Yossifon Gilad, Mushenheim Peter, Chang Yu-Chen, Chang Hsueh-Chia
Department of Chemical and Biomolecular Engineering, Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Apr;79(4 Pt 2):046305. doi: 10.1103/PhysRevE.79.046305. Epub 2009 Apr 3.
Like ion channels, nanochannels are known to exhibit curious non-Ohmic current-voltage (I-V) characteristics with an approximate piece-wise constant differential resistance. Using a nanoslot model and a nonequilibrium ion transport theory, we attribute the nonlinear resistance to overlapping double layers inside and an extended polarized layer of space charge outside the nanochannel. The overlimiting current beyond a critical voltage is shown to develop when the polarized layer is destabilized by a microvortex instability at one entrance. By extending earlier nanochannel and polarized layer models to include this instability, nonideal ion permselectivity and field-focusing effect, quantitative predictions-together with explicit differential resistance expressions-are offered for the nonlinear I-V features of a nanochannel surrounded by microreservoirs from a simple pseudo-one-dimensional model.
与离子通道一样，纳米通道已知具有奇特的非欧姆电流-电压（I-V）特性，其微分电阻近似为分段常数。使用纳米狭缝模型和非平衡离子输运理论，我们将非线性电阻归因于纳米通道内部重叠的双层以及外部扩展的空间电荷极化层。当极化层在一个入口处因微涡旋不稳定性而失稳时，超过临界电压的过极限电流就会出现。通过扩展早期的纳米通道和极化层模型以纳入这种不稳定性、非理想离子选择透过性和场聚焦效应，从一个简单的准一维模型对被微储液器包围的纳米通道的非线性I-V特性提供了定量预测以及明确的微分电阻表达式。
