電阻式氣體感測器控制電路開發之研究

Research on the Development of Control Circuits for Resistive Gas Sensors

劉亞樵(Liu Ya-Chiao)

指導教授 ： 郭金國

國立臺灣師範大學/科技與工程學院/工業教育學系/碩士(2021年)

https://doi.org/10.6345/NTNU202100418

摘要

本研究目的在於製作可因應各類電阻式氣體感測元件 (resisting gas sensor) 的控制電路，實驗中將使用二氧化鈦 (TiO2) 奈米管製作甲醛 (HCHO) 氣體感測元件，為因應使用各類電阻式氣體感測元件的需求，控制電路需包含分壓電路定電阻切換功能，並設計對應之操作介面 (User Interface) 及控制程式。本研究將以陽極氧化法製作多孔性陣列的二氧化鈦奈米管，並以熱處理方式使二氧化鈦達到銳鈦礦相 (Anatase)，控制電路採用 16Bit 的類比數位轉換晶片 (Analog-to-Digital Converter) 及 MCU (Micro Controller Unit) 級別的微控制器，並於硬體層面設計分壓電路定電阻切換介面，撰寫對應之控制程式，控制程式整合了軟體操作介面之指令，可輸入不同氣體感測元件之參數，微控制器擷取來自類比數位轉換晶片的數位訊號後，將以遞推平均濾波法進行數位濾波 (Digital Filter) 處理，濾除不必要之雜訊，控制程式帶入甲醛氣體樣本濃度資料後即可計算出感測之甲醛氣體濃度，並進行20~80 ppm的甲醛氣體濃度感測，以驗證控制電路的可行性，從實驗結果可知本研究之電阻式氣體感測器控制電路可準確判定甲醛氣體濃度。

關鍵字

電阻式氣體感測元件 ； 控制電路 ； 甲醛

並列摘要

The purpose of this study is to make a control circuit which is applicable when attached to different resistive gas sensors. Titanium dioxide (TiO2) nanotube control will be used as formaldehyde (HCHO) gas sensor in the experiment. In response to the need of using various resistive gas sensors, the control circuit needs to include a voltage divider circuit with resistance that can altered according to different applications, along with corresponding user interface and control program. In this study, titanium dioxide nanotubes with porous arrays will be created through the process of anode oxidation, and by heating it to reach the acute anatase phase. The control circuit adopts a 16Bit analog-to-digital conversion chip and MCU (Micro Controller Unit)-level microcontroller. A resistive divider of variable resistance should be created in terms of hardware. Corresponding control program which integrates all software interface commands should be designed. Such program should allow the input of different gas sensors parameters. After the microcontroller detects the digital signal from the analog-digital conversion chip, digital filtering will be carried out using recursive average filtering to remove the impact of unnecessary noise. After the program records the signal data representing the formaldehyde gas sample concentration, the actual concentration can be calculated. The program can then construct a database which indicates the resistance and its corresponding formaldehyde gas concentration (90~100ppm). In future investigations, the circuit can detect the concentration of the formaldehyde gas sample presented, and by comparing the signal generated by the resistive gas sensor to find out the resistance. Hence, the feasibility of the control circuit can be verified by comparing the results to the values obtained with other resistive gas sensor circuits. It can be seen from the experimental results that the resistance gas sensor control circuit in this study can accurately determine the concentration of formaldehyde gas.

並列關鍵字

Resistance gas sensor ； Control circuit ； Formaldehyde

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