Ultraviolet sealing and poly(dimethylacrylamide) modification for poly(dimethylsiloxane)/glass microchips

Abstract

Simple sealing methods for poly(dimethylsiloxane) (PDMS)/glass-based capillary electrophoresis (CE) microchips by UV irradiation are described. Further, we examined the possibility to modify the inner surface of separation channels, using polymethylacrylamide (PDMA) as a dynamic coating reagent. The surface properties of native PDMS, UV-irradiated PDMS, and PDMA-coated PDMS were systematically studied by atomic force microscopy (AFM), infrared absorption by attenuated total reflection infrared (ATR-IR) spectroscopy, and contact angle measurement. We found that PDMA forms a stable coating on PDMS and glass surfaces, eliminating the nonhomogeneous electroosmotic flow (EOF) in channels on PDMS/glass microchips, and improving the hydrophilicity of PDMS surfaces. Mixtures of flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), and fluorescein were separated in 35 s using PDMA-coated PDMS/glass microchips. A high efficiency of theoretical plates with at least 1365 (105 000 N/m) and a good reproducibility with relative standard deviations (RSD) below 4% in five successive separations were achieved.

Multilayer poly(vinyl alcohol)-adsorbed coating on poly(dimethylsiloxane) microfluidic chips for biopolymer separation

“…The development of routine, simple, and well-defined surface modification protocols for PDMS is still in its infancy, and such modification techniques are essential to the devel-opment of microfluidic technology in PDMS-based substrates. Oxygen plasma [7] and ultraviolet light [12] are used mostly to convent PDMS surfaces from hydrophobic and inert into hydrophilic and reactive, although the hydrophobicity recovers quickly. Polyelectrolyte [13], neutral polymers like poly(dimethyl acrylamide) (PDMA) [12], and surfactants [14] have been adsorbed to PDMS surface to adjust EOF.…”

“…Oxygen plasma [7] and ultraviolet light [12] are used mostly to convent PDMS surfaces from hydrophobic and inert into hydrophilic and reactive, although the hydrophobicity recovers quickly. Polyelectrolyte [13], neutral polymers like poly(dimethyl acrylamide) (PDMA) [12], and surfactants [14] have been adsorbed to PDMS surface to adjust EOF. Hydrophilic polymers like polyacrylamide have been linked to PDMS surfaces by UV [15,16] and cerium ion [17] inducing grafting, or atom transfer radical polymerization [18], which improved the separation of peptides.…”

Nanofluidic system for the studies of single DNA molecules

“…Two sealing techniques have been tested in this study. In the first trial an anodic bonding process [41] was used whereas an elastomer sealing [42][43][44][45] was investigated in the second test. Anodic bonding has been developed to fuse a silicon substrate to a glass under an applied voltage (500-1000 V) at an elevated temperature (300 to 6007C) for a few minutes.…”

Partial transfection of cells using laminar flows in microchannels

“…The PDMS replica was exposed under UV light, bonded with clean slide glasses, and pressed to achieve an irreversible seal. 16 The chips are shown in Figure 1.…”