WO2017112562A1 - Sterilization indicator - Google Patents

Sterilization indicator Download PDF

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Publication number
WO2017112562A1
WO2017112562A1 PCT/US2016/067428 US2016067428W WO2017112562A1 WO 2017112562 A1 WO2017112562 A1 WO 2017112562A1 US 2016067428 W US2016067428 W US 2016067428W WO 2017112562 A1 WO2017112562 A1 WO 2017112562A1
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WO
WIPO (PCT)
Prior art keywords
cover member
edge
hole
soluble substance
sterilization indicator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2016/067428
Other languages
French (fr)
Inventor
Noboru Kimura
Tomomi Ito
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of WO2017112562A1 publication Critical patent/WO2017112562A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L2/00—Disinfection or sterilisation of materials or objects, in general; Accessories therefor
    • A61L2/26—Accessories
    • A61L2/28—Devices for testing the effectiveness or completeness of sterilisation or disinfection, e.g. indicators which change colour
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
    • G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
    • G01N31/226—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating the degree of sterilisation

Definitions

  • a sterilizing process is autoclaving, in which an object is exposed to water vapor set to a temperature of about from 120°C to 130°C under high pressure.
  • a sterilization monitor (sterilization indicator) is used during the process of autoclaving in order to determine whether or not the process has been successful.
  • JP H07- 171206A discloses an indicator provided with a substrate strip that is made of aluminum foil and comprises a recess (accommodating part), a pellet of an organic compound (soluble substance) set in the recess in the substrate strip, a wicking means including a first end in close contact with the organic compound, and a vapor-permeable cover strip that covers the wicking means and the organic compound and controls water vapor permeation rate.
  • the indicator disclosed in JP H07- 171206A different materials are used for the material making up the substrate strip, the material making up the wicking means, and the material making up the cover strip. Therefore, debonding may occur within the indicator due to differences in the coefficient of thermal expansion between the substrate strip, the wicking means, and the cover strip, depending on the autoclaving conditions. In addition, the indicator may bend from the central part of the indicator along the shape of the recess provided in the substrate strip.
  • One aspect of the present invention is related to providing a sterilization indicator that is capable of suppressing the occurrence of soluble substance leakage during autoclaving.
  • a sterilization indicator according to one aspect of the present invention includes: a soluble substance capable of dissolving as the result of contact with heated water vapor;
  • a wick member provided contacting at least part of the soluble substance and extends in a first direction
  • a hole is provided in at least the cover member, the hole being in a position to the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance d l between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole.
  • the provision of the hole in at least the cover member alleviates the stress placed upon the cover member.
  • the hole is at a position to the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance d l between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole.
  • the hole is provided at a position near a location where the sterilization indicator is tends to bend, and at a suitable distance from the accommodating part. Bending of the sterilization indicator caused by the accommodating part is thereby suppressed by the hole, preventing leakage of the soluble substance through the hole. It is thus possible to suppress the occurrence of leakage of the soluble substance during autoclaving.
  • a sterilization indicator that is capable of suppressing the occurrence of soluble substance leakage during autoclaving.
  • FIG. 1 is a plan view of a sterilization indicator according to the present embodiment.
  • FIG. 2 is a bottom plan view of a sterilization indicator according to the present embodiment.
  • FIG. 3 is a cross-sectional view along line III-III in FIG. 1 .
  • FIG. 4 is a cross-sectional view along line IV-IV of FIG. 1 .
  • FIG. 1 is a plan view of a sterilization indicator according to the present embodiment.
  • FIG. 2 is a bottom plan view of a sterilization indicator according to the present embodiment.
  • FIG. 3 is a cross-sectional view along line III-III in FIG. 1.
  • FIG. 4 is a cross-sectional view along line IV-IV of FIG. 1.
  • the sterilization indicator is autoclaved along with medical instruments, including surgical instruments such as scalpels and mechanical instruments such as endoscopes, and serves as a sterilization monitor for determining whether the medical instruments have been properly autoclaved.
  • the sterilization indicator 1 illustrated in FIG. 1 and FIG. 2 includes a main body 2, a monitor part 3 , and first holes 4a, 4b.
  • the longitudinal direction of the main body 2 as seen in plan view is labeled the X direction (first direction)
  • the transverse direction thereof as seen in plan view is labeled the Y direction (second direction) .
  • the X direction and the Y direction are orthogonal to each other.
  • the main body 2 is substantially trapezoidal in shape as seen in plan view.
  • the main body 2 includes sides 2a, 2b that extend in the X direction as seen in plan view, and sides 2c, 2d that extend in the Y direction as seen in plan view.
  • the sides 2a, 2b are inclined so as to extend outward in the direction from side 2c to side 2d, and face each other.
  • the sides 2c, 2d extend substantially in parallel and face each other. Accordingly, the length of side 2c is less than the length of side 2d.
  • the length of side 2c is, for example, from 5 mm to 25 mm, and the length of side 2d is, for example, from 10 mm to 30 mm.
  • the distance between the sides 2c, 2d in the X direction is, for example, from 40 mm to 80 mm .
  • the main body 2 is a laminate including a substrate member 1 1 , a first adhesive layer 12 provided on the substrate member 1 1 , a pellet 13 provided on the substrate member 1 1 and the first adhesive layer 12, a wick member 14 provided on the substrate member 11 and the first adhesive layer 12, a cover member 15 that covers the substrate member 1 1 and the wick member 14 and is provided on the substrate member 1 1 , a second adhesive layer 16 provided on the cover member 15 , and a display member 17 provided on the second adhesive layer 16.
  • the pellet 13 is sealed in by the substrate member 1 1 and the cover member 15.
  • the substrate member 1 1 is a sheet-shaped member that supports the pellet 13 and the wick member 14.
  • the substrate member 1 1 is substantially trapezoidal in shape as seen in plan view, and extends in the X direction and the Y direction.
  • the thickness of the substrate member 1 1 is, for example, from 0.02 mm to 0. 1 mm.
  • the substrate member 1 1 has a lower level of water vapor permeability than the cover member 15. In an embodiment, the water vapor permeability of the substrate member 1 1 is less than 1 g/m 2 24 hours.
  • a metal foil such as aluminum foil, an alloy foil such as stainless steel foil, or a film constituted by a resin film on the surface of which a metal has been vapor deposited can be used as the substrate member 1 1.
  • the linear expansion coefficient of the substrate member 1 1 is 23 ppm/K.
  • the peripheral shapes of the cover member 15 and the display member 17 in the present embodiment are identical to that of the substrate member 1 1 ; therefore, description thereof will be omitted.
  • Raised and recessed parts can be formed in the substrate member 1 1 via embossing or the like.
  • a recessed part (accommodating part) 1 1 a capable of accommodating the pellet 13 is provided in the substrate member 1 1 .
  • the recessed part 1 l a is sunk inward in a substantially truncated cone shape, and is provide to the side 2d side of the center of the X direction.
  • part of the substrate member 1 1 protrudes outward in a substantially truncated conical shape as the result of the recessed part 1 1 a.
  • the maximum radius rl of the recessed part 1 1 a is, for example, 6 mm, 5 mm, or 4 mm.
  • the maximum radius rl of the recessed part 11 a is the distance from a center P of the recessed part 11 a to an edge E of the recessed part 1 1a.
  • the edge E is the location where the substrate member 1 1 begins to sink inward, and forms the boundary between the recessed part 1 1 a and the other parts of the substrate member 11 .
  • the recessed part 1 1 a may be sunk inward in, for example, a substantially truncated pyramidal shape or a substantially cylindrical shape . In short, any shape may be selected for the recessed part 1 1 a. In such cases, the maximum radius rl is selected according to the shape of the recessed part 1 1 a.
  • the first adhesive layer 12 bonds the substrate member 1 1 and the wick member 14, and bonds the substrate member 1 1 and the cover member 15.
  • the first adhesive layer 12 seals in at least part of the pellet 13.
  • the first adhesive layer 12 contains, for example, an acrylic-based adhesive or a silicone-based adhesive .
  • the pellet 13 is a member that contains a substance (soluble substance) that is capable of dissolving at a temperature used to sterilize medical instruments by autoclaving (for example, from 120°C to 135 °C) .
  • the pellet 13 is capable of dissolving via contact, for example, with water vapor (heated water vapor) heated during autoclaving .
  • the melting point of the soluble substance in the pellet 13 may decrease when water vapor is present. Therefore, the soluble substance may have a melting point that is from 2°C to 30°C higher than the temperature at which sterilization is performed.
  • An organic compound, for example, is used as the soluble substance .
  • Specific examples of the soluble substance include salicylamide, 2-chloroacetamide, ethoxy benzamide, benzoic acid, diphenyl succinate, dichlorophenol, dimethyl phenol, benzamide, urea,
  • the pellet 13 may also contain a dye in order to allow the soluble substance to be readily visible when wicked up by the wick member 14.
  • a dye that is soluble in organic compounds can be used as the dye . Examples of such dye include ethylene blue, crystal violet, malachite green, brilliant green, methyl violet, and methyl green.
  • the wick member 14 is capable of wicking the dissolved soluble substance .
  • the wick member 14 has a substantially rectangular shape that extends in the X direction as seen in plan view, and is positioned in the center of the main body 2 with respect to the Y direction.
  • An end 14a of the wick member 14 in the longitudinal direction near the side 2d side is positioned within the recessed part 1 1 a, and is sandwiched between the pellet 13 and the cover member 15. Accordingly, at least part of the wick member 14 including the end 14a contacts the pellet 13.
  • Another end 14b of the wick member 14 facing the end 14a is positioned near the side 2c side in the X direction, and is sandwiched between the first adhesive layer 12 and the cover member 15.
  • the wick member 14 is made of a porous substance that is capable of wicking liquids via capillary action.
  • the wick member 14 is a porous substance constituted, for example, by paper, plant fibers, or synthetic resin fibers. In the present embodiment, filter paper is used as the wick member 14.
  • the cover member 15 is a sheet-like member made of transparent polymer resin having the property of being permeable by high temperature water vapor.
  • the water vapor permeation rate of the cover member 15 is adjusted, as appropriate, according to autoclaving conditions (sterilization temperature, heating cycle, and the like) and the soluble substance .
  • the water vapor permeation rate of the cover member 15 is 1 g/m 2 24 hours or greater, 100 g/m 2 - 24 hours or greater, or 1000 g/m 2 24 hours or greater, and 10000 g/m 2 24 hours or less, 7500 g/m 2 24 hours or less, or 5000 g/m 2 24 hours or less.
  • the cover member 15 is made of a substance that will not be eroded or is resistant to erosion by organic compounds (especially the soluble substance) .
  • Polypropylene film, polystyrene film, or polymethyl methacrylate film, for example, can be used as the cover member 15.
  • a polypropylene film which has a high softening point and is comparatively inactive with respect to numerous compounds, is used as the cover member 15.
  • the thickness of the cover member 15 is set to, for example, from 0.02 mm to 0. 1 mm from the perspective of water vapor permeation rate .
  • the linear expansion coefficient of the cover member 15 is 120 ppm/K.
  • the linear expansion coefficient of the cover member 15 is 2 times or greater, 3 times or greater, or 5 times or greater and 20 times or less, 10 times or less, or 6 times or less of the linear expansion coefficient of the substrate member 1 1.
  • the cover member 15 may have a shape different from that of the substrate member 1 1 as seen in plan view.
  • the area of the cover member 15 may be less than the area of the substrate member 1 1.
  • the second adhesive layer 16 bonds the cover member 15 and the display member 17.
  • the second adhesive layer 16 contains, for example, an acrylic-based adhesive or a silicone-based adhesive similar to the first adhesive layer 12.
  • the display member 17 is printed with characters or the like, and is a member on which a reference line 3b and a printed part 3c of the monitor part 3, described hereafter, are provided (the reference line 3b and the printed part 3c will be described hereafter) .
  • An opening 17a that extends in the X direction is provided on part of the display member 17.
  • the opening 17a is provided above the wick member 14, and is provided so that at least a central part of the wick member 14 with respect to the Y direction is visible .
  • a region on the second adhesive layer 16 that overlaps with the opening 17a is removed. Paper, for example, is used as the display member 17.
  • the monitor part 3 is provided on the display member 17, and visibly indicates whether autoclaving was successful.
  • the monitor part 3 includes a display part 3a that displays the wick member 14, a reference line 3b for determining whether autoclaving is complete, and a printed part 3c of printed characters or the like indicating whether the sterilization process was successful .
  • the display part 3a is provided within the opening 17a of the display member 17, and allows the wick member 14 to be visible.
  • the reference line 3b is a line extending in the Y direction, and is printed on the display member 17 so as to intersect substantially the center of the opening 17a.
  • the printed parts 3c are provided on the side 2c side and the side 2d side with respect to the reference line 3b .
  • the cover member 15 may have a shape different from that of the substrate member 1 1 as seen in plan view.
  • the area of the cover member 15 may be less than the area of the substrate member 1 1.
  • the sterilization indicator 1 is autoclaved along with medical instruments, as described above .
  • the pellet 13 contacts the heated water vapor, thereby the soluble substance in the pellet 13 is dissolved.
  • the dissolved soluble substance is wicked by the wick member 14 and diffuses in the X direction toward the side 2d side .
  • it can be determined that autoclaving is complete .
  • a printed part 3c printed "Reject" is provided to the side 2d side of the reference line 3b, and a printed part 3c printed
  • the first holes 4a, 4b are provided so as to bore through the main body 2 of the sterilization indicator 1 , and are formed at least in the cover member 15.
  • the first holes 4a, 4b may have various shapes as seen in plan view, such as circular, elliptical, or polygonal.
  • the first holes 4a, 4b may also have the shape of a letter X or the like as seen in plan view.
  • the first holes 4a, 4b are provided so as to bore through the substrate member 1 1 , the first adhesive layer 12, the cover member 15 , the second adhesive layer 16, and the display member 17, and have circular shapes as seen in plan view.
  • a diameter r2 constituting the maximum outer dimension r of the first holes 4a,
  • the maximum outer dimension r of the first holes 4a, 4b refers to the maximum diameter or dimension of the first holes 4a, 4b regardless of the shape of the first holes 4a, 4b as seen in plan view.
  • the first holes 4a, 4b are provided to the side 2c side of the center P of the recessed part 1 1 a in the X direction.
  • the first hole 4a is provided to the side 2a side of the wick member 14, and the first hole 4b is provided to the side 2b side of the wick member 14.
  • the first holes 4a, 4b may also be provided so as to have line symmetry with respect to the wick member 14 as seen in plan view.
  • the first holes 4a, 4b are provided adj acent to an edge E of the recessed part 1 1 a by a minimum distance d l between the edge E and an edge ofthe cover member 15.
  • the minimum distance d l is, for example, from 3 mm to 10 mm.
  • the first holes 4a, 4b are separated from the edge E by the diameter r2 of the first holes 4a, 4b.
  • a minimum distance d2 between the edge E and the first hole 4a and a minimum distance d3 between the edge E and the first hole 4b are greater than the diameter r2.
  • the minimum distance d l is equivalent to the minimum distance from the edge E, edge E of the recessed part 11a, to the sides 2a to 2d.
  • the first hole 4a is separated from the wick member 14 by a distance greater than the diameter r2 of the first hole 4a, and the minimum distance between the first hole 4a and the wick member 14 is equivalent to the minimum distance d2 between the edge E and the first hole 4a.
  • the first hole 4b is separated from the wick member 14 by a distance greater than the diameter r2 of the first hole 4b, and the minimum distance between the first hole 4b and the wick member 14 is equivalent to the minimum distance d3 between the edge E and the first hole 4b.
  • the first hole 4a is provided within a region 21 encompassed by dotted lines 21a to 2 Id in FIG. 2, and the first hole 4b is provided within a region 22 encompassed by dotted lines 22a to 22d in FIG. 2.
  • the dotted lines 21a, 22a are part of a straight line that passes through the center P and extends in the Y direction.
  • the dotted lines 21b, 22b are partial arcs of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d l .
  • the dotted line 21c is a partial line segment connecting points set off from an edge 14c on the side 2a side of the wick member 14 in the Y direction by the minimum distance d2.
  • the dotted line 22c is a partial line segment connecting points set off from an edge 14d on the side 2b side of the wick member 14 in the Y direction by the minimum distance d3.
  • the dotted line 2 Id is a partial arc of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d2, and the dotted line 22d is a partial arc of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d3.
  • the dotted lines 21b, 22b will be straight lines rather than curves.
  • the dotted lines 21a to 2 Id and 22a to 22d vary according to the shape of the main body 2 (or the cover member 15) and the shape of the recessed part 11a.
  • the shapes of the regions 21 , 22 will also vary according to the shape of the main body 2 (or cover member 15) and the shape of the recessed part 11a.
  • An angle ⁇ formed by an imaginary line passing through the center P of the recessed part 11a in the X direction and an imaginary line connecting the center P of the recessed part 11a and the center of the first hole 4a (or the first hole 4b) as seen in plan view may be 10° or greater or 22.5° or greater, and 80° or less or 67.5° or less. Setting the angle ⁇ within this range will allow excess water vapor infiltrating the recessed part 11a via the cover member 15 to be suitably discharged through the first holes 4a, 4b.
  • phenomena that can occur when a sterilization indicator that has a shape similar to that of the sterilization indicator 1 , but is not provided with first holes 4a, 4b, is autoclaved will be described.
  • Sterilizers used to perform autoclaving have increased in performance in recent years. Specifically, the speed of introducing high-temperature water vapor into the apparatus is increased, thereby reducing the length of time required to perform the sterilization process.
  • Sterilization indicators housed within such sterilization apparatus are laminates constituted by a plurality of different layers. Because the linear expansion coefficient of the cover member is many times greater than the linear expansion coefficient of the substrate member, as discussed above, when the sterilization indicator is exposed to high temperatures, a high level of stress is placed upon the sterilization indicator due to the difference in thermal expansion between the substrate member and the cover member.
  • the provision of the first holes 4a, 4b at least in the cover member 15 alleviates the stress placed upon the cover 15, making it difficult for the stress caused by the difference in thermal expansion between the substrate member 11 and the cover member 15 to be placed upon the sterilization indicator 1.
  • the first holes 4a, 4b are provided to the side 2c side of the center P of the recessed part 11a, and are provided adjacent to the edge E of the recessed part 11a by the minimum distance dl between the edge E of the recessed part 11a and the edge of the cover member 15, and separated from the edge E of the recessed part 11a by the diameter r2 of the first holes 4a, 4b.
  • the first holes 4a, 4b are provided at locations near where the sterilization indicator 1 tends to bend, and at suitable distances from the recessed part 11a. As a result, bending of the sterilization indicator 1 caused by the recessed part 11a is suppressed by the first holes 4a, 4b, allowing leakage of the soluble substance through the first holes 4a, 4b to be prevented. It is thus possible to suppress the occurrence of leakage of the soluble substance during autoclaving.
  • the first holes 4a, 4b are separated from the wick member 14 by the diameter r2 (maximum outer dimension r) of the first holes 4a, 4b. As a result, it is possible to suppress leakage of the soluble substance wicked by the wick member 14 to the outside through the first holes 4a, 4b.
  • the minimum distance d l is from 3 mm to 10 mm. In this case, excess water vapor infiltrating the recessed part 11a via the cover member 15 is suitably discharged through the first holes 4a, 4b.
  • the diameter r2 (maximum outer dimension r) of the first holes 4a, 4b is from 0.2 mm to 0.8 mm. In this case, it is possible to suitably suppress leakage of the soluble substance to the outside through the first holes 4a, 4b during autoclaving.
  • the first holes 4a, 4b are provided so as to have line symmetry with respect to the wick member 14 as seen in plan view. In this case, stress in the substrate member 11 is uniformly alleviated, thereby allowing bending of the substrate member 11 to be suitably suppressed.
  • the main body 2 is not limited to having a substantially trapezoidal shape as seen in plan view, but may also have a substantially rectangular shape, a substantially polygonal shape, or a substantially circular shape. Accordingly, the substrate member 11 and the like can be altered to suit the shape of the main body 2.
  • the first holes 4a, 4b need not bore through the entirety of the main body 2 as long as they bore through at least the cover member 15. It is also acceptable to provide only one first hole, or three or more.
  • the sterilization indicator 1 need not be provided with the display member 17.
  • the cover member 15 constitutes the outermost layer of the sterilization indicator 1
  • a second adhesive layer 16 is not provided on the cover member 15.
  • the reference line and printed part may be printed directly on the cover member 15. This arrangement suitably suppresses debonding and bending of the sterilization indicator 1 , and also reduces manufacturing costs.
  • the reference line 3b of the sterilization indicated 1 need not extend so as to intersect the center of the opening 17a, but may be provided at any location.
  • the sterilization indicator according to one embodiment of the present invention will now be described in detail using examples .
  • the configuration of the sterilization indicator is not limited to those of the examples described hereafter.
  • An indicator was manufactured according to the following method. First, an aluminum film having a thickness of 76 ⁇ was prepared as a substrate member. Heat embossing was then performed on the aluminum film to form an accommodating part. Salicylamide was then disposed in the accommodating part as a soluble substance, and 178 ⁇ -thick filter paper was disposed on the aluminum film as a wick member so that an end thereof overlapped the soluble substance . Next, a 56 ⁇ -thick polypropylene film was bonded as a cover member pre-coated with an acrylic adhesive as a first adhesive layer to the aluminum film using an acrylic adhesive so as to cover the salicylamide and filter paper.
  • Paper constituting a display member pre-coated with acrylic adhesive as a second adhesive layer was then bonded to the polypropylene film using an acrylic adhesive .
  • an indicator was obtained by performing punching so as to yield a shape as seen in plan view substantially identical to that of the sterilization indicator 1 according to the embodiment described above as seen in FIGS . 1 and 2 (i .e ., a substantially trapezoidal shape) . Accordingly, the indicator had a shape as seen in plan view substantially identical to that of the sterilization indicator 1 according to the embodiment described above as seen in FIGS . 1 and 2 (i .e ., a substantially trapezoidal shape) .
  • the length of the indicator in the X direction was 5 1 mm, and the length of the longer side thereof in the Y direction was 19 mm.
  • the maximum radius of the recessed part was 5.0 mm, and the minimum distance from the edge of the recessed part to the cover member (substrate member) was 5.0 mm.
  • a pair of holes boring through the aluminum foil at the positions shown in Table 1 below were provided in the indicator so as to have line symmetry with respect to the filter paper as seen in plan view.
  • the positions of the pair of holes were determined based on the center of the recessed part.
  • length A is the length from the center of the recessed part along the X direction
  • length B is the length from the center of the recessed part along the Y direction
  • length C is the minimum distance from the edge of the recessed part to the holes.
  • Angle D is the angle formed by a side passing through the center of the recessed part in the X direction and a side connecting the center of the recessed part and the centers of the holes (refer to FIG. 2) .
  • Length A is represented by a positive value when the holes are positioned to the side of the center of the recessed part on which the filter paper is provided, and as a negative value when the holes are positioned to the side of the center of the recessed part on which the filter paper is not provided.
  • the indicator according to Example 1 in which the holes described above were provided was autoclaved according to a standard cycle P01 (program name : B cycle) using an HS33 rapid sterilizer (manufactured by Getinge Japan K.K.) as a sterilizer.
  • a standard cycle comprises a preliminary step in which pre-vacuuming is performed four times, a sterilization step in which the sterilizer is heated at 134°C for four minutes, and a drying step that lasts 15 minutes, performed in that order.
  • the indicator was observed following autoclaving to check whether it was possible to determine whether sterilization had been completed, whether there was any debonding of the printed part, and whether there was any leakage of ink. The results are shown in Table 1 below. In Example 1 , it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed.
  • Example 1 An indicator was prepared as in Example 1 .
  • the positions of the pair of holes provided in the indicator according to Example 2 are as shown in Table 1 below. The positions of the pair of holes differ from those of Example 1 .
  • the indicator according to Example 2 was autoclaved, it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed, as in Example 1.
  • Example 1 An indicator was prepared as in Example 1 .
  • the positions of the pair of holes provided in the indicator according to Example 3 are as shown in Table 1 below.
  • the positions of the pair of holes differ from those of Examples 1 and 2.
  • Example 5 An indicator was prepared as in Example 1 .
  • the positions of the pair of holes provided in the indicator according to Example 4 are as shown in Table 1 below.
  • the positions of the pair of holes differ from those of Examples 1 to 3.
  • Example 1 An indicator was prepared as in Example 1.
  • the positions of the pair of holes provided in the indicator according to Example 5 are as shown in Table 1 below.
  • the positions of the pair of holes differ from those of Examples 1 to 4.
  • Example 1 An indicator was prepared as in Example 1.
  • the positions of the pair of holes provided in the indicator according to Comparative Example 1 are as shown in Table 1 below. Because length A is a negative value in Comparative Example 1 , the pair of holes was provided to the side of the center of the recessed part on which the filter paper was not provided, differing from Examples 1 to 5. Length C in Comparative Example 1 was greater than 5.0 mm, the minimum distance from the edge of the recessed part to the cover member, and angle D was 112.5°. When the indicator according to Comparative Example 1 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 1.
  • Example 1 An indicator was prepared as in Example 1.
  • the positions of the pair of holes provided in the indicator according to Comparative Example 2 are as shown in Table 1 below. Because length C is 0.0 mm in Comparative Example 2, the pair of holes were provided so as to contact the edge of the recessed part.
  • the indicator according to Comparative Example 2 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 2, as in Comparative Example 1.
  • Example 1 An indicator was prepared as in Example 1.
  • the positions of the pair of holes provided in the indicator according to Comparative Example 3 are as shown in Table 1 below.
  • Length C in Comparative Example 3 was 7.7 mm, greater than the 5.0 mm constituting the minimum distance from the edge of the recessed part to the cover member.
  • the indicator according to Comparative Example 3 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 3 , as in Comparative Examples 1 and 2.
  • Table 1 Table 1

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Abstract

To provide a sterilization indicator capable of suppressing the occurrence of soluble substance leakage during autoclaving. Resolution means: A sterilization indicator comprises a substrate member provided with an accommodating part for accommodating a soluble substance and extends in a first direction and in a second direction orthogonal to the first direction as seen in plan view, a wick member provided contacting at least part of the soluble substance and extends in a first direction, and a cover member that covers the soluble substance and the wick member and is provided on the substrate member. A hole is provided in at least the cover member, the hole being in a position to the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance dl between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole.

Description

STERILIZATION INDICATOR
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority to Japanese Patent Application No. 2015-251613, filed December 24, 2015, the disclose of which is incorporated by reference in its entirety herein.
BACKGROUND
One example of a sterilizing process is autoclaving, in which an object is exposed to water vapor set to a temperature of about from 120°C to 130°C under high pressure. A sterilization monitor (sterilization indicator) is used during the process of autoclaving in order to determine whether or not the process has been successful. Japanese Unexamined Patent Application Publication No. H07- 171206A ("JP H07- 171206A") discloses an indicator provided with a substrate strip that is made of aluminum foil and comprises a recess (accommodating part), a pellet of an organic compound (soluble substance) set in the recess in the substrate strip, a wicking means including a first end in close contact with the organic compound, and a vapor-permeable cover strip that covers the wicking means and the organic compound and controls water vapor permeation rate.
In the indicator disclosed in JP H07-171206A, water vapor that penetrates the cover strip during autoclaving reacts with the soluble substance to form a liquid (ink) in which the soluble substance is dissolved. The success or failure of the autoclaving is determined by checking the amount of ink wicked by the wicking means and the like.
SUMMARY
In the indicator disclosed in JP H07- 171206A, different materials are used for the material making up the substrate strip, the material making up the wicking means, and the material making up the cover strip. Therefore, debonding may occur within the indicator due to differences in the coefficient of thermal expansion between the substrate strip, the wicking means, and the cover strip, depending on the autoclaving conditions. In addition, the indicator may bend from the central part of the indicator along the shape of the recess provided in the substrate strip.
In such cases, depending on sterilization conditions, the adhesive area between, for example, the substrate strip and the cover strip is reduced, resulting in the ink leaking out of the indicator. Such ink leakage leads to a problem of being unable to accurately determine whether autoclaving was successful. In addition, there is the risk of contaminating medical instruments disposed near the indicator. One aspect of the present invention is related to providing a sterilization indicator that is capable of suppressing the occurrence of soluble substance leakage during autoclaving.
A sterilization indicator according to one aspect of the present invention includes: a soluble substance capable of dissolving as the result of contact with heated water vapor;
a substrate member that is provided with an accommodating part for
accommodating the soluble substance and that extends in a first direction and in a second direction orthogonal to the first direction as seen in plan view;
a wick member provided contacting at least part of the soluble substance and extends in a first direction; and
a cover member covering the soluble substance and the wick member and is provided on the substrate member, wherein
a hole is provided in at least the cover member, the hole being in a position to the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance d l between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole.
According to this aspect, the provision of the hole in at least the cover member alleviates the stress placed upon the cover member. In addition, the hole is at a position to the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance d l between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole. As a result, the hole is provided at a position near a location where the sterilization indicator is tends to bend, and at a suitable distance from the accommodating part. Bending of the sterilization indicator caused by the accommodating part is thereby suppressed by the hole, preventing leakage of the soluble substance through the hole. It is thus possible to suppress the occurrence of leakage of the soluble substance during autoclaving.
According to an aspect of the present invention, it is possible to provide a sterilization indicator that is capable of suppressing the occurrence of soluble substance leakage during autoclaving.
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a sterilization indicator according to the present embodiment. FIG. 2 is a bottom plan view of a sterilization indicator according to the present embodiment.
FIG. 3 is a cross-sectional view along line III-III in FIG. 1 .
FIG. 4 is a cross-sectional view along line IV-IV of FIG. 1 .
DESCRIPTION OF EMBODIMENT
A preferred embodiment of the present invention will now be described in detail with reference to the drawings . In the following description, identical elements or elements having identical functions will be labeled with identical labels, and redundant descriptions thereof will be omitted.
FIG. 1 is a plan view of a sterilization indicator according to the present embodiment. FIG. 2 is a bottom plan view of a sterilization indicator according to the present embodiment. FIG. 3 is a cross-sectional view along line III-III in FIG. 1. FIG. 4 is a cross-sectional view along line IV-IV of FIG. 1. The sterilization indicator is autoclaved along with medical instruments, including surgical instruments such as scalpels and mechanical instruments such as endoscopes, and serves as a sterilization monitor for determining whether the medical instruments have been properly autoclaved.
The sterilization indicator 1 illustrated in FIG. 1 and FIG. 2 includes a main body 2, a monitor part 3 , and first holes 4a, 4b. In the following description, the longitudinal direction of the main body 2 as seen in plan view is labeled the X direction (first direction), and the transverse direction thereof as seen in plan view is labeled the Y direction (second direction) . The X direction and the Y direction are orthogonal to each other.
The main body 2 is substantially trapezoidal in shape as seen in plan view. The main body 2 includes sides 2a, 2b that extend in the X direction as seen in plan view, and sides 2c, 2d that extend in the Y direction as seen in plan view. The sides 2a, 2b are inclined so as to extend outward in the direction from side 2c to side 2d, and face each other. The sides 2c, 2d extend substantially in parallel and face each other. Accordingly, the length of side 2c is less than the length of side 2d. The length of side 2c is, for example, from 5 mm to 25 mm, and the length of side 2d is, for example, from 10 mm to 30 mm. The distance between the sides 2c, 2d in the X direction is, for example, from 40 mm to 80 mm .
As illustrated in FIG. 3 and FIG. 4, the main body 2 is a laminate including a substrate member 1 1 , a first adhesive layer 12 provided on the substrate member 1 1 , a pellet 13 provided on the substrate member 1 1 and the first adhesive layer 12, a wick member 14 provided on the substrate member 11 and the first adhesive layer 12, a cover member 15 that covers the substrate member 1 1 and the wick member 14 and is provided on the substrate member 1 1 , a second adhesive layer 16 provided on the cover member 15 , and a display member 17 provided on the second adhesive layer 16. The pellet 13 is sealed in by the substrate member 1 1 and the cover member 15.
The substrate member 1 1 is a sheet-shaped member that supports the pellet 13 and the wick member 14. The substrate member 1 1 is substantially trapezoidal in shape as seen in plan view, and extends in the X direction and the Y direction. The thickness of the substrate member 1 1 is, for example, from 0.02 mm to 0. 1 mm. The substrate member 1 1 has a lower level of water vapor permeability than the cover member 15. In an embodiment, the water vapor permeability of the substrate member 1 1 is less than 1 g/m2 24 hours. For example, a metal foil such as aluminum foil, an alloy foil such as stainless steel foil, or a film constituted by a resin film on the surface of which a metal has been vapor deposited can be used as the substrate member 1 1. When, for example, aluminum foil is used as the substrate member 1 1 , the linear expansion coefficient of the substrate member 1 1 is 23 ppm/K. The peripheral shapes of the cover member 15 and the display member 17 in the present embodiment are identical to that of the substrate member 1 1 ; therefore, description thereof will be omitted.
Raised and recessed parts can be formed in the substrate member 1 1 via embossing or the like. In the present embodiment, a recessed part (accommodating part) 1 1 a capable of accommodating the pellet 13 is provided in the substrate member 1 1 . The recessed part 1 l a is sunk inward in a substantially truncated cone shape, and is provide to the side 2d side of the center of the X direction. In FIG. 2, part of the substrate member 1 1 protrudes outward in a substantially truncated conical shape as the result of the recessed part 1 1 a. The maximum radius rl of the recessed part 1 1 a is, for example, 6 mm, 5 mm, or 4 mm. The maximum radius rl of the recessed part 11 a is the distance from a center P of the recessed part 11 a to an edge E of the recessed part 1 1a. The edge E is the location where the substrate member 1 1 begins to sink inward, and forms the boundary between the recessed part 1 1 a and the other parts of the substrate member 11 . The recessed part 1 1 a may be sunk inward in, for example, a substantially truncated pyramidal shape or a substantially cylindrical shape . In short, any shape may be selected for the recessed part 1 1 a. In such cases, the maximum radius rl is selected according to the shape of the recessed part 1 1 a.
The first adhesive layer 12 bonds the substrate member 1 1 and the wick member 14, and bonds the substrate member 1 1 and the cover member 15. The first adhesive layer 12 seals in at least part of the pellet 13. The first adhesive layer 12 contains, for example, an acrylic-based adhesive or a silicone-based adhesive .
The pellet 13 is a member that contains a substance (soluble substance) that is capable of dissolving at a temperature used to sterilize medical instruments by autoclaving (for example, from 120°C to 135 °C) . The pellet 13 is capable of dissolving via contact, for example, with water vapor (heated water vapor) heated during autoclaving . The melting point of the soluble substance in the pellet 13 may decrease when water vapor is present. Therefore, the soluble substance may have a melting point that is from 2°C to 30°C higher than the temperature at which sterilization is performed. An organic compound, for example, is used as the soluble substance . Specific examples of the soluble substance include salicylamide, 2-chloroacetamide, ethoxy benzamide, benzoic acid, diphenyl succinate, dichlorophenol, dimethyl phenol, benzamide, urea,
1 ,4-dihydroxy benzophenone, hydroquinone, dioxium, toluene sulfonic acid ethyl ester, or phenacetin.
The pellet 13 may also contain a dye in order to allow the soluble substance to be readily visible when wicked up by the wick member 14. A dye that is soluble in organic compounds can be used as the dye . Examples of such dye include ethylene blue, crystal violet, malachite green, brilliant green, methyl violet, and methyl green.
The wick member 14 is capable of wicking the dissolved soluble substance . As illustrated in FIGS . 1 to 3 , the wick member 14 has a substantially rectangular shape that extends in the X direction as seen in plan view, and is positioned in the center of the main body 2 with respect to the Y direction. An end 14a of the wick member 14 in the longitudinal direction near the side 2d side is positioned within the recessed part 1 1 a, and is sandwiched between the pellet 13 and the cover member 15. Accordingly, at least part of the wick member 14 including the end 14a contacts the pellet 13. Another end 14b of the wick member 14 facing the end 14a is positioned near the side 2c side in the X direction, and is sandwiched between the first adhesive layer 12 and the cover member 15. The wick member 14 is made of a porous substance that is capable of wicking liquids via capillary action. The wick member 14 is a porous substance constituted, for example, by paper, plant fibers, or synthetic resin fibers. In the present embodiment, filter paper is used as the wick member 14.
The cover member 15 is a sheet-like member made of transparent polymer resin having the property of being permeable by high temperature water vapor. The water vapor permeation rate of the cover member 15 is adjusted, as appropriate, according to autoclaving conditions (sterilization temperature, heating cycle, and the like) and the soluble substance . In an embodiment, the water vapor permeation rate of the cover member 15 is 1 g/m2 24 hours or greater, 100 g/m2 - 24 hours or greater, or 1000 g/m2 24 hours or greater, and 10000 g/m2 24 hours or less, 7500 g/m2 24 hours or less, or 5000 g/m2 24 hours or less. The cover member 15 is made of a substance that will not be eroded or is resistant to erosion by organic compounds (especially the soluble substance) .
Polypropylene film, polystyrene film, or polymethyl methacrylate film, for example, can be used as the cover member 15. In the present embodiment, a polypropylene film, which has a high softening point and is comparatively inactive with respect to numerous compounds, is used as the cover member 15. When a polypropylene film is used as the cover member 15, the thickness of the cover member 15 is set to, for example, from 0.02 mm to 0. 1 mm from the perspective of water vapor permeation rate . When a
polypropylene film is used as the cover member 15 , the linear expansion coefficient of the cover member 15 is 120 ppm/K. In an embodiment, the linear expansion coefficient of the cover member 15 is 2 times or greater, 3 times or greater, or 5 times or greater and 20 times or less, 10 times or less, or 6 times or less of the linear expansion coefficient of the substrate member 1 1. The cover member 15 may have a shape different from that of the substrate member 1 1 as seen in plan view. The area of the cover member 15 may be less than the area of the substrate member 1 1.
The second adhesive layer 16 bonds the cover member 15 and the display member 17. The second adhesive layer 16 contains, for example, an acrylic-based adhesive or a silicone-based adhesive similar to the first adhesive layer 12.
The display member 17 is printed with characters or the like, and is a member on which a reference line 3b and a printed part 3c of the monitor part 3, described hereafter, are provided (the reference line 3b and the printed part 3c will be described hereafter) . An opening 17a that extends in the X direction is provided on part of the display member 17. The opening 17a is provided above the wick member 14, and is provided so that at least a central part of the wick member 14 with respect to the Y direction is visible . A region on the second adhesive layer 16 that overlaps with the opening 17a is removed. Paper, for example, is used as the display member 17.
As illustrated in FIG. 1 , the monitor part 3 is provided on the display member 17, and visibly indicates whether autoclaving was successful. The monitor part 3 includes a display part 3a that displays the wick member 14, a reference line 3b for determining whether autoclaving is complete, and a printed part 3c of printed characters or the like indicating whether the sterilization process was successful . The display part 3a is provided within the opening 17a of the display member 17, and allows the wick member 14 to be visible. The reference line 3b is a line extending in the Y direction, and is printed on the display member 17 so as to intersect substantially the center of the opening 17a.
The printed parts 3c are provided on the side 2c side and the side 2d side with respect to the reference line 3b . The cover member 15 may have a shape different from that of the substrate member 1 1 as seen in plan view. The area of the cover member 15 may be less than the area of the substrate member 1 1.
An example of a method for determining whether autoclaving was successful using the monitor part 3 in the present embodiment will now be described. First, the sterilization indicator 1 is autoclaved along with medical instruments, as described above . During autoclaving, the pellet 13 contacts the heated water vapor, thereby the soluble substance in the pellet 13 is dissolved. The dissolved soluble substance is wicked by the wick member 14 and diffuses in the X direction toward the side 2d side . When it is visually confirmed that the diffused soluble substance has reached the side 2c side of the reference line 3b after the sterilization indicator 1 has been autoclaved, it can be determined that autoclaving is complete . Conversely, when it is visually confirmed that the diffused soluble substance has reached only the side 2d side of the reference line 3b after the sterilization indicator 1 has been autoclaved, it can be determined that autoclaving is incomplete . In the present embodiment, a printed part 3c printed "Reject" is provided to the side 2d side of the reference line 3b, and a printed part 3c printed
"Accept" is provided to the side 2c side of the reference line 3b, as illustrated in FIG. 1. This allows easy determination on whether autoclaving is complete .
The first holes 4a, 4b are provided so as to bore through the main body 2 of the sterilization indicator 1 , and are formed at least in the cover member 15. The first holes 4a, 4b may have various shapes as seen in plan view, such as circular, elliptical, or polygonal. The first holes 4a, 4b may also have the shape of a letter X or the like as seen in plan view. In the present embodiment, the first holes 4a, 4b are provided so as to bore through the substrate member 1 1 , the first adhesive layer 12, the cover member 15 , the second adhesive layer 16, and the display member 17, and have circular shapes as seen in plan view. A diameter r2 constituting the maximum outer dimension r of the first holes 4a,
4b is, for example, from 0.2 mm to 0.8 mm. When the first holes 4a, 4b have a rectangle shape as seen in plan view, the length of the diagonal lines of the first holes 4a, 4b as seen in plan view is the maximum outer dimension r. In this way, the maximum outer dimension r of the first holes 4a, 4b refers to the maximum diameter or dimension of the first holes 4a, 4b regardless of the shape of the first holes 4a, 4b as seen in plan view.
The first holes 4a, 4b are provided to the side 2c side of the center P of the recessed part 1 1 a in the X direction. The first hole 4a is provided to the side 2a side of the wick member 14, and the first hole 4b is provided to the side 2b side of the wick member 14. The first holes 4a, 4b may also be provided so as to have line symmetry with respect to the wick member 14 as seen in plan view. The first holes 4a, 4b are provided adj acent to an edge E of the recessed part 1 1 a by a minimum distance d l between the edge E and an edge ofthe cover member 15. The minimum distance d l is, for example, from 3 mm to 10 mm. The first holes 4a, 4b are separated from the edge E by the diameter r2 of the first holes 4a, 4b. In other words, a minimum distance d2 between the edge E and the first hole 4a and a minimum distance d3 between the edge E and the first hole 4b are greater than the diameter r2. When the cover member 15 has a shape identical to that of the main body 2 as seen in plan view, the minimum distance d l is equivalent to the minimum distance from the edge E, edge E of the recessed part 11a, to the sides 2a to 2d.
The first hole 4a is separated from the wick member 14 by a distance greater than the diameter r2 of the first hole 4a, and the minimum distance between the first hole 4a and the wick member 14 is equivalent to the minimum distance d2 between the edge E and the first hole 4a. Similarly, the first hole 4b is separated from the wick member 14 by a distance greater than the diameter r2 of the first hole 4b, and the minimum distance between the first hole 4b and the wick member 14 is equivalent to the minimum distance d3 between the edge E and the first hole 4b.
To summarize the aforementioned description, the first hole 4a is provided within a region 21 encompassed by dotted lines 21a to 2 Id in FIG. 2, and the first hole 4b is provided within a region 22 encompassed by dotted lines 22a to 22d in FIG. 2. The dotted lines 21a, 22a are part of a straight line that passes through the center P and extends in the Y direction. The dotted lines 21b, 22b are partial arcs of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d l . The dotted line 21c is a partial line segment connecting points set off from an edge 14c on the side 2a side of the wick member 14 in the Y direction by the minimum distance d2. The dotted line 22c is a partial line segment connecting points set off from an edge 14d on the side 2b side of the wick member 14 in the Y direction by the minimum distance d3. The dotted line 2 Id is a partial arc of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d2, and the dotted line 22d is a partial arc of a circle centered on the center P, wherein the radius of the circle is set to a value equivalent to the sum of the maximum radius rl and the minimum distance d3.
When, for example, the recessed part 11a is sunk inward in a substantially truncated pyramidal shape, the dotted lines 21b, 22b will be straight lines rather than curves. In such manner, the dotted lines 21a to 2 Id and 22a to 22d vary according to the shape of the main body 2 (or the cover member 15) and the shape of the recessed part 11a. Accordingly, the shapes of the regions 21 , 22 will also vary according to the shape of the main body 2 (or cover member 15) and the shape of the recessed part 11a.
An angle Θ formed by an imaginary line passing through the center P of the recessed part 11a in the X direction and an imaginary line connecting the center P of the recessed part 11a and the center of the first hole 4a (or the first hole 4b) as seen in plan view may be 10° or greater or 22.5° or greater, and 80° or less or 67.5° or less. Setting the angle Θ within this range will allow excess water vapor infiltrating the recessed part 11a via the cover member 15 to be suitably discharged through the first holes 4a, 4b. Next, phenomena that can occur when a sterilization indicator that has a shape similar to that of the sterilization indicator 1 , but is not provided with first holes 4a, 4b, is autoclaved will be described.
Sterilizers used to perform autoclaving have increased in performance in recent years. Specifically, the speed of introducing high-temperature water vapor into the apparatus is increased, thereby reducing the length of time required to perform the sterilization process. Sterilization indicators housed within such sterilization apparatus are laminates constituted by a plurality of different layers. Because the linear expansion coefficient of the cover member is many times greater than the linear expansion coefficient of the substrate member, as discussed above, when the sterilization indicator is exposed to high temperatures, a high level of stress is placed upon the sterilization indicator due to the difference in thermal expansion between the substrate member and the cover member. This can lead to debonding between the substrate member and the cover member and bending of the sterilization indicator at the preheating stage and the like before water vapor is introduced into the autoclave. As a result, the adhesive area between the substrate member and the cover member is reduced, potentially creating gaps. This debonding and bending are tends to occur especially in the area from around the edges of the recessed part of the substrate member to the center part of the substrate member.
The introduction of water vapor to a sterilization indicator in which debonding or bending has occurred causes the organic compound making up the dissolved pellet 13 to flow to the exterior of the sterilization indicator. In this case, it is impossible to accurately determine whether autoclaving was successful. In addition, medical instruments disposed near the sterilization indicator may become contaminated.
By contrast, in the sterilization indicator 1 of the present embodiment, the provision of the first holes 4a, 4b at least in the cover member 15 alleviates the stress placed upon the cover 15, making it difficult for the stress caused by the difference in thermal expansion between the substrate member 11 and the cover member 15 to be placed upon the sterilization indicator 1. In addition, the first holes 4a, 4b are provided to the side 2c side of the center P of the recessed part 11a, and are provided adjacent to the edge E of the recessed part 11a by the minimum distance dl between the edge E of the recessed part 11a and the edge of the cover member 15, and separated from the edge E of the recessed part 11a by the diameter r2 of the first holes 4a, 4b. As a result, the first holes 4a, 4b are provided at locations near where the sterilization indicator 1 tends to bend, and at suitable distances from the recessed part 11a. As a result, bending of the sterilization indicator 1 caused by the recessed part 11a is suppressed by the first holes 4a, 4b, allowing leakage of the soluble substance through the first holes 4a, 4b to be prevented. It is thus possible to suppress the occurrence of leakage of the soluble substance during autoclaving.
Moreover, in the sterilization indicator 1 according to the present embodiment, the first holes 4a, 4b are separated from the wick member 14 by the diameter r2 (maximum outer dimension r) of the first holes 4a, 4b. As a result, it is possible to suppress leakage of the soluble substance wicked by the wick member 14 to the outside through the first holes 4a, 4b.
The minimum distance d l is from 3 mm to 10 mm. In this case, excess water vapor infiltrating the recessed part 11a via the cover member 15 is suitably discharged through the first holes 4a, 4b.
The diameter r2 (maximum outer dimension r) of the first holes 4a, 4b is from 0.2 mm to 0.8 mm. In this case, it is possible to suitably suppress leakage of the soluble substance to the outside through the first holes 4a, 4b during autoclaving.
The first holes 4a, 4b are provided so as to have line symmetry with respect to the wick member 14 as seen in plan view. In this case, stress in the substrate member 11 is uniformly alleviated, thereby allowing bending of the substrate member 11 to be suitably suppressed.
The foregoing has been a detailed description of the present invention with respect to the embodiment thereof. However, the present invention is not limited to the embodiment described above. Various modifications can be made to the present invention without deviating from the gist thereof.
For example, the main body 2 is not limited to having a substantially trapezoidal shape as seen in plan view, but may also have a substantially rectangular shape, a substantially polygonal shape, or a substantially circular shape. Accordingly, the substrate member 11 and the like can be altered to suit the shape of the main body 2.
For example, the first holes 4a, 4b need not bore through the entirety of the main body 2 as long as they bore through at least the cover member 15. It is also acceptable to provide only one first hole, or three or more.
The sterilization indicator 1 according to the embodiment described above need not be provided with the display member 17. In this case, the cover member 15 constitutes the outermost layer of the sterilization indicator 1 , and a second adhesive layer 16 is not provided on the cover member 15. In addition, the reference line and printed part may be printed directly on the cover member 15. This arrangement suitably suppresses debonding and bending of the sterilization indicator 1 , and also reduces manufacturing costs. The reference line 3b of the sterilization indicated 1 need not extend so as to intersect the center of the opening 17a, but may be provided at any location. EXAMPLES
The sterilization indicator according to one embodiment of the present invention will now be described in detail using examples . The configuration of the sterilization indicator is not limited to those of the examples described hereafter.
Example 1
An indicator was manufactured according to the following method. First, an aluminum film having a thickness of 76 μιη was prepared as a substrate member. Heat embossing was then performed on the aluminum film to form an accommodating part. Salicylamide was then disposed in the accommodating part as a soluble substance, and 178 μπι-thick filter paper was disposed on the aluminum film as a wick member so that an end thereof overlapped the soluble substance . Next, a 56 μπι-thick polypropylene film was bonded as a cover member pre-coated with an acrylic adhesive as a first adhesive layer to the aluminum film using an acrylic adhesive so as to cover the salicylamide and filter paper. Paper constituting a display member pre-coated with acrylic adhesive as a second adhesive layer was then bonded to the polypropylene film using an acrylic adhesive . Next, an indicator was obtained by performing punching so as to yield a shape as seen in plan view substantially identical to that of the sterilization indicator 1 according to the embodiment described above as seen in FIGS . 1 and 2 (i .e ., a substantially trapezoidal shape) . Accordingly, the indicator had a shape as seen in plan view substantially identical to that of the sterilization indicator 1 according to the embodiment described above as seen in FIGS . 1 and 2 (i .e ., a substantially trapezoidal shape) . The length of the indicator in the X direction was 5 1 mm, and the length of the longer side thereof in the Y direction was 19 mm. The maximum radius of the recessed part was 5.0 mm, and the minimum distance from the edge of the recessed part to the cover member (substrate member) was 5.0 mm.
A pair of holes boring through the aluminum foil at the positions shown in Table 1 below were provided in the indicator so as to have line symmetry with respect to the filter paper as seen in plan view. The positions of the pair of holes were determined based on the center of the recessed part. In Table 1 , length A is the length from the center of the recessed part along the X direction, length B is the length from the center of the recessed part along the Y direction, and length C is the minimum distance from the edge of the recessed part to the holes. Angle D is the angle formed by a side passing through the center of the recessed part in the X direction and a side connecting the center of the recessed part and the centers of the holes (refer to FIG. 2) . Length A is represented by a positive value when the holes are positioned to the side of the center of the recessed part on which the filter paper is provided, and as a negative value when the holes are positioned to the side of the center of the recessed part on which the filter paper is not provided.
The indicator according to Example 1 in which the holes described above were provided was autoclaved according to a standard cycle P01 (program name : B cycle) using an HS33 rapid sterilizer (manufactured by Getinge Japan K.K.) as a sterilizer. A standard cycle comprises a preliminary step in which pre-vacuuming is performed four times, a sterilization step in which the sterilizer is heated at 134°C for four minutes, and a drying step that lasts 15 minutes, performed in that order. The indicator was observed following autoclaving to check whether it was possible to determine whether sterilization had been completed, whether there was any debonding of the printed part, and whether there was any leakage of ink. The results are shown in Table 1 below. In Example 1 , it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed.
Example 2
An indicator was prepared as in Example 1 . The positions of the pair of holes provided in the indicator according to Example 2 are as shown in Table 1 below. The positions of the pair of holes differ from those of Example 1 . When the indicator according to Example 2 was autoclaved, it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed, as in Example 1.
Example 3
An indicator was prepared as in Example 1 . The positions of the pair of holes provided in the indicator according to Example 3 are as shown in Table 1 below. The positions of the pair of holes differ from those of Examples 1 and 2. When the indicator according to Example 3 was autoclaved, it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed, as in Examples 1 and 2.
Example 4
An indicator was prepared as in Example 1 . The positions of the pair of holes provided in the indicator according to Example 4 are as shown in Table 1 below. The positions of the pair of holes differ from those of Examples 1 to 3. When the indicator according to Example 4 was autoclaved, it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed, as in Examples 1 to 3. Example 5
An indicator was prepared as in Example 1. The positions of the pair of holes provided in the indicator according to Example 5 are as shown in Table 1 below. The positions of the pair of holes differ from those of Examples 1 to 4. When the indicator according to Example 5 was autoclaved, it was possible to determine whether sterilization had been completed, and no debonding of the printed part or ink leakage was observed, as in Examples 1 to 4. Comparative Example 1
An indicator was prepared as in Example 1. The positions of the pair of holes provided in the indicator according to Comparative Example 1 are as shown in Table 1 below. Because length A is a negative value in Comparative Example 1 , the pair of holes was provided to the side of the center of the recessed part on which the filter paper was not provided, differing from Examples 1 to 5. Length C in Comparative Example 1 was greater than 5.0 mm, the minimum distance from the edge of the recessed part to the cover member, and angle D was 112.5°. When the indicator according to Comparative Example 1 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 1.
Comparative Example 2
An indicator was prepared as in Example 1. The positions of the pair of holes provided in the indicator according to Comparative Example 2 are as shown in Table 1 below. Because length C is 0.0 mm in Comparative Example 2, the pair of holes were provided so as to contact the edge of the recessed part. When the indicator according to Comparative Example 2 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 2, as in Comparative Example 1.
Comparative Example 3
An indicator was prepared as in Example 1. The positions of the pair of holes provided in the indicator according to Comparative Example 3 are as shown in Table 1 below. Length C in Comparative Example 3 was 7.7 mm, greater than the 5.0 mm constituting the minimum distance from the edge of the recessed part to the cover member. When the indicator according to Comparative Example 3 was autoclaved, it was possible to determine whether sterilization had been completed, as in Examples 1 to 5. However, debonding of the printed part and ink leakage were observed in Comparative Example 3 , as in Comparative Examples 1 and 2. Table 1
Comp Ex Comp Ex Comp Ex
Ex 1 Ex 2 Ex 3 Ex 4 Ex 5
1 2 3
Hole diameter r (μπι) 370 370 370 370 370 370 370 370
Length A (mm) 8.0 7.0 5.5 6.0 2.5 -5.0 0.0 9.0
Length B (mm) 3.0 5.3 5.3 7.0 8.5 9.0 5.0 9.0
Length C (mm) 3.5 3.8 2.6 4.2 3.9 5.3 0.0 7.7
Angle D (°) 22.5 22.5 45.0 45.0 67.5 112.5 90.0 45
Determination of whether
Yes Yes Yes Yes Yes Yes Yes Yes sterilization is complete
Debonding in printed part No No No No No Yes Yes Yes
Ink leakage No No No No No Yes Yes Yes

Claims

1. A sterilization indicator, comprising:
a soluble substance capable of dissolving as the result of contact with heated water vapor;
a substrate member provided with an accommodating part for accommodating the soluble substance and extends in a first direction and in a second direction orthogonal to the first direction as seen in plan view;
a wick member provided contacting at least part of the soluble substance and extends in the first direction; and
a cover member covering the soluble substance and the wick member and is provided on the substrate member, wherein
a hole is provided in at least the cover member, the hole being in a position on the first direction side of the center of the accommodating part, adjacent to an edge of the accommodating part by a minimum distance d l between the edge of the accommodating part and an edge of the cover member, and separated from the edge of the accommodating part by a maximum outer dimension r of the hole.
2. The sterilization indicator according to claim 1, wherein the minimum distance d l is from 3 mm to 10 mm.
3. The sterilization indicator according to claim 1 or 2, wherein the maximum outer dimension r of the hole is from 0.2 mm to 0.8 mm.
4. The sterilization indicator according to any one of claims 1 or 2, wherein the hole is provided so as to bore through the substrate member and the cover member.
5. The sterilization indicator according to any one of claims 1 or 2, wherein the hole is provided in plurality so as to have line symmetry with respect to the wick member as seen in plan view.
6. The sterilization indicator according to any one of claims 1 or 2, wherein a printed part indicating whether a sterilization process has been successful is printed directly on the cover member.
PCT/US2016/067428 2015-12-24 2016-12-19 Sterilization indicator Ceased WO2017112562A1 (en)

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Publication number Priority date Publication date Assignee Title
WO2017184594A3 (en) * 2016-04-22 2018-03-08 American Sterilizer Company Sterilization test strip
WO2021053430A1 (en) * 2019-09-20 2021-03-25 3M Innovative Properties Company High temperature sterilizable adhesive articles
WO2021108045A1 (en) * 2019-11-25 2021-06-03 American Sterilizer Company Chemical indicator
CN115666437A (en) * 2020-04-03 2023-01-31 3M创新有限公司 Determining the effectiveness of a sterilization program from outside the sterilization pack

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JPH07171206A (en) 1993-10-07 1995-07-11 Py Mah Corp Improved monitor for steam sterilization process
WO2014047139A1 (en) * 2012-09-18 2014-03-27 3M Innovative Properties Company Sterilant challenge device
US20140273239A1 (en) * 2012-11-28 2014-09-18 Dana Products, Inc. Air removal test strip

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US5120137A (en) * 1991-03-29 1992-06-09 Minnesota Mining And Manufacturing Company Time and temperature indicating device
JPH07171206A (en) 1993-10-07 1995-07-11 Py Mah Corp Improved monitor for steam sterilization process
WO2014047139A1 (en) * 2012-09-18 2014-03-27 3M Innovative Properties Company Sterilant challenge device
US20140273239A1 (en) * 2012-11-28 2014-09-18 Dana Products, Inc. Air removal test strip

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017184594A3 (en) * 2016-04-22 2018-03-08 American Sterilizer Company Sterilization test strip
US10119946B2 (en) 2016-04-22 2018-11-06 American Sterilizer Company Sterilization test strip
WO2021053430A1 (en) * 2019-09-20 2021-03-25 3M Innovative Properties Company High temperature sterilizable adhesive articles
WO2021108045A1 (en) * 2019-11-25 2021-06-03 American Sterilizer Company Chemical indicator
AU2020393800B2 (en) * 2019-11-25 2025-09-04 American Sterilizer Company Chemical indicator
CN115666437A (en) * 2020-04-03 2023-01-31 3M创新有限公司 Determining the effectiveness of a sterilization program from outside the sterilization pack

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