In this thesis an idea of oil/water separation in microfluidics was proposed and being demonstrated. Inspired by gravity differential separation of oily water, water droplets separation from a continuous oil flow using co-flow approach was achieved. Oil/water mixture was simulated by orderly spaced water droplets in an oil flow, by co-flowing with another water flow, water droplets was extracted from the oil flow and merged into the water flow, resulting two pure oil and water flows co-flowing. It was thought that the extraction of water droplet from oil was challenging, however initial trials showed that it is magnificently reliable; the obstacle lies in separating the two co-flowing pure flows. Therefore, channel geometries and hydrophobicity of the channel wall were varied to...[ Read more ]

In this thesis an idea of oil/water separation in microfluidics was proposed and being demonstrated. Inspired by gravity differential separation of oily water, water droplets separation from a continuous oil flow using co-flow approach was achieved. Oil/water mixture was simulated by orderly spaced water droplets in an oil flow, by co-flowing with another water flow, water droplets was extracted from the oil flow and merged into the water flow, resulting two pure oil and water flows co-flowing. It was thought that the extraction of water droplet from oil was challenging, however initial trials showed that it is magnificently reliable; the obstacle lies in separating the two co-flowing pure flows. Therefore, channel geometries and hydrophobicity of the channel wall were varied to optimize the separation of the two flows. Results show that a simple T-junction without chemical modification on channel wall attained the best performance among other geometries and chemically modified surfaces. This separation method can be generalized to any two immiscible liquids as well.

Another major work summarized in this thesis achieved temperature mapping with a Rhodamin B (RhB) grafted microfluidic chip. RhB fluorescence intensity is temperature dependent, thus it is commonly used in biotechnology for temperature sensing and as a tracer. By grafting RhB on PDMS, this functional material provides a non-invasive, rapid, full-field, high spatial resolution and acquisition rate temperature sensing method, while the material possesses excellent solvent, thermal and photo stability. 2D temperature mapping of a microfluidic chip is demonstrated, spatial resolution was estimated to be 5 μm.