研究者詳細 - 紀和　利彦

Chemical sensing plate with a laser-terahertz monitoring system. 国際誌

Toshihiko Kiwa, Junichi Kondo, Shohei Oka, Iwao Kawayama, Hironobu Yamada, Masayoshi Tonouchi, Keiji Tsukada

Applied optics 47 ( 18 ) 3324 - 7 2008年6月

記述言語：英語出版者・発行元：OPTICAL SOC AMER

A new type of laser-terahertz emission system for noncontact investigations of chemical solutions has been developed. The system monitors terahertz emission from a sensing plate, which consists of silicon oxide and silicon thin film layers on a sapphire substrate. Sensing of chemical solutions with pH values between 1.68 and 10.01 was demonstrated. The amplitude of the terahertz emission from the sensing plate increased with increasing pH value. This change in the amplitude was caused by a change in the depletion layers of the silicon thin film when protons were adsorbed on the surface of the sensing plate. This study demonstrates that full noncontact monitoring of chemical solutions is possible using the laser-terahertz emission system.

DOI： 10.1364/AO.47.003324

Magnetic measurement of the moisture content in soil: Diamagnetic measurement with the presence of ferromagnetic material

Keiji Tsukada, Yasutaka Masuda, Yudai Ishihara, Toshihiko Kiwa

Applied Physics Express 1 ( 6 ) 0670081 - 0670083 2008年6月

記述言語：英語出版者・発行元：JAPAN SOC APPLIED PHYSICS

To measure the moisture content of soil, we developed a method that measures the magnetic field generated when the primary magnetic field Is exposed. Soil contains two different types of materials: water as a diamagnetic material and Iron sand as a ferromagnetic material. Water shows a constant phase shift from the primary magnetic field as well as a frequency dependence of the magnetic field strength, and iron sand showed the opposite characteristics. Using these magnetic properties, a moisture content signal was extracted, even with Interference of the iron sand. © 2008 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.1.067008

Magneto-electrical cyclic voltammetry for visualization of current distribution in the electrolyte

K. Tsukada, F. Kobayashi, H. Arai, T. Kiwa

Electrochemistry Communications 10 ( 6 ) 938 - 942 2008年6月

記述言語：英語出版者・発行元：ELSEVIER SCIENCE INC

Cyclic voltammetry is widely used in electrochemistry. To visualize the current distribution in the electrolyte, we developed a two-dimensional magnetic imaging system, combining the electric measurement component used in conventional cyclic voltammetry with a pair of MR (magnetic resistive) sensors to detect the x- and y-magnetic components. The resulting system allows simultaneous measurement of the electronic current of the working electrode and the magnetic field resulting from the transport of ions by migration in the bulk electrolyte. The current distribution in the electrolyte was reconstructed using the magnetic field strength data obtained at multiple points. Consequently, we could observe the change in current distribution when changing the length of the working electrode immersed in the electrolyte. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.elecom.2008.04.020

Difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing

Hironobu Yamada, Teruki Hasegawa, Yudai Ishihara, Toshihiko Kiwa, Keiji Tsukada

NDT and E International 41 ( 2 ) 108 - 111 2008年3月

記述言語：英語出版者・発行元：ELSEVIER SCI LTD

We examined the difference in the detection limits of flaws in the depths of multi-layered and continuous aluminum plates using low-frequency eddy current testing. The detection limits were measured by using a magneto-resistive sensor. Comparing the frequency of an applied magnetic field, the detection limit at 50 Hz is deeper than that at 1 kHz. Comparing the sample structure, the detection limit in the multi-layered samples is deeper than that in the continuous samples. These results are likely due to the differences in the skin depth and conductivity of the sample. © 2007 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ndteint.2007.08.004

Detection of the weak magnetic properties change of stainless-steel welding parts by low frequency magnetic imaging

Takayuki Hayashi, Hironobu Yamada, Toshihiko Kiwa, Keiji Tsukada, Masaji Tamazumi

Journal of Applied Physics 103 ( 7 ) 07E923 2008年

記述言語：英語出版者・発行元：AMER INST PHYSICS

Differences in weld quality resulting from variations in welding conditions were detected via low frequency magnetic imaging. This magnetic imaging was obtained using a recently developed measurement system, consisting of an exposure coil, a magnetoresistive (MR) sensor, and a lock-in amplifier. A wide area of stainless-steel sample was exposed to the magnetic field via an induction coil, and the MR sensor measured the generated magnetic field from the sample. The frequency of the magnetic field ranged from 20 Hz to 1 kHz. A cylindrical stainless-steel sample was fabricated by rolling a stainless-steel sheet and welding each edge by an arc welder with argon gas, while the welding condition was changed by controlling the argon gas flow. The magnitude and phase shift of the generated magnetic field from the sample was measured by scanning the MR sensor on the sample surface. The change in magnetic properties caused by the welding condition change was successfully imaged. © 2008 American Institute of Physics.

DOI： 10.1063/1.2837628

Redox reactions of enzymes measured by terahertz chemical microscope

Toshihiko Kiwa, Jyunichi Kondo, Iwo Kawayama, Masayoshi Tonouchi, Keiji Tsukada

33rd International Conference on Infrared and Millimeter Waves and the 16th International Conference on Terahertz Electronics, 2008, IRMMW-THz 2008 594 - + 2008年

記述言語：英語出版者・発行元：IEEE

A terahertz chemical microscope (TCM) was proposed and developed to measure redox reaction of enzymes. TCM utilize the sensing plate which can measure the surface potential changes at the laser illuminated area by detecting the terahertz waves generated from the plate. An immobilized urease was applied to the plate and the redox reaction with the urea in the buffer solution was demonstrated. @IEEE.

DOI： 10.1109/ICIMW.2008.4665724