Sensors Manufacturing on a 3D-Printed Transwell-Based Hybrid Organ-on-a-Chip for Non-Invasive Real-Time Biological Barrier Resistance Monitoring

Biological barriers in our body are dedicated to maintaining systemic homeostasis by enabling selective transport, the dysregulation of which plays a pathogenic role in several diseases. Transendothelial/epithelial electrical resistance (TEER) analysis is conventionally used to assess the barrier permeability. Engineering TEER setups within advanced in vitro models has become essential for acquiring real-time information on barrier integrity inside organ-on-a-chip (OOC) devices. However, current approaches often involve multiple assembly steps, require external access to the culture chamber, rely on cumbersome systems, or provide highly localized measurements that do not represent the entire surface of the tissue under examination. Specifically, in Transwell-based OOC systems, continuous and nondisruptive monitoring is often precluded by the need to disassemble the system for TEER measurement. To address these limitations, we combined conventional technology for patterning thin conductive films with low-cost, benchtop 3D printing to integrate planar electrodes within a Transwell-based hybrid OOC system. Our integrated TEER electrode device, ITE-MINERVA, can be easily employed with commercial measurement instruments, representing a useful tool for real-time, in situ detection of barrier functionality, potentially altered by drug toxicity and absorption processes, on Transwell-based OOCs, both in single- and multiorgan configurations, noninvasively and without stopping the experiment. In this work, we present the design and fabrication strategy of our innovative setup and its assessment in recording real-time TEER modulation on a Caco-2 cell-based in vitro gut epithelial barrier model.