An integrated opto-fluidic miniaturized multimodal spectroscopic sensing platform for multiplexed electrolyte detection in blood serum.

Accurate and rapid monitoring of electrolytes is critical for the prognosis and treatment of metabolic and electrolyte imbalance-related disorders. In this work, a miniaturized, portable 3D-printed spectroscopic sensing device is developed for multiplex detection of clinically relevant electrolytes in human serum. The developed device integrates a multi-channel spectral sensor with an SLA-fabricated optical reaction microcell and an automated sample handling unit, enabling multimodal optical detection based on absorbance, turbidity, and spectral variation without the need for ion-selective electrodes or bulky spectroscopy instrumentation. The analytical device incorporates a stepper-driven peristaltic pump and a servo-controlled valve mechanism for automated sample aspiration and cleaning, as well as Peltier-based temperature control to maintain consistent reaction conditions. The analytical performance of the device has been evaluated for multiple electrolytes, including sodium, potassium, calcium, magnesium, and phosphorus, using human serum samples with detection limits of 1 mmol/L, 0.3 mmol/L, 0.6 mg/dL, 0.16 mg/dL, and 0.17 mg/dL, and linear range upto 180 mmol/L, 8.5 mmol/L, 20 mg/dL, 5 mg/dL, and 20 mg/dL respectively. The developed platform demonstrated a strong correlation with a commercial clinical analyzer using real serum samples, and Bland-Altman analysis further confirmed the absence of systematic bias, indicating reliable quantitative performance. The system exhibited high repeatability with a low average relative standard deviation (RSD%) of 2.6%, confirming stable optical, fluidic, and electronic performance. The miniaturized spectroscopic approach, combined with integrated microfluidic automation, enables multiplex detection in a compact, low-cost, and compact architecture.