1.  Field of the Invention
This invention is directed towards a laboratory device that facilitates studies using cell culture techniques to assay biomaterials.  Specifically this invention is a device that facilitates control of the exposure of animal cells and/or media to biomaterials and the measure of the main and interaction effects of the cells, tissue and media on the biomaterials.  By way of example, but not as a limitation, the device can be used to evaluate biomaterial toxicity or drug release from films.  The laboratory device also facilitates the recovery of biomaterials, cells, tissues, and/or the cell-material interface following controlled experiments. 
2.  Background
Technology related to the continued development of medical devices for humans comprises two fundamental areas of research and development: design and fabrication of said devices and development of minimally toxic, biologically compatible materials (biomaterials) to be used in the manufacture of said medical devices.  Safety and health considerations require that the potential of toxic effects of biomaterials that are otherwise suitable for medical devices must be fully evaluated, and performance considerations require that the material maintain its function in an in vivo environment.  Devices to facilitate cell culture and study are known in the art as shown and claimed in U.S. Pat.  Nos.  5,578,492 and 5,139,951, which are hereby incorporated by reference in their entirety. 
Direct contact cell culture is employed to evaluate biomaterial reactions and interaction of cells with a biomaterial.  Evaluation includes toxicity, drug delivery, or material degradation analysis.  Such studies require a laboratory apparatus that supports cellular growth, allows cell cultures to be exposed to known amounts of biomaterials, and to be handled for study purposes which includes observation of cells, sampling materials and media, changing media, and moving samples into and out of controlled environment facilities while protecting samples from contamination.  Additionally, such evaluation apparatuses must provide a container which provides surfaces to support cellular growth. 
Details of the preparation of media and methods of culture of cells are well known and comprehended by those skilled in the art.  Specific environmental conditions including factors such as minimizing contamination of cultures and maintaining controlled temperature, humidity, and light conditions are common to all studies although specific conditions of light, temperature, and humidity may vary with the material to be tested.  Nonetheless, the specific conditions are well known to those skilled in the art or are otherwise readily available without the need for excessive experimentation.  See for example, R. I. Freshney, “Culture of Animal Cells”, 2nd ed.,  Wiley/Liss, 1994, N.Y., N.Y., which is hereby incorporated by reference in its entirety. 
With current technology, biomaterials may float or otherwise move during the study making precise observations more difficult.  To minimize these issues, materials are commonly glued or weighted, which introduces additional complications.  Additionally, current technology necessitates mechanical collection using a spatula or similar instrument to recover the cells from bioassay apparatus.  Commonly, this results in damage to the cells thereby reducing the value of the cells for further analysis.  These and related difficulties limit aspects of the accuracy and dependability of biomaterial assays.  Accordingly, there remains room for variation and improvement in the art.