Investigation of microfluidics filtration and separation

• Main Author: Tan, Jian Hao.
• Other Authors: Yang Chun, Charles
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/53558
• Institution: Nanyang Technological University

Microfluidics filtration and separation has been an integral part of microfluidics in the recent years, offering a wide range of applications like DNA analysis, bio-defense, medical diagnostic applications etc. Further investigation of the performance of these microfilter devices will aid the course of future studies and development. This project focuses on the use of membrane filter as the selected filtration technique. After reviews of previous studies, a microfilter device capable of performing both direct and cross-flow filtration methods was designed by the author which will be used in experiments of this project. Chip fabrication was carried out using direct incorporation of membrane filter bonded with high temperature thermal bonding method. Next, an experiment was designed for users to perform filtration on the existing workstation. To evaluate the filtration results, two validation methods namely the particle count method equipped with ImageJ as the software aid and a self-designed add-on fixture and the other, the Zetasizer method will be discussed and presented. More experiments focusing on the relationship of flow rates, volume of filtered solution and filtration time were performed to find the trend of decreasing amount of smaller particles in the filtrate to better explain this phenomenon. Based on the results, it is clearly understandable that the membrane filter has its own filter capacity before clogging starts that decreases the effectiveness in filtrate collection. However, the flow rate remains a choice of the user depending on his experiment purpose while keeping the volume of filtered solution and filtration time in mind for achieving the desired amount of particles in filtrate. In a bid to overcome limitations of using syringe pumps in the existing setup, the use of pressure controller was explored. A relationship of pressure against flow rate was established and the ability to achieve a higher flow rate was able to determine the performance of the microfilter device and hence further improvisation of microfilter device.