(152d) Acoustic Wave Sensor Based on Plasticized Polymer Films for Detection of BTEX Compounds in Air | AIChE

(152d) Acoustic Wave Sensor Based on Plasticized Polymer Films for Detection of BTEX Compounds in Air


Iyer, A. - Presenter, University of South Florida
Campbell, S. W., University of South Florida
Bhethanabotla, V., University of South Florida
Although a variety of sensor technologies are available for environmental monitoring like photoionization, gas chromatography, mass spectroscopy, and e-noses sensors, chemical sensors based on piezoelectric transduction like the quartz crystal microbalance (QCM) and surface acoustic wave (SAW) device show promising results in terms of providing cost-effective real- time data, robustness, and low power requirements. Sensing films based on polymer-plasticizer films have been developed to detect the volatile organic compounds in the air, primarily benzene, ethylbenzene, toluene, and xylene (BTEX) using acoustic wave devices. This work shows for the first time how the selectivity and sensitivity of a glassy polymer film can be altered by adding a precise amount and type of plasticizer for BTEX detection.
To quantify the film saturation dynamics and understand the absorption of BTEX analyte molecules into the bulk of the sensing film, a diffusion study was incorporated to interpret the frequency vs time curve from a QCM. The sensor responses for individual analytes like benzene, toluene, etc. were collected and fit to exponentials which gives a characteristic value for response time, tau for individual analytes like benzene, toluene, ethylbenzene, and xylene which were found to be independent of the concentration of the analyte, thus helping in identifying the analyte. The model was also able to quantify individual analyte concentrations from the mixture based on the
difference in tau values using a single polymer-plasticizer film on a single sensor. Several polymer/plasticizers materials and concentrations were screened to optimize the film for best BTEX sensing performance.
Quantifying BTEX concentrations from a mixture has always been challenging due to similarity in the chemical, physical, and molecular properties of the constituents. In this work, a single polymer-plasticizer film-based sensor has been employed to detect and quantify BTEX components in air based on sorption properties (solubility, partition coefficient, tau) as opposed to the traditional approach of using sensor arrays.