Long-term exposure to Pb2+ can cause irreversible damage to the nervous, cardiovascular, and reproductive systems. Therefore, developing a fast and sensitive detection system capable of monitoring minuscule concentrations of Pb2+ is essential. In this study, we have demonstrated a fully portable sensor system enabling rapid, sensitive, and real-time monitoring of Pb2+. The sensor system adopts the remote-gate field-effect transistor (RGFET) detection scheme and is easy to operate, even for non-experts. The sensor system comprises two printed circuit boards (PCBs): a sensor PCB with a remote gate electrode and an analyzer PCB with a metal–oxide–semiconductor field-effect transistor (MOSFET) transducer and peripheral electronics to manage sensor signals. To achieve a high sensitivity for Pb2+, we utilized a graphene ink drop-casted on the sensor PCB as a sensing membrane. The graphene film is straightforward to deposit and remove, enabling the sensor PCB to be reused multiple times. The sensor system is further linked to a smartphone app that instantly monitors the sensor response, allowing for rapid point-of-use detection. The sensor has a high sensitivity of 21.7% when the limit of detection (LOD) value of 1 nM (~0.2 ppb) is being detected, and the typical detection time for each sample is approximately 60 seconds. This portable sensor system advances sensing technologies and could potentially supplement expensive, laborious conventional sensing equipment.

This article is Open Access

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