生物组织热导率的脉冲-衰减法测量

Measurement of the tissue thermal conductivity by thermal pulse-decay method

采用脉冲-衰减法测量生物组织的热导率,通过合理设计测量电路、选择电路参数,可以使脉冲输入期间探头输入功率的变化小于1%.当测量工况变化时,探头输入功率会产生较大变化,为此,提出了改进的脉冲衰减法.采用本方法,还可以适当提高脉冲输入期间探头的输入功率以增加探头温升,从而减少探头输入功率测量误差以及温度测量段温度测量误差的影响,提高热导率的测量精度.测量结果表明,由于脉冲-衰减法在推导时没有考虑探头尺寸的影响,造成热导率的测量值偏大;为此,进一步给出了一种热导率的测量值的简单修正方法,经修正后的热导率的最大误差为4.25%,平均误差为2.05%.

The thermal pulse-decay method was used to measure the tissue thermal conductivity. The change of the probe bead supplied power can be less then 1% by properly designing the measurement of circuit and the selection of circuit parameters. When the measurement condition was changed, the probe bead supplied power would be changed greatly. An improved thermal pulse-decay method was presented to solve this problem. By using it, the probe bead supplied power can also be increased to raise the probe bead temperature. Thus the errors in the measured probe bead supplied power and the bead temperature can be reduced, and the measurement precision of the thermal conductivity can be enhanced. The measurement results showed that the measured tissue thermal conductivity was consistently larger than the corresponding standard value, and a simple corrected method was given to di- minish the measured error in the tissue thermal conductivity. After the correction, the maximum error of the measured thermal conductivity was 4.25%, and its average error was 2.05%.