Device fabrication and plate assembly are summarized in Fig. 1. Device photomasks were designed using DraftSight™ software (Dassault Systèmes). Half of one well plate (48 wells) was designed to fit on one 4-inch wafer, due to wafer size constraints. Each individual well was designed to have the same footprint as in a 96 well culture dish: each well had a diameter of 6.4 mm in which two distinct compartments were separated by a series of 10 μm wide × 3 μm tall × 500 μm long microchannels, with a 9 mm center-to-center spacing between wells. The lithographic process was performed in two distinct layers, as described previously.11 Briefly, a thin layer of SU-8 2002 photoresist (Microchem) was spun onto a clean wafer at 1000 rpm to produce a 3 μm resist layer. The second layer for the chamber structures involved two stacked coats of SU-8 as described previously. This results in a total thickness of approximately 320 μm. Following completion of photolithography, the wafer was coated in trichloro(1H,1H,2H,2H perfluoro-octyl)silane for 30 minutes. Once completed, a 1 : 10 mixture of
