Device concept and layout.

<p>A) Overall microfluidic device layout. B) The devices contain an array of trapezoidal posts that cage collagen gel solution into well-defined regions with uniform surface interface. During collagen filling, the gel solution-air interface curvature sustains transient filling pressures.The posts are chosen to have an angle of 60°, supplementary to the contact angle of the liquid collagen and treated PDMS surface (found to be 120°). Post spacing is 100–125 microns, and width of gel region is 1.3 mm. C) To enable binding of cells to the gel region, the hydrostatic pressure in the input ports was managed allow for directional flow of the cells along the length of the device, coupled with interstitial flow that biases the cells against the gel region. Consequently cells bind to the collagen region, and form the basis for the monolayer that develops in the ensuing 24 hours. D) Cross section (defined in panel B) illustrating cellular monolayer forms to confluence after growth of adherent seeded cells.