Electrospun nanofibrous chitosan membranes modified with polyethyleneimine for formaldehyde detection

• Innovative fabrication of nanofiber-net-binary structured chitosan membrane.
• Solution–structure relationships were established.
• Polyethyleneimine/chitosan based quartz crystal microbalance sensors were studied.
• Rapid response and low detection limit of 5 ppm for formaldehyde were presented.

Here we describe a formaldehyde sensor fabricated by coating polyethyleneimine (PEI) functionalized chitosan nanofiber-net-binary structured layer on quartz crystal microbalance (QCM). The chitosan fibrous substrate comprising nanofibers and spider-web-like nano-nets constructed by a facile electro-spinning/netting process provided an ideal structure for the uniform PEI modification and sensing performance enhancement. Benefiting from the fascinating nanostructure, abundant primary amine groups of PEI, and strong adhesive force to the QCM electrode of PEI–chitosan membranes, the developed formaldehyde sensor presented rapid response and low detection limit (5 ppm) at room temperature. These findings have important implications in fabricating multi-dimensional nanostructures on QCM for gas sensing and chemical analysis.