Exterior-electrode electrically driven microconcentrator.

This study uses negative dielectrophoresis and AC electroosmosis as a driving mechanism and presents an electrically driven microconcentrator that concentrates the sample in the region exterior to the electrodes (termed as exterior-electrode electrically driven microconcentrator in this paper). The proposed microconcentrator uses a 3-D face-to-face electrode pair; the top electrode is a relatively large planar electrode, and the bottom electrode is formed with three to six long and thin electrodes connected into an open ring. The sample is brought to the vicinity of the open electrode at the bottom by electroosmotic flow; then, negative dielectrophoresis is used to push the sample away from the electrode and concentrate it in the region surrounded by the open ring electrode. Concentration using an exterior-electrode electrically driven microconcentrator offers promise for convenient use in conjunction with relevant detection systems. The results indicate that for the proposed exterior-electrode electrically driven microconcentrator, the optimal frequency is 100 kHz and the optimal voltage is 13 V . The corner concentration process at the corners of the bottom open electrodes enables the multi-corner electrodes to exhibit better concentration results than that exhibited by semicircular-shaped electrodes. The concentration performance is most favorable when the shape of the open electrode at the bottom is a five-vertex electrode, enabling a concentration enhancement factor of 55 times for a latex particle solution and 11 times for E. coli. The experimental results also demonstrate that the concentration phenomenon in this study is not induced by non-specific adsorption and can be repeated multiple times.