Utilization of mask through electrochemical micromaching to fabricate the frame membrane filtration device

• Main Authors: Wang, Chih-To, 王之鐸
• Other Authors: Wei-Te Wu
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/25614853968776425775

碩士 === 國立屏東科技大學 === 生物機電工程系所 === 98 === In the rapid development of modern biochemical analysis techniques, biosensors are often used in the clinical, medical, biotechnology, environmental and other important fields. Their advantages include low cost, high sensitivity and real-time monitoring. Optical biosensors are essentially optical fiber sensors. To raise the sensitivity of the sensor, part of the slender cladding is removed, exposing the slender core sensing region, which comes into contact with the sample solution. However, the removal of the cladding results in decreased mechanical strength, leaving the fiber easily broken by external forces and unsuited to testing applications. To address this issue, this research proposes the utilization of masks through electrochemical micromachining, with pulsed direct current in an AISI 304 stainless steel cavity wall, which is tested by allowing the solution to flow through the cavity to the fiber’s sensing region. Experimental results indicate that multiple cavities with an average radius of 237.97 μm can be achieved through electrochemical micromachining, but the roundness of the cavities is sub-optimal. Therefore, the use of pulsed direct current as the processing charge still results in the rough edges. By changing the electrolyte, electrochemical polishing can be carried out to smooth the rough edges of the cavities, achieving cavities with an average radius of 253.93 μm while, at the same time, improving the roundness of the cavities, and reducing the surface roughness of the cylinder. After electrochemical processing with the mask and polishing, the stainless steel AISI 304 cylinder was tested with the encapsulated fiber optic sensors. It was found that, despite an increase in mechanical strength, small and large impurities were found in the solution inflow tube, resulting in signal misinterpretation in the sensing test results. Therefore, a wafer-type cellulose acetate membrane with 0.2 µm pore size was added to the outer wall of the perforated and polished stainless steel AISI 304 cylinder where it acts as a frame membrane filtration device and increases the overall mechanical strength. This study matched a wafer-type cellulose acetate membrane filter with a pre size of 1 μm with a concentration of 4.55 × 1010 particles / ml polystyrene solution in a 100-500x dilute of de-ionized water. The membrane and the structural membrane filter are used to filter the dilute solution. A transversal-type turbidimeter was used to measure the different dilution ratios of the voltage signals, which were then compared to the same dilution rate of the filtered solution to determine the quality of the frame membrane filtration device. Experimental results indicate that, then the polystyrene is dissolved in a 200 dilute of de-ionized water, the polystyrene solution averaged a signal of 3.775 V, the wafer-type cellulose acetate membrane filter averaged a signal of 32.434 V, and the frame membrane filtration device averaged a signal of 32.409 V, the signal being the average value of the minimum. Thus, utilization of the mask through electrochemical micromachining of validation frame membrane filtration device was shown to be feasible.