A Portable Device for Ca2+ and K+ Measurements in Grapevine Sap and Berry Juice Based on Flexible and Printed Organic Electrochemical Transistors

This paper presents a portable electronic device for the on-field measurements of Ca2+ and K+ concentrations, in grapevine sap and berry juice. The sensing element is an Organic Electrochemical Transistor (OECT) for cations detection, printed on flexible substrate. The electronics is designed for the minimum size, long stand-alone device lifetime, embedding wireless network communication. In measurements, the OECT sensor shows a good linearity over a large range of molar concentration for KCl and CaCl2 solutions. The full device has proven to correctly acquire cations concentrations from solutions, grapevine xylem sap, and grape berry juice.