Microfluidic chip development for bio-defence application

• Main Author: Sim, Bernard Wee Jun
• Other Authors: Li King Ho Holden
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/60986
• Institution: Nanyang Technological University

The developments in Microfluidic applications have enabled a breakthrough in the creation of Lab-on-chip devices which allows rapid bio-chemical analysis for fast diagnostics. These chips give significant benefits in terms of low sample volume, less sample wastage, fast analysis time, cost effectiveness as well as the possibility of developing different diagnostic on different chips all at one go. Hence, in this report, it focuses on the development of a novel idea of using a magnetic membrane to create a micromixer which could be used to introduce a turbulent flow to a fluid enhancing the mixing process. A structured research is then conducted, firstly, with the study, fabrication and characterisation of an electromagnet to enable a steady and constant magnetic flux to be produced. Secondly, the characterisation of Spin Speed vs. Membrane thickness using Polydimethylsiloxane (PDMS) is done, to enable the accurate prediction of membrane thickness during the actual creation of the magnetic membrane. Next, the actual membranes are created with different concentrations of Iron(III)Oxide cores as well as a 200 and 500 micron thick magnetic paper core. These cores are embedded between two 25 micron thick PDMS membranes to allow the membrane to keep its elasticity but at the same time deflect with an application of magnetic flux. Static and dynamic deflection tests are then conducted to characterise deflections using a microscope and high speed camera respectively. During the static deflection test, Iron(III)Oxide cores show no deflection and the 500 micron magnetic paper produced better deflection results as compared to the 200 micron magnetic paper. Hence, the 500 micron thick magnetic paper core was chosen to undergo the dynamic deflection testing which showed significant deflection of more than 200 microns dynamically at 100Hz. Fluorescent dye is then added to water within the well with and without actuation of the membrane to show the diffusion process and the enhanced mixing process respectively. Images are than being captured to prove the success in using the concept of the magnetic membrane for a micromixing application and finally, possible improvements and future works are listed to show the probable further research that could be carried out.