Planar waveguide ion-selective sensors

A potassium ion-selective planar waveguide total internal reflection (TIR) mode optical sensor was prepared for flow injection application by casting thin film optode membranes onto a glass substrate. For this sensor, a potassium selective ionophore is incorporated in plasticized polyvinyl chloride film sensitized with a hydrogen selective ionophore. The sensor response to potassium ion is determined by measuring the attenuation of a HeNe laser propagated in this thin film device. The laser was coupled into and out of the sensor using grating couplers providing an inexpensive, environmentally stable sensor. The sensitivity of the waveguide based flow injection device is approximately 0.05 mM K+, while the rate of analysis is about 180 samples per hour.