Printed circuit technology for fabrication of plastic-based microfluidic devices

One of the primary advantages of using plastic-based substrates for microfluidic systems is the ease with which devices can be fabricated with minimal dependence on specialized laboratory equipment. These devices are often produced using soft lithography techniques to cast replicas of a rigid mold or master incorporating a negative image of the desired surface structures. Conventional photolithographic micromachining processes are typically used to construct these masters in either thick photoresist, etched silicon, or etched glass substrates. The speed at which new masters can be produced using these techniques, however, can be relatively slow and often limits the rate at which new device designs can be built and tested. In this paper, we show that inexpensive photosensitized copper clad circuit board substrates can be employed to produce master molds using conventional printed circuit technology. This process offers the benefits of parallel fabrication associated with photolithography without the need for cleanroom facilities, thereby providing a degree of speed and simplicity that allows microfluidic master molds with well-defined and reproducible structural features to be constructed in approximately 30 min in any laboratory. Precise control of channel heights ranging from 15 to 120 microm can be easily achieved through selection of the appropriate copper layer thickness, and channel widths as small as 50 microm can be reproducibly obtained. We use these masters to produce a variety of plastic-based microfluidic channel networks and demonstrate their suitability for DNA electrophoresis and microfluidic mixing studies.