Fig. 1. Concept and fabrication of the islet microphysiological system device. (A) Three main elements of the device: PDMS stamps obtained from soft-lithography sandwich. (B) Bis[3-(trimethoxysilyl)propyl]amine functionalized PET membrane. Representative XPS spectrum of the functionalized PET membrane. (C) An exploded assembly is shown. The PDMS media layer is separated from the cell layer by a porous PET membrane. (D) Islet β clusters cultured in parallel multiplexed trenched channels can be exposed to different concentrations of compounds, obtained via a gradient generator upstream. Shown is a gradient generated with compound X & Y. Supernatant flowing out of each multiplexed channel can be collected for analyses, such as measurement of C-peptide.