Significance: Monitoring human organ-on-a-chip systems presents a significant challenge, where the capability of in situ continual monitoring of organ behaviors and their responses to pharmaceutical compounds over extended periods of time is critical in understanding the dynamics of drug effects and therefore accurate prediction of human organ reactions. In this work, we report a fully integrated modular physical, biochemical, and optical sensing platform, interfaced through a fluidics-routing breadboard with a multi–organ-on-a-chip system to achieve in situ, continual, and automated sensing of microenvironment biophysical and biochemical parameters. It is anticipated that our platform technology that is conveniently compatible with existing organ-on-a-chip models will potentially enhance their performance in drug screening by providing a multitude of sensing data not previously available.

Development of an efficient sensing platform capable of continual monitoring of biomarkers is needed to assess the functionality of the in vitro organoids and to evaluate their biological responses toward pharmaceutical compounds or chemical species over extended periods of time. Here, a novel label‐free microfluidic electrochemical (EC) biosensor with a unique built‐in on‐chip regeneration capability for continual measurement of cell‐secreted soluble biomarkers from an organoid culture in a fully automated manner without attenuating the sensor sensitivity is reported. The microfluidic EC biosensors are integrated with a human liver‐on‐a‐chip platform for continual monitoring of the metabolic activity of the organoids by measuring the levels of secreted biomarkers for up to 7 d, where the metabolic activity of the organoids is altered by a systemically applied drug. The variations in the biomarker levels are successfully measured by the microfluidic regenerative EC biosensors and agree well with cellular viability and enzyme‐linked immunosorbent assay analyses, validating the accuracy of the unique sensing platform. It is believed that this versatile and robust microfluidic EC biosensor that is capable of automated and continual detection of soluble biomarkers will find widespread use for long‐term monitoring of human organoids during drug toxicity studies or efficacy assessments of in vitro platforms.

Nanoscale extracellular vesicles (EVs) including exosomes (50–150 nm membrane particles) have emerged as promising cancer biomarkers due to the carried genetic information about the parental cells. However the sensitive detection of these vesicles remains a challenge. Here we present a label-free electrochemical sensor to measure the EVs secretion levels of hypoxic and normoxic MCF-7 cells. The sensor design includes two consecutive steps; i) Au electrode surface functionalization for anti-CD81 Antibody and ii) EVs capture. The label-free detection of EVs was done via Differential Pulse Voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS). The working linear range for the sensor was 10²–10⁹EVs/ml with an LOD 77 EVs/mL and 379 EVs/ml for EIS and DPV based detection. A blood-abundant protein, RhD was used for the selectivity test. In order to assess the performance of the biosensor, the level of EVs secretion by the human breast cancer MCF-7 cell line was compared with enzyme-linked immunosorbent assays (ELISA) and Nanoparticle Tracking Analysis (NTA). Designed label-free electrochemical sensors utilized for quantification of EVs secretion enhancement due to CoCl₂-induced hypoxia and 1.23 fold increase with respect to normoxic conditions was found.