Abstract
Integrating three-dimensional (3D) microelectrodes on microfluidic chips based on polydimethylsiloxane (PDMS) has been a challenge. This paper introduces a composite 3D electrode composed of Ag powder (particle size of 10 nm) and PDMS. Ethyl acetate is added as an auxiliary dispersant during the compounding process. A micromachining technique for processing 3D microelectrodes of any shape and size was developed to allow the electrodes to be firmly bonded to the PDMS chip. Through theoretical calculations, numerical simulations, and experimental verification, the role of the composite 3D microelectrodes in separating polystyrene particles of three different sizes via dielectrophoresis was systematically studied. This microfluidic device separated 20-, 10-, and 5-μm polystyrene particles nondestructively, efficiently, and accurately.
Highlights
Operations such as sample preparation [1], biological and chemical reactions [2], and separation and detection can be completed within one chip only a few square centimeters in size [3]
This paper introduces a composite 3D microelectrode made of PDMS and Ag nanopowder
Positive and negative values of the real part of the CM factor indicated that the particle was subjected to a positive and negative dielectrophoretic force in the electric field, respectively
Summary
Operations such as sample preparation [1], biological and chemical reactions [2], and separation and detection can be completed within one chip only a few square centimeters in size [3]. Microfluidic technology has several advantages, such as a low cost, low sample consumption, and rapid [4] and high-sensitivity detection [5] It exhibits considerable potential for many applications, e.g., biomedicine [6], drug synthesis and screening [7], environmental detection [8], health quarantines [9], forensic identification, and biological reagent detection [10]. Two-dimensional (2D) planar metal electrodes are widely used in electrokinetic particles or cell separation because of the relatively mature fabrication techniques, e.g., liftoff and etching. These fabrication processes require evaporating or sputtering the metal film on a substrate as an electrode material, necessitating expensive equipment and complex operations. The electric-field intensity is exponentially attenuated with the increasing vertical distance from the electrode [20]
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