A novel gas sensor using polymer-dispersed liquid crystal doped with carbon nanotubes

This study presents the development of a novel chemical sensor that uses a sensing film consisting of a polymer-dispersed liquid crystal (PDLC) doped with carbon nanotubes (CNT) for acetone detection. The sensing element comprises a PDLC sensing film and planar interdigital electrode pairs. Chemical gas can be detected by measuring the changes in the electrical resistance of the sensing film caused by the orientational ordering transitions of the CNT and LC. The PDLC film in a rubbery state can be easily packaged and stabilized against mechanical shock. The devices can operate with a simple read-out circuit. The sensor gives a linear response for gas concentration from 100 to 1500 ppm, and the response time is less than 32 s. The influences of the film thickness and LC mixing ratio are also discussed.