title: Characterization of SU-8 for electrokinetic microfluidic applications.
abstract: The characterization of SU-8 microchannels for electrokinetic microfluidic applications is reported. The electroosmotic (EO) mobility in SU-8 microchannels was determined with respect to pH and ionic strength by the current monitoring method. Extensive electroosmotic flow (EOF), equal to that for glass microchannels, was observed at pH > or =4. The highest EO mobility was detected at pH > or =7 and was of the order of 5.8 x 10(-4) cm(2) V(-1) s(-1) in 10 mM phosphate buffer. At pH < or =3 the electroosmotic flow was shown to reverse towards the anode and to reach a magnitude of 1.8 x 10(-4) cm(2) V(-1) s(-1) in 10 mM phosphate buffer (pH 2). Also the zeta-potential on the SU-8 surface was determined, employing lithographically defined SU-8 microparticles for which a similar pH dependence was observed. SU-8 microchannels were shown to perform repeateably from day to day and no aging effects were observed in long-term use.
authors: Viikki Drug Discovery Technology Center, Faculty of Pharmacy, P.O. Box 56, FI-00014 University of Helsinki, Finland. tiina.sikanen@helsinki.fi
authors: Tiina
authors: T
authors: Sikanen
authors: Santeri
authors: S
authors: Tuomikoski
authors: Raimo A
authors: RA
authors: Ketola
authors: Risto
authors: R
authors: Kostiainen
authors: Sami
authors: S
authors: Franssila
authors: Tapio
authors: T
authors: Kotiaho