Figure 1.

Fabrication of arrays of posts. (A) With the appropriate surface density of vertical posts positioned on a substrate, a cell should spread across multiple posts as depicted. Under the proper geometric constraints of post height and width, cells exerting traction forces would deflect the elastomeric posts. (B) Schematic drawing of the method used to fabricate posts. (C–G) Scanning electron micrographs of fabricated arrays (C, D, and F) and schematic drawings indicating the compliance of posts (E and G). (C) A uniform array of posts. (D and E) An array of posts whose tips all lie in one plane, but the bases of certain posts are raised with respect to surrounding posts to generate spatially controlled step-increases in substrate stiffness. (F and G) An array of posts with oval cross sections to introduce anisotropic stiffness. Lengths of arrows in E and G indicate the relative magnitude of the deflection with the application of a constant force in the direction of the arrow. (Scale bars indicate 10 μm.)