Pencil lead microelectrode and the application on cell dielectrophoresis |
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Authors: | Bo-Chuan Hsieh Tzong-Jih Cheng Syuan-He Shih Richie L.C. Chen |
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Affiliation: | Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, 136 Chou-Shan Rd., Taipei City 106, Taiwan, ROC |
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Abstract: | A microelectrode was fabricated by electrochemical etching of a pencil lead (0.5 mm in diameter) in 1.0 M NaOH aqueous solution. The pencil lead was dipped into the solution and then an ac voltage (3.0 Vrms for 10 min) was imposed against a stainless plate under mild stirring (450 rpm). The electrochemically sharpened pencil tip was about 10 μm in diameter (12 ± 3 μm, n = 5), and the lateral part was insulated within a polypropylene micro-pipette tip (2–200 μL volume range). The cyclic voltammograms conducted in 2.0 mM ferricyanide/ferrocyanide buffer solution (pH 7.0) are with low capacitive current and a typical sigmoidal signal of micro-sized electrodes.The microelectrode was used to perform dielectrophoresis of polystyrene latex microbeads (nominal diameter of 3 μm) and human red blood cells. A conducting glass (indium tin oxide coated glass, 40 mm × 40 mm × 1 mm) served as the counter electrode (0.5 mm beneath the microelectrode) to generate the asymmetrical electric field and also as the window for microscopic observation. With the sinusoidal bias voltage (30 Vrms) ranged from 20 Hz to 2 MHz, positive and negative dielectrophoretic phenomena were identified. |
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Keywords: | Pencil lead Microelectrode Dielectrophoresis Red blood cells |
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