U.S. patent application number 10/358027 was filed with the patent office on 2003-06-26 for self-contained sterilant monitoring assembly and method of using same.
Invention is credited to Mondiek, David A., Wang, Jianjun.
Application Number | 20030115933 10/358027 |
Document ID | / |
Family ID | 23419348 |
Filed Date | 2003-06-26 |
United States Patent
Application |
20030115933 |
Kind Code |
A1 |
Wang, Jianjun ; et
al. |
June 26, 2003 |
Self-contained sterilant monitoring assembly and method of using
same
Abstract
A system for monitoring concentrations of sterilant, such as
hydrogen peroxide vapor, within a sterilization apparatus, includes
a self-contained, sterilant monitoring assembly that is freely
positionable within the sterilization apparatus. The assembly
includes a gas-detecting sensor and associated temperature sensor
mounted on a portable structure, as well as a suitable data
collection circuit for receiving output signals from the sensors.
The assembly also includes signals connectors, such as a physical
data port or a remote transmitter, or both. Signals can be
transmitted concurrently with data collection, or an electronic
memory may be provided for subsequent transfer of the collected
data. Collected data is transferred to a remote communication unit
positioned exteriorly of the sterilization apparatus. The collected
data is processed by a processor, which is either provided as part
of the monitoring assembly or provided remotely as part of the
monitoring system as a whole, to identify the corresponding
detected sterilant levels. The assembly is operated by a power
source, which can be activated manually, by preprogrammed relays,
or remotely by a control system capable of receiving control
signals via near infrared or radio wave transmissions. A carrier
element is provided to carry the sterilant monitoring assembly
along the conveyor path of the sterilization apparatus and, thus,
collect data at each sterilization station.
Inventors: |
Wang, Jianjun; (Dublin,
OH) ; Mondiek, David A.; (Dublin, OH) |
Correspondence
Address: |
STEVEN F. WEINSTOCK
ABBOTT LABORATORIES
100 ABBOTT PARK ROAD
DEPT. 377/AP6A
ABBOTT PARK
IL
60064-6008
US
|
Family ID: |
23419348 |
Appl. No.: |
10/358027 |
Filed: |
February 4, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10358027 |
Feb 4, 2003 |
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09992133 |
Nov 16, 2001 |
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6532794 |
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09992133 |
Nov 16, 2001 |
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09360772 |
Jul 26, 1999 |
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6318151 |
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Current U.S.
Class: |
73/25.04 |
Current CPC
Class: |
A61L 2/28 20130101; A61L
2/24 20130101 |
Class at
Publication: |
73/25.04 |
International
Class: |
G01N 025/56 |
Claims
What is claimed is:
1. A sterilant monitoring assembly for a sterilization apparatus
using a sterilant, the sterilant monitoring assembly comprising: a
sterilant sensor configured to provide output signals corresponding
to detected levels of the sterilant; a data collection circuit
operatively coupled to said sterilant sensor to receive the output
signals from said sterilant sensor as collected data; and a power
source to provide electrical power to said sterilant sensor and
said data collection circuit; wherein the sterilant sensor, the
data collection circuit and the power source are self-contained on
a portable structure so as to be freely positionable proximate the
sterilization apparatus to monitor levels of the sterilant
thereat.
2. A sterilant monitoring assembly in accordance with claim 1,
wherein the data collection circuit includes an electronic memory
to create a readable memory of the data collected during a selected
time interval, and a signal connector to allow transfer of signals
representative of the collected data from said electronic memory to
a remote communication unit in communication with the signal
connector.
3. A sterilant monitoring assembly in accordance with claim 1,
wherein the data collection circuit includes a transmitter to
transmit signals representative of the collected data to a remote
communication unit.
4. A sterilant monitoring assembly in accordance with claim 1,
further including a temperature sensor operatively coupled to the
data collection circuit to provide output signals corresponding to
the ambient temperature proximate the sterilant sensor for
collection in combination with the output signals from said
sterilant sensor.
5. A sterilant monitoring assembly in accordance with claim 1,
wherein: said sterilant sensor includes a gas-detecting
semiconductor element and a heater to elevate the temperature of
the gas-detecting semiconductor element.
6. A sterilant monitoring assembly in accordance with claim 1,
further comprising a control system provided on the portable system
and in communication with the power source to allow the power
source to be activated remotely.
7. A sterilant monitoring assembly in accordance with claim 1,
wherein said sterilant is hydrogen peroxide (H.sub.2O.sub.2) vapor,
said sterilant sensor providing output signals corresponding to
detected levels of H.sub.2O.sub.2 vapor.
8. A sterilant monitoring assembly in accordance with claim 1,
further including: a carrier element configured as an article to be
sterilized by the sterilization apparatus, said portable structure
being positionable on said carrier element during sterilization by
the sterilization apparatus to monitor a sterilization cycle to
which articles are subjected.
9. A hydrogen peroxide (H.sub.2O.sub.2) vapor monitoring assembly
for a sterilization apparatus using H.sub.2O.sub.2 vapor to sterile
articles, the H.sub.2O.sub.2 vapor monitoring system comprising: an
H.sub.2O.sub.2 vapor sensor configured to provide output signals
corresponding to detected levels of H.sub.2O.sub.2 vapor, said
H.sub.2O.sub.2 vapor sensor including a gas-detecting semiconductor
element and a heater to elevate the temperature of said
gas-detecting semiconductor element; a temperature sensor
configured to provide output signals corresponding to the ambient
temperature proximate said H.sub.2O.sub.2 vapor sensor; a data
collection circuit operatively coupled to said H.sub.2O.sub.2 vapor
sensor and said temperature sensor to receive output signals
therefrom as collected data; and a power source to provide
electrical power to said H.sub.2O.sub.2 vapor sensor, said
temperature sensor and said data collection circuit; wherein the
H.sub.2O.sub.2 vapor sensor, the temperature sensor, the data
collection circuit and the power source are self-contained on a
portable structure so as to be freely positionable proximate a
sterilization apparatus to monitor levels of the H.sub.2O.sub.2
vapor thereat.
10. An H.sub.2O.sub.2 vapor monitoring assembly in accordance with
claim 9, wherein the data collection circuit includes an electronic
memory to create a readable memory of the data collected during a
selected time interval and a signal connector to allow transfer of
signals representative of the collected data from said electronic
memory to a remote communication unit in communication with the
signal connector.
11. An H.sub.2O.sub.2 vapor monitoring assembly in accordance with
claim 9, wherein the data collection circuit is configured to
perform data collection in accordance with selected conditions, the
data collection circuit including a signal connector to allow entry
of selected conditions for such data collection.
12. An H.sub.2O.sub.2 vapor monitoring assembly in accordance with
claim 9, wherein the data collection circuit includes a transmitter
to transmit signals representative of the collected data to a
remote communication unit.
13. A method of monitoring levels of sterilant within a
sterilization apparatus, the method comprising the steps of:
providing a self-contained sterilant monitoring assembly including:
a sterilant sensor configured to provide an output signal
corresponding to detected levels of the sterilant, a data
collection circuit operatively coupled to said sterilant sensor to
receive the output signal from said sterilant sensor as collected
data, and a power source to provide electrical power to said
sterilant sensor and said data collection circuit, wherein the
sterilant sensor, the data collection circuit and the power source
are self-contained on a portable structure; and positioning said
sterilant monitoring assembly proximate said sterilization
apparatus to collect data representative of sterilant levels
thereat; and transferring the collected data from the data
collection circuit to a processor to identify the sterilant levels
detected by the sterilant sensor.
14. A method of monitoring sterilant in accordance with claim 13,
wherein: the data collection circuit of the sterilant monitoring
assembly provided by the providing step further includes an
electronic memory to create a readable memory of the data collected
during a selected time interval, and a signal connector to allow
transfer of signals, which are representative of the collected
data, from the electronic memory to a remote communication unit in
communication with the signal connector; and the method further
including the step of removing said sterilant monitoring assembly
from said sterilization apparatus after said selected time
interval, the transferring step including transferring the
collected data to the processor as signals transferred through the
signal connector from said electronic memory to the remote
communication unit after the sterilant monitoring assembly has been
removed from the sterilization apparatus.
15. A method of monitoring sterilant in accordance with claim 14,
wherein the data collection circuit is configured to perform data
collection in accordance with selected conditions, the data
collection circuit including a signal connector to allow entry of
selected conditions for such data collection; the method further
including the step of entering selected conditions for such data
collection.
16. A method of monitoring sterilant in accordance with claim 13,
wherein: the sterilant monitoring assembly provided by the
providing step further includes a temperature sensor operatively
coupled to the data collection circuit to provide output signals
corresponding to the ambient temperature proximate the sterilant
sensor for collection in combination with the output signals from
said sterilant sensor; and wherein the transferring step further
includes transferring collected data from the data collection
circuit representative of the detected ambient temperature to the
processor.
17. A method of monitoring sterilant in accordance with claim 13,
wherein: the data collection circuit of the sterilant monitoring
assembly provided by the providing step further includes a
transmitter to transmit signals representative of the collected
data to a remote communication unit in communication with the
processor; and further wherein the transferring step includes
transmitting collected data from the data collection circuit to the
processor as signals transmitted through the transmitter.
18. A method of monitoring sterilant in accordance with claim 13,
wherein said sterilization apparatus sterilizes articles moved
along a conveyor path, said positioning step including moving said
sterilant monitoring assembly along said conveyor path of said
sterilization apparatus.
19. A method of monitoring sterilant in accordance with claim 18,
wherein: the positioning step includes providing a carrier element
configured as an article to be sterilized by the sterilization
apparatus, said portable structure being placed on said carrier
element; and loading the carrier element on the conveyor path as an
article to be sterilized by the sterilization apparatus.
20. A method of monitoring sterilant in accordance with claim 13,
wherein: said sterilant includes hydrogen peroxide (H.sub.2O.sub.2)
vapor, said sterilant sensor providing output signals corresponding
to detected levels of the H.sub.2O.sub.2 vapor.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a system for
monitoring levels of a sterilant during a sterilization process,
and more particularly to a self-contained monitoring assembly
configured to monitor hydrogen peroxide (H.sub.2O.sub.2) vapor
levels during sterilization of articles such as packages, vessels,
machines or the like.
BACKGROUND OF THE INVENTION
[0002] Aseptic processing of consumable goods, such as nutritional
compounds and food products, is typically effected by separate
sterilization of the contents and the containers within which the
contents are packaged. Subsequent to separate sterilization, the
contents are placed in the containers and sealed in a sterile
environment for shipment, storage and use.
[0003] Sterilization of such containers prior to contacting the
desired sterilized contents can be performed efficiently by use of
a sterilant such as hydrogen peroxide (H.sub.2O.sub.2) vapor. In
such a process, the containers are introduced into a sterilization
apparatus in which the containers are flushed with hydrogen
peroxide vapor. The containers are subsequently flushed with warm
air or any other fluid suitable to achieve desirably low levels of
residual hydrogen peroxide. This general procedure is highly
effective in achieving sterilization of the containers, and
likewise can be performed on any other suitable articles that will
come into contact with the desired compound.
[0004] Notwithstanding the effectiveness of hydrogen peroxide
(H.sub.2O.sub.2) sterilization, accurate monitoring of
H.sub.2O.sub.2 vapor concentration levels can be problematic. This
is due in part to the physical and chemical property changes of
hydrogen peroxide vapor under processing conditions, and further
due to decomposition upon contact with surfaces of various
materials within the processing area. As such, undesired deviation
of hydrogen peroxide vapor concentration, and excessive
decomposition, can result in loss of sterility of the containers
and surrounding aseptic processing area. By contrast, hydrogen
peroxide vapor is corrosive in nature, and thus excessive
concentration levels can result in detrimental effects to the
surrounding equipment and surfaces. Furthermore, and in accordance
with government standards, low residual sterilant levels must be
maintained for subsequent use of the sterilized containers.
[0005] Heretofore,, hydrogen peroxide vapor detection systems have
been undesirably bulky, as exemplified by conventional near
infrared (NIR) analysis apparatus. Additionally, known off-line
testing is typically too slow to monitor sterilant levels with
sufficient accuracy. Previous arrangements have not provided "real
time" monitoring throughout an aseptic processing cycle, and
particularly have not been capable of monitoring hydrogen peroxide
vapor concentrations within a container or like article as it is
sterilized.
[0006] The present sterilant monitoring system, and the
self-contained assembly thereof, overcomes these deficiences the
prior art by providing a highly accurate, cost effective
arrangement for providing real-time monitoring of a sterilant, such
as hydrogen peroxide vapor, and is configured to facilitate
monitoring of the sterilant levels throughout the processing cycle
of a sterilization apparatus.
SUMMARY OF THE INVENTION
[0007] The purpose and advantages of the present invention will be
set forth in and apparent from the description that follows, as
well as will be learned by practice of the invention. Additional
advantages of the invention will be realized and attained by the
methods and systems particularly pointed out in the written
description and claims hereof, as well as from the appended
drawings.
[0008] To achieve these and other advantages and in accordance with
the purpose of the invention, as embodied and broadly described,
the invention includes a sterilant monitoring system particularly
suited for monitoring concentrations of a sterilant, such as
hydrogen peroxide (H.sub.2O.sub.2) vapor, as used by a
sterilization apparatus. The system includes a self-contained
monitoring assembly that can be readily positioned proximate the
sterilization apparatus. It is particularly contemplated that the
monitoring assembly be positioned within a carrier element
configured as one of the articles to be sterilized by the
sterilization apparatus. In this manner, the sensor, structure can
be moved through the sterilization apparatus so as to monitor
sterilant concentration levels throughout a processing cycle.
[0009] In accordance with the illustrated embodiment, the present
sterilant monitoring system is particularly configured for a
sterilization apparatus using a sterilant such as hydrogen peroxide
vapor. Further in accordance with the invention, and as embodied
herein, the system uses a sterilant monitoring assembly for data
collection purposes. The sterilant monitoring assembly includes a
sterilant sensor configured to provide output signals corresponding
to detected levels of the sterilant. The sterilant sensor
preferably includes a gas-detecting semi-conductor element, and a
heating element operatively associated therewith to elevate the
temperature of the gas-detecting semi-conductor element to an
appropriate operating temperature. A data collection circuit is,
operatively coupled to the sterilant sensor to receive the output
signals from the sensor as collected data, with the assembly
including a power source to provide electrical power to the sensor
and the data collection circuit as needed. In the preferred form, a
temperature sensor also is operatively connected to the data
collection circuit to provide output signals corresponding to the
ambient temperature proximate the sterilant sensor for collection
in combination with the output signals from the sterilant sensor.
In this manner, the temperature data may be used as a reference to
correlate more accurately the sensor output signals with
corresponding H.sub.2O.sub.2 vapor concentration levels.
[0010] The sterilant monitoring assembly of the present invention
is configured as a self-contained, portable unit. That is, the
sterilant sensor, data collection circuit, and power source, as
well as the preferred temperature sensor, are self-contained on a
portable structure so as to be freely positionable proximate the
sterilization apparatus to monitor levels of sterilant thereat. In
a preferred form, the portable structure is mounted on a carrier
element configured as an article to be sterilized by the
sterilization apparatus, such as a container or like article.
[0011] In accordance with the invention, collected data can be
processed by configuring the monitoring system as a whole, and the
data collection circuit particularly, in any of a variety of
different arrangements. In one arrangement of the invention, the
data collection circuit includes an electronic memory to create a
readable memory of the data collected during a selected time
interval. The assembly of this arrangement may include a signal
connector, such as data port or a transmitter, to allow transfer of
signals representative of the collected data from the electronic
memory to a remote communication unit that is joined in
communication with the signal connector. In this manner, the
collected data can be transferred or downloaded to a processor,
which forms a part of the sterilant monitoring system as a whole.
Once downloaded, the collected data can thereafter be stored,
graphically displayed in various forms, or otherwise analyzed and
processed to identify and monitor the detected sterilant
concentration levels.
[0012] Alternatively, or additionally, the monitoring assembly may
be configured to transmit remotely the collected data simultaneous
with collection to a remote communication unit positioned
exteriorly of the sterilization apparatus. In this configuration,
the data collection circuit of the monitoring assembly preferably
includes a transmitter to transmit signals representative of the
collected data to a remote communication unit. Radio frequency or
near infrared transmission are presently preferred for such remote
transmission. If desired, an electronic memory and physical signal
connector also may be provided in combination with the transmitter
for back-up purposes.
[0013] As will be appreciated, sterilization processing typically
entails the passage of articles through a sterilization apparatus,
with attendant variations in temperature and sterilant
concentrations during the process. It is desirable to collect data
corresponding to selected intervals or conditions during the
processing cycle. The present monitoring assembly therefore may
also include a circuit to select certain conditions, such as time
or temperature, for data collection, and a signal connector or a
control device to allow entry of such: selected conditions.
[0014] In order to effect data collection in a manner that
accurately corresponds to the processing conditions to which
articles are subjected by the sterilization apparatus, the present
monitoring system preferably includes a carrier element for
mounting the self-contained portable structure of the monitoring
assembly thereon. Preferably, the carrier element is configured as
an article similar to that to be sterilized by the apparatus. In
the illustrated embodiment, this carrier element is configured as a
container having a shape and dimensions essentially the same as
containers normally sterilized in the apparatus. Notably, the
carrier element is configured such that the portable structure can
be positioned inside the carrier element, thus providing data
collection corresponding to conditions within a container during
the sterilization process.
[0015] Other features and advantages of the present invention will
become readily apparent from the following detailed description,
the accompanying drawings, and the appended claims.
[0016] The accompanying drawings, which are incorporated in and
constitute part of this specification, are included to illustrate
and provide a further understanding of the method and system of the
invention. Together with the description, the drawings serve to
explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a diagrammatic view of a sterilization apparatus
of a type for which the present sterilant monitoring system is
suited;
[0018] FIG. 2 is a diagrammatic cross-sectional side view of a
representative embodiment of the sterilant monitoring assembly of
the present invention;
[0019] FIG. 3 is a diagrammatic, top plan view of the sterilant
monitoring assembly shown in FIG. 2;
[0020] FIG. 4 is a diagrammatic side view of the present monitoring
system, including the monitoring assembly of the system, and an
associated remote communication unit to which data collected by the
sensor structure is transmitted;
[0021] FIG. 5 is a partially fragmented side view illustrating the
sterilant monitoring assembly of the present system in operative
association with a carrier element configured as an article to be
sterilized by the sterilization apparatus.
[0022] FIG. 6 is a schematic side view depicting the various stages
of the processing cycle of the sterilization apparatus and the
corresponding output signals collected by the sterilant monitoring
assembly of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] Reference will now be made in detail to the present
preferred embodiments of the invention, an example of which is
illustrated in the accompanying drawings. The method and
corresponding steps of the invention will be described in
conjunction with the detailed description of the system and
assembly.
[0024] While the present invention is susceptible of embodiment
various forms, there is shown in the drawings and will hereinafter
be described presently preferred embodiments, with the
understanding that the present disclosure is to be considered as an
exemplification of the invention, and is not intended to limit the
invention to the specific embodiments illustrated.
[0025] FIG. 1 diagrammatically illustrates a sterilization
apparatus 10 of the type used for effecting sterilization of
containers C, such as packages, vessels or like articles. This
representative sterilization apparatus typically effects
sterilization of the containers C by exposing portions of the
interior and exterior of each container to a sterilant, such as
hydrogen peroxide (H.sub.2O.sub.2) vapor. The containers C are
processed in this fashion for subsequent filling with sterile
contents, thus completing aseptic processing and packaging of the
contents. The contents may include any of a variety of consumable
products including, but not limited to, nutritional and therapeutic
compounds, as well as food products or beverages.
[0026] The sterilization apparatus 10 includes an enclosure 12
within which an article conveyor 14 operates for movement of
containers C or other like articles to be sterilized along a
conveyor path through the apparatus. The containers C are typically
introduced into the apparatus at a product infeed station,
generally designated by reference character 16. The containers C
are then received by the conveyor 14 for movement through the
apparatus 10, and subsequently discharged after sterilization at
container discharge 18. As the containers C are moved through the
apparatus 10, both the interior and exterior of each container C is
subjected to sterilizing contact with an appropriate sterilant. A
variety of know sterilants are available, such as ethylene oxide,
although hydrogen peroxide vapor is preferred. In the
representative embodiment of the sterilization apparatus, the
exterior of each container is fogged with the sterilant at an
appropriate station 13 along the conveyor path. The apparatus 10
also includes suitable probe-like elements at a subsequent station
15 for introducing a hydrogen peroxide vapor fog into the interior
of each container C. The sterilization apparatus also may include
pre-warming and drying stations along the conveyor path as needed
for efficient sterilization and effective removal of any sterilant
residue prior to filling the containers C with the desired
contents. Such sterilization apparatus are known and available from
a variety of sources, such as Robert Bosch GmbH.
[0027] As previously noted, it is desirable to monitor sterilant
levels within the sterilization apparatus 10. Often, however, and
particularly when H.sub.2O.sub.2 vapor is used as the sterilant,
monitoring can be difficult. For example, hydrogen peroxide vapor
is subject to decomposition and oxidation, and thus can be
difficult to monitor accurately due to its unstable and corrosive
nature. While it is desirable to monitor the various stations
within the apparatus 10, the hydrogen peroxide vapor itself is a
very strong oxidizing agent, and thus excessive levels of hydrogen
peroxide vapor within the sterilization apparatus 10 complicate
maintenance and operation of certain permanently mounted sensors.
Furthermore, it can be particularly desirable to monitor sterilant
levels actually within the containers C being moved through the
apparatus 10 for greater accuracy. Heretofore, however, such
precise monitoring has not been possible.
[0028] In accordance with the present invention, a sterilant
monitoring system is provided for the sterilization apparatus, with
the monitoring system particularly suited for monitoring
concentrations of hydrogen peroxide vapor within the apparatus. The
present monitoring system, which is generally designated by
reference character 100 as shown in FIG. 4, includes a sterilant
monitoring assembly 120. In accordance with the invention, the
monitoring assembly 120 is self-contained on a portable structure
for disposition within the sterilization apparatus 10. As will be
further described, the sterilant monitoring assembly 120 is
configured to collect data from within the sterilization apparatus
10, and to permit analysis of the collected data either by an
on-board processor chip or by its transfer to a remote processor
150, which forms part of the sterilant monitoring system 100 as a
whole. The present monitoring system 100 therefore further includes
a remote communication unit 140, preferably positioned exteriorly
of the sterilization apparatus 10 to receive and communicate
signals to the processor 150. The remote communication unit 140 is
configured to receive data from the sterilant monitoring assembly
120 by a signal connector; either by a physical connection, such as
a data port 134 or by a wireless transmitter 136, such as by radio
frequency or near infrared transmission.
[0029] Notably, the monitoring assembly 120 is sized and configured
to be positioned proximate the sterilization apparatus 10, such as
within a desired chamber or cavity of the sterilization apparatus
10. Preferably, however, the sterilant monitoring assembly 120 is
configured to be positioned on a carrier element 160 having a shape
and size similar to that of an article to be sterilized (e.g., a
bottle or container). The sterilant monitoring assembly is thus
optimally positioned to monitor sterilant concentrations within the
sterilization apparatus 10 throughout a sterilization cycle.
[0030] The sterilant monitoring assembly 120 includes a portable
structure 122, which may be in the form of a base member, or, more
preferably, as an outer housing capable of self-containing the
various components of the sterilant monitoring assembly 120.
Preferably, the external housing 122 is constructed of suitable
corrosion-resistant material so as to withstand the effects of
repeated exposure to hydrogen peroxide vapor. Examples of such
corrosion-resistant material include stainless steel and certain
plastic or synthetic materials, although Teflon is preferred.
Depending upon the material selected, the portable structure 122
can be electrically conductive, such that the portable structure
122 may be employed as an electrical contact for transmission of
collected data via a hard-wire connection as will be described.
[0031] In accordance with the present invention, the sterilant
monitoring assembly includes a sterilant sensor to provide output
signals corresponding to detected levels of the sterilant. As
embodied herein, and as shown in FIGS. 2-4 the sensor 124 includes
a commercially available gas-detecting sensor, preferably of the
type which employs a semi-conductor sensing element 125. This
sensing element 125 generally includes a metal dioxide (such as tin
dioxide), which is sintered to form a film on the surface of an
associated ceramic tube (such as alumina ceramic). A heating
element, such as a resistance heating coil, is positioned within
the ceramic tube to elevate the temperature of the gas-detecting
semi-conductor element up to about 400.degree. C. When the sensing
element 125 is exposed to sterilant H.sub.2O.sub.2 vapor, the metal
dioxide surface absorbs the vapor molecules and causes oxidation.
In this manner, it has been found that electrical resistance is
reduced and, thus, the output signal generated by the sensor 124
increases proportionally with increasing vapor concentration level.
In an illustrative preferred embodiment of the present sterilant
monitoring assembly for use with hydrogen peroxide vapor sterilant,
a Model 816 sensor from FIGARO U.S.A., Inc., of Glenview, Ill., is
employed as the sterilant sensor to detect H.sub.2O.sub.2 vapor
concentration levels. Alternative sensor configurations capable of
performing the similar function as described likewise may be used
if desired and suitable.
[0032] In accordance with an additional aspect of the invention, it
is desirable for the sterilant monitoring assembly 120 to include a
temperature sensor 126, such as a thermistor or the like, to
provide output signals corresponding to the ambient temperature
proximate the sterilant sensor 124. A variety of conventional
temperature sensors are known and may be adapted for use with the
monitoring assembly of the present invention. The illustrative
sterilant monitoring assembly embodied herein, for example,
includes an FRB Pressure Micropack available from DATATRACE, Inc.
of Lakewood, Colo., which has been modified to accommodate the
FIGARO Model 816 sensor in place of a conventional pressure sensor.
Because sterilant concentration levels are affected by the ambient
temperature, the output signals from the temperature sensor 126, if
provided, are used to correlate more accurately the output signals
from the sterilant sensor 124 with the proper corresponding
sterilant concentration levels. This function can be performed
either by an on-board processor chip, if provided, or by the
processor 150 of the sterilant monitoring system 100, as will be
described. If desired, pressure, relative humidity or other
parameter sensors may be provided in addition to or in place of the
temperature sensor 126 to obtain corresponding data
respectively.
[0033] Further in accordance with the invention, a data collection
circuit 130 is operatively coupled to the sterilant sensor 124 to
receive the output signals from the sterilant sensor 124 as
collected data. FIG. 2 shows that the data collection circuit 130
also is operatively coupled to receive output signals from any
additional sensors that are provided, such as the temperature
sensor 126 to provide signals corresponding to ambient temperature
proximate the sterilant sensor 124. The data collection circuit 130
may be provided as a conventional hard wire assembly or, as in the
preferred embodiment, be configured to include a chip or printed
circuit in a known manner for reduced size and increased capacity.
As described further below, the data collection circuit may include
a memory chip to store entered data, a central processing unit
(CPU) configured to control select functions, as well as
programmable solid state relays for operation of the sterilant
monitoring assembly.
[0034] As previously noted, the sterilant monitoring assembly 120
of the present invention is self-contained on a portable structure.
The sterilant monitoring system therefore includes a power source
128 for the various electrically driven components, such as the
sterilant sensor 124, the temperature sensor 126, the data
collection circuit 130 and any additional components provided as
needed. Any of a variety of known power sources may be used
depending on its desired characteristics, such as size, weight, and
capacity. In the preferred embodiment herein, a conventional DC
lithium battery is provided. Additionally, the power source 128
will include a converter and/or transformer if necessary to provide
the appropriate power to each of the various components of the
sterilant monitoring assembly 120. For example, the illustrative
embodiment disclosed herein includes a DC/DC converter 128' to
covert a 9 volt supply into the appropriate voltage requirements
for the components of the assembly 120. A light-emitting diode
(LED) indicator 127 is provided to indicate activation of the power
source 128. The power source 128, and associated components, are
provided in the portable structure and, therefore, should be of
suitable size.
[0035] An additional aspect of the invention involves the
transmission of the collected data from the various sensors of the
sterilant monitoring assembly 120 to the processor 150 of the
sterilant monitoring system 100. FIG. 4 diagrammatically
illustrates the components of the present sterilant monitoring
system which cooperate with the sterilant monitoring assembly 120
to transfer and process the collected data. The sterilant
monitoring system includes a remote communication unit 140 which
can be operatively coupled in any of a variety of configurations
with the sterilant monitoring assembly 120 and further is in
operative communication with the processor 150. Data transfer may
be performed via a physical connection between the sterilant
monitoring assembly 120 and the remote communication unit 140, or
via a transmitter for wireless transmission, or both as shown in
FIG. 4.
[0036] To perform data transfer via a physical connection,; the
data collection circuit 130 of the sterilant monitoring assembly
120 preferably includes an electronic memory 132, such as a
suitable chip or a circuit, to create a readable memory of the
collected data during a selected time interval. For example, a
suitable electronic memory 132 for the illustrative assembly
embodied herein is incorporated using an FRB Pressure Micropack
having an increased memory capacity from DATATRACE, Inc., as
modified to accommodate the FIGARO sensor.
[0037] Once data collection is complete, transfer of the collected
data that is stored in the electronic memory 132 can be performed.
This is accomplished by providing the sterilant monitoring assembly
120 of this embodiment with a signal connector, such as a data port
134 for physical connection with a data port 45 on the remote
communication unit 140, to permit transfer of signals
representative of the collected data from the electronic memory
132. Use of this system configuration thereby allows transfer of
the collected data via a physical connection to the remote
communication unit 140. If desired, the collected data from the
electronic memory 132 can be transmitted remotely via a transmitter
136 to the remote communication unit 140 as described further
below.
[0038] Alternatively, or in addition to the delayed transfer of
collected data using a physical connector, such transfer can be
effected simultaneously with data collection by including a
transmitter 136 as the signal connector. The transmitter 136
transmits signals representative of the collected data via a
wireless connection, such as by radio frequency or near infrared,
to a receiving element 147 of the remote communication unit 140
during the selected interval of operation. It thus can be
appreciated that the sterilant monitoring assembly 120 and remote
communication unit 140 can be configured to provide "real time"
transfer of collected data, thereby providing output signals
representative of sterilant levels within sterilization apparatus
10 during an actual sterilization cycle. In this manner the
electronic memory 132 is not necessary, although may still be
provided if desired.
[0039] The interval for data collection can be selected simply by
activating a power switch 129 connected to the power source 128, or
through more sophisticated means. For example, the data collection
circuit can be configured to collect data during selected
conditions. Such selected conditions may include start time and
stop time, or detected temperature or pressure conditions at which
to activate or deactivate data collection. In this manner, a signal
connector, such as a physical data port 135 or a receiver 137, is
provided on the monitoring assembly 120 to receive signals from a
corresponding data port 144 or transmitter 146 on the remote
communication unit 140 to preprogram the selected conditions into
the data collection circuit 130. Alternatively, it is possible for
the power source to be programmed, such as by using programable
relays or the CPU 132, to activate the sterilant sensor 124 at a
certain time prior to data collection or in accordance with a
preselected schedule.
[0040] Remote real time operations of the monitoring assembly 120
also can be accomplished, preferably by providing a near infrared
or radio frequency control signal receiver or the like on the
sterilant monitoring assembly 120 as part of the data collection
circuit 130. In accordance with this aspect of the invention, and
as embodied herein, a near infrared control system 138 and a
programmable solid state relay circuit group 139 are provided for
remote power activation of the monitoring assembly 120. A variety
of such control systems and relay configurations are available. The
presently preferred embodiment includes a NIKON ML-3 Modulite
Remote Control Set F5/N90 from B&H Photo-Video of New York as
modified appropriately in a conventional manner for operation of
the sterilant monitoring assembly. For example, two
transistor-transistor logic (TTL) compatible relays and a
multicontact relay, each available from Philips ECG Products of
Greeneville, Tenn., can be used to modify this control set. A
normally opened relay (RLYF71A05) is provided to activate a
multicontact miniature relay (RLY5140) for heating circuit power
activation to latch the heating circuit, while a normally closed
relay (RLYF71B05) is used to turn off the heating power and break
the latch. Because the heating circuit is nearly 200 mA, it is
beneficial to use a relay group and optocouplers to isolate the
signals. Additionally, it is preferred that the heating circuit
resistance remain constant; therefore, a mechanical contact is
preferred.
[0041] By virtue of its self-contained, portable nature, the
sterilant monitoring assembly 120 is freely positionable proximate
the sterilization apparatus 10 to monitor levels of hydrogen
peroxide vapor, or any other sterilant for which the sterilant
sensor 124 is suited. If the collected data is to be recorded in
the memory 132 of the monitoring assembly 120, and thereafter
downloaded or transferred, the monitoring assembly can be
positioned as desired within the sterilization apparatus 10, and
subsequently removed for downloading of collected data.
Alternatively, and if provided with the transmitter 136 to transmit
collected data to the remote communication unit 140, the monitoring
assembly 120 can be positioned proximate the sterilization
apparatus 10, with transmission of collected data occurring
subsequent to collection, or on a real-time basis. In this manner,
the monitoring assembly 120 can be used to collect data related to
sterilant concentration levels at select locations in or around the
sterilization apparatus, or as a portable device to sample randomly
and search for sterilant leaks if desired.
[0042] With reference to FIG. 5, a particularly preferred aspect of
the present monitoring system is illustrated, wherein the
monitoring assembly 120 is positioned in operative association with
a carrier element 160 configured similar to an article (e.g., a
container) to be sterilized by the apparatus 10. The monitoring
assembly 120 is positionable on the carrier element 160 and,
preferably, within the carrier element 160, to facilitate
monitoring of sterilant levels at various stations of the
sterilization apparatus 10. FIG. 5 illustrates the carrier element
160 including a fragmented portion illustrated in cutaway. While
the carrier element 160 is shown in this form for purposes of
illustration, it will be appreciated that the carrier element 160
may be provided with at least one removable portion, such as a
removable side wall or removable bottom wall, to facilitate
disposition and mounting of the sterilant monitoring assembly 120
within the carrier element 160. Because disposition of the portable
sensor structure on the carrier element during sterilization by the
sterilization apparatus 10 facilitates monitoring of the
sterilization cycle to which the containers C are subjected,
container C embodied herein is preferably configured to represent
an actual container in all aspects to simulate real processing
conditions.
[0043] Use of the present monitoring system will be apparent from
the foregoing description, and is further illustrated by FIG. 6.
The self-contained, portable sterilant monitoring assembly 120 is
prepared for data collection, including selection of any
conditions, such as time or temperature, that are required or
desired for activation of the sensors and, if provided, the
electronic memory and programable relays. The monitoring assembly
120 is positioned proximate the sterilization apparatus 10 to
collect data representative of the sterilant levels thereat. While
the monitoring assembly 120 may be simply positioned near or within
the sterilization apparatus 10, it is particularly contemplated
that the monitoring assembly 120 be moved along the conveyor path
of the sterilization apparatus 10 by being placed first in the
carrier element 160, and then loaded on the conveyor path defined
by article conveyor 14 as shown schematically in FIG. 6.
[0044] The sterilant monitoring assembly 120 collects data
representative of sterilant concentrations at each station of the
sterilization apparatus 10. If the collected data is to be
downloaded or transferred subsequent to removal of the monitoring
assembly 120 from within the apparatus 10, the monitoring assembly
120 is provided with the readable electronic memory 132 from which
collected data can be subsequently transferred to the remote
communication unit 140 via signal connector 134, 136. Thus, use in
this fashion contemplates that the monitoring assembly 120 is
removed from within the sterilization apparatus 10 for transfer of
the collected data. Transferred data includes not only output
signals from the gas-detecting sensor 124, but also can include
output signals collected from the temperature sensor 126 as shown
in FIG. 6, or any other sensor that may be provided. The position
of the structure within the apparatus 10 therefore can be traced by
identifying the associated time and temperature. Alternatively, a
separate timer or position tracer may be provided within monitoring
assembly 120 if desired.
[0045] In the preferred embodiment, however, collected data is to
be transferred from the monitoring assembly 120 without requiring
removal of the monitoring assembly 120 from within the
sterilization apparatus 10. The monitoring assembly 120 therefore
is provided with a transmitter 136 to transmit signals
representative of the collected data from the data collection
circuit to the receiving element 147 of the remote communication
unit 140. While the present monitoring system is particularly
suited for detecting and monitoring sterilant levels within the
sterilization apparatus 10, it will be appreciated that use of an
arrangement including transmitter 136 ultimately can permit
operation of the sterilization apparatus 10 itself by real-time
monitoring of processing conditions within the apparatus 10 if
desired.
[0046] Data collected by the monitoring assembly 120 and
transferred via the remote communication unit 140, as
illustratively represented in FIG. 6, is analyzed by the processor
150 to correlate the transferred signals into corresponding
sterilant concentration levels using a known functional relation
stored in the processor 150. This known relation can be programmed
as a numeric formula, or established through the acquisition of
sufficient experimental test data points at known test conditions.
A variety of suitable remote communication units may be used, such
as that of the THERMO.DOT system available from Stock, America,
Inc. of Milwaukee, Wis. Similarly, exemplary processors include any
of a variety of personal computers and compatible data analysis
software, such as that provided by DATATRACE, Inc. for use in
conjunction with its sensors as modified to correlate the collected
data with corresponding sterilant levels. Once processed, this
information can be further analyzed, displayed, printed, or
otherwise used as desired.
[0047] Alternatively, or additionally, the sterilant monitoring
assembly 120 itself can include an on-board processor in the form
of a chip or circuit to correlate the collected data into
corresponding sterilant levels for subsequent storage in the memory
132 and/or for data transfer to the remote communication unit 140.
The processor chip is preprogramed with the appropriate correlation
using a known functional relation. As with the remote processor,
this known relation can be programmed as a numeric formula, or
established through the acquisition of sufficient experimental test
data points at known test conditions. The processor chip or circuit
is further configured to generate and transmit corresponding
signals for storage or transfer. The processor chip can be formed
integral with the data collection circuit, as embodied herein, or
provided separately. An example of a suitable processor circuit
includes the EPAC.TM. electrically programmable analog circuit,
Model No. IMP50E10C, available from Digi-Key Corporation of Thief
River Falls, Minn., as modified accordingly, although alternatives
are available.
[0048] It will be apparent to those skilled in the art that various
modifications and variations can be made in the method and system
of the present invention without departing from the spirit or scope
of the invention. Thus, it is intended that the present invention
include modifications and variations that are within the scope of
the appended claims and their equivalents. Furthermore, the
technical descriptions provided regarding the theory of operation
are for purpose of explanation and not limitation.
* * * * *