Chemical indicator for determining the adequacy of a liquid sterilization process

Abstract

A sterilization indicator that presents a visually distinct and uniform color transition after having been passed through sterilizing conditions. This sterilization indicator has a base layer with an indicator compound applied to at least an indicating region thereon. It also has a raised lamina attached to the base layer so as to substantially surround the indicating region.

I claim:  
     
         1 . A sterilization indicator for a liquid sterilization procedure, comprising: 
 a base layer having an indicator composition associated with an indicating region thereof, the indicator compound designed to changed color when the sterilization indicator is placed in a liquid sterilization procedure; and    a raised portion attached to the base layer so as to substantially surround the indicating region.    
     
     
         2 . The sterilization indicator according to  claim 1  further comprising a receptacle enclosing the base layer and the raised portion, the receptacle comprising: 
 a vapor permeable backing, and  
 a cover attached to the backing and having a transparent portion allowing visual inspection of the indicating region without removing the base layer from the receptacle.  
 
     
     
         3 . The sterilization indicator according to  claim 1  wherein the liquid sterilization procedure is liquid peracetic acid sterilization procedure.  
     
     
         4 . The sterilization indicator according to  claim 3  wherein the indicator composition comprises one or more dyes and one or more halogen sources.  
     
     
         5 . The sterilization indicator according to  claim 1  wherein the raised portion is a lamina that entirely surrounds the indication region,and further wherein the raised lamina is at least 0.25 mm in thickness.  
     
     
         6 . The sterilization indicator according to  claim 1  wherein the raised portion is an ink printed on the base layer that the raised portion does not change color when the sterilization indicator is exposed to the sterilization procedure.  
     
     
         7 . A method of evaluating the uniformity of a chemical sterlization indicator change comprising the steps of: 
 subjecting a first chemical indicator to a lethal sterilization cycle;    subjecting a second chemical indicator to a non-lethal sterilization cycle;    objectively reading the color of the first chemical indicator;    objectively reading the color of the second chemical indicator;    comparing the colors of the first and second readers to determine the color change.    
     
     
         8 . A method of evaluating the uniformity of a chemical sterilization indicator change comprising the steps of: 
 subjecting a chemical indicator to a lethal sterilization cycle;    objectively reading the color of the first chemical indicator at a first location;    objectively reading the color of the first chemical indicator at a second location that is spaced from the first location;    comparing the colors at the first and second locations to assess the uniformity of the color.