Open-ended coaxial probes are widely used to gather dielectric properties of biological tissues. Due to the lack of an agreed data acquisition protocol, several environmental conditions can cause inaccuracies when comparing dielectric data. In this work, the effect of a different measurement probe-to-tissue contact pressure was monitored in the frequency range from 0.5 to 20 GHz. Therefore, we constructed a controlled lifting platform with an integrated pressure sensor to exert a constant pressure on the tissue sample during the dielectric measurement. In the pressure range from 7.74 kPa to 77.4 kPa, we observed a linear correlation of - 0 . 31 ± 0 . 09 % and - 0 . 32 ± 0 . 14 % per kPa for, respectively, the relative real and imaginary complex permittivity. These values are statistically significant compared with the reported measurement uncertainty. Following the literature in different biology-related disciplines regarding pressure-induced variability in measurements, we hypothesize that these changes originate from squeezing out the interstitial and extracellular fluid. This process locally increases the concentration of membranes, cellular organelles, and proteins in the sensed volume. Finally, we suggest moving towards a standardized probe-to-tissue contact pressure, since the literature has already demonstrated that reprobing at the same pressure can produce repeatable data within a 1% uncertainty interval.

中文翻译：

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开放式同轴探针与组织的接触压力对介电测量的影响。

开放式同轴探针被广泛用于收集生物组织的介电特性。由于缺少约定的数据采集协议，在比较电介质数据时，几种环境条件可能会导致不准确。在这项工作中，在0.5至20 GHz的频率范围内监测了不同的测量探针与组织的接触压力的影响。因此，我们构建了带有集成压力传感器的受控升降平台，以便在电介质测量过程中对组织样本施加恒定压力。在7.74 kPa至77.4 kPa的压力范围内，我们观察到-0的线性关系。31±0。09％和-0。32±0。相对实电容和虚电容的相对介电常数分别为每kPa 14％。与报告的测量不确定度相比，这些值具有统计学意义。根据不同生物学相关学科中有关压力引起的测量变异性的文献，我们假设这些变化源于挤压间隙和细胞外液。该过程局部增加了感测体积中的膜，细胞器和蛋白质的浓度。最后，我们建议朝着标准的探针与组织接触的压力发展，因为文献已经表明，以相同的压力进行探测可以在1％的不确定区间内产生可重复的数据。我们假设这些变化源于挤压间隙和细胞外液。该过程局部增加了感测体积中的膜，细胞器和蛋白质的浓度。最后，我们建议朝着标准的探针与组织接触的压力发展，因为文献已经表明，以相同的压力进行探测可以在1％的不确定区间内产生可重复的数据。我们假设这些变化源于挤压间隙和细胞外液。该过程局部增加了感测体积中的膜，细胞器和蛋白质的浓度。最后，我们建议朝着标准的探针与组织接触的压力发展，因为文献已经表明，以相同的压力进行探测可以在1％的不确定区间内产生可重复的数据。