PROJECT SUMMARY/ABSTRACT Human organoids are miniaturized model systems of organs produced by three-dimensional (3D) cultures of tissue-resident-adult stem cells (ASCs) or pluripotent stem cells (PSCs) in vitro. They have emerged as a promising platform for modeling tissue development and disease, personalized medicine development, drug screening and drug toxicity investigations. Despite their great potential, current human organoids suffer from immature structure and functionality, limited heterogeneity, as well as limited accessible readouts for organoid evaluation. For example, detailed investigations of these 3D biosystems, such as 3D electrophysiological mapping for brain and heart organoids, cannot be achieved using conventional approaches such as two- dimensional (2D) multi-electrode arrays (MEAs) for modulation and multimodal sensing. Furthermore, most current biosystems lack stable and mature vascularization that exists in vivo, which poses challenges to controlled delivery of oxygen, nutrition, and molecules like neural patterning factors to enhance organoid size, lifespan, and complexity. Our goal is to develop a soft electronic/microfluidic hybrid 3D network for online monitoring, regulation, and vascularization of human organoids. The resulting system will integrate separately addressable electrical, optical, electrochemical, and thermal sensors and stimulators of designated locations with 3D biomimetic microvascular networks for simultaneous sensing, stimulation, and well-controlled delivery of molecules into deep tissues to study tissue development and modulation. We will achieve this goal through pursuing three specific aims: (1) Develop multifunctional 3D electronic networks with high spatiotemporal resolution for online monitoring and regulation of organoid function, (2) Develop biomimetic 3D microvascular networks for the vascularization of 3D tissues and integrate them with 3D electronic networks into a hybrid system, and (3) Evaluate the efficiency and functional robustness of the integrated system in vitro using brain organoids as an example. Our proposed multifunctional hybrid system incorporates the following notable innovative features: 1) Soft, stretchable 3D networks for electrical, optical, electrochemical, and thermal sensing and stimulation of human organoids, 2) Biomimetic 3D microvascular networks for the vascularization of human organoids, 3) Fully integrated electronics and microfluidics networks as a micro-lab for investigating various induced and natural behaviors of human organoids. This work will create a new route to study neurodevelopment and neurological disorders through simultaneous monitoring, regulation, and vascularization of brain organoids throughout their 3D interior, which is of broad potential interest to the neuroscience community. In addition, the developed 3D hybrid system can be applied to other types of organoids, including heart, lung, and kidney for in vitro studies of related diseases.