In this talk, Prof. Takayama will describe development and use of aqueous two-phase system (ATPS) droplets for biological assays. Specific topics to be presented include use of ATPS droplet arrays that incorporate immunoassays for analysis of proteins, and ATPS droplet protocell arrays that incorporate in vitro transcription/ translation for simultaneous analysis of small molecules, RNA, and DNA. Another topic will be the application of ATPS droplets to studies of bacteria communication, biofilm formation, and antibiotic studies. Bacteria-interaction analysis with neutrophil extracellular trap (NET)-mimetic materials will also be presented. Finally, use of ATPS droplet-based bioprinting of fibroblast-extracellular matrix droplets that mimic microscale scars will be presented.