Minimal dead-volume connectors for microfluidics using PDMS casting techniques

This paper presents a minimal dead-volume micro-connector fabricated using poly-dimethylsiloxane (PDMS) casting techniques for microfluidic applications. A simple and versatile method of fabricating a micro-connector to have an efficient interconnection to external large-scale fluid equipment was demonstrated. To eliminate the dead volume, a capillary was bridged to a micro-channel via a connection channel, which was formed by the removal of a metal wire after the PDMS casting process. The new method does not require any adhesive, precise drilling, delicate alignment procedure and micromachining processes. It could also effectively prevent blocking of the capillaries which was commonly observed while using adhesives. With this approach, detachable and reusable micro-connectors with a minimal dead volume could be achieved. According to leakage tests, the micro-connector could withstand pressures up to 150 psi and a maximum flow rate of 50 mul min(-1). The pull-out tests indicated that the PDMS fitting could provide enough mechanical strength for practical applications. Not only does this micro-connector significantly eliminate the dead volume, but it also increases the detection signal. While compared with more conventional Teflon tubing fitting, the micro-connector could reduce by at least 50% the dilution effect for sample loading analysis due to substantial elimination of the dead volume. Most importantly, this micro-connector has greater versatility for coupling capillaries to various kinds of microfluidic chips made of different materials.