Dielectric spectroscopy in a micromachined flow cytometer: theoretical and practical considerations
Dielectric spectroscopy in a micromachined flow cytometer: theoretical and practical considerations
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DOI：
10.1039/b313761a
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发表时间：
2004-01-01
期刊：
影响因子：
6.1
通讯作者：
Renaud, P
中科院分区：
文献类型：
--
作者：
Gawad, S;Cheung, K;Renaud, P
我们提出了一个模型，以确定不同的细胞特性，如大小，膜电容和细胞质电导率的影响，在一个微型细胞仪测量的阻抗谱。等效复介电常数的介质球被用作描述生物细胞的简化模型。测量发生在充满盐溶液的微通道中的一对相对的微电极之间。该模型结合了各种细胞参数，如介电性能，大小和位置的通道。使用3D有限元模型来评估通道中的电场的大小以及当细胞流过时测量电极边界处的电荷密度的所得变化。电荷密度在电极表面上积分，以确定计算频率范围内的位移电流和通道阻抗。完整的阻抗模型结合了有限元模型、电极-电解质界面阻抗和杂散阻抗，这些阻抗是从真实的器件测量的。模型化的介电复谱的各种细胞参数进行了讨论，并提出了一种测量策略，细胞歧视与这样的系统。我们最后讨论了传感器的噪声量和测量波动。
We propose a model to determine the influence of different cell properties, such as size, membrane capacitance and cytoplasm conductivity, on the impedance spectrum as measured in a microfabricated cytometer. A dielectric sphere of equivalent complex permittivity is used as a simplified model to describe a biological cell. The measurement takes place between a pair of facing microelectrodes in a microchannel filled with a saline solution. The model incorporates various cell parameters, such as dielectric properties, size and position in the channel. A 3D finite element model is used to evaluate the magnitude of the electric field in the channel and the resultant changes in charge densities at the measurement electrode boundaries as a cell flows past. The charge density is integrated on the electrode surface to determine the displacement current and the channel impedance for the computed frequency range. The complete impedance model combines the finite element model, the electrode-electrolyte interface impedance and stray impedance, which are measured from a real device. The modeled dielectric complex spectra for various cell parameters are discussed and a measurement strategy for cell discrimination with such a system is proposed. We finally discuss the amount of noise and measurement fluctuations of the sensor.