Polymer-stabilized blue phase liquid crystal sensor for sensitive and selective detection of organic vapors

Polymer-stabilised blue-phase liquid crystal (PS-BPLC) is a soft artificial three-dimensional photonic crystal (PC) functional material for optics and optoelectronics because of its superior optical properties. In this work, we demonstrated that PS-BPLC film could sense and selectively detect the xylene, heptane, cyclohexane, dichloromethane and ethyl alcohol vapours rapidly and accurately. When the PS-BPLC film was alternately exposed to volatile vapours and air, the Bragg reflection wavelength of the PS-BPLC could reversibly and significantly shift because of the adsorption and desorption of the volatile vapours. Different organic vapours could be well discriminated by the linearity and the critical concentration at which the Bragg reflection disappeared. This organic vapour sensor also had a good sensitivity, high repeatability, humidity independence and long-term stability, which promote a widespread use in environmental monitoring, point-of-care biomedical analysis and optical security coatings.