適用於電子鼻系統化學電阻式氣體感測器之適應介面電路

Adaptive Interface Circuits of Chemiresistive Gas Sensors for an Electronic Nose System

張佳琳(Chia-Lin Chang)

指導教授 ： 鄭桂忠

國立清華大學/電機資訊學院/電機工程學系/碩士(2013年)

摘要

人類不能聞有毒或具危險性的氣體，且人類對嗅覺有不同的感覺而無一定的標準。相較於傳統的大型氣體檢測儀器，電子鼻系統的體積小、成本低、功耗消耗低、可將嗅覺量化而定出標準並可長時間暴露在危險氣體，因此可以被廣泛應用到食品品質監控、環境監測、污染測量和疾病診斷等等。電子鼻系統是由氣體感測器陣列、信號擷取電路和資料識別系統所組成。氣體感測器有許多種類，我們選擇使用化學式電阻感測器中的導電聚合物氣體感測器(Conducting Polymer Gas Sensor, CP )，其感測機制為電阻值變化，此種感測器之靈敏度高，訊號讀取電路較簡單，並且可操作在室溫下，因此很適用於可攜式裝置；然而，此種感測器的電阻值容易受到溫度、濕度與背景氣味而改變，且在感測器陣列中，每個感測器會塗佈不同感測材料而有不同的電阻值。因此，本論文提出三種由TSMC 0.18μm CMOS 1P6M製程所製作之氣體感測器適應介面電路：半數位式、數位式與類比式，各別以三種不同技術消除感測器之基線電阻漂移，並將感測器訊號轉換為電訊號，首先呈現三種介面電路之模擬、量測與比較，之後將電路與導電聚合物氣體感測器相接並與氣體做反應，並呈現其讀取與辨識結果。我們也將感測器整合於半數位式與數位式介面電路，以達到微小化電子鼻晶片之目的。

關鍵字

電子鼻 ； 氣體感測器 ； 適應介面電路

並列摘要

Many odors are not suitable for human to smell, such as poisonous and exhausted gases. In addition, olfaction is different from person to person. Compare to the traditional gas detection instrument, an electronic nose (E-nose) system has various advantages including small size, low cost, low power, quantization of olfaction, and the capability of being exposed to dangerous gases. Therefore, it can be applied to quality control of foods, environmental monitoring, pollution measurement and disease diagnosis, etc. E-nose system is composed of a gas sensor array, a signal acquisition circuit and a pattern recognition system. Conducting polymer sensor is one of the chemiresistive gas sensors. It has the advantages of working at room temperature, high sensitivity (about a few ppm), and its readout circuit is simple, which would be suitable for portable devices. However, the sensor resistance could be easily affected by temperature, humidity, and background odors. In addition, the resistances of each sensor in the sensor array are not the same after the deposition of different sensing materials. Therefore, an adaptive interface circuit is required to cancel the baseline drift and read the sensor signal. Three types of adaptive interface circuits fabricated by TSMC 0.18μm CMOS 1P6M processes would be introduced in this paper: semi-digital type, digital type and analog type. Simulation and measurement result of these three interface circuits would be presented and be compared. Lastly, an external conductive polymer gas sensor array connected with adaptive interface circuit was exposed to different odors, and the results were presented. Gas sensors were respectively integrated with the semi-digital type and digital type interface circuits on the same chip.

並列關鍵字

Electronic nose ； Gas sensor ； Adaptive interface circuit

參考文獻

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