奈米孔道的電動力學行為:不連續截面與介電性質的影響

Electrokinetic Behaviors of Nanochannels: Influences of Nonuniform Cross Section and Dielectric Properties

嚴維寬(Wei-Kuan Yen)

指導教授 ： 徐治平

國立臺灣大學/工學院/化學工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202002169

摘要

奈米流體為一門專門探討流體侷限於奈米尺度結構的學問。近年來由於其在生醫領域的應用，已有許多針對諸如離子整流效應及離子選擇性等離子傳輸現象的研究發表於世。
第一章節中，我們針對一串聯不同截面大小之圓形直管，且可受pH調控的奈米孔道進行探討，並專注於探討兩直管半徑、長度的比例，以及濃度和溶液酸鹼值所造成的影響。數值模擬的結果顯示，整流效應係數會隨著半徑、長度比例的變化而呈現局部最大值，並且該值隨著濃度的變化出現在不同的尺度比例上。除此之外，溶液酸鹼值對於整流效應係數的影響亦出現局部最大值；從通篇的結果可以觀察到溶液酸鹼值對於此奈米孔道的整流行為有最顯著的影響。 以上研究成果已發表於國際期刊Electrophoresis.
第二章節中，我們以數值模擬探討介電薄膜對於帶電表面和離子之間的靜電作用力的影響；其中與過去相關研究不同的地方是，本研究採用基於Poisson–Nernst–Planck以及Navier–Stokes方程式的連續方程式，並運用其計算離子電導值。在本章節研究中，主要探討薄膜自體的介電係數對於圓管狀奈米孔道的離子傳輸行為的影響，並輔以探討奈米孔道的尺寸、溶液的濃度以及酸鹼度對其造成的影響。

關鍵字

離子整流 ； 不連續截面 ； 表面極化 ； 介電效應

並列摘要

Nanofluidic is the study of the transport of fluids that are confined to the structures of the nanometer length scale. In recent years, due to the application in biotechnology, several interests such as ion current rectification (ICR) and ionic selectivity have been investigated.
In chapter 1, the ICR behavior of a pH-regulated nanochannel comprising two series connected cylindrical nanochannels of different radii is examined theoretically, focusing on the influences of the radii ratio, the length ratio, the bulk concentration, and the solution pH. The results of numerical simulation reveal that the rectification factor exhibits a local maximum with respect to both the radii ratio and the length ratio. The values of the radii ratio and the length ratio at which the local maximum in the rectification factor occur depend upon the level of the bulk salt concentration. The rectification factor also shows a local maximum as the solution pH varies. Among the factors examined, the solution pH influences the ICR behavior of the nanochannel most significantly. The above results were published in Electrophoresis.
In chapter 2, we demonstrate a theoretical model to investigate how a dielectric membrane governs the electrostatic interaction between ions and charged surfaces via the induced dipole. The model is based on the continuum dynamics composed of the Poisson–Nernst–Planck and the Navier–Stokes equations to calculate the ionic conductance. In this study, we focus on the influence of the permittivity of the membrane on a cylindrical nanopore, in addition, we explore the effects of dimension of nanopores, electrolyte concentration, and electrolyte pH.

並列關鍵字

ionic current rectification ； nonuniform cross section ； surface polarization ； dielectric effect

參考文獻

Chapter 1:

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[2] Zhang, H. C., Tian, Y., Hou, J., Hou, X., Hou, G. L., Ou, R. W., Wang, H. T., Jiang, L., Acs Nano 2015, 9, 12264-12273.

[3] Xiao, K., Chen, L., Zhang, Z., Xie, G. H., Li, P., Kong, X. Y., Wen, L. P., Jiang, L., Angew. Chem. Int. Ed. Engl. 2017, 56, 8168-8172.

[4] Xie, G. H., Xiao, K., Zhang, Z., Kong, X. Y., Liu, Q., Li, P., Wen, L. P., Jiang, L., Angew. Chem. Int. Ed. Engl. 2015, 54, 13664-13668.