Measurement of total organic carbon (TOC) is of great importance to establish the purity of drinking water with respect to biological contaminants, and is generally achieved by optical absorption at wavelengths ~ 250 nm in the ultraviolet region of the spectrum. However, long optical path lengths (~10 cm) are required to achieve the desired limit of detection in the sub-parts-per-million regime, making devices bulky and impractical for some purposes.
This project involves using optical microresonators developed by the group as a means to extend the optical path length by a factor of ~1000 so that high sensitivity can be achieved in a microfluidic device. It will involve adapting existing apparatus set up for visible light measurements to UV analysis, and performing systematic tests to establish the achievable specifications. The project will be carried out in close contact with Oxford HighQ Ltd, a recent spinout from the group which is developing commercial sensors using the technology.
