We recently reported a puma fierce new UV-curable polyurethane-meth-acrylate (PUMA) resin that is non-elastomeric and has excellent qualities as a disposable microfluidic substrate, especially for clinical diagnostic applications. 18 This PUMA substrate is transparent optically, resistant to biofouling, compatible with many chemicals encountered in microfluidic applications, curable to a typical thickness (about the thickness of glass slides), bondable to form enclosed devices easily.

Aclar sheets (Honeywell, Morristown, NJ), which is a polychloro-trifluoro-ethylene (PCTFE) polymer containing no plasticizer, may be used in lieu of cellophane in critical applications. To form fluidic reservoirs or holes for external connection, PTFE posts (3 mm (D) × 3 mm (H)) were embedded in the PUMA resin before curing. The entire assembly was placed in a high-intensity UV rihanna puma creepers source (ADAC Cure Zone 2 UV Flood Light Source, fitted with a 400W metal halide lamp.

PUMA resin; 3 : PTFE posts; 4 : polypropylene sheet; 5 : cellophane (or Aclar). ( B ) Two methods of interfacing PUMA chip with fenty puma slides external tubing: 1 : PUMA chip; 2 : barb elbow connector; 3 : polyurethane tubing; 4 : additional resin to seal leak (Dymax 186M); 5 : PTFE tubing; 6 : 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.

For creating small through-holes in PUMA, we found laser-cutting to be more convenient than embedding and then puma ignite removing PTFE posts. Sharpened punches do not produce clean holes in PUMA as they do in PDMS. We had tested an Epilog Helix CO 2 laser-cutting system (45W; laser made by Coherent) which is commonly used as a computer-controlled souvenir or sign engraver. We noticed two minor issues with laser-cutting: (1) sputtering of melted plastic could damage structures or block channels; and (2) rastering rate.

A 180° bend was incorporated in the design to help troubleshooting if there were directional issues in either the replication or demolding process. As evident in Fig. 2A , the columns produced in PUMA had a sharp vertical profile with no evidence of leaning.We found that for low-aspect-ratio features the cured PUMA resin could be released from the PDMS mold either by (1) peeling the mold slightly away from the cured resin or black puma (2) wedging a scalpel between the resin and the mold to gently lift up the resin.

UMA replica taken under a stereoscope (same pattern as Fig. 2A ), released from the mold without the assistance of the pulling station. Two types of defects were evident: (1) wavy walls, and (2) irregular vertical column spacings. The waviness of the wall is generally attributable to improper cleaning of the PDMS mold between replication runs, which increases the adhesion between the mold and the resin. Consequently it is not possible to lift apart without some horizontal motion to counter the adhesive force.