%0 Journal Article
%T Photonic Crystal-Based Sensing and Imaging of Potassium Ions
%A Christoph Fenzl
%A Michael Kirchinger
%A Thomas Hirsch
%A Otto S. Wolfbeis
%J Chemosensors
%P 207-218
%D 2014
%I MDPI AG
%R 10.3390/chemosensors2030207
%X We report on a method for selective optical sensing and imaging of potassium ions using a sandwich assembly composed of layers of photonic crystals and an ion-selective membrane. This represents a new scheme for sensing ions in that an ionic strength-sensitive photonic crystal hydrogel layer is combined with a K +-selective membrane. The latter consists of plasticized poly(vinyl chloride) doped with the K +-selective ion carrier, valinomycin. The film has a red color if immersed into plain water, but is green in 5 mM KCl and purple at KCl concentrations of 100 mM or higher. This 3D photonic crystal sensor responds to K + ions in the 1 to 50 mM concentration range (which includes the K + concentration range encountered in blood) and shows high selectivity over ammonium and sodium ions. Sensor films were also imaged with a digital camera by exploiting the RGB technique.
%K photonic crystal
%K chemical sensor
%K hydrogel
%K RGB readout
%K potassium sensing
%K imaging
%U http://www.mdpi.com/2227-9040/2/3/207