有機薄膜電晶體生化感測器應用於Cysteine Amino Acid, CN- 及金屬離子之偵測

Abstract

猶如本論文中所提到，有機薄膜電晶體廣泛地應用在可撓式面板、電子書、主動矩陣有機發光二極體、無線射頻辨識系統及偵測器上。在此我們將著重於生化感測、胰島素、胺基酸與離子偵測，離子包括金屬離子(汞離子、銅離子)及陰離子(氰離子)。在第一章中我們將統整有機薄膜電晶體的發展歷程與工作原理以及在偵測器上之應用。在第二章中、我們將利用有機半導體材料N-N’-dioctyl-3,4,9,10-perylenedicarboximide(PTCDI-C8)製作成有機薄膜電晶體應用在含水介質之偵測，我們發現藉由在介電層與主動層間多置一層含氟聚合物(CYTOP)，可使N型材料PTCDI-C8為通道製作成的元件穩定度長達2000小時，並改善其電子遷移率從0.005cm2/Vs增加至0.29±0.04cm2/Vs，增加開關電流比一個數量級(103到104)。藉由觀察電流及門檻電壓的變化，可將有機薄膜電晶體應用在不同濃度磷酸鉀溶液和中性pH值醋酸汞溶液的偵測。同時我們也將元件用在電荷對pH值4.5胰島素(此時胰島素為淨正電荷)及pH值7.5胰島素(淨負電荷)影響之偵測。在第三章中，我們將製作一主動層為perylenebisimide(PBI)之有機薄膜電晶體，可用於偵測二價汞離子之感應器。當在主動層(PBI)及介電層中多鍍一層PTCDI-C8, 可使N型通道元件電子遷移率從0.002 cm2/V-s改善至0.25 ± 0.04 cm2/V-s並且增加開關電流比兩個數量級(102到104)。基於“thymine-Hg2+-thymine”機制造成門檻電壓的變化，我們將可利用此電晶體從混合離子溶液中分辨出汞離子，並發展至不同濃度的汞離子溶液(從50到350μM)。藉由觀察電流及門檻電壓的變化我們也可將此元件用在cysteine(一種硫醇類胺基酸)的偵測。對cysteine的選擇性偵測會造成PBI在螢光分析的最大峰值從532奈米轉移到537奈米。在第四章中，我們利用五苯環/schiff base pyrene 衍生物製作出一個雙層主動層之電晶體，並求得其載子遷移率為0.12cm2/V-s，門檻電壓為-22.2V，開關電流比高達五個數量級。我們發現在13種陽離子中，元件只有遇到含有銅離子的溶液時，門檻電壓及關路電流會發生變化，而在9種陰離子中，只有遇到含氰離子的溶液，飽和電流會降低。在混合兩種離子的溶液中，元件還是只對銅離子、氰離子做選擇性偵測，而在元件的敏感性測試，我們則將銅離子溶液濃度稀釋成20到350微莫爾，氰離子溶液稀釋成100到350微莫爾。從原子力顯微鏡和紅外線光譜的結果可看出pyrene與銅離子反應形成pyrene-pyrene*coordination，而與氰離子形成 benzoxazolering，因此造成晶粒從長棒狀重新自我組織成細小星型的形狀。

As exemplified by this thesis, organic transistor were used in an application like flexible display, e-paper, AMOLED, RFID and sensors. Herein, we specially use for the sensor application to detect the biochemical, insulin, amino acid and metal ions like Hg2+ and Cu2+ ions, including anion (CN-). In chapter one we summarize the history of organic transistor with working principle and its application in sensors. In the second In the second In the second In the second In the second In the second In the second chapter we developed developed developed N-N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8)–based OTFTs for sensing applications in aqueous media. We converted an n-channel PTCDI-C8 into a stable device when a fluoropolymer (CYTOP) was positioned between the dielectric and the active layer. The resulting device was stable for up to 2000 h; its electron mobility (μ) improved to 0.29 ± 0.04 cm2 V–1 s–1 from 0.005 cm2 V–1 s–1 for the device lacking CYTOP, with the on/off ratio (Ion/Ioff) enhanced by one order of magnitude (from 103 to 104). By monitoring the shifts in drain current (IDS) and threshold voltage (Vth), we used these OTFTs as sensors for different concentrations of potassium phosphate buffer and mercuric(II) acetate solutions at neutral pH. We also used them to investigated the influence of charge on the detection of insulin at pH 4.5 (where insulin possesses a net positive charge) and pH 7.5 (net negative charge). In chapter three, we report a sensor for divalent mercuric (Hg2+) ions that we constructed from a perylene bisimide (PBI)–based OTFTs. We improved the performance of n-channel device by positioning N,N´-dioctyl-3,4,9,10-perylenedicarboximide between the dielectric and the active layer (PBI), increasing the electron mobility (μ) from 0.002 to 0.25 ± 0.04 cm2 V–1 s–1 and enhancing the on/off ratio (Ion/Ioff) by two orders of magnitude (from 102 to 104). Based on a “thymine–Hg2+–thymine” mechanism and monitoring the shift in the threshold voltage (Vth), we used this transistor to discriminate Hg2+ ions from mixed ion solutions and it extended to different concentration Hg2+ solutions (from 50 to 350 μM). By monitoring the shifts in drain current (IDS) and Vth, we also used this bilayer device as a sensor for cysteine, a thiol-containing amino acid; the selective detection of cysteine was accompanied by a red shift in the fluorescence maximum of PBI, from 532 to 537 nm. In fourth chapter we developed organic thin film transistors (OTFTs) for the sensing of metal ions and anions through the self-assembly of a pentacene/Schiff base pyrene derivative. Our bilayer OTFTs displayed attractive device parameters: an electron mobility (μ) of 0.12 cm2 V–1 s–1, a threshold voltage (Vth) of 22.20 V, and a five-orders-of-magnitude on/off ratio. This device was sensitive toward Cu2+ among 13 metal cations and toward CN– among nine anions, as measured through changes in the values of Vth and Ioff in the presence of Cu2+ cations and a change in the value of Isat in the presence of CN– anions. We observed selectivity toward both of these ions in mixed ion solutions, with sensitivity over different concentrations (from 20 to 350 μM for Cu2+; from 100 to 350 μM for CN–) as well as in sea water. The pyrene derivative self-assembled through pyrene–pyrene* coordination in the presence of Cu2+ ions; the rods of the pyrene derivative broke into smaller pieces upon formation of benzoxazole rings in the presence of CN– ions, as confirmed using atomic force microscopy and fourier transform attenuated total reflection spectroscopy.