Charge transfer complex-forming dyes incorporated in solid polymer electrolyte for optical humidity sensing

Our experimental observations shows that certain dyes when incorporated in solid polymer electrolytes (SPE) can serve as an excellent candidates for optical humidity sensing. Crystal Violet (CV) and Methylene Blue (MB) are incorporated in PVA/H3PO4, which is known to be a SPE and a good proton conductor. Films of PVA/H3PO4 containing dyes are studied for use in optical humidity sensing and the interesting results are discussed in this paper. A mechanism is proposed for the changes observed in the optical properties of such films by the variation of humidity.