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

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 diffusion-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 10 μm 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.