Barrier tissues, particularly the endothelium, play a central role in controlling substance exchange across the body. Trans-endothelial/epithelial electrical resistance (TEER) serves as a key bioelectrical indicator of barrier function. While commercial TEER systems exist, they are typically costly, large, and difficult to adapt to specialized experimental configurations such as microfluidic platforms. Building on our previous Arduino-based TEER sensor, this work introduces a significantly improved generation featuring: 1) a wide measurement range of 242–11, 880 Ω·cm² with excellent accuracy (>95%), suitable for most TEER applications, 2) integration with a 3D-printed microfluidic platform that enables modular cell seeding and flow-based experiments, 3) programmable on-off measurement cycles to minimize electrical stress on cells, 4) fully automated long-term recordings with adjustable time intervals. Using this system, we examined the impact of doxorubicin on endothelial barrier function at 1-minute intervals over 24 hours. Endothelial toxicity represents an emerging and poorly understood aspect of cardiotoxicity. At a clinically relevant concentration, barrier integrity remained largely stable until ~16 hours, after which TEER values began to decline (indicating increased permeability), followed by partial recovery. At a higher concentration (2.5 μM), TEER decreased markedly after 5 hours and showed no recovery, suggesting significant endothelial damage. In summary, we introduce a versatile, low-cost TEER platform capable of continuous monitoring of drug effects on barrier tissues. Its adaptable design makes it suitable for diverse applications, including personalized drug dosing on stem-cell-derived barriers and studies of transient permeability changes in disease models.
