氧化銥比較電位式固態二氧化碳感測器製作與改進研究

Abstract

本實驗研製出以氧化銥薄膜作為感測動作電極,並且利用內含碳酸氫 鉀離子的聚乙稀醇為固態電解質之電位式二氧化碳感測元件. 其反應機制 為因氧化銥電極的電位會隨著電解質的 pH 值變化而改變. 而電解質的 pH 值則與溶於其內的二氧化碳達成平衡,藉此可偵測到被測氣體中的二氧 化碳含量. 同時也作了氧化銥薄膜電極電位對 pH 值的依賴性實驗,結 果顯示氧化銥薄膜電極的電位對 pH 值具有良好的線性關係,且由斜率 -60.2mV/pH 可看出本濺鍍系統所濺鍍的氧化銥薄膜是比較接近不含水的 成份. 對於聚乙稀醇裡所含的碳酸氫鉀濃度同時也作了一系列的實驗, 濃度從 2mM 到 20mM顯示以含 2mM 濃度的碳酸氫鉀為對感測元件的感測 性能最為理想.本感測器在二氧化碳含量為 0.04% - 1.2% 的條件下具有 線性以及可逆的關係. 對元件感測部位注射 0.2ml的二氧化碳, 其反應時 間為 0.4 秒.並以本感測元件進行對人體呼吸的感測實驗. A sputtered iridium oxide film, base micro-sensor, covered with a solid electrolyte,sensitive to carbon dioxide has been fabricated. The solid electrolyte is made bybicarbonate contained, gas permeable transparent poly(vinyl alcohol). From measurements of the open-circuit potential, the sensitivity slope of IrO2 inacide and base solution is -60.2 mv/pH. The characteristics of devies with different concentrations of KHCO3 used on the working electrode section( 2mM, 10mM, 20mM )are measure. The result shows that 2mMKHCO3 in PVA used on the working electrode section is favorable to sensitivity tocarbon dioxide. The response to CO2 concentration is linear and reversible between0.04% - 1.2% at 1 atm and 298K. The lowest concentration,400ppm of CO2 has been detected. The rising time is only 0.4 seconds when 0.2ml CO2 is injected on the sensing region. And the exhalation of human is also recorded through our sensor.