substrate material. This approach makes it possible to design, produce, and fabricate a microfluidic system with channel features >10 µm in poly(dimethylsiloxane) (PDMS) in under 8 hours utilizing instrumentation common to most machine shops. The procedure involves the creation of a master template with negative features, using high precision machining. This master is then employed to create an acrylic mold that is used in the final fabrication step to cast channel structures into the PDMS substrate. The performance of the microfluidic system prepared using this fabrication procedure is evaluated by constructing a miniaturized capillary gel electrophoresis (micro-CGE) system for the analysis of DNA fragments. Agarose is utilized as the sieving medium in the micro-CGE device and is shown to give reproducible (RSD (n = 34) ∼ 5.0%) results for about 34 individual separations without replenishing the gel. To demonstrate the functionality of the micro-CGE device, a DNA restriction ladder (spanning 26–700 base pairs) and DNA fragments generated by PCR are separated and detected with laser-induced fluorescence (LIF). The microchip is shown to achieve a separation efficiency of 2.53 × 105 plates m−1.