微電磁閥門之分析與應用

Abstract

近年來微流體裝置中微電磁閥門的使用，主要是利用磁性材料和外部磁鐵的相吸或相斥來擠壓薄膜，經由薄膜再擠壓腔體，故得知薄膜厚度將決定閥門開合效果。然而在高寬深比的流道中，卻無法使用薄膜變形來達到關閉效果。本論文將使用平面閥門外型設計，配合纏繞漆包線方式，使得能夠控制微流體裝置內部微電磁閥門的開和關。此外，將量測閥門所受的淨力，以充分掌握微閥門的磁滯現象和其應用。本研究中平面微電磁閥之工作原理為，利用漆包線所產生的磁場，讓鐵製的微閥門產生極性，進而因極性的相吸來推動微閥門，以完成開關的動作。根據實驗結果，線圈在0.4A時，會產生14.7Gauss的磁場即可驅動閥門。由量測磁滯曲線的結果可知，閥門在0.9A所產生的磁場下，被磁化的磁感應不超過7Gauss，且殘磁和矯頑力分別為0.4Guass和0.005A/m。而兩線圈分別通過不同向位的方波經過高速電子藕合攝影機拍攝分析後，可以得到微閥門在0.9A下的開和關動作皆可在0.005秒完成。而在背景流速15μL/hr時，閥門在線圈通過0.9A所產生的磁場下，能阻擋大部分流體且能使流體些微轉向。

In recent years, the valves are essential component in microfluidic devices and micro-total-analysis-system. In general, the micro-solenoid valve was made of magnetic materials and the external magnets was applied to attract or repel squeeze the membrane. Based on the squeeze through the chamber, the thickness of membrane is the key factor about the moving behavior of the micro-solenoid valve. However, in the microchannel with high aspect ratio, the deformation of membrane can not be used to achieve the valve moving. The planar valve and enameled wire used to build the microfluidic devices were presented in this study. The magnetic field to drive the present planar micro-solenoid valve was generated by enameled wires. The polarity of iron microvalve can be attracted or repelled by magnetic. The currents were applied to control the opening and closing of the micro-solenoid valve. In addition, the measurements of the net force and hysteresis curves from valve motion. According to the experimental results, the magnetic induction will produce 14.7 Gauss to drive the valve with the load current of the coil is 0.4A. From the analysis results of the hysteresis curve, the magnetic induction by valve is 7.0 Gauss when the loading current is 0.9A. The residual magnetism and coercive force are 0.4 Gauss and 0.005 A/m, respectively. The moving behaviors of the microvalve were measured by the high-speed CCD. The period of opened and closed is 0.005 second when two coils are loading in different phase of 0.9A square wave. Furthermore, the present valve can obstruct most of fluid and change fluidic direction slightly with the background flow is 15μL/hr.