| The development of miniaturized, microfabricated devices for chemical analysis is a new and exciting application of micromachining technology. The research presented in this work demonstrates the feasibility of developing microfluidic systems for immunoassay, a technique which is increasingly used in clinical diagnostics and environmental monitoring.; Microfabrication has provided a means of fabricating a miniaturized, three dimensional network of channels in a small device (chip) capable of consuming only nano- to picoliters of sample and reagent and generating very little waste. Computers, relays and high voltage were used to control fluid flow within the valveless microchannels. Solution delivery and fluid manipulation were facilitated by electroosmosis, while efficient separation was achieved by electrophoresis in the glass microchannels. Separation efficiencies with submicron plate heights were achieved on-chip. Capillary electrophoresis allowed the separation of reagents and reaction products to take place in solution and led to rapid on-chip separation, typically within less than one minute. The laser induced fluorescence system used with these microdevices gave picomolar detection limits satisfactory for many immunoassays.; Integration of reagent mixing with diluted serum samples, immunological reaction and separation on-chip was also achieved. The ability to integrate these sample processing steps with separation on one monolithic device showed that the entire group of laboratory steps used in immunoassays can be integrated. No sacrifice is made through integration as the assay performance of the device is comparable to conventional instrumentation. Successful integration demonstrates the level of automation that can be achieved within such microdevices implying more rapid analysis times and a potential reduction in cost. |
