English Anthony E, Squire James C, Bodmer James E, Moy Alan B
University of Tennessee, Knoxville, TN 37996, USA.
IEEE Trans Biomed Eng. 2007 May;54(5):863-73. doi: 10.1109/TBME.2007.893468.
Frequency dependent cellular micro-impedance estimates obtained from a gold two-electrode configuration using phase sensitive detection have become increasingly used to evaluate cellular barrier model parameters. The results of this study show that cellular barrier function parameter estimates optimized using measurements obtained from this biosensor are highly susceptible to both time dependent and systematic instrumental artifacts. Based on a power spectral analysis of experimentally measured microelectrode voltages, synchronous, 60 Hz, and white Gaussian noise were identified as the most significant time dependent instrumental artifacts. The reduction of these artifacts using digital filtering produced a corresponding reduction in the optimized model parameter fluctuations. Using a series of instrumental circuit models, this study also shows that electrode impedance voltage divider effects and circuit capacitances can produce systematic deviations in cellular barrier function parameter estimates. Although the implementation of an active current source reduced the voltage divider effects, artifacts produced by coaxial cable and other circuit capacitive elements at frequencies exceeding 1 kHz still remained. Reducing time dependent instrumental fluctuations and systematic errors produced a significant reduction in cellular model barrier parameter errors and improved the model fit to experimental data.
使用相敏检测从金双电极配置获得的频率依赖性细胞微阻抗估计值越来越多地用于评估细胞屏障模型参数。本研究结果表明，使用该生物传感器获得的测量值优化的细胞屏障功能参数估计值对时间依赖性和系统性仪器伪像都高度敏感。基于对实验测量的微电极电压的功率谱分析，同步、60 Hz和白色高斯噪声被确定为最显著的时间依赖性仪器伪像。使用数字滤波减少这些伪像会相应减少优化模型参数的波动。通过一系列仪器电路模型，本研究还表明电极阻抗分压器效应和电路电容会在细胞屏障功能参数估计中产生系统性偏差。尽管有源电流源的实施减少了分压器效应，但在频率超过1 kHz时，同轴电缆和其他电路电容元件产生的伪像仍然存在。减少时间依赖性仪器波动和系统性误差显著降低了细胞模型屏障参数误差，并改善了模型与实验数据的拟合。
