Tamaki Yaji

LB film immobilized immunosensor with a charge detection type amplifier

Abstract In order to fabricate a miniturized solid-state sensor, a novel potentiometric immunosensor was designed by incorporating a new amplification system of charge detection type and an electrode covered with immunogloblin-G (IgG, antigen) immobilized in a Langmuir-Blodgett (LB) film. A surface potential change of 1 μV generated by the immuno-reaction between IgG and anti-IgG (antibody) could be measured with the amplification system, which made it possible to detect the anti-IgG with concentrations less than 5 x 10-8M. The intensity of surface potential change observed in the reaction was successfully correlated with the activity of the immobilized IgG by using luminescent enzyme immunoassay.

An Amperometric Sensor for Chemical Imaging Using Photoconductive Organic Film

We have developed an amperometric sensor employing a photoconductive organic thin film that enables the measurement of the two-dimensional distribution of redox current on a sensor surface. The sensor simply consists of photoconductive film and transparent electrode. A focused light beam through the transparent electrode excites the photoconductive film that leads to detect local redox current at the beam position. Intensity of the redox current depends on local concentration of redox species of solution on the sensor. We investigated several materials for the photoconductive film and found a suitable structure is Cu-phthalocyanine doped polyvinylcarbazole film/indium tin oxide/glass substrate. Compared with a conventional two-dimensional chemical sensor, our newly developed sensor can be prepared by lower cost fabrication methods without complex semiconductor processes. The sensor showed a good signal dependence on the concentration of K 3 Fe(CN) 6 /K 4 Fe(CN) 6 in an aqueous solution at 15.4 nA/dec at a constant bias voltage of 0.8 V. We measured the two-dimensional distribution of ions in an agarose gel of 2 mm thickness. The result showed a photograph of the diffusion process of redox species. We also discuss the discrimination of redox species like voltammetry.

Electrically controllable optical attenuator with high deposition rate IrOxitx film

Abstract An electrically controllable optical attenuator was constructed with a solid type electrochromic (EC) device consisting of an “iridium oxide (IrO x )/ion conductive polymer film (PSSA)/WO 3 ” structure. A sputtered iridium oxide film (SIROF) was successfully applied as the EC material to get a uniform absorption change in a wide range of wavelengths (350–1500 nm). It was also shown that a low temperature deposition technique makes it possible to achieve a high depostion rate for the SIROF as well as improved transparency in the bleached state.