Accueil du site Séminaires Séminaire QUEST

Séminaire QUEST

Jeudi 14 septembre à 9h30,
Salle Louis Weil, K223

Orateur : Toshihiko Kiwa (Okayama University, JAPAN)
"Laser excitation technique for bio-sensing"


We have developed various types of sensing systems and devices, including terahertz systems, SQUIDsystems, and electrochemical sensors.
In this talk, our recent results on the two topics related to bio-sensing ; laser-excited terahertz systems and SQUID magnetic particle imaging systems, will be presented.

A terahertz chemical microscopy
Chemical sensing of the water solution with the small amount of volume is important in terms of low-invasive medical diagnosis. In our group, a terahertz chemical microscopy (TCM) based on the laser-excited terahertz technology [1] has been proposed and developed to visualize the distribution of the antibody-antigen bindings on the silicon based sensing plate without any labels on the antibody. The sensing plate can radiate the terahertz pulses by femtosecond laser and the amplitude of the detected terahertz pulses can be related to the chemical or electric potential of the sensing plate surface at where the laser pulses are irradiated. Thus, the potential distribution related to the antibody-antigen bindings can be visualized as the map of the terahertz pulses amplitude [2-4]. Because the sensing area can be limited to the irradiation area of femtosecond laser, a small amount of sample solution is required for this technique.
In this presentation, chemical sensing and imaging of the solution samples as well as pH sensing of small amount of water droplet is demonstrated. Also, as one of our recent results, a THz time-of-flight measurement of penetration speeds of cosmetic liquids into the skin are introduced.

Laser-Assisted Magnetic nanoParticle Imaging
Magnetic nanoparticle imaging (MPI) has been studied as one of useful options of non-invasive medical diagnosis. MPI generally applied the magnetic field to the magnetic nanoparticles and the magnetic field distributions generated by the magnetized nanoparticles are observed. Therefore, the spatial resolution of this type of imaging was decreased as increasing the distance between the magnetic sensors and the nanoparticles. In our group, a Laser-Assisted Magnetic nanoParticle Imaging (LAMP) system with high-Tc SQUID has been proposed to visualize the nanoparticles distribution with the spatial resolution of higher than 1 mm [5].
LAMP system utilized the magneto susceptmeter [6] with laser scanning system to illuminate the nanoparticle. When laser hits the nanoparticles, the susceptivity of nanoparticles changes mainly due to heating effects. Because the susceptivity changes exactly when laser hit the nanoparticles, the LAMP system can map the position of nanoparticles by measuring changes in the susceptivity of nanoparticles as a function of two-dimensional position of laser focus.

1.T. Kiwa, M. Tonouchi, M. Yamashita, and K. Kawase, Opt. Lett. 28, 2058 (2003).
2.T. Kiwa, J. Kondo, S. Oka, I. Kawayama, H. Yamada, M. Tonouchi, and K. Tsukada, Appl. Opt., 47 [18], 3324 (2008).
3.T. Kiwa, T. Hagiwara, M. Shinomiya, K. Sakai, and K. Tsukada, Opt. Express 20, 11637 (2012).
4.T. Kiwa, T. Akira, T. Shinji, S. Kenji, and K. Tsukada, Sens. Act. B : Chem., 187, 8 (2013).
5.MM Saari, et al., J. Appl. Phys.117 (17), 17B321, 2015
6.T. Kiwa, et al., IEEE Trans. ASC, in press.

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