多頻道有機壓電感測器研製與應用

Multichannel piezoelectric crystal detection system with principal component analysis for air pollutants from PVC plants

王雅玲(Ya-Ling Wang)

指導教授 ： 施正雄

國立臺灣師範大學/理學院/化學系/碩士(2001年)

摘要

壓電晶體感測器是利用塗佈在石英晶體電極表面的辨識元，即所謂的塗佈物種，吸附待測分子造成電極表面的質量產生變化，導致石英壓電晶體本身共振頻率的下降，在藉由此頻率變化值來了解待測物的特性。本研究利用自行研製之一六個頻道(六個石英晶片)之多頻道氣體壓電感測器，用以偵測由高分子工業常用來溶解高分子之有機溶劑(如：甲醇(Methanol)、二硫化碳(Carbon disulfide)、二甲基甲醯胺(N,N-Dimethyl formamide)等)而散佈在高分子工廠空氣中之有機污染物。
本研究中亦利用電腦主成份分析法(Principal Component Analysis，PCA)來分析各頻道對各有機污染物之頻率訊號，以助於眾多塗佈物種中選擇出最適合偵測目的的塗佈物質。進行主成份分析後，前三個主成份便可解釋總變異量的98.66﹪，且C60/PPA、Polyethylene glycol、Nafion、Triphenyl phosphine、Cryptand-22及Polyvinyl pyrrolidone等六種在主成份分析中具有代表性的石英晶體塗佈物被選出。利用主成份分析法中的成分分數，以成份1(Factor 1 or PRIN 1)為X軸，成份2(Factor 2 or PRIN 2)為Y軸作圖，所得之X-Y主成份分析散佈圖(PCA Scores Map)，能夠有效地分辨出Methanol、Formic acid、Propionaldehyde、Carbon disulfide及N,N-Dimethyl formamide這五種不同的揮發性有機污染物。再者，利用雷達圖描繪不同有機污染物的訊號強度，可以發現每種揮發性有機分子都有其獨特型態的雷達圖，可以此來作為辨識的依據。
本研究中也分別探討了各種石英晶體塗佈物之塗佈量效應、各種揮發性有機污染物之濃度效應以及水氣所造成的影響，結果顯示此自製多頻道氣體感測器對五種有機物均具有很不錯的偵測下限。而在水氣所造成的影響實驗中，發現所選用的六種塗佈物中有些塗佈物質具有吸溼性，會受到水氣的干擾，且隨著相對溼度的增加，訊號的漂移也愈顯著，尤其以Polyvinyl pyrrolidone作為塗佈膜之石英晶體感應頻率變化受到水氣的干擾較嚴重。
而後嘗試著探討混合有機污染物氣體之雷達圖和濃度關係，結果發現可以藉由觀察混合有機物的雷達圖譜中某幾條特定軸之訊號強度，來判別混合有機污染物中特定氣體的可能存在情形，以提供參考。往後應可朝此發展，以期將來可將此系統方法應用於各高分子工業，作為辨識所排放之空氣污染物成份及污染指標。

關鍵字

多頻道壓電感測器 ； 主成分分析

並列摘要

Piezoelectric(PZ) quartz crystal is well-known to be sensitive to pressure exerted on its surface. The vibrational frequency of an oscillating piezoelectric quartz crystal decreases when a foreign substrance is adsorbed onto its surface. This phenomenon enables us to detect the characteristics of the substance. In this study, a multi-channel piezoelectric quartz crystal gas detection system with various organic material coated quartz crystals and a home-made computer interface for data processing were prepared and employed to detect various organic pollutants from PVC plants such as methanol, formic acid, propionaldehyde, carbon disulfide and N,N-dimethyl formamide.
The principal component analysis (PCA) method was than applied to analyze the signals from each channel with each coating material, and the appropriate coating materials for organic pollutants were selected. After performing PCA assay, the data set obtained from 29 piezoelectric crystal sensors for 5 analytes and the first three factors of the reduced set explained 98.66﹪of the variation. Six representative coating materials such as C60/PPA, Polyethylene glycol, Nafion, Triphenyl phosphine, Cryptand-22 and Polyvinyl pyrrolidone were selected. Five vaporized organic pollutants, Methanol、Formic acid、Propionaldehyde、Carbon disulfide and N,N-Dimethyl formamide could be effectively distinguished from PCA Scores Map generated by employing factor 1(PRIN1) as the x-axis and factor 2(PRIN2) as the y-axis. Furthermore, since different evaporated organic molecules tend to have distinguishing profile discrimination maps, profile discrimination maps can be used as finger-prints for distinction.
Effects of coating load, concentration and interference of water were also investigated and discussed. The result of multi-channel piezoelectric quartz crystal gas detection system showed the good detection limit, but the detection with some coating materials such as Polyvinyl pyrrolidone was found to be interfered by water.
The relationship between concentration and profile discrimination maps of organic mixtures with methanol, carbon disulfide, propionaldehyde and N,N-dimethyl formamide detected by the six-channel piezoelectric detection system were also probed and discussed afterward in this study. By comparing the signal intensity of specific axis in profile discrimination maps of the organic mixtures, specific gases could be identified. The multichannel piezoelectric crystal detection system developed in this study can be potentially expected to be applied for organic pollutants from other polymer industrial plants.

並列關鍵字

Multichannel Multichannel piezoelectric crystal detection system ； Principal Component Analysis，PCA

參考文獻

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