Mechanistic Investigation of Nanoparticle Motion in Pulsed Voltage Miniaturized Electrical Field Flow Fractionation Device by in Situ Fluorescence Imaging
mediaposted on 15.05.2004, 00:00 by Alex Ieng Kin Lao, Yi-Kuen Lee, I-Ming Hsing
In our previous study, we reported a miniaturized electrical field flow fractionation device (μ-EFFF) that used a pulsed voltage (PV) to increase the effective electric field and, hence, improved the separation performance. In this work, we developed two μ-EFFFs with planar or segmented electrode design and investigated the particle movement in the flow channels under a PV. Numerical simulation was used to understand the electric field distribution in the μ-EFFFs. When the calculations for the μ-EFFF with a segmented electrode (segmented μ-EFFF) and the μ-EFFF with planar electrodes (planar μ-EFFF) are compared, a stronger electric field at the top electrode segments is found in the segmented μ-EFFF, with the strongest field at the edges of the electrode segments. Nanoparticle motion in both devices was in situ visualized by using a fluorescence microscope equipped with a CCD-camera. Results reveal that electrophoresis governs the nanoparticle movement in the planar μ-EFFF and dielectrophoresis dominates the movement in the segmented μ-EFFF. Two models are postulated to explain the experimental observations of the nanoparticle movement. The mechanistic understanding of controlling nanoparticle motion in a miniaturized environment will help the design and application of μ-EFFF for the separation of charged biomolecules (proteins and DNAs).