Embedded, Multimodal (TEER, EIS, Transparency) Sensing Chips for In Vitro Cellular Models

In this letter, we introduce a pioneering sensing system for multimodal sensing that utilizes microfabricated electrodes fabricated out of several electrode materials on glass wafers, achieving an impressive 98% fabrication yield. Our approach leverages a direct-write laser lithography process, where meticulous tuning of process parameters results in well-defined undercut profiles and a highly efficient lift-off process. The glass chips are subsequently packaged at the wafer-level using 3D-printed culture wells and soldered connections. Employing full-spectrum electrical impedance spectroscopy measurements, we characterized the electrode materials and extracted the 12.5 Hz value to determine baseline transendothelial/transepithelial electrical resistance values without cells of 6356 Ω·cm² for indium tin oxide (ITO), 4834 Ω·cm² for Ti/Au, and 5522 Ω·cm² for Ti/Pt. These measurements represent the first direct, quantitative comparison of these electrode materials under acellular conditions, establishing a robust electrical baseline for future biological model integration. In addition, the high transparency of ITO (83.37%) demonstrates multimodal sensing that combines both electrical and optical interrogation, paving the way for comprehensive biosensing applications.