Control of the polymer surface chemistry is a crucial aspect of development of plastic microfluidic devices. When commercially available plastic substrates are used to fabricate microchannels, differences in the electroosmotic flow mobility (EOF) from plastic to plastic can be very high. Therefore, we have used polyelectrolyte multilayers (PEMs) to alter the surface of microchannels fabricated in plastics. The PEMs are easily fabricated and provide a means for controlling the flow direction and the electroosmotic mobility in the channels. Optimal modification of the microchannel surfaces was obtained by coating the channels with alternating layers of poly(allylamine hydrochloride) and poly(styrene sulfonate). The efficiency of the surface modification has been evaluated by measuring the electroosmotic flow mobility. When microchannels prepared in different polymer substrates were modified with PEMs, they demonstrated very similar electroosmotic mobilities. The PEMs have also been used to immobilize chemically selective molecules in the microchannels. In addition, relatively complex flow patterns, with simple arrangements of applied voltages, have been realized by derivatization of different arms of a single device with oppositely charged polyelectrolytes. In addition, flow in opposite directions in the same channel is possible; a positively derivatized plaastic substrate with a negatively charged lid was used to achieve top-bottom opposite flows.
Proceedings Title: Advanced Environmental and Chemical Sensing Technology, Conference | |Advanced Environmental and Chemical Sensing Technology | SPIE
Conference Dates: November 1, 2000
Conference Title: Proceedings of SPIE--the International Society for Optical Engineering
Pub Type: Conferences
derivatization, electroosmotic flow, imprinting, microfluidics, plastic, polyelectrolyte multilayers