Optical sensor for butylamine vapour based on the photonic structure infiltrated by liquid crystal

We propose an optical sensor based on the inverse opal (IOP) photonic structure infiltrated by a typical liquid crystalline material doped by the reactive compounds. Benefiting from the unique photonic property of the IOP structure, the composite sensor shows not only a typical textural change but also a responsive photonic band gap (PBG) upon the exposure to butylamine (BA) vapour, due to the reorientation of the liquid crystalline molecules induced by the chemical reaction between the dopant and the BA vapour. This approach simplifies the measurement process by capturing the PBG signal instead of the polarised optical texture, which does not require high cost or complex instruments and might be instructive for detecting other volatiles.