Liquid/vapor sterilization container systems

A tray and process for hydrogen peroxide vapor sterilization of medical articles. The tray includes a bottom surface and side walls defining a space to receive articles to be sterilized. The bottom surface of the tray includes a number of inlet passages and wells with a known volume. In the process of the present invention, articles to be sterilized are placed in the tray, and aqueous solutions of hydrogen peroxide is delivered into the tray. When the excess hydrogen peroxide is drained through the inlet passages, a known volume of peroxide remains in the wells. Such remaining hydrogen peroxide is then vaporized to achieve sterilization.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an apparatus and process for using hydrogen 
peroxide vapor to sterilize articles such as medical instruments, and more 
particularly, to the use of liquid hydrogen peroxide and a container 
system for such a process. 
2. Description of the Related Art 
Modern medical and dental practices require the use of aseptic materials 
and devices, i.e., the materials and devices must be generally free from 
germs, bacteria, etc., and many of these devices are meant for repeated 
use. In order to achieve this asepsis, efficient sterilization processes 
are needed for treatment of reusable materials and devices. These 
processes are needed not only at hospitals and dental offices, but also at 
the manufacturers of these materials and devices. 
Medical instruments have traditionally been sterilized using either heat, 
as is provided by steam, or a chemical, such as formaldehyde or 
ethylene-oxide gas or vapor state. Each of these methods has drawbacks. 
Many medical devices, such as fiber optic devices, endoscopes, power 
tools, etc., are sensitive to heat, moisture, or both. Formaldehyde and 
ethylene oxide are both toxic gases that pose a potential hazard to health 
care workers. Problems with ethylene oxide are particularly severe, 
because its use requires long aeration times to remove the gas from 
articles that have been sterilized. This makes the sterilization cycle 
time undesirably long. 
Sterilization using hydrogen peroxide has been shown to have some 
advantages over other chemical sterilization processes. In the prior art, 
many sterilization methods use hydrogen peroxide either in the form of 
liquid solutions or in the form of hydrogen peroxide vapor that has been 
generated from a liquid solution of hydrogen peroxide. 
The sterilization of articles in liquid solutions of hydrogen peroxide can 
be achieved using a wide variety of methods. In one application, articles 
to be sterilized can be simply dipped into the liquid hydrogen peroxide 
solutions. In another application, articles can be first placed onto a 
perforated tray and then immersed into the liquid hydrogen peroxide 
solution to achieve sterilization. An example of this type of perforated 
tray is shown in patent to Casle, U.S. Pat. No. 1,187,498. A more 
complicated prior art application is, however, disclosed in patent to 
Schneider et al., U.S. Pat. No. 5,091,343. This patent describes a liquid 
sterilization apparatus using a removable container to receive articles to 
be sterilized. The container includes apertures to receive and drain 
liquid sterilants. During the process, the container is placed into a 
housing inside the sterilization apparatus. A liquid sterilant solution is 
pumped into this housing filling the housing and the container thereby 
treating articles inside the container. At the end of the sterilization 
cycle, the liquid sterilization cycle, the liquid sterilant is completely 
drained and the container is removed. 
In the prior art, aqueous solutions of hydrogen peroxide are used to 
generate sterilizing hydrogen peroxide vapor in vacuum chambers to 
sterilize articles. During the sterilization process, articles to be 
sterilized are exposed to the hydrogen peroxide vapor. Accordingly, one 
major parameter of the process needed to achieve satisfactory 
sterilization is the amount of liquid hydrogen peroxide entering into the 
chamber to be evaporated. In fact, the amount of liquid peroxide utilized 
in the system directly affects the sterilization process. For the 
efficiency of the sterilization process, it is important that the liquid 
peroxide be delivered to the chamber in measured quantities or volumes. 
SUMMARY OF THE INVENTION 
One aspect of the present invention relates to a system for sterilization 
of articles using liquid sterilant. This system includes a bottom surface 
to receive the articles to be sterilized and at least one well formed in 
the bottom surface which defines a known volume. The well is positioned so 
that when the liquid is introduced onto the bottom surface, a known volume 
of the liquid sterilant fills the well and when the liquid sterilant is 
drained from the surface, the known volume of liquid sterilant remains in 
the well so that a subsequent sterilization process can be performed on 
the articles positioned on the bottom surface with the known volume of 
liquid sterilant positioned within the bottom surface. The system also 
includes a heat source or a vacuum source for vaporizing the liquid 
sterilant in the well, and can optionally include a source of plasma. The 
bottom surface preferably has at least one perforation for draining the 
liquid sterilant from the bottom surface. The system also can include a 
plurality of sidewalls attached to the bottom surface, so that the bottom 
surface and the plurality of sidewalls define a space. The well formed in 
the bottom surface can be curved, flat or angled. Thus, the well can be an 
inwardly extending hemispherical projection. The well can also be formed 
in the bottom surface as an inwardly extending rectangular projection 
having rounded ends. In another embodiment, the system includes at least 
one upwardly extending projection adjacent the well. The well formed in 
the bottom surface can also be a rectangular box having side walls, 
defining an opening. Where perforations are provided, they can be disposed 
adjacent the well, and can be roughly spherical in shape. The upwardly 
extending projection can include a perforation thereon, which can be on 
top of the projection or on a side of the projection. The bottom surface 
can be a sloped surface, a convex or concave surface or a V-shaped 
surface. The bottom surface is comprised can be of a variety of materials 
including stainless steels, aluminum, aluminum alloys, liquid crystal 
polymers, polyesters, polyolefin polymers or fluorinated polyolefins. If 
the bottom surface is comprised of a composite material, the composite 
material can include a filler of high thermal conductivity. Examples of 
composite materials include a metal-filled polymer, a ceramic-filled 
polymer and a glass-filled polymer. The liquid sterilant is preferably 
liquid hydrogen peroxide. 
Another aspect of the present invention relates to method for sterilization 
of an article. This method includes placing the article on a bottom 
surface having one or more wells formed therein. Each of the wells defines 
a known volume. The method also includes introducing liquid sterilant onto 
the bottom surface, thereby filling the one or more wells with the known 
volume of sterilant, and vaporizing the known volume of sterilant in the 
one or more wells, thereby sterilizing the article using the vaporized 
liquid sterilant. The introducing step can include immersing the bottom 
surface into the liquid sterilant, thereby filling the one or more wells, 
removing the bottom surface from the liquid sterilant, and draining the 
liquid sterilant from the bottom surface, whereby the known volume of 
liquid sterilant remains in the one or more wells. The bottom surface can 
include one or more perforations extending therethrough, and a plurality 
of sidewalls in contact with the bottom surface such that the bottom 
surface and the plurality of sidewalls define a space. Thus, the 
introducing step can include flowing the liquid sterilant through the 
perforations onto the bottom surface to thereby contact with the article, 
and draining the sterilant through the inlet passages. The article can 
have a lumen therein, and the introducing step can include attaching an 
adaptor to the lumen and flowing the liquid sterilant through the adaptor 
and into the lumen. The liquid sterilant preferably comprises hydrogen 
peroxide. The sterilization can include placing the bottom surface with 
the article and known volume of sterilant in a diffusion-restricted 
environment. Thus, the sterilizing can include exposing the 
diffusion-restricted environment to vacuum for a period of time. The known 
quantity of the liquid sterilant ordinarily vaporizes during the 
sterilizing, and the sterilizing ordinarily occurs within a chamber. A 
suitable diffusion restricted environment can be provided as a diffusion 
restricted container. The method can include enclosing the article within 
a gas permeable material, which can be performed before the vaporizing 
step. The article can also be enclosed within a gas permeable pouch or 
container. Thus, both the article and the bottom surface can be enclosed 
within the gas permeable material, such as CSR-wrap or TYVEK.TM.. The 
vaporizing step can include heating or reducing pressure. The method can 
also include exposing the article to plasma after the vaporizing step to 
enhance efficacy of sterilization and/or remove residual sterilant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Sterilizing lumened devices or other articles has always posed a challenge 
to sterilization systems. The system of the present invention is directed 
to the use of both liquid and vapor phase sterilants to sterilize 
articles. In the present invention, a hydrogen peroxide solution is used 
to perform the sterilization process of the present invention. During the 
sterilization process, articles are first pretreated with the liquid 
hydrogen peroxide and then exposed to a vacuum to vaporize a predetermined 
volume of liquid hydrogen peroxide. One such example of a sterilization 
system that pretreats articles with liquid peroxide before vapor phase 
sterilization is disclosed in copending application to the applicant, U.S. 
Ser. No. 08/628,965, entitled "Method of Sterilization Using Pretreatment 
with Hydrogen Peroxide". The entire contents of this copending application 
are hereby incorporated by reference. However, this system is described 
only in connection with diffusion-restricted environments. As used herein, 
a "diffusion-restricted" area refers to any one or more of the following 
properties: (1) the ability of the area of an article placed within the 
sterilization system of the present invention to retain 0.17 mg/L or more 
hydrogen peroxide solution after one hour at 40.degree. C. and 10 torr; 
(2) having the same or more diffusion restriction than provided by a 
single entry/exit port of 9 mm or less in internal diameter and 1 cm or 
greater in length; (3) having the same or more diffusion restriction than 
provided by a lumen 27 cm in length and having an internal diameter of 3 
mm; (4) having the same or more diffusion restriction than provided by a 
lumen having a ratio of length to internal diameter greater than 50; (5) 
the ability of an article placed within the sterilization system of the 
present invention to retain 17% or more of the hydrogen peroxide solution 
placed therein after one hour at 40.degree. C. and 10 torr; or (6) being 
sufficiently diffusion-restricted to completely sterilize a stainless 
steel blade within a 2.2 cm by 60 cm glass tube having a rubber stopper 
with a 1 mm by 50 cm stainless steel exit tube therein at a vacuum of 10 
torr for one hour at 40.degree. C. in accordance with the present 
invention. It is acknowledged that characteristics (1) and (5) will vary 
depending on the initial concentration of hydrogen peroxide placed into 
the article; however, this can be readily determined by one having 
ordinary skill in the art. 
The system described by the inventors in their previous application is not 
able to provide a predetermined liquid peroxide to vaporize. In the 
process of the present invention, articles to be sterilized are first 
placed in a sterilization container. Next, the hydrogen peroxide solution 
is delivered into contact with articles in the container so that articles 
can be treated with the liquid peroxide. As a first sterilization step in 
the process, this treatment in liquid peroxide is called pretreatment. In 
this respect, the delivery of the liquid peroxide into contact with 
articles may be facilitated through means such as flowing the peroxide 
into the container, submerging the container into the peroxide or spraying 
the peroxide onto articles in the container. As will be described more 
fully hereinbelow, the sterilization container is configured to retain a 
certain volume of liquid hydrogen peroxide in the container when the rest 
of the liquid hydrogen peroxide is drained. Such retained hydrogen 
peroxide is then vaporized in an evacuated chamber to achieve 
sterilization. Several embodiments of the sterilization container are set 
forth below. 
Reference will now be made to the drawings wherein like numerals refer to 
like parts throughout. As illustrated in FIG. 1A, in the preferred 
embodiment the sterilization container of the present invention may be 
configured as a tray 100. The tray 100 comprises a base plate 102 and a 
peripheral side-wall 104 which is preferably perpendicularly attached to 
the periphery of the base plate 102. The base plate 102 and the side wall 
104 define a cavity 110 of the tray 100 to receive the articles to be 
sterilized. As shown in FIGS. 1A and 1B, the base plate 102 of the tray 
100 preferably comprises a plurality of evenly spaced wells 106 and 
perforations 108. In this embodiment, wells 106 are preferably configured 
to have a hemispherical shape; however, as discussed in more detail 
hereinbelow in conjunction with FIGS. 6A(1)-6C(4), the shape of the wells 
106 can take any of a variety of forms. The wells 106 are downwardly 
projected to the plane of the base plate 102 in a manner shown in FIG. 1B. 
These wells 106 are dimensioned to hold a desired volume of liquid 
hydrogen peroxide. Perforations 108 are disposed evenly adjacent to wells 
106 on the tray 100. It will be apparent from the foregoing that 
perforations 108 render the tray 100 permeable to fluids and therefore 
permit washing of the articles in the tray 100 with liquids. In the 
preferred embodiment these perforations 108 enable the tray 100 to drain 
the liquid peroxide which has been delivered into contact with the 
articles in the tray 100. 
The perforations also enable the tray to be immersed into the liquid 
hydrogen peroxide so that the articles in the tray 100 can be washed with 
the liquid peroxide. However, when the excess liquid peroxide is drained 
through the perforations 108, a predetermined volume of the liquid 
peroxide remains in the wells 106. Since the wells 106 of the tray 100 
have a predetermined volume, the amount of the remaining hydrogen peroxide 
in these wells 106 is known. However, as is well known in the art, volume 
of a liquid in a container also depends on the surface tension of the 
liquid and the material of the container. Additionally, temperature will 
affect the surface tension and density of the liquid, which would also 
affect the volume. As will be explained in detail hereinbelow, this 
remaining liquid peroxide will be vaporized during the following 
sterilization process. 
FIG. 2A shows a second embodiment of the peroxide tray with the tray 200 
comprising a base plate 202 and a peripheral side-wall 204. Similar to the 
first embodiment, the peripheral side-wall 204 is attached to the 
periphery of the base plate 202. Preferably, the side-wall 204 is attached 
perpendicular to the base plate 202. As shown in FIGS. 2A and 2B, the base 
plate 202 and the side-wall 204 define a cavity 210 to receive articles to 
be sterilized. The base plate 202 of the tray 200 can comprise a plurality 
of evenly spaced wells 206 and perforations 208. In this embodiment, the 
wells 206 are configured to have a rectangular shape with rounded ends 
207, and are downwardly projected to the plane of the base plate 202 of 
the tray 200. The wells 206 are preferably positioned transversely 
relative to the longitudinal axis of the tray 200 in a manner shown in 
FIGS. 2A-2B. As is explained in the first embodiment, these wells 206 are 
dimensioned to retain a predetermined amount of liquid peroxide when the 
peroxide is drained. Perforations 208 are disposed evenly adjacent to the 
wells 206 in a manner shown in FIGS. 2A-2B. As is explained in detail in 
the first embodiment, perforations 208 allow the liquid peroxide to fill 
the tray 200 and then drain the liquid peroxide from the tray 200. 
As shown in FIG. 3A, in a third embodiment, a tray 300 comprising a base 
plate 302 and a peripheral side wall 304 is configured as is explained in 
the previous embodiments. As shown in FIGS. 3A-3B, the base plate 302 of 
the tray 300 comprises a plurality of upwardly extending projections 306. 
In this embodiment, these projections 306 are preferably configured to 
have a hemispherical shape and are upwardly extended on the plane of the 
base plate 302 as in the manner shown in FIGS. 3A-3B. As shown in FIGS. 
3A-3B, the tops of the projections are perforated to render the tray 300 
permeable to fluids. In this embodiment, although perforations 308 
facilitate the draining of the liquid peroxide from the tray 300, the 
remaining liquid peroxide is retained in a space 307 defined by the outer 
surface of the projections 306 and peripheral side-wall 304 of the tray as 
well as the upper surface of the base plate 302. Since the volume occupied 
by projections and the depth of the liquid peroxide (level of 
perforations) are known, the amount of peroxide retained in the tray 300 
can easily be determined. 
As shown in FIG. 4A, in a fourth embodiment, a tray 400 comprising a base 
plate 402 and a peripheral side wall 404 is constructed in a manner 
described in the previous embodiments. As shown in FIGS. 4A-4B, the base 
plate 402 of the tray 400 may comprise a plurality of wells 406 and 
perforations 408. In this embodiment, the wells 406 are preferably 
constructed as open containers comprising a wall section 407 which is 
perpendicular to the surface of the base plate 402. As shown in FIG. 4A, 
both ends of the wall section 407 may terminate on the peripheral side 
wall 404 so that the well 406 is surrounded by both a portion 405 of the 
peripheral wall 404 and the wall section 407. In this embodiment, wells 
are located at the inner corners of the tray 400 and have a rectangular 
shape. Perforations 408 are disposed evenly over the base plate 402 as in 
the manner shown in FIGS. 4A-4B. 
Although these are several embodiments to construct the liquid peroxide 
trays, it is understood by those skilled in the art, that the peroxide 
trays can also be advantageously manufactured in numerous alternative 
ways. As illustrated in cross-section in FIG. 5A, for the preferred 
embodiment, a base plate 102A of a peroxide tray 100A can be configured to 
have a convex shape so that faster draining through perforations 108A can 
be provided. Similarly, FIG. 5B illustrates the plate 102B of a peroxide 
tray 100B which has a concave shape. As shown in FIG. 5C, a base plate 
102C of a peroxide tray 100C can be configured to have a slope to provide 
faster draining. Further, as shown in FIG. 5D, the base plate 102D of a 
peroxide tray 100D can be configured to have a V-shape in the manner shown 
in FIG. 5D. The base plate 102D can also be configured to have a reverse 
V-shape (not shown). Such convex, concave, inclined, V-shape and reverse 
V-shape base plate designs may enhance draining of liquid peroxide from 
the tray, and hence from the surface and the inner lumen of the 
instruments. Alternatively, as illustrated in FIG. 5E, a tray 100E may be 
comprised of a base plate 102E without a peripheral side-wall. However, 
the tray 100E may include a pair of handle means (not shown) attached to 
the sides of the tray 100E. A handle mean can, for example, be a wire 
frame. The base plate 102E of the tray 100E comprises wells 106E and 
perforations 108E. In this alternative embodiment, fluid is retained 
within the wells 106E and drained off the sides of the base plate 102E; 
however, the base plate 102E can also include perforations 108E to 
facilitate draining. The base plate 102E can also take a non-planar shape 
to facilitate drainage of fluid. 
In accordance with the principles of the present invention, wells and the 
upward projections as well as accompanying perforations can be configured 
in a wide variety of shapes. Examples of these shapes are illustrated in 
FIGS. 6A(1)-6C(4). As illustrated in FIGS. 6A(1)-6C(1) the upwardly 
extending projections may comprise various profiles. The perforations 608 
are disposed on top of the projections 607 as in the manner shown in FIGS. 
6A(1),6B(1) and 6C(1). As illustrated in FIGS. 6A(2), 6B(2) and 6C(2), 
perforations may be distributed 608 evenly around wells 606 as in the 
manner shown in FIGS. 6A(2), 6B(2) and 6C(2). In FIGS. 6A(3), 6B(3), 
6C(3), 6A(4), 6B(4) and 6C(4), perforations 608 are alternatively disposed 
around the top ends of both wells 606 and the upward projections 607 as in 
the manner shown in FIGS. 6A(3), 6B(3), 6C(3), 6A(4), 6B(4) and 6C(4). 
In the preferred embodiment, the tray 100 can be manufactured from any 
material which has minimum interaction with hydrogen peroxide. In this 
respect, the tray material should have a minimal hydrogen peroxide 
absorption or decomposition. Examples of common materials used to 
manufacture the tray 100 include, but are not limited to, metallic 
materials and polymeric materials. Metallic materials may preferably be 
stainless steels such as 304, 316, 304L and 316L (in AISI standards), and 
aluminum and aluminum alloys. Preferred polymeric materials may be 
reinforced or unreinforced materials such as liquid crystal polymers 
reinforced with a filler of high thermal conductivity, polyolefin polymers 
and fluorinated polyolefins. A liquid crystal polymer may be a polyester 
including wholly aromatic polyester such as VECTRA.TM. (Hoechst-Celenese) 
or a poly ethylene teraphthalate (PET) such as THERMX.TM. (Eastern 
Chemical). Polyolefin polymers may include high or low density 
polyethylene, polypropylene and polybutylene. An exemplary fluorinated 
polyolefin polymer may be TEFLON.TM.. In the preferred embodiment, a tray 
material may comprise either a material with a high thermal conductivity 
to enhance heat transfer or a material reinforced with high thermal 
conductivity metal, ceramic or glass. Among the above mentioned materials, 
stainless steels, aluminum and aluminum alloys, as well as liquid crystal 
polymers reinforced with a filler of high thermal conductivity, are 
preferred high thermal conductivity materials. The tray can be made using 
techniques well known in the art. 
As previously mentioned, the process of the present invention involves both 
liquid and vapor phase sterilization process steps. In either process, 
however, articles to be sterilized are contained and transported in the 
peroxide tray 100 of this invention. In the method of the present 
invention, articles in the tray 100 (FIG. 1A) may be first treated with 
liquid sterilant, such as hydrogen peroxide, by delivering dilute, aqueous 
solutions of hydrogen peroxide into the tray 100. In one embodiment, the 
liquid peroxide is delivered by immersion of the tray 100A into the liquid 
sterilant. In this step of treatment with liquid sterilant, the articles 
in the tray 100 contact with the liquid sterilant so that the inner and 
outer surfaces of the articles are substantially washed and soaked by the 
liquid peroxide. In particular, at this step, hydrogen peroxide solution 
effectively contacts with the inaccessible or hard-to-reach places of the 
articles. Such articles may include long narrow lumens, hinges and other 
articles having spaces where diffusion of vapors is restricted. The 
aqueous solutions of hydrogen peroxide can be relatively dilute, e.g., as 
low as 1-6% or lower by weight. In the preferred embodiment, a preferred 
concentration range for the peroxide solution may be 3-15% by weight, or 
more preferably 6-10% by weight. As previously explained, when the 
peroxide solution in the tray 100 is drained through perforations 108 in 
the bottom plate 102 of the tray 100, a predetermined quantity of hydrogen 
peroxide can be retained in the wells 106 of the peroxide tray 100. In the 
second step of the process, this retained hydrogen peroxide and the 
peroxide remaining in inaccessible spaces of the articles are vaporized to 
achieve sterilization. This sterilization step can be performed by placing 
the tray into a sterilization environment such as a vacuum chamber, and 
subsequently applying vacuum and/or heat to vaporize the peroxide. As is 
well known in the art, sterilization is not easily achieved through 
contact with dilute liquid peroxide solutions at low temperatures. 
However, sterilization can be achieved at low temperatures and in short 
periods of time upon exposure to hydrogen peroxide vapor under vacuum or 
vacuum combined with a plasma process. As will be explained more fully 
hereinbelow, the liquid hydrogen peroxide treatment and the vaporization 
of the peroxide can also be performed within the same vacuum chamber. 
Consequently, it would be understood that the present process particularly 
pretreats the articles in the tray 100 with the liquid peroxide and 
subsequently vaporizes the retained liquid peroxide in a vacuum chamber to 
achieve sterilization. 
The preferred embodiment of the process of the present invention comprises 
an in-situ sterilization process to achieve the pretreatment and vapor 
sterilization steps in a sterilization system. As illustrated in FIG. 7A, 
In-situ sterilization process of the present invention is carried out in a 
sterilization container 700. The sterilization container 700 comprises a 
bottom wall 702 and a peripheral side wall 701, and a removable container 
lid 703 through which articles to be sterilized can be introduced. 
Preferably, the peripheral side-wall 701 of the container 700 is 
perpendicularly attached to the periphery of the bottom wall 702. In this 
embodiment, the bottom wall 702 and the peripheral side-wall 701 define a 
housing 706 of the container 700. The housing 706 of the sterilization 
container is preferably configured and dimensioned to receive at least one 
tray 100 (FIG. 7B) containing articles to be sterilized. 
As is shown in FIG. 7A, the peripheral side-wall 701 of the chamber 700 
includes a first opening 711 which is preferably connected to a 
T-connector 705 attached to the side-wall 701. The T-connector connects 
the container 700 to both a vacuum source and a liquid peroxide source. 
Therefore, T-connector 705 preferably comprises a first-end 713 to the 
vacuum source (not shown) and a second-end 710 to the liquid peroxide 
source (not shown). The first-end 710 of the T-connector 705 contains a 
first valve 712 or a vacuum valve 712 to isolate the container 700 from 
the vacuum source. Similarly, the second-end 710 contains a second valve 
709 or an inlet valve 710 to isolate the liquid peroxide source from the 
chamber 700. 
As is further shown in the FIG. 7A, the bottom wall of the container 700 
comprises a second opening 707 which is connected to an outlet connector 
715 which allows the draining of the liquid peroxide from the container 
700. The connector 715 include an outlet valve 714 to control the draining 
of the liquid peroxide. The draining of the liquid peroxide is controlled 
by opening and closing of the outlet valve 714. The container 700 may also 
comprise an optional heater 720 which may be attached to bottom wall 702 
or/and outside the peripheral wall 701 (not shown) of the container 700, 
in a manner shown in FIG. 7A. 
The preferred embodiment of the in-situ sterilization process of the 
present invention is shown in FIG. 7B. As illustrated in FIG. 7B, the tray 
100 containing articles to be sterilized is initially placed into the 
housing 706 of the sterilization container 700. The liquid peroxide is 
delivered into chamber 700 through opening 711 and fills the container 
700, and hence covers articles in the tray 100 to pretreat articles. The 
articles to be sterilized are then pretreated with liquid peroxide for a 
required period of time before draining the liquid peroxide through outlet 
valve 714. The draining of the liquid peroxide is carried out by opening 
the outlet valve 714. Once the draining is completed, the outlet valve 714 
is closed and the container is evacuated to vaporize the liquid peroxide 
retained in the wells 106 of the tray 100. Articles remain in the peroxide 
vapor for a period to effect complete sterilization. It will be understood 
that, for lumened articles, an adaptor can be used to connect flow of 
liquid peroxide to the interior of the article. As is well known in the 
art, a wide variety of time, temperature an pressure conditions can be 
used to effect sterilization. In a second embodiment, in-situ 
sterilization process can be alternatively carried out using one of the 
alternative tray embodiments. As illustrated in FIG. 7C, the tray 100D can 
also be used during the in-situ sterilization process. Absence of 
peripheral side-walls may facilitate a faster liquid peroxide draining. 
As shown in FIG. 8, in a third embodiment, in-situ sterilization process 
can be carried out in an alternative sterilization container 800. Similar 
to the container 700 of the previous embodiment, the container 800 also 
comprises a bottom wall, a peripheral side-wall and a container lid as 
well as other features configured in a manner shown in FIG. 8. However, as 
a departure from the previous container embodiment, the bottom wall 802 of 
the container 800 comprise a plurality of wells 806 to retain the liquid 
peroxide. The liquid peroxide can be drained through opening 807 which is 
connected to an outlet valve 814 through connector 815. As is understood, 
the container 800 does not require the use of tray 100 during the 
sterilization process. Articles to be sterilized can be directly placed 
into the container 800 and rest of the process flow is proceeded as is 
explained above. Optionally, a metal grid 820 can be provided to keep the 
articles to be sterilized out of the liquid sterilant at the bottom of the 
container 800. 
In an alternative process of the present invention, an ex-situ 
sterilization process can be used to sterilize articles. In this process, 
the tray 100 containing articles is manually submerged into a liquid 
hydrogen source such as a liquid hydrogen tank to pretreat articles in 
liquid peroxide. As previously explained above the tray 100 can carry or 
retain a predetermined amount of liquid peroxide in the tray 100 when the 
tray 100 is removed from the liquid peroxide container. Following this 
step, the tray 100 containing articles and the remaining liquid peroxide 
is placed into the container 700 or another vacuum chamber. The chamber 
700 is sealed and evacuated to vaporize the hydrogen peroxide in the wells 
106 of the tray 100. The articles are exposed to hydrogen peroxide vapor 
for a period of time at a temperature sufficient to effect sterilization. 
In an alternative embodiment of the ex-situ sterilization process of the 
present invention, a similar process is used to treat articles in liquid 
hydrogen peroxide. As a departure from the previous embodiment, this 
alternative embodiment may use a CSR-wrap to wrap the tray 100 containing 
the articles and the remaining hydrogen peroxide. Specifically, the 
CSR-wrap restricts the diffusion of germs and bacteria, but allows the 
diffusion of hydrogen peroxide vapor through the CSR-wrap. In the 
following step, the CSR-wrap wrapped tray 100 is placed into the container 
700 and the container is sealed and evacuated to vaporize the hydrogen 
peroxide to achieve sterilization. In another embodiment, the CSR-wrap can 
be replaced with a pouch or so that the tray 100 containing articles can 
be inserted into the this pouch. The pouch can be readily made of a gas 
permeable material layer. This gas permeable material layer may comprise 
TYVEK.TM. materials, including combinations of MYLAR.TM. and TYVEK.TM.. 
Alternatively, the tray 100 can be placed into a gas permeable container 
before placing into the container 700. This gas permeable container may 
for example be a container having at least one perforation thereon, 
preferably on a top portion thereof. Alternatively, the container can be 
fitted with a valve. 
Hence, although the foregoing description of the preferred embodiment of 
the present invention has shown, described and pointed out the fundamental 
novel features of the invention, it will be understood that various 
omissions, substitutions, and changes in the form of the detail of the 
apparatus and method as illustrated as well as the uses thereof, may be 
made by those skilled in the art, without departing from the spirit of the 
present invention. Consequently, the scope of the present invention should 
not be limited to the foregoing discussions, but should be defined by the 
appended claims.