High Pressure Open Channel Electroosmotic Pump

The objective of lab-on-chip (LOC) or -TAS is to integrate and perform multiple analytical processes (e.g. sample pretreatment, solution distribution/mixing, separation, detection, etc.) on a microchip platform. So far, most LOC research has been focused on electrophoretic separations. Little has been done on multi-process integration, due mainly to the lack of a robust and miniaturized pump that can deliver constant flow and be integrated with LOC devices. Microchip HPLC can and will play an important role in point-of-care measurements, remote sensing and chemical and biological warfare agent detections. Highly parallel configurtaions can enhance the sample throughput considerably with commensurate impact on drug screening and biomarker discovery. Microchip HPLC combined with emerging small footprint mass spectrometers can vastly accelerate proteomic research and reduce present costs greatly. A major challenge toward microchip HPLC is the lack of a robust and miniature high-pressure pump that can be integrated with LOC devices. The goal of this project is to address this issue. Among the various micropumps developed, electroosmotic (EO) or electrokinetic (EK) pumps are one of the most promising alternatives for -TAS applications. The first electroosmotic pump (EOP) was constructed using a silica bead packed column in 1974, and it generated moderate pumping pressures (~600 psi). Since then, progress has been made on packed-column EOPs. Pumping pressures of as high as 8000 psi have been reported, and HPLC separations have been carried out using these pumps. However, electrical connections are problematic, causing pump solution leakage and/or bubble formation. Additionally, packed column pumps require frits which lead to large pressure/voltage drop, production irreproducibility and bubble formation. Column packing is tedious and challenging, especially on-chip. Frit incorporation and column packing are incompatible with LOC device fabrication. Since the early 1990s, open capillaries/channels and, more recently, monoliths have been utilized to build EOPs. These fritless designs and their productions are compatible with LOCm devices. Unfortunately, so far they have generated only & lt;100 psi pumping pressures and bubbleless electrical connections are difficult to achieve. We propose to develop a serially-connected EOP to solve the above problem. The major innovative component of this proposal is a serially-connected pump with alternately-arranged + and - pumps, able to generate flow rates of up to 1 L/min at pressures of up to 1000 psi for microchip HPLC applications. A bubbleless electrode (another major innovative component) will also be integrated with the EOP to enalbe us to apply high voltages onto EOPs while prevent pump solutions from leaking out. In addition, it will minimize the change in pump solution composition and eliminate electrolytic bubble formation in the pump channels. In Phase II, we will develop a miniaturized microchip HPLC system that integrates a serially-connected EOP, an on-chip smaple injection valve, and a monolith separation column for chemical and biochemical separations.Specific Aim 1. Develop a serially-connected EOP that consists of alternately-arranged +and - EOPs and bubbleless electrodes. All components may be on a single chip or several chips that are stacked together. The pump will be capable of producing flow rates of up to 1 L/min and pressures of up to 1000 psi. These targets will be examined/validated using a nanoflow HPLC pump.