The development of chemical microinstrumentation is a rapidly expanding field. The interest of this laboratory is in the application of micromachining and microfabrication technology to chemical and biochemical sensors and to instrumentation. New semiconductor fabrication methods can be adapted to the design and fabrication of three dimensional structures, which may be used as chemical sensors. Microfluidic devices, capable of sample pretreatment, reaction and separation all integrated onto a single microchip are a new development arising from this technology. We refer to these devices as a lab-on-a-chip, and they are the focus of much of our present work.
The lab-on-a-chip is based on microfabricated flow channels etched into glass or silicon substrates. We can perform capillary electrophoresis within these channels, to provide a powerful integrated separation technique. We use the phenomenon of electroosmotic flow as a pumping mechanism, allowing for fluid transport within the chip, without a need for pumps or even valves, as the fluid follows the path of the electric field. Consequently, we can integrate both flow injection analysis methods for sample processing with separation methods. Rections such as enzyme digestions of proteins or DNA can be performed on-chip, followed by separation of the products. We have even begun to transport, manipulate and process biological cells as part of an effort to develop a complete biosample processing and analysis system on a microchip scale. Students working on these projects gain expertise in microfabrication, bioanalytical chemistry, separation science and fluid mechanics, as well as the computer and electronic control techniques needed to operate the chips.
We also have an extensive program investigating integrated ion and biosensors based on electrochemical detection. This research involves the development of new polymers for microfabricated sensors, and the study of their critical role in sensor stability and performance. Fundamental studies of transport within polymers, synthesis of new materials and applications of the sensors in biochemical and clinical environments represent some of the work we have ongoing.
This cartoon illustrates the concept of a lab-on-a-chip. The object shown consists of capillary fluid paths etched into a glass substrate using integrated circuit micromachining techniques. A sample is introduced to the chip, then mixed with reagents and buffers, reacted to form products, then mobilized to a separation unit for analysis, integrated on the same wafer.