Use of photopatterned porous polymer monoliths as passive micromixers to enhance mixing efficiency for on-chip labeling reactions.

We introduce a passive micromixer with novel architecture using photopatterned porous polymer monoliths (PPM) and demonstrate an improvement in mixing efficiency by monitoring the fluorescence of an on-chip labeling reaction. UV light was used to photopattern a periodic arrangement of PPM structures directly within the channel of a plastic microfluidic chip. By optimizing the composition of the polymerization solution and irradiation time we demonstrate the ability to photopattern PPM in regularly repeating 100 microm segments at the tee-junction of the disposable device.

Hydrophilic surface modification of cyclic olefin copolymer microfluidic chips using sequential photografting.

The plastic material known as cyclic olefin copolymer (COC) is a useful substrate material for fabricating microfluidic devices due to its low cost, ease of fabrication, excellent optical properties, and resistance to many solvents. However, the hydrophobicity of native COC limits its use in bioanalytical applications. To increase surface hydrophilicity and reduce protein adsorption, COC surfaces were photografted with poly(ethylene glycol) methacrylate (PEGMA) using a two-step sequential approach: covalently-bound surface initiators were formed in the first step and graft polymerization of PEGMA was then carried out from these sites in the second step.

Room-temperature bonding for plastic high-pressure microfluidic chips.

A generic method for the rapid, reproducible, and robust bonding of microfluidic chips fabricated from plastics has been developed and optimized. One of the bonding surfaces is exposed to solvent vapor prior to bringing the mating parts into contact and applying a load. Nanoindentation measurements performed by atomic force microscopy show that a reversible material softening occurs upon exposure to solvent vapor.

Injection molded microfluidic chips featuring integrated interconnects.

An injection molding process for the fabrication of disposable plastic microfluidic chips with a cycle time of 2 min has been designed, developed, and implemented. Of the sixteen commercially available grades of cyclo-olefin copolymer (COC) that were screened for autofluorescence and transparency to ultraviolet (UV) light, Topas 8007 x 10 was identified as the most suitable for production. A robust solid metal mold insert defining the microfluidic channels was rapidly microfabricated using a process that significantly reduces the time required for electroplating.