Segmented gas-liquid flow in microfluidics device

• Main Author: Koh, Quan Yong
• Other Authors: Wong Teck Neng
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering::Fluid mechanics
• Online Access: https://hdl.handle.net/10356/141870
• Institution: Nanyang Technological University

Droplet-based microfluidics offers controlled synthesis which is a multidisciplinary platform that is widely used because the behaviour of fluid flow can be manipulated with high precision. Fabrication of novel particles such as the Janus particles with two or more distinct chemical constitutions have gained popularity as it broadens the horizon of biomedical applications. Incorporation of magnetic functionality in one constitution phase promotes actuation without contact, which is favourable in numerous applications such as nucleic acids separation and magnetic resonance imaging detection. The experiment studies for the generation of a spherical magnetic Janus particles was carried out in a flow-focusing microfluidic device made from standard lithographic process. The width and height of the microchannels are 100μm by 50μm. The fluids used in this experiment consists of 10% wt Polyvinyl alcohol in de-ionized water (Continuous phase), mineral oil with 0.5% wt Span 80 surfactant (Dispersed phase I) and 1,6-Hexanediol diacrylate with 8% wt 1-hydroxycyclohexyl phenyl ketone solution with 10% wt 8nm iron oxide nanoparticles (Dispersed phase II). The shape and size of the particles can be readily adjusted with various flow rates and the observed results were presented. The increase in flow rate ratio at fixed flow rate of the continuous phase has shown to decrease the droplet size and leads to a spherical shape. At higher continuous phase flow rate, smaller diameters droplets and higher throughput can be obtained. Synthesized magnetic Janus particles exhibited magnetically controllable motion under the effects of a rotating magnetic field. The contactless manipulation capabilities coupled with a polymeric component could be a promising candidate for biomedical applications such as drug delivery, DNA detection, 3D bioprinting, sensors and micromixers.