Organ-on-a-chip systems are miniaturized microfluidic 3D human tissue and organ models designed to recapitulate the important biological and physiological parameters of their in vivo counterparts. They have recently emerged as a viable platform for personalized medicine and drug screening. These in vitro models, featuring biomimetic compositions, architectures, and functions, are expected to replace the conventional planar, static cell cultures and bridge the gap between the currently used preclinical animal models and the human body. Multiple organoid models may be further connected together through the microfluidics in a similar manner in which they are arranged in vivo, providing the capability to analyze multiorgan interactions. Although a wide variety of human organ-on-a-chip models have been created, there are limited efforts on the integration of multisensor systems. However, in situ continual measuring is critical in precise assessment of the microenvironment parameters and the dynamic responses of the organs to pharmaceutical compounds over extended periods of time. In addition, automated and noninvasive capability is strongly desired for long-term monitoring. Here, we report a fully integrated modular physical, biochemical, and optical sensing platform through a fluidics-routing breadboard, which operates organ-on-a-chip units in a continual, dynamic, and automated manner. We believe that this platform technology has paved a potential avenue to promote the performance of current organ-on-a-chip models in drug screening by integrating a multitude of real-time sensors to achieve automated in situ monitoring of biophysical and biochemical parameters.organ-on-a-chip | microbioreactor | electrochemical biosensor | physical sensor | drug screening D rug discovery is a lengthy process associated with tremendous cost and high failure rate (1). On average, less than 1 in 10 drug candidates are eventually approved by the Food and Drug Administration (2), during which successful transition ratios to next phases are roughly 65, 32, and 60% for phase I, phase II, and phase III, respectively (3). Among the primary causes of failure, nonclinical/ clinical safety (>50%) and efficacy (>10%) stand out in the front, more than all other factors (e.g., strategic, commercial, operational) combined (3, 4). These two major causes not only contribute to the low success rates during the drug development but also lead to the withdrawal of approved drugs from the market. Among all of the drug attritions, it is estimated that safety liabilities related to the cardiovascular system account for 45%, whereas 32% are due to hepatotoxicity (5, 6). These high failure/attrition ratios of drugs SignificanceMonitoring 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 reacti...