Porous Poly(vinyl alcohol)/Carbon Nanotube Sensitive Layer for Detection of Lung Cancer Biomarkers

Introducing the porosity into the conductive polymer composite (CPC) sensitive layer improves the performance parameters of the prepared gas detectors.

In this research, porous poly(vinyl alcohol)/carbon nanotube (CNT) composite was used as the sensitive layer for detecting methanol, ethanol, and water (as lung cancer biomarkers). Vapor-induced phase separation method was used for introducing the porosity into the polymer matrix. The solution consisted of 2% (by wt) polymer in water and 4% (by wt) CNT. The film was exposed to the acetone vapor for introducing the porosity. The morphology of the prepared porous composite was investigated by SEM and BET tests. The responses of prepared sensitive layers toward the target analytes were analyzed by a home-made apparatus.     

The SEM images indicated the porous structure of the composite with nodular structures. Also, the BET test indicated the remarkable increase in the specific surface area of the porous composite in comparison with the dense one. The results showed that the specific surface area was increased to10.93 m2/g for porous composite. The final results illustrated the remarkable improvement in performance parameters such as response time and sensitivity in porous composites. The lower level of detection (LLD) of dense and porous composites toward water vapor was equal to 1000 and 50 ppm, respectively. Such enhancement was related to the increasing the specific surface area of the composite, and consequently, increasing the accessibility of analyte molecules to the sensitive sites of CPCs. Also, the response of the prepared sensitive layer was investigated based on the thermodynamic. The final investigations indicated that δa correctly explained the sensitivity of prepared CPCs.