Abstract: Devices and methods are provided that allow for the casting of flat, controlled thickness layers of gel or polymer on a test surface, such as within the wells of a microplate. A spacer device is interposed between the test surface and the planar lower face of a movable pillar, defining a highly uniform volume. Addition of a gel or polymer precursor in solution followed by curing generates a highly uniform gel or polymer layer with a planar upper surface within this volume, which is exposed on removal of the pillar. In some embodiments a group of pillars is provided in a manifold that provides spacing and arrangement corresponding to a group of test wells. The pillars are mounted in the manifold so as to provide translation movement normal to the test surface, allowing them to rest against the spacer device and facilitating gentle removal from the wells. A variety of spacer devices are considered, including beads, flattened rings, and toroidal spacers.

Abstract: The inventive subject matter provides an apparatus for reproducibly fabricating hydrogel-based organ and tumor models inside multi-well plates. For example, tumor models made using the inventive apparatus can be used for studying the progression of cancer, cancer diagnostics, and therapeutic screening. A mold controls the thickness of each hydrogel layer. A photomask controls the size and shape of each hydrogel layer, allowing the hydrogel diameter to be smaller than the diameter of each well so that liquid media can be exchanged around both the sides and top of the hydrogels. A holder aligns the photomask with the multi-well plate, and polymerization is initiated by a light source.