Cancer is one of the primary causes of death and long-term illness in the developed world. Early detection before noticeable symptoms appear, or cheap options for population screening and ongoing patient analysis are equally as important as advancements in treatment. Currently, cancer detection and prognosis happens for the most part via a scan or biopsy. If this information could instead be obtained from a simple blood sample the world of cancer treatment and detection would be revolutionised. To that end, this thesis outlines the work undertaken towards completion of a PhD on the topic of magnetophoretic cell handling on a centrifugal micro fluidic platform for rare cancer cell detection in blood. This resulted in rst using \bio-mimetic" microbeads to prove the physical principle and then using magnetically tagged MCF7 breast cancer cells spiked into a blood sample to simulate circulating tumour cells (CTC's). This strategy proved successful and resulted in detecting magnetically tagged cancer cells in a blood background at a concentration of as low as 1 cell/l and with a sensitivity of over 80%. On completion of this phase in the research, the usability of the device using patient blood samples was investigated through a collaboration with pathologists at St. James' Hospital, Dublin. The rst step in this phase was to redesign the system to process clinically relevant volumes which, due to the rarity of CTC's in the circulatory system, were on the millilitre scale, as opposed to the microlitre scale. After the redesign it was now possible to successfully analyse 0.2ml of blood and detect cancer cells at a concentration of as low as 0.1 cells/l. As well as focusing on the main topic, the author has also investigated various other methods of magnetic and stopped ow particle control for other purposes and all of these also-explored areas of stopped-flow micro fluidics fit in well with the broader picture of creating low-cost, easy to use lab-on-a-disc technologies that utilise stopped-flow micro fluidic systems and magnetic forces to enable detection of specific cells in blood.