Research On Photochromic Composite Based Optical Sensing And Detecting Device

At present,sensing technique is generally focused on optical signal responses.Therefore,it is an urgent need to develop sensing and detection devices for all-optical communication uses.With the development of material science,it is possible to design and utilize various functional materials to manufacture sensors with excellent performance,which brings new opportunities for the development of modern sensing technology.Spiropyran is one of the earliest and most widely studied organic photochromic materials.Under UV exposure conditions,spiropyranoids can produce photochromic phenomenon,and their molecular structure is converted to the form of anthocyanins,which further fluoresces in visible light under UV excitation.In addition,hydrogen chloride will protonize the anthocyanin molecules,resulting in the disappearance of its fluorescence,and the above process is reversible.This determines the application of spiropyran in optical sensing detection and other aspects.Spiropyran has more advantages as a photochemical sensor material than other colorimetric and fluorescent probes in detecting organic and inorganic target molecules due to its light conversion ability.By using external and non-invasive stimuli,such as light field stimuli,the interaction of spiropyran with the substance can be controlled,and thus extending its application.In this thesis,a spiropyran doped polydimethylsiloxane device was developed by studying the photochromic characteristics of spiropyran and combining with the transmission ability of optical fiber.The device is designed to detect the ultraviolet light intensity and HCl concentration.The research contents are as follows:（1）A spiropyran doped polydimethylsiloxane composite is fabricated and investigated.The properties of spiropyran doped polydimethylsiloxane composites are demonstrated by the changes of the color,absorption and fluorescence spectra of the composites under UV irradiation and HCl gas.（2）The response fluorescence of spiropyran is effectively collected into the spectrometer by using the waveguide ability of the capillary,which greatly enhanced the fluorescence intensity detected,and thus improves the sensing detection range of the device.By such strategy,the ultraviolet light intensity and the concentration of HCl gas can be detected with higher precision.By studying the effect of spiropyran doping concentration on the fluorescence and absorption spectra of the device,the fabrication method and the performance of the device is further optimized.The device is small in size,light in weight,simple in structure and easy to fabricate.It realizes the proposed device is able to detect a large range of ultraviolet light intensity and a sub-ppm concentration of HCl gas,and is easily compatible with optical fiber transmission system.It provides a new technique for the development of sensing and detection devices for all-optical communication uses.