Photonic crystal based optical chemical sensor for environmental monitoring

The nanostructured materials such as nanoparticles have great possibilities as a novel sensing device. In this study, development of the photonic crystal based optical chemical sensor for environmental monitoring was aimed. The sensor consists of a glass substrate with a three-dimensional photonic crystal using nanoparticles and poly(dimethylsiloxane) (PDMS) elastomer. Such a photonic crystal was generated by infiltrating the voids within an opaline lattice of nanoparticles with a liquid prepolymer to PDMS, followed by thermal curing. When a nonpolar organic solvents capable of swelling the elastomer matrix, was introduced to the surface of this sensor, the lattice constant and thus the wavelength of Bragg diffracted light was increased. On the basis of this mechanism, we demonstrated the detection of volatile organic compounds (VOCs). As a result, this photonic crystal based optical chemical sensor could be used to specifically determine the VOCs concentrations. Additionally, using this photonic crystal based optical chemical sensor, the change in the optical characteristics could be observed with the naked eye. Therefore, this optical chemical sensor can be applicable to on-site monitoring for environmental applications.