Integrated Phosphate and pH Sensing System for Water Quality Monitoring

Cobalt (Co) ion selective electrode (ISE) has been studied for selective phosphate detection. As the electromotive force (EMF) response of this electrode to phosphate is affected by surrounding pH conditions, it has not been readily utilized for in-situ monitoring. In this work, we present an integrated Co based phosphate and antimony (Sb) based pH sensing system, which enables us to monitor precise phosphorous concentration taking into account a local pH level in aqueous solution. Platinum is used as the reference electrode. An extremely broad sensing range of phosphate concentration with 9 orders of magnitude concentration ranging between $5\times 10^{-3}$ to $5\times 10^{-12}$ M is reported. The sensing sensitive of 5 pM is one of the best reported in this kind of sensors in literature. Also, simultaneous detection of pH and phosphate concentration is presented using integrated wireless Bluetooth module. The total area of the fabricated sensor is 4 cm2.