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Dielectric relaxation method has been proposed for the possibility of real-time detection of thrombosis by exploiting the electrical properties of the blood. In-vitro experiments were conducted with bovine blood to measure relative permittivity and dielectric loss in the case of various hematocrit values under static blood condition. As a result, the relaxation frequency of the electrode and red blood cells were observed at 20 kHz and 2 MHz respectively. The characteristics frequency showing the permittivity of the red blood cells membrane was in the range of 60 kHz to 1 MHz. The time variations of resistivity and relative permittivity were observed at this frequency range of characteristics frequency of red blood cell membrane. Resistivity and relative permittivity measured at this frequency range increased in the case of the increase in the hematocrit values. Additionally, a peak was observed in the temporal change in relative permittivity only in the case of that frequency range. Moreover, from the results of visual check of thrombosis, this peak indicated the start of the micro-thrombus formation. This phenomenon was specific to the thrombosis, and was observed only in the presence of red blood cells. The experiments showed the possibility of the real time detection of thrombosis for implantable ventricular assistance devices, heart-lung machines and artificial kidney. : Dielectric relaxation method, Relaxation frequency, Thrombus formation, Red blood cell, Artificial heart 1. 緒 言 現在,体内植込み型補助人工心臓をはじめとして,人工心肺,人工腎臓などの人工臓器が開発され,実用化に 至っている(Yamane, 2000).しかしながら,その実用化において血栓の形成が最大の問題点となっており,従来ま で,血栓形成のセンシングとシミュレーションに関する研究が多くなされている.例えば,光を用いたセンシン グ技術では,玉川らは,CFD(Computational Fluid Dynamics)を用いて活性化したフィブリノーゲンによる血栓生成 予測のシミュレーション(Tamagawa, et al. 2009)を行い,レーザの散乱光量を用いて,血栓濃度分布を計測し,せ 誘電緩和法によるヘマトクリットをパラメータとした赤血球の特性周波数と 血栓形成過程の計測 朝倉 悠太,サプコタ アチュタ,丸山 修 小阪 亮,山根 隆志,武居 昌宏 Measurement of characteristic frequency of red blood cells and thrombogenic process for various hematocrit values using dielectric relaxation method Yuta ASAKURA, Achyut SAPKOTA, Osamu MARUYAMA Ryo KOSAKA, Takashi YAMANE and Masahiro TAKEI *1,*2 Division of Artificial Systems Science, Graduate Course of Mechanical Engineering, Chiba University 1-33 Yayoi, Inage-ku, Chiba 263-8522, Japan *3 National Institute of Advanced Industrial Science and Technology 1-2-1 Namiki, Tsukuba-shi, Ibaraki 305-8564, Japan *4 Department of Mechanical Engineering, Graduate school of Engineering, Kobe University Received 20 January 2014