The effect of blood adhesion on the amplitude-frequency characteristics of a piezoelectric sensor in the method of low-frequency piezothromboelastography is studied. As a result of adhesion, a layer of blood cells can accumulate on the surface of the resonator needle immersed in blood, which changes its configuration and mass and, as a consequence, its amplitude-frequency characteristics. Experiments showed that during coagulation, the free frequency of the resonator needle oscillations decreases in direct proportion to the increase in the mass of adhered blood. To confirm this regularity, we carried out a numerical experiment on the basis of 3D-mathematical model of a piezoelectric sensor used in the piezotromboelastograph ARP-01M Mednord. The experiment was performed with the help of the COMSOL Multiphysics® 4.2 software package and the finite element method. We calculated the change in the free frequency of the resonator needle oscillations as a function of the adhered blood mass and their time dependence in the blood coagulation process. It is shown that during coagulation, the mass of adhered blood increases starting from the third minute and reaches its maximum of 0.42 milligram in 15 minutes, which leads to a noticeable shift in the resonance frequency of the piezoelectric sensor towards lower frequencies.

研究了低频压电血栓弹力描记法中血液粘附对压电传感器幅频特性的影响。由于粘附，血细胞层可积累在浸没在血液中的谐振器针的表面上，这改变了它的构型和质量，并因此改变了它的幅频特性。实验表明，在凝结过程中，谐振器针振动的自由频率与所附着的血液质量的增加成正比地降低。为了确认这种规律性，我们在压电伸缩弹力图ARP-01M Mednord中使用的压电传感器的3D数学模型的基础上进行了数值实验。实验是在COMSOLMultiphysics®4的帮助下进行的。2软件包和有限元方法。我们计算了共振器针振荡的自由频率的变化与所粘附的血液质量及其在血液凝固过程中的时间依赖性的关系。结果表明，在凝结过程中，粘附的血液质量从第三分钟开始增加，并在15分钟内达到最大值0.42毫克，这导致压电传感器的共振频率朝着较低的频率明显偏移。