ÿþWe recently reported puma creepers a new UV-curable polyurethane-methacrylate (PUMA) resin that has excellent qualities as a disposable microfluidic substrate for clinical diagnostic applications. This article discusses strategies to improve the production yield of PUMA chips that contain dense and high-aspect-ratio features, which presents unique challenges in demolding and bonding steps. These fabrication improvements were deployed to produce a microfiltration device that contained closely spaced and high-aspect-ratio columns.
PUMA resin; 3 : PTFE posts; 4 : polypropylene sheet; 5 : cellophane (or Aclar). ( B ) Two methods of interfacing PUMA chip with external tubing: 1 : PUMA chip; 2 : barb elbow connector; 3 : polyurethane tubing; 4 : additional resin to seal leak (Dymax 186M); 5 : PTFE tubing; 6 : puma fenty polyolefin heat-shrink; 7 : retaining ring.Fig. 1B shows two examples of interfacing a PUMA chip for external fluidic delivery. The left side of Fig. 1B illustrates the use of a barbed elbow connector.
The elbow connector was inserted into a puma slides thick-wall polyurethane (PU) tubing (1/8-in outer diameter (OD), 1/16-in inner diameter (ID)), which served as a mechanical anchor against shear. The PU tubing was then inserted into a 1/8-in hole, formed either by embedding PTFE posts or laser cutting, in the PUMA substrate and additional resin (Dymax 186M) was dispensed around the junction and cured for 2 4 min. A tubing (1/163 ID) was attached to the external end of the barbed elbow connector.
The right side of Fig. 1B puma rihanna illustrates interfacing a 1/16-in OD (or of equivalent dimensions as PE100 tubing from Becton Dickinson) PTFE tubing with a PUMA chip. We found that conventional polyethylene (PE) tubing ( e.g. PE100), which is commonly used to interface with PDMS-based microfluidic devices, did not work well with PUMA chips, because (1) polyethylene surfaces are resistant to adhesive bonding, and (2) highly elastic tubings collapse easily when pulled in the longitudinal direction.
Fig. 3 shows the schematic of the pulling station. It was based on a Dremel Workstation 220-01 assembly, which was intended to be a table-top drill press. The Workstation featured a spring-loaded lever that controlled the vertical translation along a shaft; upon releasing the lever, the upper mount translated upward until hitting a stop, ensuring that the chip is pulled 180-degrees away from the PDMS mold. A 1-in diameter puma suede classic vinyl suction cup was secured to the upper mount for attachment to the PUMA chip.
After UV curing, the PUMA-PDMS assembly was placed on the base suction cup and the vacuum pump was turned on. The base suction cup held the PDMS mold in place while the upper suction cup was slowly brought down to contact the transparent polypropylene cover on top of the cured resin. The touch-down speed should be sufficiently slow such that minimal downward force was exerted on the resin. Once the vacuum gauge on the pump dropped from atmospheric pressure to the ultimate pressure of the pump.