Visual Film Sensors for Organic Vapors Based on Functional compounds-infiltrated SiO2 inverse opal photonic crystal

Y. Zhang, J. Qiu, L. Mu
Yan'an University,
China

Keywords: volatile organic compounds, photonic crystals, sensing

Summary:

Volatile organic compounds (VOCs), which have been commonly found in atmosphere, soil, and groundwater, can damage the human liver, kidney, immune system and nervous system through the skin, breathing and eating.1,2 Here, we developed some functional compounds infiltrated SiO2 inverse opal photonic crystals (SiO2 IOPC), whose stopbands can be shifted reversibly in visible light region when they are alternately placed VOCs and air, accompanied with reversible color change.3-5 For example, the stopband of the silole-infiltrated SiO2 IOPC had a red shift more than 100 nm (Figure B), and the color changed from green to red clearly when the film was put in diethyl ether or petroleum ether vapor. After that, when exposed to air, the stopband had a blue shift and the color turned back to green (Figure C).4 The reversible aggregation state transfer, adsorption/desorption of organic vapors, and the effective refractive index of the film varied repeatedly caused the reversible stopband shift and color change. A tetraphenylethene polymer infiltrated SiO2 IOPC can also be used to visual detection of tetrahydrofuran and acetone, in which a red shift more than 50 nm of reflectance peak due to increase the IOPC’s effective refractive index caused by the strong adsorption of TPEP, companying with the color change from violet to cyan clearly (Figure D).5 The visual detection of organic vapors can be realized by remarkable color change of the IOPC film, which provides a simple way for monitoring volatile organic compounds and is of importance for chemical and biological sensors.