Droplet microfluidics is a new approach for chemical and biological analysis. Discrete nano-litre droplets ensure chemical reactions occur quickly without cross-talk, allowing samples to be processed without dispersion. Droplet microfluidics is effectively a digital sample processing platform enabling sample droplets to be handled in a continuous serial format. This thesis describes a method for in situ compartmentalization of biological and chemical samples after separation using Slipchip technology. Isoelectric focusing (IEF) was used to separate biomolecules within the Slipchip. The device was used to compartmentalise the IEF separated samples into micro-droplets. This approach solves the compartmentalization challenge faced by current IEF systems. The digitised sample droplets can be collected serially or in parallel. In serial collection, droplets are collected in tubing that maintains their spatial sequence. For parallel collection, droplets are collected with a multi-pipette. Separated samples were assayed by gel electrophoresis on an Agilent Bioanalyzer. Separated samples were also postprocessed on-chip by mixing with pH indicator droplets for calibration of droplet pH. Such continuous-flow/micro-droplet conversion methods have the potential of hyphenating different separation techniques for performing advanced analysis of complex samples. One disadvantage with droplet microfluidics is the very small dimensions of the sample meaning that classical absorption assays are difficult. Therefore, a high sensitivity absorption-based optical method called Cavity Ring Down Spectroscopy (CRDS) was developed and evaluated. The integration of CRDS with microfluidic devices was explored. Microfabricated cylindrical lenses were used to increase the light coupling efficiency within a chip, but results showed that light losses in the system were too high to enable the effective use of CRDS for analysis.