Inkjet Printed Graphene Sensors for Electrochemical Detection of Phosphates

Phosphate is an essential element in our eco-systems, regulating biochemical reactions starting form living matter/biological cells to environmental presence such as in soils. Both limitation as well as over exposure of phosphates can cause detrimental consequences. As such, continuous monitoring of electrochemically inactive phosphates in real samples is crucial for studying number of applications, such as soil health to human health. The present study aimed at developing graphene-based inkjet printed electrochemical sensors to identify different phosphate ions. Large scale exfoliation of few-layer graphene material was synthesized by liquid phase exfoliation from bulk stacked graphite samples, with an effort to achieve highly conductive graphene inks. Defined patterns of sensing electrodes were fabricated using additively manufactured graphene inks with aid of inkjet printing method. The few-layers of exfoliated graphene was uniformly patterned onto the flexible substrate and forms low resistive conducting network. Structural and morphological characterizations are provided to aid large charge transfer in electrochemical cell. Molybdenum based redox electrochemical species on printed graphene electrodes was applied for wide concentration range detection of phosphates using cyclic voltammetry and amperometry. The performance of inkjet printed electrodes was validated with commercial electrodes by different electrochemical sensor characterization parameters such as sensitivity and limit of detection which showed superior results. The additive manufacturing and phosphate sensing performance of graphene based inkjet printed electrodes could be further utilized for monitoring real-time phosphate sensing using a portable hand held potentiostat.