以新型奈米多孔碳製作之微機電氣體感測器

Novel MEMS gas sensors using mesoporous carbon nano-powder immobilized by the dielectrophoresis process

廖冠勛(Kuan-Hsun Liao)

指導教授 ： 呂志誠

國立臺北科技大學/機電學院/製造科技研究所/碩士(2008年)

摘要

本研究提出一種使用多孔碳顆粒(Mesoporous carbon powder, MCP)作為氣敏材料(gas-sensitive material)的新型MEMS氣體感測器,主要利用此材料的高表面積與氣體吸附特性，並採用了調控電極工作電壓進行氣體脫附的新模式，無需建置額外的加熱器，並且證實了低電阻值之氣敏材料使用此方法的可行性,此感測器利用微加工(micromachining)的方式製作介電薄膜,而氣敏材料是在室溫下利用介電泳(dielectrophoresis, DEP)方式排列沉積 MCP，在DEP過程中MCP因為受到電場極化作用下聚集並沿著電場方向排列，最後成功的吸附在兩電極間；本研究完成了感測器結構的製作，亦驗證Mesoporous carbon的感測特性及溫溼度影響等項目，隨後之氣體測試結果成功的證實多孔碳對多種氣體吸附的可逆性(reversible)，在此實驗之中針對500~4000ppm的氧氣濃度和100~500ppm的一氧化碳濃度進行量測,並將氨氣之量測分為乾濕兩型，在50~800ppm濃度下分別完成分析,由實驗可知多孔碳對感測氣體響應良好，且敏感度隨著氣體濃度的昇高而增加，藉由本研究的成果，對於結合多孔碳的氣體感測及實現MEMS智慧型氣體感測器技術，提供了基礎而有效的整合。

關鍵字

Mesoporous carbon ； 微機電氣體感測器 ； 介電泳動(DEP) ； MEMS製程相容性 ； 薄膜結構

並列摘要

Innovative micro gas sensors using mesoporous carbon powder (MCP) as the sensitive film is presented for the first time with MEMS manufacturing technology. Powdered mesoporous carbon is employed as active sensing layers and deposited between electrodes on a thin membrane. The basic concept of the mesoporous carbon gas sensor features is a thin membrane (including silicon dioxide and silicon nitride) and electrodes. Mesoporous carbon layers are aligned and immobilized between electrodes over the membrane by AC-powered dielectrophoresis, Due to its nano-scale structure, the MCP active layer is found very sensitive to heater operation and thus it causes significant noise during measurement. A new method using high-voltage to recover MCP material and measure resistance changes after gas tests without heater implementation is successfully proposed. Mesoporous carbon gas sensors are tested with a variety of gases like O2, NH3 and CO and significant resistance changes are measured to detect various. The sensors are located in a vacuum environment (10-2 ~10-3 Torr) and employed gas concentrations of O2, NH3 and CO gases ranging between 500~4000ppm, 200~800ppm and 100~400ppm, respectively. The result of resistance changes at the MCP active layer is found distinct and their sensitivity is also prominent up to 14.2%. The chemoresistive effect of gas detections using MCP gas sensors is proven and promising for further applications with CMOS and MEMS compatibility.

並列關鍵字

Mesoporous carbon ； Gas sensor ； Dielectrophoresis ； MEMS

參考文獻

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