Page 1 Class: Introduction to the Nano- electromechanical Systems Date ： 2011/11/04 Name ：梁詠翔 Long-Xiang, Liang Teacher ： Professor Hsu

Page 2 1. Abstract( 摘要 ) 2. ExperImental( 實驗 ) 3. Dielectrophoretic( 介電泳 ) 4. Automatic pencil lead as the electrode( 鉛筆芯 ) 5. Note etching( 蝕刻注意事項 ) 6. Automatic pencil for etching parameters( 參數 ) 7. Experiment of results( 實驗結果 ) 8. ConclusIons( 結論 ) O u t l i n e

Page 3 1.A microelectrode was fabricated by electrochemical etching of a pencil lead (0.5 mm in diameter) in 1.0 M NaOH aqueous solution. 2. The pencil lead was dipped into the solution and then an ac voltage (3.0 Vrms for10 min) was imposed against a stainless plate under mild stirring (450 rpm). 3. The microelectrode was used to perform dielectrophoresis of polystyrene latex microbeads (nominal diameter of 3 m) and human red blood cells. A b s t r a c t

Page 4 ( 樣品 ) ( 示波器 ) ( 函數發生器 ) ( 鉛筆芯微電極 ) ( 顯微鏡 ) ( 控制器 ) ( 三立體定位 ) ( 詳細鉛筆芯微電極 ) ( 微電極 ) ( 隔熱層 ) E x p e r I m e n t a l Materials and chemicals

Page 5 Dielectrophoretic ? Dielectrophoresis (DEP) refers to the migration of dielectric particles under the net force. 1.Device compared to optical tweezers control more easily set up and sound equipment need to rely on low cost and high degree of experience with complex procedures. 2. Designed according to the size of the electrode can control the particle size from sub-micron to tens of microns.

Page 6 Why should application of automatic pencil lead as the electrode ? 1.The composition ratio of carbon a high degree of control. 2. Pencil tough mechanical strength, unlike the hard glassy carbon electrode. 3. Cheap. Graphite pencil leads of 0.5 mm in diameter and 60 mm in length. (Pentel C205 series of grade 4H, 2H, H, HB, 2B, 4B; and Pilot ENO series of grade 4H, 2H, H, HB, 2B, 4B)

Page 7 ( 電源供應器 ) ( 石墨鉛筆芯 ) ( 不鏽鋼板 ) Fig. Schematic diagram of the etching bath. Both graphite pencil lead and stainless plate were submerged into the solution with an angle of about 30 ◦ to avoid thebubbling effect. N o t e e t c h I n g

Page 8 Automatic pencil for etching parameters K2Cr2O7 Efficiency for the etching solution concentration.

Page 9 1. DEP latex particles 2. DEP red blood cells Experiment of results

Page 10 Experiment of results

Page 11 C o n c l u s I o n s With a simple electrochemical etching process, our group has successfully fabricated a graphite pencil lead microelectrode with Its diameter approaching 10 um. The insulation for the microelectrode was achieved by shielding with a polypropylene layer.The low-cost microelectrode can be easily manufactured with a reproducible quality and high analytical performance. Equipped with a conductive glass as the counter electrode and the microscopic window, a simple dielectrophoretic chamber was designed using the mentioned microelectrode to generate an asymmetrical electric field. The economic and simple system was proven to be suitable for manipulating microparticles under direct microscopic observation.

Page 12 Thank for your attention.