| This dissertation describes our contribution to the development of using plug-based microfluidics to perform reactions. Plugs provide a simple method to miniaturize and multiplex reactions. Using cartridges preloaded with different reagent plugs, the activity of many reagents against a common substrate can be tested in parallel. The optimization of an organic reaction on sub-microgram scale by using MALDI-MS detection was demonstrated as an example. Plugs also allow controlled mixing of solutions. By using plugs to control mixing of protein and salt solutions and set up hundreds of crystallization trials, we observed that the number of nucleation events was affected by the mixing. Plug-based microfluidics eliminates dispersion by compartmentalizing reagents in nanoliter volumes, and dynamical chemical information can be stored in an array of plugs. We developed a new plug-based microfluidic device, the chemistrode, for the delivery and recording of chemical signals with high temporal and spatial resolution. Temporal resolution down to 50 milliseconds was demonstrated for both delivery and recording of chemical signals. The chemistrode also allowed analysis of recorded signals using multiple, independent offline techniques in parallel. We demonstrated the compatibility of the chemistrode with live cell experiments by measuring insulin secretion from single mouse islets every 1.5 seconds. |
