| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 107 === Ion current rectification (ICR) is interesting and important phenomena in nanochannels and many researchers have been studied this due to its applications in the past few decades. In the following chapter, two kind of application will be introduced, thermal gate and heavy metal ion detection. In Chapter 1, the influence of electroosmotic flow (EOF), bulk concentration and temperature on the degree of ICR are investigated in the conical nanochannel by a thorough numerical simulation. Assuming that the bulk salt concentration ranges from 1 to 1000 mM and temperature from 278 to 313 K, we show that neglecting the EOF effect can lead to ca. 90 % deviation in the degree of ICR. In general, the higher the temperature the greater the conductance and the less significant the ICR effect, and the degree of this effect has a local maximum as the bulk salt concentration varies. A three-dimensional plot correlating the degree of ICR effect on the bulk salt concentration and the temperature is prepared for designing a thermal gate for ionic transport. In Chapter 2, a new way of heavy metal detection is introduced due to the health problem caused by abnormal metal ion concentration in human body. We propose an ion sensing method based on the ion current rectification behavior of a conical nanochannel, using a polyethylene terephthalate nanochannel surface modified by 18-crown-6 to estimate the level of Pb2+ concentration as an example. Numerical simulation is conducted to examine the performance of such as nanochannel under various conditions by varying the bulk LiCl concentration, the level of Pb2+ concentration, and the degree of surface modification. Regression analysis is also conducted to obtain the range of Pb2+ concentration suitable for detection and its lower limit. We show that the performance of the nanochannel proposed is satisfactory. The possibility of detecting Cu2+ by this nanochannel is also discussed.
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