AC ELECTROHYDRODYNAMICS PHENOMENON IN 2D AND 3D MICROELECTRODES

Abstract

Alternating current electrohydrodynamics (ac-EHD) has been reported as a promising technique for enhancing sensor performance by the intimate mixing of the analyte solution at the electrode surface. The lateral fluid motion created by the ac-EHD phenomenon can be tuned by changing the frequency, voltage, and electrode geometry. To date, various studies have been conducted on the use of 2D electrodes based ac- EHD devices for sensor applications. However, the use of 3D electrodes may provide better fluid mixing as compared to the 2D electrodes due to the high surface area of the electrodes. To test this hypothesis, 2D and 3D microelectrodes with different sizes were designed and fabricated for ac-EHD studies using standard lithography and etching processes. Previous methods to achieve 3D microstructures and common issues faced during fabrication are also discussed. The lateral fluid motion created by the 2D and 3D electrodes after the application of different voltages and frequencies was analyzed by tracking the motion of fluorescent beads present in the mixing fluid. Fluorescence microscopy technique was used to capture videos of the movement of fluorescent beads in the fluid. The videos were analyzed using ImageJ to calculate the speed of fluorescent beads in the case of 2D and 3D electrodes. Furthermore, a different pattern of the fluid motion was observed in the case of 3D electrodes, which highlights the complex fluid movement in the case of 3D electrodes as compared to the 2D electrodes.