Electrochemical biosensor microchip platform for rapid whole-blood chloride ions quantification in CKD point-of-care monitoring

Chloride ion imbalance serves as a sensitive indicator of fluid status and disease progression throughout chronic kidney dysfunction, but conventional measurements remain confined to centralized analyzers that slow clinical decision-making. An electrochemical microchip platform now enables direct quantification from only 16 μL of whole blood in approximately 2 min, without centrifugation or external pumping. During lateral transport across the paper matrix, blood cells are progressively removed, forming a stable serum zone prior to reaching the sensing interface. Within this clarified region, a silver-modified screen-printed carbon electrode produces a well-defined linear sweep voltammetry signal. Two calibration intervals provide strong linearity across physiologic and pathological ranges (1–40 mM, R 2 = 0.9907; 40–120 mM, R 2 = 0.9974). Measurements from chronic kidney disease specimens closely match indirect ion-selective electrode readings, with recoveries of 103.6 % for serum (n = 50) and 104.6 % for whole blood (n = 10). The disposable format reduces testing burden, supports near-patient electrolyte evaluation, and establishes a practical platform for future AI-assisted longitudinal renal monitoring.