調控聚(3,4-乙烯二氧噻吩)傳導層電鍍製程以提升固態式離子選擇電極長時間電位穩定性

Enhancing Long-Term Potential Stability of a Solid-State Ion-Selective Electrode via Tuning Electrodeposition of a Poly(3,4-ethylenedioxythiophene) Transducer

呂奇翰(Chi-Han Lu)

指導教授 ： 陳林祈

國立臺灣大學/生物資源暨農學院/生物產業機電工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802756

摘要

固態式離子選擇電極 (solid-state ion-selective electrode, SS-ISE) 擁有利於微小化、平面化與較不受環境影響等優勢，為目前離子感測領域最為熱門的研究主題。然而，固態式離子選擇電極普遍長時間電位穩定性不佳，每次使用前皆須經過校正。因此，本研究藉由調控離子選擇薄膜與聚(3,4-乙烯二氧噻吩) (poly(3,4-ethylenedioxythiophene), PEDOT) 導電高分子離子電子傳導層的製程，如離子選擇薄膜的製程方法與PEDOT 的厚度、相對離子 (counter ion) 種類、電鍍方法等，以製作出長時間電位穩定性高的固態式離子選擇電極。首先，調整離子選擇薄膜的製程方法可以縮小其孔隙，進而降低水分子滲入電極的速率，減緩固態式離子選擇電極的水層效應。離子與電子之間的訊號轉換與離子選擇薄膜與PEDOT表面發生的氧化還原反應有關，因此PEDOT的電化學性質對大幅影響固態式離子選擇電極的電位穩定性。一般而言，離子電子傳導層應具有電化學穩定性高、贋電容值高與電荷轉移阻抗低等性質。在定電流的電鍍條件下，以ClO4-作為相對離子、厚度最大的PEDOT滿足此條件，以其製作鈉離子選擇電極的長時間電位穩定性表現最佳，一週之內的電位飄移為58.3 ± 3.1 mV。不過，循環伏安法電鍍的PEDOT:ClO4的雖然贋電容值較低，但是製成固態式離子選擇電極仍然可以大幅提升其長時間電位穩定性。以此一條件製作的鈉離子選擇電極在一週之內的電位飄移僅有5.7 ± 3.1 mV，為本研究中表現最佳者。

關鍵字

固態式離子選擇電極 ； 離子電子傳導層 ； 聚(3,4-乙烯二氧噻吩) ； 長時間電位穩定性 ； 免校正

並列摘要

Nowadays, solid-state ion-selective electrodes (SS-ISEs) have been a hot research topic because they are advantageous for miniaturization and planarization as well as less influenced by environment. However, the long-term potential stability of SS-ISEs are usually low, hence calibrations are needed before every use. In this study, poly(3,4-ethylenedioxythiophene) (PEDOT) was used as ion-to-electron transducer (IET) in SS-ISEs. We aimed to enhance the long-term potential stability of SS-ISEs by tuning the parameters of its manufacturing process, including casting method of ion-selective membrane (ISM) as well as thickness, counter ion and electrodeposition method of IET. First of all, changing fabrication method of ISM reduced its pore size, which significantly decelerated water leaking into the SS-ISE, hence easing the water layer effect of SS-ISE. Secondly, in an IET, signal transfer between ion and electron is related to the redox reaction on the surface of PEDOT. Thus, electrochemical properties of PEDOT has a great effect on the potential stability of SS-ISEs. In general, the IETs suitable for SS-ISEs are those with high electrochemical stability, high pseudocapacitance and low charge transfer resistance. When constant potential method was used as electrodeposition method, the thickest PEDOT with as ClO4- counter ion met the requirements, and Na+-SS-ISE with it had the lowest long-term potential drift of 58.3 ± 3.1 mV in one week. On the other hand, although PEDOT:ClO4 electrodeposited using CV method had lower pseudocapacitance, the long-term potential stability of Na+-SS-ISE with it was enhanced drastically. Its long-term potential drift was merely 5.7 ± 3.1 mV in one week, which is the best in the whole study.

並列關鍵字

solid-state ion-selective electrode ； ion-to-electron transducer ； poly(3,4-ethylenedioxythiophene) ； long-term potential stability ； calibration-free

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