Abstract-Evaluation of Bio-materials Using a Laser-excited Terahertz Wave

Toshihiko Kiwa, Tatsuki Kamiya, Masahiro Iida, Hirofumi Inoue, Kenji Sakai, Shinichi Toyooka, Keiji Tsukada,

https://www.jstage.jst.go.jp/article/jslsm/39/4/39_jslsm-39_0031/_article/-char/en

We have developed various types of terahertz sensing systems for evaluation of bio-related materials. Here, we describe a terahertz chemical microscopy that we have invented and demonstrate a label-free immune assay and evaluation of penetration speed of cosmetic liquid, each of which was realized using different way of use of the terahertz chemical microscopy.

Abstract-pH measurements in 16-nL-volume solutions using terahertz chemical microscopy

Toshihiko Kiwa, Tatsuki Kamiya, Taiga Morimoto, Kenji Sakai, and Keiji Tsukada

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-26-7-8232

Terahertz chemical microscopy has been developed for measuring the pH of a solution using only a small volume. The microsolution wells were fabricated on the surface of the sensing plate using a conventional photolithograph technique. Because the pH value can be calculated from the amplitude of a terahertz wave directly radiated from a sensing plate by a femtosecond laser irradiation, this method does not require any reference electrode in the solution. Thus, pH measurement can be achieved with a volume as small as 16 nL.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Stabilization method for signal drifts in terahertz chemical microscopy

Toshihiko Kiwa, Kenji Sakai, and Keiji Tsukada 
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http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-2-1330

A stabilization method for signal drifts in terahertz chemical microscopy (TCM) due to unexpected chemical potential changes in sample solutions was proposed and developed. The sensing plate was separated into two areas: a detection area and a control area. The detection area radiated a THz pulse whose amplitude was related to both the chemical reactions in the sample solutions and unexpected potential changes. The THz pulse from the control area was related only to unexpected potential changes. In the proposed system, the THz pulse from each area was interfered and detected. By adjusting the timing of the positive peak of the THz pulse from the detection area and the negative peak of the THz pulse from the control area, we detected the difference in both peaks as the interference signal. Thus, the signal deviation of 390 when the environmental condition changes in the temperature range of 38 °C and the pH range of 8.33 was stabilized to be the signal deviation of 31. As the result, the TCM with stabilization method could detect the signal shift of 121 when the 275-nmol/L immunoglobulin G was immobilized on the sensing plate.

© 2014 Optical Society of America