延伸式閘極離子敏感場效電晶體結合晶片上 Ag/AgCl 參考電極應用於微流道系統中人工唾液之多離子感測

Abstract

本論文提出一款整合式延伸式閘極離子敏感場效電晶體（EG-ISFET）感測平台，於單一晶片上同時量測人工唾液中的鈉離子、鉀離子與氫離子。感測層以二氧化鈦（TiO₂）作為 pH 感測介面，並分別以鈉、鉀離子選擇膜（ISM）達成選擇性感測；參考電極則以晶片上自製 Ag/AgCl 電極取代傳統外接商用參考電極，並以微流道系統作為試液遞送方式。為釐清各因素之影響，本研究設計三種量測配置並分別驗證。實驗結果顯示，晶片上 Ag/AgCl 為一準參考電極，對氯離子仍保有約 5–10 mV/decade 之殘餘響應，使鈉、鉀離子之表觀斜率上升（此為參考端假象而非膜之效應）；導入微流道後，鈉、鉀離子之遲滯明顯下降。最後於人工唾液中驗證此平台可解析約 0.25 decade 之濃度變化。

This thesis presents an integrated extended-gate ion-sensitive field-effect transistor (EG-ISFET) platform that simultaneously measures sodium (Na⁺), potassium (K⁺), and proton (H⁺) in artificial saliva on a single chip. In the developed device, titanium dioxide (TiO₂) serves as the pH-sensitive interface, while sodium- and potassium-selective membranes (ISMs) provide selective Na⁺/K⁺ transduction. In addition, the external commercial reference electrode is replaced by an on-chip Ag/AgCl reference, and the sample is delivered through a microfluidic chamber. To identify the contribution of each element, three measurement configurations were defined and validated separately. In brief, the developed on-chip Ag/AgCl behaves as a quasi-reference that retains a weak chloride response of about 5-10 mV/decade, which inflates the apparent Na⁺/K⁺ slope; this shift is a reference artifact rather than a membrane effect. Introducing microfluidic flow markedly reduces the Na⁺/K⁺ hysteresis, and the platform is validated in artificial saliva and resolves concentration steps of about 0.25 decade.