T1 - Aging effect of a molecularly imprinted polymer on a quartz tuning fork sensor for detection of volatile organic compounds The changes were significantly reduced by stabilizing the polymer under low storage temperatures.", Although the polymer was able to maintain its physical and chemical properties at microscopic, BET adsorption, and spectroscopic levels, the intrinsic adsorption properties of hydrocarbons onto MIP binding sites altered over time, which suggest that the 3-D conformational changes of the polymer binding sites occurring at nanoscopic/angstrom level may cause the sensitivity degradation in MIP. In addition, kinetic binding analysis of the MIP-modified QTF sensor was carried out for the sensors stored and operated under ambient conditions (740 mmHg, 20-23 ☌). The MIP was deposited on a quartz crystal tuning fork (QTF) resonator, whose chemical and physical properties were monitored over time, using Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller adsorption isotherm analysis (BET), and Fourier transform infrared spectroscopy (FTIR). The changes were significantly reduced by stabilizing the polymer under low storage temperatures.Ībstract = "The sensing stability and sensitivity of a molecularly imprinted polymer (MIP) selective to the adsorption of hydrocarbons was studied. Differently modified array of QTFs along with the use of LDA can be a useful pathway towards development of a QTF based sensor array for human breath analysis.The sensing stability and sensitivity of a molecularly imprinted polymer (MIP) selective to the adsorption of hydrocarbons was studied. For this purpose, features extracted from sensor responses -shift in resonant frequency, response time and recovery time of the sensors- have been used as features in the model. Linear Discriminants Analysis (LDA) has been used to classify seven different VOCs. Two differently modified QTFs have been used to detect 1 ppm of 1,4-dimethoxy-2,3-butanediol and 20 ppm of cyclohexanone. The sensor has been developed using modified Quartz Tuning Forks (QTFs) with the intent of developing an array of such sensors identifying different VOCs present in a healthy human’s breath. The selectivity of the sensor towards these two compounds in the presence of other VOCs commonly present in human breath like acetone, ethanol and methanol has been studied. CH and BD have been reported to be present in the exhaled human breath of breast cancer patients in ppm levels and can be used to distinguish between a healthy person and a person with breast cancer. Except for BD and CH, the rest of the VOCs are present in a healthy person in ppm levels. In the present work, a sensor has been developed to detect VOCs such as 1,4-dimethoxy-2,3-butanediol (BD), and cyclohexanone (CH), acetone, methanol and ethanol. These changes in the concentration or the occurrence of a particular VOC can be used as signature of a particular disease in a person. Several volatile organic compounds (VOCs) are present in the exhaled human breath whose concentration can vary depending on the physiological changes occurring within a human being.
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