本研究係以電紡法製備二氧化鈦/氟摻氧化錫(TiO2/FTO )薄膜作為延伸式閘極，並結合場效電晶體製作pH感測元件，旨在探討製備變因，包括：電紡液之PVP添加、工作電壓、射出流率、電紡收集時間及丙酮浸泡等條件對所得TiO2/FTO薄膜形態、結構及片電阻之影響，並進一步探討各元件之pH感測特性。為進一步評估元件使用之穩定性及量測準確度，以最佳元件進行感測溫度、鈉離子共存干擾、遲滯及時漂等效應之探討。
實驗結果顯示，製備變因對TiO2/FTO薄膜之表面性質影響甚鉅，進而影響所得元件之pH感測特性，當電紡液未添加PVP時，電紡後沉積形成TiO2奈米粒子(TiO2 NP)；當添加5% PVP時，則形成TiO2 奈米絲 (TiO2 NF )。隨著電紡工作電壓之增大，TiO2 NP粒徑亦增大，且逐漸形成中空珠狀；而TiO2 NF則於工作電壓為10 kV時呈現一最小絲徑。當收集時間增長時，TiO2 沉積量隨之增加，雖然可增加感測膜表面之活性座，但亦造成膜層片電阻之增大，不利於電訊之傳遞。另外，以丙酮液浸泡處理TiO2 NF / FTO薄膜，可增加紡絲間、紡絲與FTO間之黏結性，進而降低膜電阻。
由pH感測結果得知，TiO2沉積量與膜電阻是決定元件pH感測靈敏度之關鍵因素。TiO2 NF/FTO、TiO2 NP/FTO兩系列元件之最適射出流率為0.3 ml/h，收集時間為3 min，煅燒溫度為500 oC，而兩者之最佳工作電壓則分別為5、10 kV。在20 oC下，最佳TiO2 NF/FTO元件在pH 2~12間之感測靈敏度為75.16 mV/pH，線性度為0.9992；而最佳TiO2 NP/FTO元件之靈敏度更高達79.73 mV/pH，線性度為0.9965；兩元件對pH之感測均呈現super-Nernstian特性。
實驗結果亦顯示，TiO2 NF/FTO及TiO2 NP/FTO元件之靈敏度與感測溫度大致呈線性正向關係，且對鈉離子之選擇性佳；而遲滯電位分別為62.66 、61.4 mV。另外，TiO2 NF/FTO元件之時漂速率甚小，於 pH 2、7、12下分別為0.71 、1.15、0.87 mV/h，顯示此元件具備長時間使用之穩定性。
綜上所述，以電紡法製備TiO2/FTO感測元件，無論中空珠狀或絲狀TiO2膜，對pH量測均展現良好之感測性能，具有應用開發價值。

Titania films based extended gate field-effect transistor (EGFET) pH sensors were fabricated in this work. Experimentally, titania films were deposited on FTO substrate by electrospinning. The influences of preparation parameters including PVP concentration in electrospinning solution, working voltage and collection time on the surface morphology, crystalline structure and sheet resistance of TiO2 films were investigated. Furthermore, sensing performances of resulting TiO2 devices toward pH were also studied. Among all studied devices, the best NF device obtained at working voltage of 5 kV exhibited a sensitivity of 75.16 mV/pH. Whereas, the best NP device obtained at working voltage of 10 kV exhibited a superior sensing sensitivity of 79.73 mV/pH at 20 oC.

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