Coloration of colloidal polymer particles through selective extraction of Mie backscattering for cation-responsible colorimetric sensors

Mie backscattering-based coloration of water-dispersed polymer particles is investigated. Diluted colloids and light absorber-added colloids are individually prepared to study the scattering properties. Light absorber-added colloids show ~2.9-fold higher colour saturation than diluted colloids because of the effective elimination of Mie forward scattering. Mechanism of selective extraction of Mie backscattering-based colour in the presence of light absorbers is explained by path length difference of Mie forward and backscattering. Using stimuli-responsive polymer particles, Mie scattering colour-based sensors that respond to pH and heavy metal ions are prepared.