ACTIVE OPTICAL THIN-FILM WAVE-GUIDE SENSOR FOR ION SENSING

In this paper, an active PVC optical thin-film waveguide sensor is pro posed which can select a specific ion and measure its concentration. T he waveguide was fabricated using the plasticized poly(vinyl chloride) (PVC), bis ethyl hexyl phthalate (BEHP), lipophilic anionic dye (LAD- 3), and ionophores (K23E1 for calcium, or C14DD16C5 for sodium) in whi ch the PVC membrane plays important roles for both incident light prop agation and selective ion sensing. In order to investigate the applica bility of this sensor to Ca2+ and Na+ measurement, the sensor was appl ied to sample solutions whose CaCl2 concentration was gradually altere d. Also, we applied it to a NaCl solution. In this experiment, we foun d that this PVC thin-film waveguide possessed good light propagation f or argon laser light at 488 nm. Also, the comparison of the experiment al responses between the active waveguide sensor and a commonly utiliz ed waveguide sensor (evanescent waveguide spectrometry), indicated tha t the sensitivity of the active waveguide sensor is obviously higher t han that of the conventional waveguide sensor. These findings suggeste d that the proposed PVC waveguide ion sensor is applicable to the dete rmination of various ions with high sensitivity.