Development and validation of a low-cost, direct-current-based biosensor for real-time monitoring of transendothelial...

Real-time monitoring of biological barrier integrity is crucial for drug development and disease modeling. The gold-standard technique, transendothelial electrical resistance (TEER), is often limited by the cost and complexity of commercial alternating current systems. To address this, we developed a novel, low-cost biosensor based on a direct current (DC) series voltage division principle, featuring custom hardware and open-source firmware. Validation demonstrated a wide dynamic range (155-105 600 Ω cm2) and high accuracy (±3%). The device showed excellent correlation with a commercial EVOM3 system in monitoring TEER trends during endothelial barrier formation and oxidative stress-induced disruption. Biosensor readings were consistent with barrier kinetics captured by xCelligence RTCA and live-cell imaging. Furthermore, a strong negative correlation was established between decreasing TEER values and increasing paracellular leakage of sodium fluorescein. These results collectively validate our DC-based system as a reliable, accurate, and accessible tool for quantifying in vitro barrier integrity, with significant potential to democratize research in biomedicine and toxicology.