Towards outperforming optical detection of organic liquid via hollow particles and interphase voids based multiple-scattering medium

Abstract

Optical sensor have gained enormous interest because it can be readily used by the general public without extensive training. Among a variety of analytes for the optical sensors, organic liquids are known to be one of the most critical materials. Many of household goods contain organic chemicals and some compounds may be toxic to our health and environment. An easy-to-use detector for toxic organic liquids can be used as an early warning system, preventing harm to community. In organic chemistry, optical sensing of organic compounds allow researchers to monitor and examine the chemical reaction before using expensive equipment. Despite such high demands for optical sensors for organic liquids, ranging from the general population to laboratories with chemicals, however, the realization of optical responses to liquid organic compounds is still challenging. Traditional techniques (using media such as porphyrins and photonic crystals) involve complex preparation and suffer from limited discrepancy between target liquids. Particularly, they also require additional analaysis tools such as spectrometer. Here, amorphous scattering films based on hollow silica and polymer composite are reported as a radically designed optical detector of the organic liquids. In contrast to commonly used optical sensing approaches, our optical sensor has advantages of facie fabrication, fine sensing of chemical species, and naked-eye detection. Its advantages stem from the multiple light scattering medium that is fabricated by one-step method and generates characteristic transparency (opaque, semi-transparent, and transparent) when immerged in organic liquids. This optical change is clearly visible without additional equipment and the response completes within tens of seconds. With the integration of the scattering matrixes into a sensor array, outperforming multi-analyte recognition is obtained between solvents, polymer monomers, and even homologues. It also enables semi-quantitative identification by simple arranging the same medium with different thicknesses into an array.