二极管器件SPICE电路模型对锥形离子通道I-V特性曲线的模拟

Simulation of SPICE Model of Diode for Conical Ion-channel I-V Curve

离子整流性是纳米离子通道的一个重要特征,具有整流性的离子通道体系也被称为纳米流体二极管.本文比较了离子通道的泊松-能斯特-普朗克(PNP)方程组模型和固体半导体的扩散-漂移模型,提出可以使用二极管器件的仿真电路模拟器(SPICE)电路模型对离子通道体系的电流-电压(I-V)曲线进行模拟.以锥形离子通道的PNP数值模型的计算结果为基础,通过对这一体系进行讨论,给出一个锥形离子通道的SPICE电路模型,它可以较好地模拟I-V特性曲线.离子通道SPICE电路模型的建立可用于研究纳米流体二极管作为一个器件在电路中的应用.

Ion rectification is a main property of nanochannel.The ion-channel system with ion current rectification is so-called nanofluidic diode.In this paper,Poisson-Nernst-Planck(PNP)equations model of ion-channel and diffu⁃sion-drift model of semiconductor diode were compared,and Simulation Program with Integrated Circuit Emphasis(SPICE)model of diode was suggested,which could be used for I-V characteristic curves simulation of ion-channel system.Comparing I-V curves of several kinds of ion-channel from reported works,that is found that besides the saturated current term of ideal PN junction diode SPICE model,the reverse saturated current term should be used to build SPICE model of ion-channel systems within the‒2—+2 V experiment range.Usually,PNP equations numerical model has a good fit to conical ion-channel I-V curve experiment.So,firstly based on PNP equations model,a conical ion-channel 2D model with a 10μm length,a 400 nm base diameter and a 10 nm tip diameter was built in COMSOL multiphysics software,ion-channel systems with a series of surface charge densities in 1,10 and 100 mmol/L KCl aqua solutions were simulated.After discussed I-V curve properties of conical ion-channel system based on this model,especially composition of diffusion and electrophoresis currents,the suggested SPICE model with the reverse saturated current term of diode would be built.In the SPICE model of conical ion-channel system,junction potential and series resistance of diode could be estimated from PNP model simulation,reverse saturated current and grading coefficient of diode would be set to fit PNP model simulation.As a result,SPICE model fit PNP equations model well simulating I-V curves of conical ion-channel system.SPICE model of ion-channel system would be useful to research the property of nanofluidic diode as an electrical element in electric circuit.