Development of a real-time and multitasking system for long-term monitoring of aqueous metallic elements using plasma...

In this work, we integrated a Raspberry Pi (RPi) board, an open-sourced hardware, with a spectrometer, a high voltage DC power source, and a plasma system to develop a multi-tasking monitoring system for metallic elements in solution. In this system, RPi precisely controls voltage pulses, synchronizes them with the spectrometer, and performs real-time analysis using data acquired in real-time. This integration enables continuous monitoring of multiple metallic elements in solutions of varying conductivities. Synchronization of voltage pulses and spectrometer triggering is crucial for reliable measurements and prolongs the lifetime of the electrode. This multitasking capability significantly improves the quality of the overall spectroscopic data and enables operation in a long-term manner. Two operating modes are proposed, namely regular detection mode (RDM) and event-based mode (EBM). RDM is used to identify the existence of metallic elements and EBM is used for quantification upon detection. A 24-h long-term test shown in this work demonstrates the system capability in of utilizing RDM to monitor the presence of Pb and Mg every 30 min. Injection of Pb- and/or Mg-containing solutions is performed to activate EBM for quantification analysis. Instant warning messages can be sent upon metal detection showcasing the system potential for real-time monitoring and efficient quantification. We believe this work can contribute to multiple fields such as environmental monitoring, industrial quality control, or process monitoring.