Kimihiro Adachi

A novel fiber-optic gas-sensing configuration using extremely curved optical fibers and an attempt for optical humidity detection

Abstract A novel configuration for optochemical sensors is proposed using a single optical fiber which is extremely curved at an angle of 180° and turned back. Although the curvature of optical fiber caused some loss in the transmission of the incident light, this loss was not very large. To examine the utility of a sensor head using the curved fiber, all or part of the curved region was coated with a Rhodamine B/hydroxypropyl cellulose humidity sensing film instead of the normal cladding. When the curved fiber was used instead of a straight fiber, the modulation of the incident light by the sensing film was dramatically enhanced, and the change with humidity in the transmission of the incident light through the sensor became much larger. The light signal of the humidity sensor using the curved fiber exhibited a short response time, a high reproducibility, and a smooth dependence on humidity with little hysteresis effect in a wide humidity range.

Effect of the Chaotropic Nature of Supporting Electrolytes on the Electrochemical Properties of Conducting Polymers: A Study Using an In-Situ/Real Time Technique

Abstract The elfed of the naiure of the cation employed in the electrolyte during electrochemical switching of conducting polymers has been explored. It has been found that the nature of the cation, while not obvious in cyclic voltammetry, has a marked effect on the changes in resistance and mass that occur within the polymer upon reduction/oxidation. We suggest that the chaotropic nature of the salts employed be considered in interpreting results concerned with the “salt effect” on the properties of conducting polymers.

Effect of humidity on the dynamic fluorescence properties of aminonaphthalenesulphonate derivatives in a hydrophilic polymer film

Abstract The fluorescence lifetimes and time-resolved fluorescence spectra of 5-dimethylamino-1-naphthalenesuphonic acid (DNSA), 5-dimethylamino-1-naphthalenesuphonamide (DNSM) and 8-anilino-1-naphthalenesuphonic acid (ANSA) were investigated in hydroxypropyl cellulose film under varying ambient relative humidity (RH). The fluorescence lifetime obtained by assuming a single exponential decay increased with RH for DNSA and DNSM but decreased for ANSA. The fluorescence decays gave much better fits to dual exponential kinetics. The dependence of the lifetimes and fractional contributions of the two components on the RH was in fair agreement with the results obtained by single exponential analysis. The maxima of the time-resolved spectra of the fluorophores shifted to a lower energy with an increase in time and RH. The rate constant of the spectral shift was determined by fitting the data to a single exponential equation, and increased with increasing RH.

Dynamic polymeric electrodes, dynamic computer modeling and dynamic electrochemical sensing

Three techniques, namely cyclic voltammetry, cyclic resistometry, and cyclic gramometry (EQCM) have been used simultaneously to investigate the nature of the anion/cation inclusion/exclusion process occurring at a polypyrrole chloride modified electrode. This online/real time study confirms that the redox reaction is a dynamic process that results in time dependent signals when a polymeric sensor is utilized. Although the use of cyclic voltammetry does not show distinct cation/anion responses clearly the other two techniques used enable distinct cation and anion responses to be observed. The collected data were saved into several files and introduced to a powerful computer as test and training files. Later the output prediction process was carried out.

Polymer surfaces, interfaces, and computer modeling: an investigation of smart conducting polymer sensors

The discovery of new sensing materials and electrodes has greatly expanded the range of scientific methods including electrochemical techniques. Conducting polymer such as polypyrrole and polyaniline represent a new class of organic polymers that are capable of molecular interactions and being able to interact, chemically or electrochemically, with the species of interest for detection. Although these conductive materials have unique properties they have their specific problems with respect to their reproducibility and reusability. Problems exist due to the dynamic nature of these polymers thereby mitigating against their successful applications as novel sensors. This has also hindered the production of analytical useful, sensitive, and reversible signals using these polymers. This paper has sought to examine the problems due to the lack of useful analytical, sensitive, reversible and reusable signals through the introduction of new series of integrated artificial intelligence/conducting polymer based sensors. In these types of sensors analytical responses, which look irreversible and nonreproducible, are combined by an artificial intelligence trained computer by which reproducible output can be predicted based on the created model and pattern by the computerized system.