A piezoelectric quartz crystal sensor for the determination of coagulation time in plasma and whole blood.

A Peizoelectric Quartz Crystal (PQC) system possessing an adequate sensitivity to a slight viscosity change is employed to monitor the blood coagulation. In the case of an anticoagulated plasma specimen, prothrombin time (PT) was determined by the PQC sensor on the basis of the introduction of tissue thromboplastin (TF) and calcium ion. Discussing the PQC data statistically, we found that at 90% of the total frequency shift (delta f) the best linear relationship in a double-logarithmic plot of PT versus TF concentration in the range of 5.466-22.311 unit/ml is shown. The PQC result was compared with commercial optical coagulometry and showed a good linear correlation (ca. 0.98). The clotting and recalcification of whole blood were also studied by the PQC system. The testing time for one measurement could be completed within 20 min. and had a good agreement with that obtained conventionally.