The combination of reduced Graphene oxide and Fluorescein dye serves as a highly selective optical switch for sensing fluoride ion via colorimetric and fluorimetric modes. A turn off stage viz., quenching of optical signal of fluorescein was observed by the formation of a supramolecular assembly between reduced graphene oxide (host matrix) and the dye (indicator). This OFF stage was turned ON instantly with the advent of fluoride ion (guest), with high selectivity. The limit of detection values obtained are 4.2 ppm and 1.7 ppb respectively, via colourimetric and fluorimetric strategy. Solid state test strips of the sensor unit could detect fluoride in aqueous media at concentration down to 3 ppm with the help of UV source.

还原的氧化石墨烯和荧光素染料的组合可作为高选择性光学开关，用于通过比色和荧光模式感应氟离子。通过在还原的氧化石墨烯（主体基质）和染料（指示剂）之间形成超分子组装体，观察到关闭阶段，即荧光素的光学信号的猝灭。随着氟离子（客体）的出现，该OFF阶段立即打开，具有高选择性。通过比色法和荧光法获得的检测极限分别为4.2 ppm和1.7 ppb。传感器单元的固态测试条可以借助紫外线源检测浓度低至3 ppm的水性介质中的氟化物。