Plaintiffs Ecolab USA Inc. and Kleancheck Systems, LLC survived a motion for summary judgment of non-infringement filed by Defendant Diversey, Inc. The patent teaches a method of cleaning a surface. The patented method requires that a “contiguous amount” of transparent indicator material is applied to a surface before cleaning. After cleaning, an ultraviolent light is used to measure the amount of indicator material remaining on the surface. The process demonstrates where cleaning has been effective and where it has not.

Diversey argued that all of the indicator material sprayed on the surface had to be touching to meet the “contiguous amount” limitation in the patent. Ecolab contended that Diversey was reading limitations into the claims that were not imposed by the Court’s claim construction. Ecolab pointed out that the transition “comprising” precedes the “contiguous amount” limitation in the patent claims, indicating that a portion of the indicator material must be contiguous, but that the entirety of the indicator material need not be contiguous.

Judge Nelson agreed with Ecolab. First, Judge Nelson noted that the patent does not specifically require all of the indicator material to touch. Second, Judge Nelson held that Diversey waived its “all must touch” argument because the argument was based on a construction of the term “amount” that Diversey did not propose during the claim construction process. Third, Judge Nelson relied on the transition word “comprising.” When used in a patent claim, the transition word “comprising” signals “that the entire claim is presumptively open-ended.” Thus, all of the limitations in the patent must be present to establish infringement, but the existence of additional elements will not defeat infringement. With respect to the “contiguous amount” limitation, Judge Nelson held that the limitation may be established if there is an area where the indicator material touches, even if there is also an area where the indicator material does not touch.