Fig. 4.
EOF. (a) Schematic of current-monitoring method for measurement of the EOF velocity. (b) Typical measurement (E = 20 kV/m). The channel resistance (Lower) changes over Δt ≈ 20 s upon changes of voltage (Upper). (c) Measured EOF velocities in a single channel with different surface coatings as function of E. From the fits we find μEOF = (+ 2.00 ± 0.04) × 10−8 m2/Vs, (+ 1.41 ± 0.01) × 10−8 m2/Vs, and (+1.29 ± 0.01) × 10−8 m2/Vs for the untreated channel (bare SiO2), the casein-coated, and the casein–kinesin-coated channel, respectively. (Inset) Measurements for the channel that was used in the electrophoresis experiments.