Measurement of characteristic frequency of red blood cells and thrombogenic process for various hematocrit values using dielectric relaxation method

Abstract

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.

Keywords

• dielectric relaxation method
• relaxation frequency
• thrombus formation
• red blood cell
• artificial heart