Fig. 1. Soft lithographic process to generate PC of iPSC-aCMs and CFs within multiwell plates.

(A) Tissue culture polystyrene (TCPS) is first treated with oxygen plasma, followed by APTES. Next, a PDMS mask/stencil is placed atop the surface followed by oxygen plasma treatment to etch the unprotected APTES. BSA is then loaded into the channels created between the TCPS and PDMS mask via vacuum force to passivate the surface for CM attachment. The PDMS mask is then removed, and FN is added to create alternating lines (B) with BSA. Seeded CMs preferentially attach to the FN patterns as seen via (C) phase contrast and calcein AM. Seeded fibroblasts attach to the BSA-coated areas to create the (D) PC. Green color and purple color indicate the patterned iPSC-aCMs and atrial fibroblasts, respectively. Scale bar, 250 µm.