利用雙閘極敏感場效應電晶體結合離子選擇膜及微流道進行水質六價鉻離子濃度檢測

Abstract

水質重金屬離子濃度檢測為檢驗水質品質的一大指標。但傳統量測技術往往需要專業技術人員於實驗室操作精密儀器才能得到檢驗結果，而樣品運送途中也可能對樣本產生影響，造成量測誤差。為解決傳統技術問題，我們開發出一種整合雙閘極離子敏感場效電晶體(Dual-gate ion-selective field-effect transistor, DG-ISFET)的微流道裝置進行水質重金屬檢測。本裝置使用離子選擇膜(Ion selective membrane, ISM)以捕捉特定離子，並透過DG-ISFET量測捕捉行為所產生的訊號差異，進而確認離子濃度。為驗證上述技術，我們首先使用已知重金屬離子濃度的標準液以最佳化離子選擇膜的體積/表面積比，達到最大的捕捉效率，接著進行DG-ISFET結合ISM的標準液離子濃度測試，並以相關理論說明ISM與重金屬離子的捕捉反應是如何被DG-ISFET偵測並記錄。最終我們利用壓力幫浦系統自動注入水圳廢水到流道晶片中進行六價鉻離子捕捉與濃度檢測。此實驗應證了該晶片可在機台最大時長區間持續偵測訊號，並同時含有優異的靈敏度與選擇性。上述的研究結果表明此可攜式水質檢測晶片可用於即時且連續性的自動化水質重金屬離子檢測，並能透過訊號差動量測完全排除環境雜訊，有望在未來將其應用在家用定點水質重金屬檢測、探勘水質重金屬檢測或是搭載於無人機的遠端檢測環境中。

Testing water for heavy metal ions is vital for assessing its quality. However, traditional methods require skilled technicians and complex lab equipment, posing logistical challenges. To address the above problems, we developed a microfluidic device with a Dual-gate Ion-Selective Field-Effect Transistor (ISFET) for heavy metal ion detection. Using an Ion-Selective Membrane (ISM), our device captures target ions and measures the signal difference via ISFET to determine ion concentration. We optimized ISM thickness and concentration of buffer solution using known ion standard solutions to validate our method, achieving maximum capture efficiency. We then evaluated sensing performance against standard ion solutions, elucidating the capture response mechanism. Finally, we tested the device used in ditch wastewater for chromium(VI) ion detection, demonstrating its sensitivity and selectivity. Our findings confirm the device's real-time water quality monitoring potential, with noise reduction capabilities for various applications, including household use and environmental monitoring.