Gold Nanofilm in Optically-Induced Dielectrophoresis Chip for The Manipulation of Polystyrene Microparticles

Abstract

In this study, an optically induced dielectrophoretic platform (ODEP) was used to project a radial pattern onto a photosensitive layer of a chip to perform optically induced imaging. After a non-uniform electric field was formed, an optically induced dielectrophoresis force was generated to drive the movement of polystyrene particles. First, the simulation software (COMSOL) was used to conduct electric field analysis of radial patterns and the microelectromechanical systems (MEMS) technology was used to produce a gold nanofilm on optical dielectrophoresis chips. Experiments show that the chip with no gold nanofilm (filmless) is intended to drive polystyrene particles with a diameter of $90 \mu \mathrm{m}$ to move. At $20 \mathrm{V}_{pp}$, the particle driving frequency ranges from 500 Hz to 60 kHz, and have only negative dielectrophoresis forces, with the particle moving speed of approximately $6.7 \mu \mathrm{m} /$s. In addition, the 5-nm gold film chip exhibits negative dielectrophoresis force from 600 Hz to 18 kHz, with a particle moving speed of $10 \mu \mathrm{m} /\mathrm{s}$, while the positive dielectrophoresis force is generated from 23 kHz to 70 kHz. The 50 kHz drive works is best condition, accumulating $90 \mu \mathrm{m}$ particles within a radius of 1 mm into the center of the radial pattern in 60 s, with a particle moving speed of $16.7 \mu \mathrm{m} /$s.