| In this thesis, an approach to fabricate epoxy and polystyrene microdevices with encapsulated tubing and electrodes is described. Key features of this approach include a fixed alignment between the fluidic tubing and electrodes, the ability to polish the device when desired, and the low dead volume nature of the fluidic interconnects. It is shown that a variety of tubing can be encapsulated with this approach with the resulting tubing/microchip interface not leading to significant band broadening or plug dilution. The applicability of the devices with embedded tubing is demonstrated by integrating several off-chip analytical methods to the microchip. This includes droplet transfer, droplet desegmentation, and microchip-based flow injection analysis. Off-chip generated droplets can be transferred to the microchip with no significant coalescence, while flow injection studies showed improved peak shape and sensitivity when compared to the use of fluidic interconnects with an appreciable dead volume.;Importantly, it is shown that the capillary and electrode embedding approach can be extended to enable the integration of more efficient electrophoretic separations with electrochemical detection. To extend the PDMS channel, a loop of fused silica capillary was embedded in polystyrene connecting two channels necessary for injection and detection coupling. Electrochemical detection was achieved with a platinum detection electrode and a palladium decoupler (for grounding the electrophoresis voltage). The coupling of electrophoresis with in-channel electrochemical detection allowed for successful detection of dopamine, thus demonstrating proposed functionality of the encapsulation method. Furthermore, it is shown that the encapsulation of capillaries and electrodes allowed for coupling to the mass spectrometer for separation and detection of a wide verity of analytes. The analysis of small molecules, such as caffeine and ornithine, was achieved by utilizing the embedded electrode (high voltage source) for nanospray ionization, to the system. In all cases, the tubing and electrodes are housed in a rigid base; this results in extremely robust devices that will be of interest to researchers wanting to develop microchips for use by non-experts. |
