Metal ion-responsive photonic colloidal crystalline micro-beads with electrochemically tunable photonic diffraction colours

Du, X., Chiu, S. H.-M., Ong, D. H.-C., Vellaisamy, R. and Lam, M. H.-W. (2016) Metal ion-responsive photonic colloidal crystalline micro-beads with electrochemically tunable photonic diffraction colours. Sensors and Actuators B: Chemical, 223, pp. 318-323. (doi: 10.1016/j.snb.2015.09.116)

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Abstract

This work reports a metal ion-responsive photonic colloidal crystalline (PCC) microspheric material and the convenient, reversible switching of its photonic diffraction properties by the redox reaction of copper in a simple electrochemical cell. The PCC micro-beads were fabricated from the orderly three-dimensional packing of core-shell nanoparticles with hydrogel coatings laden with anionic phosphate functionalities. Electrostatic binding of metal cations by the hydrogel coating lowered its internal osmotic pressure and caused shrinkage of the core-shell nanoparticles. This brought about a blue-shift of the photonic diffraction λmax of the micro-beads. The maximum shift, from 650 to 590 nm (colour change from magenta to green) was found to be produced by Cu2+ at a concentration of 1 mM. A simple electrochemical photonic device was constructed by sandwiching a suspension of the photonic micro-beads in 1 mM Cu2+ solution between two transparent ITO-glass electrodes. Photonic diffraction colour of the micro-beads was reversibly switched via the electrochemical reduction/oxidation of Cu2+ inside the device. The colour change can be observed by naked eyes under ambient light. This concept of rapid electrochemical regulation of photonic diffraction colour of PCC micro-beads may be useful in reflective displays applications.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Vellaisamy, Professor Roy
Authors: Du, X., Chiu, S. H.-M., Ong, D. H.-C., Vellaisamy, R., and Lam, M. H.-W.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Sensors and Actuators B: Chemical
Publisher:Elsevier
ISSN:0925-4005
ISSN (Online):1873-3077
Published Online:28 September 2015
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