Visible LED-based instrumentation for photometric determination of electroosmotic flow in microchannels

Abstract

An instrumental setup for electroosmotic flow (EOF) determination in microfluidic devices is described. The system is based on a trinocular microscope and an integrated photodiode OPT101. The radiation was provided by a high-intensity white LED. For the determinations, patent blue V and methylene blue aqueous solutions were used. The setup was applied for EOF monitoring in hybrid toner/glass and PDMS microchips. For the toner/glass device, the EOF mobility was determined to be (5.75 ± 0.01) 10-4 cm2 V-1 s-1 at pH 7.0. For PDMS devices the measured EOF mobility was (3.2 ± 0.1) 10‑4 cm2 V‑1 s‑1. Reproducible measurements were obtained in all experiments, which produced results with small errors. The proposed method was compared to the conventional current monitoring method.