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This paper describes the development of a prototype fluid pumping system for incorporation into a miniaturized flow injection analyzer. The strategy couples the well-established capabilities of reagent-based flow injection analyses (FIA) with our novel concepts for the design of a miniaturized, low-power pumping system, i.e., an electrochemically-driven micropump. The basis of pump actuation relies on the electrochemically-induced surface tension changes at the electrolyte/mercury interface, resulting in a “piston-like” pumping process devoid of mechanically moving parts. We present herein the results from the preliminary performance tests of a miniaturized fluid flow system with the micropump. As described, the flow rates and pumping displacement volumes have been studied as a function of the amplitude and the frequency of the applied voltage waveform.

This paper describes the development of a thin-film optical sensor for measuring pH. The indicator behaves as a polyprotic acid with differing optical properties in each of its chemical forms. Together, these properties facilitate the development of an internally calibrated sensor by calculating the ratios of the absorption maximas for each form of the indicator. The covalent immobilization procedure developed demonstrated long term stability of 4 months without recalibration.

This paper focuses on the design, construction, preliminary testing, and potential applications of three forms of miniaturized analytical instrumentation. The first is an optical fiber instrument for monitoring pH and other cations in aqueous solutions. The instrument couples chemically selective indicators that have been immobilized at porous polymeric films with a hardware package that provides the excitation light source, required optical components, and detection and data processing hardware. The second is a new form of a piezoelectric mass sensor. The sensor was fabricated by the deposition of a thin (5.5 μm) film of piezoelectric aluminum nitride (AlN). The completed deposition process yields a thin film resonator (TFR) that is shaped as a 400 μm square and supports a standing bulk acoustic wave in a longitudinal mode at frequencies of ∼1 GHz.