Solid State Ph And Chloride Sensor With Microfluidic Reference Electrode

We present for the first time a miniaturized multi ion-selective sensor to simultaneously determine pH and chloride (Cl-) levels in fluid. The sensor combines solid state iridium oxide (IrOx) and silver chloride (AgCl) electrodes fabricated on a Si substrate with a microfluidic reference electrode (RE). The drift of the RE is similar to a standard RE while the internal reservoir is orders or magnitude smaller. The drift rate depends on the RE geometry as predicted by a model based on diffusion. The sensitivity, response time and accuracy were determined using solution with known composition, household solutions and samples of sweat and saliva. Overall performance is similar or even exceeds standard, relatively large and expensive ion-selective sensors.