Temperature Sensitive Characteristics Of A New Holographic Gel Sensor Based On Hydroxyethyl Methacrylate

Holographic sensor has a high degree of visualization,can provide colorful,graphic threedimensional and beautiful intuitive sensing marking.It has extremely important application value in the field of cheap,high visualization,narrow response spectrum and simple preparation of universal sensing.In this paper,a new polyhydroxyethyl methacrylate photosensitive gel was prepared by thermos-induced polymerization using phenanthrenequinone as photosensitizer.The transmission and reflection holographic gratings are written inside the material and used as the response unit of the holographic sensor.The temperature sensitivity and PH sensing response characteristics of the new holographic sensor are tested.The main work is as follows:(1)Using 473 nm and 532 nm green light as recording light source and using double-beam interference principle,two kinds of holographic gratings are recorded in the material.The moving trend of the peak diffraction spectrum of the grating with the increase of temperature was measured experimentally.When the temperature rises to 60 ?,the peak wavelength of diffraction spectrum of transmission grating produces 4nm red shift.The peak wavelength of diffraction spectrum of reflective grating also produces about 3nm red shift.The peak intensity of the diffraction spectrum of the transmission grating decays close to 80% of the peak value when the temperature increases,while the reflective grating decays to 40% of the peak value.The experimental results show that the effect of reflective grating on temperature is weak.This has a certain reference value for the environmental characteristic response of the holographic sensor,especially for the PH sensing response of the solution.The measurement of the average refractive index with temperature shows that the thermal expansion of the material is the main cause of wavelength red shift.(2)Using methacrylic acid as selective sensing response monomer,a new polymer gel holographic sensor with solution PH sensing response was obtained by cross-linking copolymerization.The response process of diffraction spectra of reflective gratings in different PH buffers was measured.The experimental results show that the sensor can exist stably in aqueous solution.Although the material can adsorb and expand the solution,the acidity and alkalinity of the solution will make a significant difference in the degree of expansion of the material.With the increase of PH value,the inhibition time and response time constant of gel expansion process were significantly shortened,and the corresponding expansion degree increased at the same time.In the process of buffer sensing,there is a good linear relationship between the steady-state peak wavelength shift of the grating and the PH value.The repeated tests of the two PH solutions show that the PH holographic sensor has high stability and reversibility.Therefore,the sensor based on polyethyl methacrylate gel is a new holographic sensor which can be used to sense the characteristics of solution.The experimental results provide an important experimental basis for the application of the device.