In Situ Investigation of Small Molecule Mass Transport in Sensor-Based Organ-on-Chip Systems

The supply of 3D cell cultures with oxygen, nutrients, and drugs is essential for organ-on-chip systems. However, the exact mass transport properties of extracellular matrix materials are often not precisely known. For the first time, we report on a microfluidic lab-on-chip system with integrated electrochemical microsensors that allow the direct measurement of small molecule diffusion in hydrogels using a time-of-flight method and, thus, enable the precise determination of diffusion coefficients within an organ-on-chip setting. In contrast to optical approaches targeting only large dye molecules, measuring the small molecule cellular metabolites such as oxygen and reactive species directly provides essential information for microfluidic drug screening and cancer research experiments.