Functional limitations can be structural even when recited as a negative limitation. Here, for example, a plasticizer claimed as being “not removed from” an internal matrix prior to transplantation into a human was found to be directly infringed by a competing product itself even though it may be unknown how the product will be used by a third-party surgeon. “Functional limitations recited in the negative may describe a capability or structural element.”
Background / Facts: The patent being asserted here is directed to plasticized soft tissue grafts suitable for transplantation into humans. The tissue is preserved not by freeze-drying but by replacing the tissue’s water with biocompatible plasticizers, such as glycerol, that provide the hydrating functions of water. The claims recite one or more plasticizers contained in an internal matrix that “are not removed from said internal matrix of said plasticized soft tissue graft prior to transplantation into a human.”
Issue(s): Whether the non-removal limitation can be met by the accused product, before an independent third party, such as a surgeon, actually prepares and uses the accused products.
Holding(s): Yes. “Functional limitations recited in the negative may describe a capability or structural element. [] Here, the preceding language in each asserted claim states that the relevant plasticizers are already part of the tissue graft. [] The non-removal limitation simply provides a negative limitation that those plasticizers remain in the internal matrix prior to transplantation.”