A number of channels 103 are also formed in the first layer, and each cell 102 is in fluid communication with at least one of the number of channels 103.The material in which the cells 102 and channels 103 are formed can be various materials including, but not limited to, a polymeric material such as polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyester, polyamide, ch