Sensor ToolKit (STK): Compact Multiplexing Potentiostat for Point-of-Care Applications

Embedded potentiostats have enabled the possibility of implementing electrochemical applications in a wide range of areas, from industry to healthcare. However, the optimization for either small size, low-cost devices, or sensor interfacing in existing platforms may lead to impractical outcomes. In this work, we propose Sensor ToolKit (STK), prototyped using off-the-shelf components and engineered to be a highly versatile, small, and low-cost platform of minimal complexity for the deployment of distributed IoT electrochemical sensors applications. The board implements an on-chip sequential input multiplexer that is especially suited for open-circuit potentiometry studies. The performance of the board was validated in potentiometric detection of potassium, hydrogen peroxide, glucose, and lactate, as well as self-current detection of hydrogen peroxide. Results show excellent analytical performance, comparable to that of benchtop instrumentation standards. The developed firmware and IoT framework enable the retrieval of sensor data wirelessly by a remote data server, which automates its real-time visualization using the Grafana web application, highlighting the potential of STK in distributed hyperconnected applications.