UV Laser Machined Polymer Substrates for the Development of Microdiagnostic Systems

Abstract

This report describes a UV laser photoablation method for the production of miniaturized liquid-handling systems on polymer substrate chips. The fabrication of fluid channel and reservoir networks is accomplished by firing 200 mJ pulses from an UV excimer laser at substrates moving in predefined computer-controlled patterns. This method was used for producing channels in polystyrene, polycarbonate, cellulose acetate, and poly(ethylene terephthalate). Efficient sealing of the resulting photoablated polymer channels was accomplished using a low-cost film lamination technique. After fabrication, the ablated structures were observed to be well defined, i.e., possessing high aspect ratios, as seen by light, scanning electron, and atomic force microscopy. Relative to the original polymer samples, photoablated surfaces showed an increase in their hydrophilicity and rugosity as a group, yet differences were noted between the polymers studied. These surface characteristics demonstrate the capability of generating electroosmotic flow in the cathodic direction, which is characterized here as a function of applied electric field, pH, and ionic strength of common electrophoretic buffer systems. These results show a correlation between the ablative changes in surface conditions and the resulting electroosmotic flow. The effect of protein coatings on ablated surfaces is also demonstrated to significantly dampen the electroosmotic flow for all polymers. All of these results are discussed in terms of developing liquid-handling capability, which is an essential part of many μ-TAS and chemical diagnostic systems.

Peer Reviewed: Polymeric Microelectromechanical Systems.

“…This can be accomplished by spin-coating a resist over the chromium/ quartz plate and then transferring the design (optical proximity printing); developing the resist; and finally, etching the chromium to remove exposed metal. A typical channel fabricated in polycarbonate is shown in Figure 1b (9). The angles of the 75-µm side walls are sharp and vertical.…”

Polyelectrolyte‐modified short microchannel for cation separation

“…The fabrication of microchip has been previously described [26]. Briefly, the PET sheet is photoablated by a UV excimer laser (Argon Fluor Excimer Laser at 193 nm; Lambda Physik LPX 2051, Göttingen, Germany).…”

Surface modification in microchip electrophoresis

“…This approach was used to elegantly reduce band broadening around 907 turns by selectively modifying the surface charge of the outer-wall. The approach of laser modification of channel surfaces has also been applied to other polymeric substrates including polystyrene, cellulose acetate, PETG, poly(vinyl chloride), and polycarbonate [30,88].…”

“…There are, however, some manufacturing issues associated with glass microchips, which makes the use of alternative materials like different polymers attractive [28]. An advantage of polymer-based microfluidic chips is the wide choice in microfabrication techniques like injection molding [29], laser ablation [30], imprinting [31], or hot embossing [32]. For such microfluidic devices inexpensive mass production is possible which makes them attractive as disposable devices for commercial applications.…”