Light-addressable potentiometric sensor with nitrogen-incorporated ceramic Sm₂O₃ membrane for chloride ions detection

A light-addressable potentiometric sensor (LAPS) with ceramic samarium oxide (Sm₂O₃)-sensing membrane treated by nitrogen plasma immersion ion implantation (PIII) has been proposed for chloride ion detection. For the pure Sm₂O₃-LAPS, a potassium ion sensitivity of 39.21 mV/pK is obtained. With the nitrogen PIII treatment on Sm₂O₃-sensing membrane, the N-O peak is observed by X-ray photoelectron spectroscopy, implying the formation of positive charges, (N-O)⁺ and (N-O-N)⁺, within the Sm₂O₃ film. The positive charges can attract the chloride ions to react with the surface sites of OH₂⁺, achieving a superior chloride ion sensitivity of 36.17 mV/pCl for the Sm₂O₃-LAPS with nitrogen PIII treatment. The LAPS structure with ceramic Sm₂O₃-sensing membrane can be used for future biosensing applications, especially for the potassium and chloride ions detection in serum.