Novel polydimethylsiloxane (PDMS) based microchannel fabrication method for lab-on-a-chip application

A novel method is presented for fabricating PDMS-based microchannel. The mold consists of a tunable PDMS structure rather than the commonly used SU-8 mold with fixed shape. This structure is prepared by transferring the desired microchannel pattern into one PDMS substrate via soft lithography and bonding it to a spin-coated PDMS membrane with the oxygen plasma activated technology. Through applying proper pressure to this structure and keeping it constant during the whole molding process, the resulted membrane deformation shape with rounded cross-sectional contour is totally replicated into the device layer, constituting the final main body of the microchannel. Besides the inherent feature of rounded cross-section provided by this method, the depth of the microchannel can be easily controlled by changing the pressure. At the same time, through designing different widths at different positions in one microchannel, it is straightforward to realize microchannel structure with multi-depth in one step using one photomask. Both of these characteristics have been successfully demonstrated in our experiments and it will definitely find wide applications in lab-on-a-chip area.