We report measurements of the electrical impedance of human erythrocytes in the frequency range from 1 Hz to 10 MHz, and for temperatures from 4 to 40 degrees C. In order to achieve high sensitivity in this frequency range, we embedded the cells in the pores of a filter, which constrains the current to pass through the cells in the pores. Based on the geometry of the cells embedded in the filter a circuit model is proposed for the cell-filter saline system. A constant phase angle (CPA) element, i.e., an impedance of the form Z = A/(j omega)alpha, where A is a constant, j = square root of -1, omega is angular frequency, and 0 less than alpha less than 1 has been used to describe the ac response of the interface between the cell surface and the electrolyte solution, i.e., the electrical double layer. The CPA and other elements of the circuit model are determined by a complex nonlinear least squares (CNLS) fit, which simultaneously fits the real and imaginary parts of the experimental data to the circuit model. The specific membrane capacitance is determined to be 0.901 +/- 0.036 microF/cm2, and the specific cytoplasm conductivity to be 0.413 +/- 0.031 S/m at 26 degrees C. The temperature dependence of the cytoplasm conductivity, membrane capacitance, and CPA element has been obtained. The membrane capacitance increases markedly at approximately 37 degrees C, which suggests a phase transition in the cell membrane.
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机译:我们报告了在1 Hz到10 MHz的频率范围内以及在4到40摄氏度的温度下对人类红细胞的电阻抗的测量结果。为了在该频率范围内实现高灵敏度,我们将细胞嵌入了过滤器,它限制电流通过孔中的细胞。基于过滤器中嵌入的细胞的几何形状,提出了用于细胞过滤器盐水系统的电路模型。恒定相角(CPA)元素,即Z = A /(j omega)alpha形式的阻抗,其中A是常数,j = -1的平方根,omega是角频率,0小于alpha小于1的值已用于描述电池表面与电解质溶液(即双电层)之间的界面的ac响应。电路模型的CPA和其他元素由复杂的非线性最小二乘(CNLS)拟合确定,该拟合同时将实验数据的实部和虚部拟合到电路模型中。测定在26摄氏度下的比膜电容为0.901 +/- 0.036 microF / cm2,比细胞质电导率为0.413 +/- 0.031 S / m。细胞质电导率,膜电容和CPA的温度依赖性元素已获得。膜电容在大约37摄氏度时显着增加,这表明细胞膜中发生了相变。
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