In recent years, as biological information analysis technology rapidly develops in hematology, biochemistry and microbiology areas, demand for portable measurement systems become more and more important. This study makes efforts in developing disposable hydrogen and potassium ion sensor and microsystem for analysis application. The measured ion concentration data by this analysis microsystem provide people a judgement on their health condition, and furthermore an important reference for medical treatment for patients. There are several advantages in using IC or MEMS technology to manufacture portable measurement system, the advantages are down-scaling, short reaction time, trace chemical analysis, low power dissipation, and low cost. So the thesis uses extended gate field effect transistor, in order to measure multiple ions at the same time, multiple transistors are manufactured on the same chip with an ion selective membrane on top of the gate sensitive layer. This allows the measurement result of the multiple ion be shown at the same time. The main processing steps of the ion sensor developed in this study involve at least four photolithographic and three thin-film deposition processes. Based on the measurement result, the hydrogen ion sensor¡¦s sensitivity is 30.7 mV/decade for a sensing range pH1 ~ pH13. The sensitivity of the potassium ion sensor is 11.5 mV/decade for a sensing range 10-1M to 10-3M.

In this study we have investigated the frequency dependence of bilayer lipid membranes for a series of glycerylmonoolein/ n-decane bilayers in various aqueous ionic solutions containing the ionophore valinomycin. Reliable values of membrane capacitance and conductance were obtained over the frequency range 0.2 - 200 KHz using an automatic balancing bridge under the control of a microprocessor unit. The admittance data was then normalized and curve-fitted to produce relaxation times and amplitudes from which the kinetic rate parameters, as deduced from a single slab dielectric membrane model, were calculated. These ac experimental rate constants were then compared with those obtained from charge-pulse relaxation methods.

A series of bicyclic peptides have been designed and synthesized to provide ammonium ion complexation sites via hydrogen bonding in a tetrahedral geometry. Molecular modeling dynamics and electrostatics studies indicate that target compounds 1d-6d may provide better selectivity for ammonium ions over potassium ions than the ammonium ionophore currently used for blood analysis applications, nonactin. Attempts to synthesize 1d, cyclo(L-Glu1�D-Val2�L-Ala3�D-Lys4�D-Val5�L-Val6)-cyclo-(1ã-4å), were unsuccessful due to poor solubility of the synthetic intermediates. This led to the design of 2d-6d in which specific amino acid residues were chosen to provide higher solubility. Compound 2d, cyclo(L-Glu1�D-Ala2�D-Ala3�L-Lys4�D-Ala5�L-Ala6)-cyclo-(1ã-4å), was successfully synthesized, but was also too insoluble for characterization or testing in an ion selective electrode (ISE) sensor format. Compound 6d, cyclo(L-Glu1�D-Leu2�Aib3�L-Lys4�D-Leu5�D-Ala6)-cyclo-(1ã-4å), was successfully synthesized and characterized. When 6d was incorporated into an ISE sensor and tested as an ammonium ionophore, results indicated that the bicyclic peptide lacked solubility in the ISE membrane. A 13C-NMR study has been initiated in order to evaluate selectivity of 6d for ammonium over potassium and sodium cations in solution. Preliminary results with the potassium ionophore valinomycin as a control have been completed.

Membrane transport processes underlie many purification technologies. The efficiency of a membrane separation process depends upon material throughput (flux), and the degree to which the membrane discriminates amongst species in the feed stock (selectivity). In a supported liquid membrane, flux may be enhanced by carrier molecules, which act as catalysts of translocation. Carrier molecules also confer selectivity, via differential molecular recognition of the substances in the feed stock. The effect of electrical potential on the flux and selectivity of carrier-containing supported liquid membranes is not well documented. We elected to study the effect of electrical potential on supported liquid membranes containing valinomycin, a potassium ionophore, and a calixarene ester, a sodium ionophore. In these systems, the open circuit membrane potential could be made positive or negative by the choice of anion. With both of these carriers, we observed that selectivity for potassium or sodium salts was dependent on the open circuit membrane potential. To confirm that electrical potential was responsible for the observed selectivity variance, we applied a potential across the membrane using a potentiostat. The applied potential created conditions for carrier-mediated electrodialysis, where oxidation and reduction reactions on either side of the membrane act as the driving force for transmembrane flux of charged species. In chronoamperometry experiments, we found that selectivity for potassium or sodium ion was dependent on the applied electrical potential. Subject to some constraints, selectivity and flux could be controlled by the application of positive or negative electrical potentials. Linear sweep voltammetry experiments allowed for the rapid prediction of the potential that must be applied to achieve optimal selectivity. We also found that membrane potential measurements, as well as the magnitude of current that flows in chronoamperometry experiments, could be interpreted to predict Eisenman and Hofmeister sequences. These results are novel, and await a convincing theoretical justification. The results also suggest that a separation technology could be developed around the idea of modulating selectivity with electrical potential. In this regard, carrier-mediated electrodialysis may be suitable for the sequestration of toxic or radioactive heavy metals, and a large number of carrier molecules for metal ions are currently known. The technique may also be suitable for separating organic molecules, such as high-value chiral pharmaceuticals. Supported liquid membranes are a useful research tool, but industrial applications may require a more stable membrane architecture. / Graduate