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Flexible enclosure for fluidic sealing of microcomponents

A flexible enclosure for fluidic sealing of SU-8 microcomponents was developed using polydimethylsiloxane (PDMS). The flexible enclosure can be mechanically assembled to SU-8 microchannels even in the presence of liquid. The seal is mechanical and completely reversible, thus allowing the channels to already contain immobilized enzymes or cells prior to assembly. To provide such a reversible fluid tight lid, the PDMS and SU-8 substrates contain interlocking structures that facilitate assembly and sealing together of the two substrates. Interlocking 1 mm ridges/holes and 400 μm ridges/grooves were fabricated on PDMS and SU-8 surfaces that hold the two pieces in place to prevent PDMS lid and SU-8 microchannels separation during handling and fluid flow. Furthermore, a 20 μm bump on the PDMS surface, which has the same width and length dimensions as the 400 μm deep SU-8 microchannel, acts as a plug to keep the fluid within the microchannel and prevent leakage between the PDMS-SU-8 interface. The assembled microchannels and enclosures can withstand manually applied fluidic pressure via a syringe which is noticeably higher than channels with a simple lid and no interconnect structures. The device was additionally quantified for pressure versus flow rate using a syringe pump and pressure sensor. The seal remained leak free up to 0.6 ml/min and 2.36 kPa. In addition, a preliminary cell viability test was conducted with leukemia cells and we observed that cells lived in the channel microenvironment for 24 hours.