Microfluidic devices and biological lasers for biophotonic applications

Abstract

The increasing collaboration between physicists and biologists in recent years has led to a series of breakthroughs enabled, in part, by the use of lasers in biological experiments. Once such recent development is the biological laser where a living cell containing a fluorescent protein or dye acts as a laser gain medium. This thesis presents work designed to develop the idea of the living laser leading to their implementation as a research tool. This work has consisted of two main areas of research; microfluidics and biological lasers. The use of microfluidics enables the miniaturisation of many existing types of biological diagnostics. In this thesis devises are demonstrated for use in temperature sensing and flow cytometry. These were fabricated through the use of Ultrafast Laser Inscription (ULI) and selective chemical etching. As part of this work we have also investigated the integration of silver nanoparticles into microfluidic devices, using photo-reduction, for the enhancement of Raman sensing. Several types of living laser have been fabricated containing different fluorescent dyes and Enhanced Green Fluorescent Protein (eGFP). Lifetime extension has been achieved using vitamin C and work has been conducted towards demonstrating calcium sensing inside cells. As an alternative to the dyes used in these experiments we have also investigated the use of upconverting nanoparticles.