Tricolor dual sensor for ratiometrically analyzing potassium ions and dissolved oxygen

A potassium ion‑oxygen (K–O) dual fluorescent sensing film was developed. The film contains three probes, which are K probe (KS), O probe (OS), and reference probe (RP) in a polymer film composed of poly(ethylene glycol) methyl ether methacrylate (PEGMA), poly(ethylene glycol) dimethacrylate (PEGDMA) and methacrylic acid (MAA). The RP showed blue emission, the KS exhibited green emission, and the OS showed red emission. The emission peaks of three probes do not interfere with each other, which enable the sensing film to be used for ratiometrically and quantitatively detecting the concentrations of K and dissolved oxygen (DO). The sensing films showed high sensitivity and selectivity to potassium ions over other metal ions and also good sensitivity for DO from deoxygenated to oxygenated conditions. The sensing film was demonstrated to be capable of analyzing K and DO concentrations with experimental errors smaller than ±8.5% in aqueous solutions, showing the potential applications of the sensing films.