Sensor response of electrospun poly(lactic acid)/polyaniline nanofibers to aliphatic alcohol vapors of varying sizes

Poly(lactic acid)PLA is a biocompatible and biodegradable polyester with lactic acid being a byproduct of decomposition. PLA can be produced via processing starch, it is mechanically robust and environmentally stable and has therefore attracted interest in applications such as biomedical implants, controlled drug delivery and other kitchen variety commodity products. Making PLA electrically conductive via blending it with conducting polymers will extend its range of applications to include electronic devices and sensors. Commercial PLA has a hard grainy morphology, but is readily soluble in organic solvents and can be cast into thin films, fibers, foams or other forms. A fiber typically has a larger surface area to volume ratio compared to films and is thus technologically advantageous for sensor applications. We have successfully prepared conducting PLA/PANi nanofibers at low PLA concentrations in CHCl₃ and used it to sense alcohol vapors of increasing molecular size. The larger the size of the alcohol molecule, the longer it took for the sensor to reach saturation and the sensitivity was smaller. The sensor response times were found to be slower than the recovery times by more than two orders of magnitude for the larger alcohol molecules. Since larger molecules were not able to penetrate the fibers, they were easier to remove. The fiber sensors could be tested on various alcohols without damage and hence were reusable. Conducting PLA based nanofibers therefore present yet another means of fabricating gas sensors and that are biocompatible.