| The high-resolution pH detection has important research significance in biochemistry,food,marine environment and pharmacy.In some conditions,people prefer naked-eye detection methods with low cost and no energy consumption rather than pH meter and other instruments to achieve high-precision detection.However,the pH paper used for naked-eye detection cannot achieve high-resolution naked-eye detection due to its limited color change range and low color saturation.The recently developed photonic crystal colorimetric sensor has the color change range and high color saturation covering the whole visible spectrum,which is expected to achieve the instrument resolution(0.01 pH).However,the existing photonic crystals cannot maintain the structure order in the gel with low crosslinking degree and high fixed charge density,resulting in their low sensitivity.In view of the above problems,this paper forms a high-sensitivity pH photonic crystal colorimetric sensor by combining 1-D magnetic photonic crystal with a high concentration of functional groups and low crosslinking degree gel based on the characteristics of the steric hindrance photonic crystal which is not interfered by ionic strength.The sensitivity of the photonic crystal pH sensor is improved by an order of magnitude(1000 nm/pH),and the resolution reach the instrument level(0.01 pH)by naked-eye detection.The method and principle of stable retention of photonic crystal ordered structure in responsive gel are studied.The influence of the component and structure of the sensor on the sensitivity is investigated as well as the motion characteristics of the photonic band gap.The main research contents of this paper are as follows:(1)The naked-eye detecting resolution of high sensitivity photonic crystal colorimetric sensor could reach common instrument in horizontal(0.01 pH),and has good brightness and color saturation for the colorimetric detection,with shorter response time and good cycle stability,convenient to use,fast and stable way of naked-eye pH test.(2)The constructs principle of high sensitivity photonic crystal colorimetric sensor: using superparamagnetism Fe3O4 @ PVP(polyvinyl pyrrolidone)nanoparticles as primitives,to overcome the electrostatic repulsion primitives affected by ionic monomers,and magnetic assembly 1-D photonic crystals with high gel proportion,using magnetic assembly and homogeneous solution in-situ polymerization method for preparation of the high sensitivity photonic crystal colorimetric sensor.(3)The preservation of ordered structure in the preparation of photonic crystals: with a choice of polymerization and the precursor composition during the preparation of photonic crystals,to ensure the ordered structure of photonic crystal in the precursor and polymerization are not destroyed,and the sensor has high brightness and color saturation,provides the basis for open hole colorimetric detection.(4)Control of sensor sensitivity and pH detection range: pH response property of the sensor was changed by exploring factors affecting the swelling performance of the gel,such as the cross-linking degree,monomer type and copolymerization ratio.The problem of limited color variety of colorimetric detection is compensated by means of hierarchical detection,and the high-resolution detection of wide pH detection range is realized.(5)To prepare a photonic crystal colorimetric sensor that can be used for highresolution detection of the humoral environment.It can read whether the pH of the humoral fluid is within the normal range of the human body by comparing with the colorimetric card.It provides a convenient and fast way for the detection and online monitoring of the humoral fluid,which is not limited by the energy consumption and the size of the detection environment. |
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