Active visualized solvent sensor based on copolymer hydrogel photonic crystals containing white LEDs

This study demonstrated the achievement of rapid chemical solvent detection by a copolymer hydrogel photonic crystal sensor (CHPCS) created by a simple infiltration of the copolymer hydrogel precursor inside the voids of three-dimensionally opal photonic crystal templates. CHPCS with strong mechanical strength was used as copolymer poly(HEMA-co-MMA-co-NVP) hydrogel and composite poly(St-co-AA-co-MMA) sub-microspheres. CHPCS was immersed in different chemical solvents, including alcohols (hydroxyl compounds) and acetone (carbonyl compounds). The interlayer spacing of CHPCS was swollen and exhibited optical diffraction, which could be detected by the optical measurements and theoretical prediction based on the Bragg diffractive theory. We proposed and demonstrated that CHPCS combined with white LEDs could serve as active naked eye detection solvent sensors that further exhibit great potential as real-time monitoring detectors for chemical solvents.