UiO-66 與 UiO-66-NH₂ 修飾之有機場效電晶體用於提升乳酸感測

Abstract

有機場效電晶體 (OFETs) 常用於作為感測器的一部分，但在過往的酸性感測應用中，往往受限於酸性目標物所能引發的電流訊號過於微弱，使得感測結果觀察不易。為了解決感測訊號微弱的缺點，本研究將金屬有機骨架 (MOFs) 材料整合至 OFETs 元件中，利用 MOFs 特有的多孔隙結構、高比表面積以及表面官能基的修飾，將其作為酸性分子的捕捉與訊號放大器。當酸分子進入 MOF 結構後，能透過增強的化學閘極效應，有效改變高分子半導體通道的載子傳輸能力，使得原本難以量測的微弱訊號變化，轉換並放大為清晰且穩定的電晶體電流輸出。本研究使用兩種做法：（1）將UiO-66或UiO-66-NH2直接旋轉塗佈於元件上（2）將UiO-66或UiO-66-NH2與PMMA溶液混合，再進行旋轉塗佈。以結果而言，將UiO-66或UiO-66-NH2與PMMA溶液混合的方法使感測乳酸的電流有所提升，此變化歸功於UiO-66上帶電的離子團、UiO-66-NH2上胺基與乳酸上的羧基進行結合，改變半導體通道內電荷濃度的分佈，使感測電流發生變化。本研究提升了傳統 OFETs 於乳酸感測上靈敏度，也提供了相對簡單的方法進行元件的表面修飾。

Organic field-effect transistors (OFETs) are commonly used as components in sensors. However, past applications in acid sensing have often been limited by the excessively weak current signals induced by acidic targets, making the sensing results difficult to observe. To address the shortcoming of weak sensing signals, this study integrates metal-organic framework (MOF) materials into OFET devices. By utilizing the unique porous structures, high specific surface areas, and surface functional group modifications of MOFs, they serve as capture and signal amplifiers for acidic molecules. Once acid molecules enter the MOF structure, they can effectively alter the carrier transport capability of the polymer semiconductor channel through an enhanced chemical gating effect. This converts and amplifies previously hard-to-measure, weak signal variations into clear and stable transistor current outputs. This study employed two approaches: (1) direct spin coating of UiO-66 or UiO-66-NH₂ onto the device, and (2) mixing UiO-66 or UiO-66-NH₂ with a PMMA solution prior to spin coating. The results indicate that the method of mixing UiO-66 or UiO-66-NH₂ with the PMMA solution successfully enhanced the lactic acid sensing current. This variation is attributed to the binding between the charged ion clusters on UiO-66, or the amino groups on UiO-66-NH₂, and the carboxyl groups on lactic acid. This interaction alters the distribution of charge concentration within the semiconductor channel, thereby causing changes in the sensing current. This research not only enhances the sensitivity of traditional OFETs in lactic acid sensing but also provides a relatively straightforward method for device surface modification.