Microfluidic organ/cancer organoid-on-a-chip. (a) A brain organoid-on-a-chip system is established to model neurodevelopmental disorders under nicotine exposure.152 Reprinted with permission from Wang et al., Lab Chip 18, 851 (2018). Copyright 2018 The Royal Society of Chemistry. (b) An islet organoid-on-a-chip system enables controllable maturation of islet organoids from induced pluripotent stem cells and real-time imaging and in situ tracking of islet organoid growth.153 Reprinted with permission from Tao et al., Lab Chip 19, 948 (2019). Copyright 2019 The Royal Society of Chemistry. (c) A 3D perfusable liver organoid-on-a-chip system displays improved cell viability and high-fidelity reduction of liver functions.154 Reprinted with permission from Wang et al., Lab Chip 18, 3606 (2018). Copyright 2018 The Royal Society of Chemistry. (d) A microphysiological system reproducibly yields patient-derived small-cell lung cancer organoids in a size-controllable manner and efficiently predicts anti-cancer drug efficacy.155 Reprinted with permission from Jung et al., Lab Chip 19, 2854 (2019). Copyright 2019 The Royal Society of Chemistry.