Recently we developed a damped oscillation type rheometer. This rheometer consists of a cylindrical tube filled with blood, suspended from a torsion wire. The tube is excited in torsional oscillation and subsequent damped osillation is observed. From damped oscillation curves measured at a certain interval, the change of logarithmic damping factor of blood during coagulation is measured.
Characteristics of the apparatus are follows; 1) the sensitivity is very high, that is, the detectable lowest value of viscosity is as low as 0.5 centi-poise and 2) the tube can be exchanged for one made of a different material with diffrent size. Therefore, it is expected that the apparatus is available for clinical test of blood coagulation and for in vitro evaluation of anti-coagulability and/or anti-thrombogenecity of artificial materials.
In this paper, to determine a tube material suitable for clinical uses, the change of logarithmic damping factor during coagulation for blood is compared among different kinds of tube material. It is concluded that the glass is one of the best material for the measuring cell in the present apparatus since it is possible to measure the whole coagulation prorecess including the initial stage and clot retraction in the glass tube. Also, analytical method of experimental data to evaluate anti-thrombogenecity or anti-coagulability of materials is descussed.
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