This application claims the benefit of U.S. Provisional Application No. 61/021,104, filed Jan. 15, 2008, the entire contents of which are hereby expressly incorporated by reference.
This invention relates to the field of sterilizable packaging using color-changing indicators to display the sterilization status thereof.
In the past, packages such as pouches were used to retain contents for medical or veterinary or dental applications and to enable sterilization thereof, with an indication of whether the packaging had undergone sterilization. The two most popular techniques of sterilization for such packages are processing using either steam or ethylene oxide (hereinafter referred to as “ETO”).
In the prior art, as discussed in the “BACKGROUND” section of U.S. Pat. No. 4,091,921, it was known to apply indicator ink to the exterior of the package, with a color change indicating that the package was subject to the sterilization process. Different inks were used for steam and ETO as the sterilizing medium. Indicator inks were also applied to the interior of the package, to indicate that the interior sealed chamber containing the contents to be sterilized was subject to at least a partial exposure to a sterilization process. U.S. Pat. Nos. 4,091,921 and 5,344,017 each illustrate a prior art approach in which the indicator ink was sealed in a segregated interior compartment in the pouch to prevent the pouch contents from coming in contact with the interior ink indicator. U.S. Pat. No. 3,093,242 relates to an internal indicator not protected from contact with the contents of the pouch. The entire contents of each of U.S. Pat. Nos. 4,091,921, 5,344,017, and 3,093,242 are expressly incorporated herein by reference.
The present invention is an improvement over the prior art in that it provides a package having both exterior and interior indicators, for either steam or ETO, or both, with at least the interior indicator having a multi-parameter indicium responsive to steam as the sterilizing medium. This arrangement has the advantage of indicating when a package has been subjected to “partial” steam sterilization conditions such that the external indicator may change color to a desired ending color while the steam responsive multi-parameter indicium of the internal indicator does not change to the same desired ending color, giving an indication of “deficient” (in contrast to “absent”) sterilization, informing users to troubleshoot and correct their sterilization procedure and/or equipment. The desired ending color may also be referred to as a “designated end color.”
