Design and development of an electrochemical sensor for real-time lithium monitoring: Safer and smarter patient care

• Electrochemical sensor based on LiMn₂O₄, GO, and pyrrole electrodeposited on SPCE. • The LGOPy sensor showed high sensitivity, stability, and reproducibility in biofluids. • Non-invasive real-time lithium monitoring in clinically relevant ranges. • Lithium detected in urine, saliva, and blood with LoDs from 141.1 to 162.2 nM. • Disposable low-cost sensor with fast detection time response. Lithium is a first-line treatment for bipolar disorder, but its narrow therapeutic window requires constant monitoring to avoid both deficiency and overdose, which may lead to severe adverse effects. Rapid, simple, and minimally invasive detection methods are therefore essential for real-time lithium monitoring and for reducing patient discomfort associated with conventional invasive procedures. In this work, a lithium sensor based on LiM n 2 O 4 spinel, graphene oxide (GO) and pyrrol (Py) electrochemically deposited on screen-printed carbon electrodes (SPCEs) for lithium analysis in biological fluids was developed. The LGOPy film was characterized using Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and electrochemical techniques. Linear scan voltammetry revealed two lithiation-related peaks, with the first lithiation step enabling amperometric detection of lithium at −0.25 V. In buffered aqueous solution, the sensor achieved a limit of detection (LoD) of 0.076 µM. In urine, saliva, and whole blood, lithium LoDs ranged from 0.141 to 0.162 µM, values well below the therapeutic lithium range. These results demonstrate that LGOPy-modified SPCEs provide a fast, sensitive, robust, and cost-effective platform for real-time lithium quantification in biological fluids.