ÿþWe recently reported a new puma creepers 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.

We recently reported a 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 puma fenty thickness of glass slides), bondable to form enclosed devices easily.

Providing nominally 80 mW/cm 2 at 365 nm) for 80 sec (expose through resin side), followed by an additional 40 sec (expose through mold). Once released from the mold, puma slides PUMA substrate was conformally bonded to another PUMA-coated (cured) glass coverslip with gentle mechanical pressure. This conformal bond was converted to permanent bond by placing the PUMA chip under the UV flood source for an additional 10 min. Material layout during molding of PUMA chip. 1 : PDMS mold; 2 .

PUMA resin; 3 : PTFE posts; 4 : polypropylene sheet; 5 : cellophane (or Aclar). ( B ) Two methods of interfacing PUMA chip with external tubing: puma rihanna 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.

PDMS cannot be used as the material of fabrication because of low shear modulus; 6 the features would simply lean and topple over under gravity.Fig. 2 shows an example of features that can be fabricated in PUMA but not PDMS. Fig. 2A shows a scanning electron microscopy (SEM) image of a replica in PUMA resin; this test pattern for replication consists of densely spaced vertical columns alternating with solid walls. puma suede classic The feature height was ~40 ¼m and the aspect ratio of the vertical columns was ~3.5.

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.