本研究主要是使用厚膜網版印刷的方法來製作ZnO、SnO2基一氧化碳感測器(CO Sensor),此方法的優點在於製程簡單、材料的使用少、又易整合數種元件於一體且可大量批次生產,因此可大幅降低製造的成本。
本ZnO、SnO2基一氧化碳感測器是一種積層(Multi-layer)元件的結構,這些元件分別是氧化鋁(Al2O3)基材層、量測電極層(Au)、加熱器層(RuO2)及感測材料層等。其中感測材料層是使用具有半導體特性的氧化鋅(ZnO)及二氧化錫(SnO2)作爲材料,以網版印刷的方法將此感測材料網印在Al2O3基材上,之後再以旋轉塗佈的方法將含有Au、Pd的觸媒溶劑沉積在此感測相料層上,此目的在增加感測材料的感度與選擇性。
由實驗的結果可知ZnO感測材料對CO氣體具有較佳感度(Sensitivity),它在50 ppm CO濃度下(TLV)的感度約爲7倍,反應時間(T90)爲80秒、回復時間(T20)爲66秒,對H2S、H2、CH4等等氣體所造成的干擾性並不大。SnO2感測材料對CO氣體的感度並不佳,反而是對H2S氧體具有相當高的感度,在10ppmH2S濃度時其感度就可達到40倍。ZnO、SnO2兩種感測材料對CH4氧體幾乎是沒有感度。
The purpose of this research is to develop a semiconductor type CO sensor by using thick film screen printing method. The successful approach allows for the production of simply manufacture processes, small, geometrically well-define sensors that are reliable and mechanically robust. Individual sensor cost is also greatly reduced because the sensors are batch fabricated. The ZnO and SnO2 mixture powders were coated on Al2O3 substrate of the sensing layer as the catalyst. The sensitivity for 50ppm CO reaches as high as 7 with 8 s and 66 s for the response and recovery time, respectively, at an operating temperature of 220℃.