Detection of formaldehyde vapor using conductive polymer films

We have developed conductive elements incorporating thin poly(aniline)/poly(ethyleneimine) composite films prepared by spin casting and report on their characteristics for formaldehyde detection via changes in conductivity. We find significant increases in the resistance, for example greater than 10 kΩ at a concentration of 38 ppm exposed for 1 min, of these films upon exposure to formaldehyde vapor in a laboratory gaseous exposure chamber. The films are less responsive to other volatile organic vapors, such as methanol, acetone and dichloromethane. The morphology of the films was analyzed by scanning electron microscopy, which indicated a porous surface well suited to vapor phase adsorption.