Apparatus having sterilant monitoring system

[0002] The present invention relates generally to a sterilization apparatus having a system for monitoring levels of a sterilant therein, and more particularly to a sterilization apparatus including a sterilant monitoring system operatively joined with the sterilant supply assembly of the sterilization apparatus to monitor levels of sterilant therein, such as hydrogen peroxide (H₂O₂) vapor.

[0003] 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.

[0004] Sterilization of such containers prior to contacting the desired sterilized contents can be performed efficiently by use of a sterilant such as hydrogen peroxide (H₂O₂) 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.

[0005] Notwithstanding the effectiveness of hydrogen peroxide (H₂O₂) sterilization, accurate monitoring of H₂O₂vapor 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.

[0006] 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 the sterilization apparatus at select locations along the sterilant supply system during actual operations.

[0007] In view of the foregoing, it is desirable to monitor the concentration of a sterilant, such as hydrogen peroxide, during sterilization processing. The present invention is directed to a sterilization apparatus having an integral, yet efficient, sterilant monitoring system operatively joined to the sterilant supply of the sterilization apparatus. Substantially continuous monitoring of sterilant concentrations can be achieved as sterilant is employed by the apparatus for effecting sterilization of articles therein.

[0008] 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.

[0009] To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, the invention is directed to a sterilization apparatus having a sterilant monitoring system particularly suited to monitor concentrations of the sterilant employed by the sterilization apparatus, such as hydrogen peroxide (H₂O₂) vapor. The sterilization apparatus generally includes a sterilization chamber and a sterilant supply conduit to supply a sterilant to the sterilization station for sterilization of at least one article thereat. A sensor chamber is joined in fluid communication with the supply conduit at a select location to allow at least a representative portion of the sterilant from the supply conduit to flow through the sensor chamber. A sterilant sensor is positioned to provide output signals corresponding to detected levels of sterilant within the sensor chamber. Operatively coupled to the sterilant sensor is a data collection circuit to receive output signals from the sterilant sensor as collected data. In this manner, sterilant concentration levels can be monitored continuously during sterilization processing, with the monitoring system operable to provide a greater degree of correlation between the sterilant levels detected within the sensor chamber and actual concentrations of a sterilant acting upon the articles.

[0010] Particularly, the present sterilization apparatus includes an enclosure within which an article conveyor operates to move a plurality of containers or like articles along a conveyor path through the apparatus. One or more sterilization stations are located along the conveyor path. Sterilant, such as hydrogen peroxide (H₂O₂) vapor in the presently preferred embodiment, is supplied to each sterilization station of the apparatus through a supply conduit for sterilization the articles. For example, the sterilant can be applied in the form of a fog to the external surface of each article at one sterilization station, and injected against the internal surface of each article at a different station. Preferably, the fog applied to the external surface and the vapor injected against the internal surface are applied at different concentration levels to achieve different sterilization values as may be desired.

[0011] The sterilant monitoring system of the present invention includes a sensor chamber joined in fluid communication with the supply conduit at a select location to allow at least a portion of the sterilant from the supply conduit to flow through the sensor chamber. A sterilant sensor is positioned to provide output signals corresponding to detected levels of sterilant within the sensor chamber. In the preferred embodiment, the sterilant sensor itself includes a gas-detecting semiconductor element and a heater to elevate the temperature at the gas-detecting semiconductor element. A temperature sensor, such as a thermocouple, also may be positioned to provide output signals corresponding to the ambient temperature proximate the sterilant sensor. Depending upon the type of sensor used, these sensors may be positioned within or integral with a wall of the sensor chamber. The output signals of the temperature sensor are collected in combination with the output signals from the sterilant sensor. Similarly, other sensors to detect operating parameters, such as pressure or relative humidity, also may be provided.

[0012] A data collection circuit is operatively coupled to the sterilant sensor, and to the temperature sensor or any other sensor that is provided, to receive output signals from these sensors as collected data. The collected data is processed to provide an output corresponding to the detected levels of the sterilant in the sensor chamber. Processing can be performed by a processor chip or circuit operatively coupled with the data collection circuit at the sensor chamber. Alternatively, correlation between the output signals and the corresponding sterilant levels can be performed by a remote processor located external to the sterilization apparatus. In this manner, signals representative of the collected data are transferred via the data collection circuit by a “hard-wired” configuration to the external processor, or via a wireless transfer, such as by near infrared or radio frequency transmission, to a remote communication unit operatively connected to the external processor. Accordingly, the data collection circuit includes a signal connector, such as a data port for physical connection or a transmitter for wireless transfer, to transfer the signals representative of the collected data. The output signals from the sensor, and the corresponding sterilant concentration levels correlated by the processor, can be provided to a suitable display, printer, recording device, or the like.

[0013] An electronic memory operatively coupled to the data collection circuit can be provided to create a readable memory of the data collected during a selected time interval. This electronic memory also can be operatively coupled to the internal processor, if provided, to create a readable memory of the correlated sterilant levels as well. A circuit may also be provided as part of the data collection circuit to select conditions for data collection, in combination with a signal connector, such as a data port or receiver, to allow entry of the selected conditions for such data collection.

[0014] In accordance with one illustrated embodiment, a supply manifold is joined in fluid communication with the supply conduit and includes a plurality of flow lines joined fluidly in parallel. Sterilant from the sterilant supply conduit thereby can flow through the plural flow lines respectively to the sterilization station for sterilization of a corresponding number of articles positioned thereat. The conveyor of the sterilization apparatus thus is configured to move a plurality of articles in an array corresponding to the flow lines of the supply manifold so as to allow simultaneous sterilization of a plurality of articles. To detect the sterilant concentration level at the sterilization station, a sensor chamber of the monitoring system is joined in fluid communication with the supply conduit via one of the flow lines of the supply manifold. Preferably, this sensor chamber is joined to an outermost one of the flow lines of the supply manifold; that is, at the flow line located furthest from the supply conduit and thus most likely to have the greatest flow resistance and lowest concentration level within the manifold.

[0015] The present invention further contemplates a method of sterilizing articles comprising the steps of providing a sterilization apparatus including a sterilization station and a sterilant supply conduit to supply sterilant to the sterilization station. The method further includes positioning a sterilant sensor at a select location in communication with the supply conduit to provide output signals corresponding to detected levels of the sterilant at the select location, and placing at the sterilization station at least one article to be sterilized. Sterilant is directed through the supply conduit and onto the article placed at the sterilization station, with at least a representative portion of the sterilant from the supply conduit flowing by the select location. The present method also includes the step of generating output signals from the sterilant sensor corresponding to detected levels of the sterilant at the select location.

[0016] In the preferred practice of the present method, a temperature sensor is positioned at the select location to provide output signals corresponding to the ambient temperature proximate the sterilant sensor. A data collection circuit is operatively coupled to the sterilant sensor and to the temperature sensor to receive output signals therefrom as collected data. Signals representative of these output signals can be transferred via a signal connector, such as a data port or a transmitter, to a remote communication unit operatively coupled to a processor. An electronic memory may be provided to create a readable memory of data collected during a selected time interval.

[0017] The select location for the sterilant sensor may be varied, depending upon the relevant conditions to be monitored. For example, a sensor chamber may be joined in fluid communication with the sterilant supply conduit to monitor overall sterilant concentration levels introduced to the sterilization apparatus. Hence, the generating step includes generating output signals from the sterilant sensor corresponding to the detected levels of sterilant within the sensor chamber. Alternatively, or additionally, the select location may include a flow line proximate a sterilization station of the sterilization apparatus. For example, the sterilization chamber may include a supply manifold joined in fluid communication with the supply conduit, wherein the supply manifold includes a plurality of flow lines joined fluidly in parallel. Sterilant from the supply manifold thus can flow through these flow lines respectively to the sterilization station for sterilization of a corresponding number of articles positioned thereat. The select location of the positioning step of this embodiment is at one of the flow lines of the supply conduit to provide output signals corresponding to detected levels of sterilant. Preferably, the method includes joining a sensor chamber in fluid communication with an outermost one of the flow lines of the supply manifold, with the generating step including generating output signals from the sterilant sensor corresponding to the detected levels of sterilant within the sensor chamber.

[0018] Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.

[0019] 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.

[0020] FIG. 1 is a diagrammatic side view of representative embodiment of a sterilization apparatus, including a sterilant monitoring system of the present invention;

[0021] FIG. 2 is an enlarged diagrammatic view of a representative embodiment of the sterilant monitoring system of the present invention, including an “in-line” sensor chamber joined in fluid communication with the supply conduit of the sterilization apparatus of FIG. 1;

[0022] FIG. 3 is a diagrammatic end view of a sterilant supply manifold of the sterilization apparatus shown in FIG. 1, as taken along line III—III; and

[0023] FIG. 4 is an enlarged diagrammatic view of a representative embodiment of the sterilant monitoring system of FIG. 3.

[0024] Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are 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.

[0025] While the present invention is susceptible various embodiments, 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 or the theory described.

[0026] 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 10 generally sterilizes the containers C by exposing portions of the interior and exterior of each container to a sterilant, such as hydrogen peroxide (H₂O₂) 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.

[0027] The sterilization apparatus 10 itself is generally conventional in nature, and 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 10. The containers C are introduced into the apparatus at a product infeed station, generally designated by reference character 16. The containers C are received by the conveyor 14 for movement through the apparatus 10 to respective sterilization stations for processing before subsequent discharge at container discharge 18 upon completion of sterilization and filling of the processing cycle.

[0028] As the containers C are moved through the apparatus 10, both the exterior and interior of each container C is subjected to sterilizing contact with an appropriate sterilant. A variety of known sterilants are available and may be used, such as ethylene oxide, although hydrogen peroxide vapor is preferred. In the representative embodiment of the sterilization apparatus, the exterior of each container is first fogged with the sterilant at an appropriate station 13 along the conveyor path. Sterilant is supplied to the exterior fogging station via an extension 23 of a sterilant supply conduit 20 of known construction suitable for such sterilant flow.

[0029] An interior fogging sterilization station 15 also is provided, preferably downstream of station 13. Station 15 includes a supply manifold 25 having suitable probe-like flow lines 24 in fluid communication with the sterilant supply conduit. Preferably, the flow lines are moveable between an extended position and a retracted position, such that a sterilant fog can be introduced into the interior of respective containers C when the flow lines 24 are moved to the extended position, and further that the containers C can be moved along the conveyor path by the conveyor 14 for subsequent processing when the flow lines 24 are in the retracted position. As described further with regard to FIG. 3, an array of these flow lines may be provided to allow a plurality of containers C to be processed simultaneously. The sterilization apparatus 10 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. Variations of such sterilization apparatus as described are available from a variety of sources, including Robert Bosch GmbH.

[0030] As previously noted, it is desirable to monitor sterilant levels within the sterilization apparatus 10. Often, however, and particularly when H₂O₂vapor 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. Furthermore, and as will be recognized, it is particularly desirable to monitor the concentration levels of sterilant as it is directed against articles as they are moved through the apparatus 10 on conveyor 14. Heretofore, however, such precise monitoring has not been possible.

[0031] Accordingly, the sterilization apparatus includes a monitoring system configured in accordance with the present invention to detect and monitor concentration levels of sterilant supplied to the apparatus and directed to the sterilization stations for sterilization of containers C or like articles. The sterilant monitoring system embodied herein, generally designated by reference character 100, includes a sensor chamber 120 joined in fluid communication with the supply conduit 20 at a select location to allow at least a portion of the sterilant from the supply conduit 20 to flow through the sensor chamber 120. Use of a sensor chamber, although not necessary for in-line applications, provides a variety of advantages. For example, the sensor chamber protects the components contained therein, as well as minimizes or eliminates condensation due to parametric conditions. Furthermore, the sensor chamber 120 also isolates the mixing effect between the sterilant and the surrounding environment when the two are exposed together, such as when the concentration level within the enclosure 12 of the apparatus 10 is different from that discharged from the container spraying nozzle 120 (e.g., H₂O₂concentration is reduced due to space increase in the enclosure). The sensor chamber 120 also serves as a heat insulation/isolation jacket to prevent direct heat exchange and thus further avoid condensation there within.

[0032] The sensor chamber may be located at any of a variety of select locations along the sterilant supply system. Indeed, and as embodied herein, more than one sensor chamber 120 may be provided. The construction, shape and size of the sensor chamber 120 will depend upon the select location and the components to be housed within the chamber 120. If no sensor chamber is desired, however, a sterilant sensor may be positioned directly at a select location within the sterilant supply conduit 20 itself as will be described further below.

[0033] For purpose of illustration and description, and not by limitation, reference is made to FIG. 2, which shows an “in-line” sensor chamber 120 joined in fluid communication with the supply conduit 20 of the sterilization apparatus 10. The select location of this sensor chamber 120 may be proximate the inlet to the sterilization apparatus 10, or at a junction of a branch line, or simply at a location having adequate space to accommodate the sensor chamber. The sensor chamber 120 is constructed of a material capable of withstanding the operating conditions of the sterilant supply conduit 20, and includes an inlet 127 and an outlet 129 for the sterilant passing therethrough. A valve 125 may be provided, if desired, at the inlet 127 or outlet 129 of the sensor chamber 120 to control sterilant flow therethrough. In a preferred embodiment, a valve 125 is provided at both the inlet 127 and the outlet 129 to allow capture of a sterilant sample for static testing if desired. A bypass line may be provided for continued operation of station 13. Preferably, although not necessarily, an opening with a removeable cover 123 also can be provided to allow access to the components within the sensor chamber 120.

[0034] It is preferable to maintain substantially steady state conditions within the sensor chamber for enhanced detection and monitoring of the sterilant concentration levels. The sensor chamber 120 therefore is configured to isolate the influence of the surrounding environment, such as airflow, relative humidity, pressure and temperature gradients. This may be accomplished, at least in part, by constructing the sensor chamber of material having low heat transfer characteristics, such as Teflon, as well as by providing suitable insulation if desired to minimize the effects within the sensor chamber 120 resulting from the surrounding environment. It also is preferred to locate the sensor chamber 120 within the enclosure 12 of the sterilization apparatus 10 to further isolate the sensor chamber. Additionally, a heater 121, such as a heating wire and film heating element, may be provided to heat the sensor chamber, if desired or necessary, to minimize or eliminate any temperature gradient between the interior of the sensor chamber 120 and the surrounding environment. This is particularly beneficial because too extreme of a temperature gradient between the interior and exterior of the chamber 120 may result in quick condensation of the sterilant at saturated gas concentration, and thus result in inaccurate measurements.

[0035] The sterilant monitoring system 100 also includes a sterilant sensor 124 to provide output signals corresponding to detected levels of the sterilant in accordance with the present invention. As embodied herein, and as shown in FIGS. 2 and 4, the sensor 124 includes a commercially available gas-detecting sensor, preferably of the type which employs a semi-conductor sensing element. This sensing element 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° C. When the sensing element is exposed to sterilant H₂O₂vapor, 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 H₂O₂vapor concentration levels. Alternative sensor configurations capable of performing a similar function as described likewise may be used if desired and suitable.

[0036] It also is desirable, in accordance with an additional aspect of the invention, for the sterilant monitoring system to include a temperature sensor 126, such as a thermocouple or the like, to provide output signals corresponding to the ambient temperature proximate the sterilant sensor 124. A variety of conventional temperature sensors 126 are known and may be adapted for use with the monitoring system of the present invention. A thermocouple is preferred for the present invention because temperature is expected to fluctuate within a specified window during the process. The illustrative sterilant monitoring system embodied herein, for example, includes a suitable thermocouple from Ecklund-Harrison Technologies, Inc. of Fort Myers, Fla. 33912, U.S.A. Because sterilant concentration levels are affected by the ambient temperature, the output signals from the temperature sensor 126 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 providing a processor chip or circuit 132 proximate the sensor chamber, if desired, or by transferring the collected data to a remotely located processor 150, as will be described. If desired, a thermister may be used in place of or in addition to the thermocouple. Furthermore, pressure, relative humidity or other parameter sensors may be provided in addition to or in place of the temperature sensor 126 to obtain corresponding parameter data respectively.

[0037] FIGS. 2 and 4 show that 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. The data collection circuit also is operatively coupled to receive output signals from any additional sensors, if provided, such as temperature sensor 126 to provide signals corresponding to ambient temperature proximate the sterilant sensor 124. In a preferred embodiment of the invention, the data collection circuit 130 is provided simply as a conventional hard wire assembly extending from the sensor chamber 120 for connection with a remote processor as will be described. Alternatively, the data collection circuit may include a chip or printed circuit provided proximate the sensor chamber, either inside or outside, in a known manner. As described further below, and as shown, the data collection circuit 130 also may include a memory chip 132 to store entered data, a central processing unit (CPU) 136 configured to control select functions, as well as programmable solid state relays 139 for operation of the sterilant monitoring system. Preferably, these various components are provided within a housing 131 of suitable construction located proximate the sensor chamber 120.

[0038] The sterilant monitoring system of the present invention can include a hard-wired or permanent connection to a power source 138 for the electrically-driven components, such as the sterilant sensor 124 and the data collection circuit 130. In this manner, the sterilant monitoring system can be operated virtually continuously if desired. Alternatively, portable power source 138 can be provided proximate, either inside or outside, the sensor chamber 120 as part of the sterilant monitoring system for stand alone operation. Any of a variety of known portable power sources 138 may be used, such as a conventional DC lithium battery. Additionally, the power source will include a converter and/or transformer 138′ as necessary to provide the appropriate power to each of the various components of the sterilant monitoring assembly 120. A light-emitting diode (LED) indicator (not shown) also can be provided to indicate activation of the power source 138. If the power source 138, and associated components, are provided proximate the sensor chamber 120, they need to be sized and housed accordingly.

[0039] An additional aspect of the invention involves the transmission of the collected data from the various sensors to a processor 150 of the sterilant monitoring system 100. FIG. 2 diagrammatically illustrates further components of the present sterilant monitoring system 100 for transfer and processing of the collected data. The sterilant monitoring system includes a remote communication unit 140 that can be operatively coupled in any of a variety of configurations with the data collection circuit 130, 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. 2.

[0040] To perform data transfer via a physical connection, the data collection circuit 130 generally includes a signal connector 134, such as a conventional data port. A compatible data port is provided at the remote communication unit 140, such as the I/O port of a personal computer, to permit transfer of signals representative of the collected data from the data collection circuit 130 as shown schematically by solid line 134′ in FIG. 2. This configuration is particularly applicable when the data collection circuit 130 is a conventional hard wire connection extending from the sensors. Use of this system configuration thereby allows transfer of the collected data via a physical connection to the remote communication unit 140.

[0041] Alternatively, or in addition to the transfer of collected data using a physical connector, such transfer of the collected data can be made using a conventional transmitter. The transmitter transmits signals representative of the collected data via a wireless connection, such as by radio frequency or near infrared, as shown by dotted line 134″ in FIG. 2, to a receiving element of the remote communication unit 140 during the selected interval of operation. It thus can be appreciated that the sterilant monitoring system can be configured to provide “real time” transfer of collected data by either a physical connection or a wireless connection with a remote communication unit 140, thereby providing output signals representative of sterilant levels within sterilization apparatus 10 during an actual sterilization cycle.

[0042] It also is possible, in accordance with an additional aspect of the invention, to provide an electronic memory 132, such as a suitable chip or a circuit, to create a readable memory of the data collected during a selected time interval. This electronic memory 132 can be provided proximate the sensor chamber 120 or in operative communication with the remote communication unit 140. For example, a suitable electronic memory 132 for the illustrative assembly embodied herein could be incorporated using an FRB Pressure Micropack having an increased memory capacity from DATATRACE, Inc. of Lakewood, Colo., as modified to accommodate the FIGARO sensor.

[0043] The interval for data collection can be selected simply by activating a power switch (not shown) connected to the power source 138. The power switch can be located proximate the sensor chamber 120 or at the remote communication unit 140. Indeed, the selected interval can be indefinite for continuous data collection if a suitable power source is used, such as a conventional AC power outlet supply. The sterilant monitoring system 100 also may be wired in communication with the sterilization apparatus 10, such that the sterilant monitoring system 100 is activated whenever the sterilization apparatus is activated.

[0044] Alternatively, more sophisticated means may be used to select the desired interval for data collection. For example, the data collection circuit 130 may 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 or a receiver, is provided on the monitoring system 120 to receive signals from a corresponding data port or transmitter of 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 139 or the CPU 136, to activate the sterilant sensor 124 at a certain time prior to data collection or in accordance with a preselected schedule.

[0045] Wireless real time operations of the monitoring assembly 120 also can be accomplished, preferably by providing a near infrared or radio frequency controlled signal receiver or the like on the sterilant monitoring system 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 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 for operation of the sterilant monitoring system 100. For example, two transistor-transistor logic (TTL) compatible relays and a multicontact relay, each available from Philips ECG Products of Greeneville, Tenn., are 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 current 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.

[0046] Data collected and transferred by the sensors and data collection circuit are processed to correlate the collected data with corresponding sterilant concentration levels. This may be performed by a processor chip or circuit 136 provided proximate the sensor chamber 120. The processor chip or circuit, if provided, is preprogrammed with the appropriate correlation using a known functional relation. 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 to either the electronic memory 132, if provided, or to the remote communication unit 140 as desired. The processor chip can be formed integral with the data collection circuit, or provided separately. An example of a suitable processor chip or circuit includes the EPAC™ electrically programmable analog circuit, Model No. IMP50E10C, from Digi-Key Corporation of South Thief River Falls, Minn., U.S.A. as modified accordingly, although alternatives are available.

[0047] Alternatively, or in addition to the processor chip or circuit 136, a processor 150 may be provided in operative communication with the remote communication unit 140 as illustratively represented in FIG. 2. A variety of suitable remote communication units may be used to receive the collected data. For example, if signals are to be transferred by a physical connection with the data collection circuit 130, the remote communication unit 140 may include the conventional I/O ports of a commercially available personal computer. If signals are to be transferred by wireless transmission, a suitable remote receiver may be used, such as that of the THERMO•DOT system available from Stock America, Inc. of Milwaukee, Wis. Such signals received by the remote communication unit 140 are then provided to the processor 150 to correlate the transferred signals into corresponding sterilant concentration levels using the known functional relation. 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 analyzed, displayed, printed, or otherwise used as desired.

[0048] As previously noted, various components of the sterilant monitoring system are or may be located proximate the sensor chamber 120. For example, the sterilant sensor 124 and any other sensor that is included, such as the temperature sensor 126 in accordance with the preferred embodiment, may be positioned inside the sensor chamber 120, or be mounted outside the sensor chamber 120 and operatively extend therein. If positioned inside the sensor chamber 120, these sensors should be of suitable construction to prevent corrosion or damage thereto, or sealed within a suitable housing to prevent such damage. Additional components positioned proximate the sensor chamber may include the portable power source 138, the data collection circuit 130 and the processor chip or circuit, if provided. Specifically, these components may be positioned within the sensor chamber 120 or, as schematically shown in FIG. 2, located outside the sensor chamber 120. Regardless, it is preferred that these components are contained within a housing of suitable material to prevent damage or breakage due to their relatively delicate construction.

[0049] Reference is now made to FIG. 3, which is directed to an additional aspect of the sterilization apparatus and another embodiment of a sterilant monitoring system of the present invention. In this embodiment, a plurality of articles, such as containers C, are carried in an array by article conveyor 14 and moved simultaneously to the various sterilization stations of the sterilization apparatus 10, which has been microbiologically sterilized to a certain desired level. For example, and not limitation, FIG. 3 shows a conveyor 14 configured to carry ten (10) articles in a side-by-side relation, although any of a variety of different array configurations may be used.

[0050] FIG. 3 also shows a representative end view of sterilization station 15, including a supply manifold 25 joined in fluid communication with the supply conduit 20. The supply manifold 25 includes a plurality of flow lines 24 joined fluidly in parallel through which sterilant from the supply conduit 20 can flow respectively to the sterilization station 15 for sterilization of a corresponding number of articles C positioned thereat. Preferably, and as embodied herein, the number of flow lines 24 extending from the supply manifold corresponds to the array of articles C moved by the conveyor 12, such as ten (10) flow lines 24 as shown in FIG. 3. The parallel flow lines 24 of the preferred embodiment also are moveable, as shown by arrow A, between an extended position, in which each flow line is capable of introducing sterilant into the interior of a respective container C, and a retracted position to allow relative movement of the containers along the conveyor path by the conveyor. A variety of such moveable assemblies are known and available.

[0051] In accordance with the invention, a sensor chamber is joined at a select location in fluid communication with the sterilant supply conduit to detect corresponding levels of sterilant. That is, and as embodied herein, the sensor chamber 120 is joined in fluid communication with the sterilant supply conduit 20 at the supply manifold 25. The select location of the sensor chamber of this embodiment is located proximate the sterilization station 15 and, preferably, in fluid communication with one of the flow lines of the supply manifold 25, designated 24′ in the illustrated embodiment.

[0052] In the preferred embodiment of the invention, the sensor chamber is joined in fluid communication with an outermost one of the flow lines 24 so as to be located furthest from the supply conduit. This location is preferred because the sterilant flow within the remaining flow lines 24 is less likely to be impacted by the flow differential, if any, generated by the sensor chamber 120. Additionally, this location is preferred because it is representative of the worst case conditions; that is, the sterilant concentration at the outermost flow line 24′ is most likely to be the lowest due to flow resistance. By this configuration, detected levels of sterilant within the sensor chamber 120 at the outermost flow line 24′ generally will provide an accurate, yet conservative, indication of the sterilant concentration levels of the remaining flow lines at the sterilization station. Furthermore, by locating the sensor chamber and related components as indicated, the sterilant supply system and the containers are less susceptible to contamination.

[0053] FIG. 4 is a schematic illustration of the sterilant monitoring system 100 of the present invention as used in conjunction with the manifold flow line 25. Generally, this sterilant monitoring system 100 includes the same desired features and components as described in detail with regard to that of FIG. 2. The configuration of the sensor chamber 120 is modified, however, so as to be joined in fluid communication with the outermost flow line 24′ of the manifold 25. As shown in FIG. 4, the sensor chamber 120 includes an inlet 127 joined in parallel fluid communication with the flow line, and an outlet vent 129 for the ejection of sterilant therefrom. The inlet 127 and outlet vent 129 are appropriately sized to create a flow resistance substantially equivalent to that of the remaining flow lines. A flow control valve likewise may be provided on either the inlet or the outlet vent, or both if desired. By providing a valve at both the inlet 127 and the outlet 129, a sterilant sample can be captured within the sensor chamber 120 for static testing if desired. Furthermore, the outlet vent 129 can be open to atmosphere or, if desired or necessary, the outlet vent 129 can be joined in fluid communication with the supply manifold to return sterilant flow thereto if flow balance must be maintained.

[0054] As shown in FIG. 4, a sterilant sensor 124 is positioned to provide output signals corresponding to detected levels of sterilant within the sensor chamber 120, and a data collection circuit 130 is operatively coupled to the sterilant sensor 124 for communication with the remote communication unit 140 and processor 150 as previously described with regard to the embodiment of FIG. 2. In this manner, detection of concentration levels of sterilant within the interior of sensor chamber 120 provides data substantially corresponding to sterilant concentration levels within the flow lines of supply manifold 25 without risk of dilution with the enclosure air or condensation due to lower pressure at the sterilization station. Additional sensors, such as a temperature sensor 126 as previously described, also may be included to provide corresponding output signals representative of respective conditions within the sensor chamber 120. Furthermore, one or more of the additional components previously described with regard to the embodiment of FIG. 2, such as a memory circuit 132 and a processor chip or circuit 136, may be included in the embodiment of FIG. 4 as schematically presented by reference character 131. Each of these components is described in detail above and need not be repeated.

[0055] The embodiment of FIG. 4, as shown, may be used for branch line sampling as desired. Additionally, and as noted above, programmable or operable valves may be provided at the inlet 127 and outlet 129 to capture a preschedule test profile or to perform a periodic test under static conditions. In this manner, more accurate concentration levels can be detected by eliminating parametric influence, such as flow rate and pressure, if desired.

[0056] The method of operating the present apparatus for sterilizing articles will be readily appreciated from the foregoing description. The method includes the steps of providing a sterilization apparatus such as in the form of apparatus 10, which includes a sterilization station as generally indicated at 15. A sterilant supply conduit, designated by reference character 20 in the illustrated embodiment, is provided to supply sterilant, such as hydrogen peroxide vapor, to the sterilization station 15.

[0057] The method further entails positioning a sterilant sensor 124 at a select location in communication with the supply conduit 20 to provide output signals corresponding to detected levels of sterilant at the select location. The select location may be anywhere along or in communication with, either directly or indirectly, the sterilant supply conduit 20. For example, it is preferable to position a sensor at each location wherein micro validation is desired to detect a minimum hydrogen peroxide vapor concentration level as required to reach a predetermined spore log reduction as is known in the art. Although alternative sensors may be suitable, the preferred embodiment uses a sterilant sensor having a gas-detecting semiconductor sensor 124 positioned within the sensor chamber 120 for detection of sterilant thereat.

[0058] At least one article to be sterilized, such as exemplified by container C, is placed at the sterilization station 13, 15. This may be accomplished manually, although the preferred embodiment includes an article conveyor 14 to move one or more articles into proper placement at the sterilization station 13, 15. Sterilant is directed through the supply conduit 20 and to the article C placed at the sterilization station 13, 15, with at least a portion of the sterilant from the supply conduit flowing by the select location at which sterilant levels are to be detected. In this manner, output signals from the sterilant sensor 124 are generated corresponding to detected levels of the sterilant at the select location.

[0059] The preferred method embodied herein further includes joining a sensor chamber, illustrated as sensor chamber 120, in fluid communication with the supply conduit 20 at the select location such that at least a portion of the sterilant from the supply conduit 20 flows therethrough. As will be appreciated, the step of generating output signals from the sterilant sensor 124 includes generating signals corresponding to detected levels of sterilant within the sensor chamber 120. Preferably, additional sensors are positioned at the sensor chamber to collect additional data representative of the sterilant thereat. As embodied herein, a temperature sensor 126, such as a thermocouple as previously noted, is positioned at the select location, and particularly within the sensor chamber 120, to provide output signals corresponding to the ambient temperature proximate the sterilant sensor 124.

[0060] In accordance with the invention, a data collection circuit 130 is operatively coupled to the sterilant sensor 124, and any additional sensors that may be provided, to receive output signals therefrom as collected data. The data collection circuit 130 may be a conventional physical signal connection with the remote communication unit of a processor 150. Alternatively, or additionally, the signal connector 134 of the data collection circuit 130 may include a transmitter to transmit signals representative of the collected data to a remote receiver 140. In this manner, signals representative of the collected data can be transmitted simultaneous with collection or, if the data collection circuit further includes an electronic memory 132 as previously discussed, the signals can be recorded as a readable memory and transmitted or otherwise transferred at a later time. It also is preferred that the data collection circuit 130 include a circuit to select conditions for data collection, with a signal connector provided to allow entry of such selected conditions. A remote control also may be provided for remote operation of the sterilant monitoring assembly. When the present method is practiced by use of hydrogen peroxide (H₂O₂) vapor as the sterilant, the sterilant sensor 124 provides an output signal corresponding to detected levels of hydrogen peroxide (H₂O₂) vapor.

[0061] In accordance with the illustrated embodiment of FIG. 4, the step of providing a sterilization apparatus includes providing a supply manifold 25 joined in fluid communication with the supply conduit 20. The supply manifold 25 includes a plurality of flow lines, 24, joined fluidly in parallel through which the sterilant from the supply manifold 25 can flow respectively to the sterilization station for sterilization of a corresponding number of articles C positioned thereat. The select location at which the sterilant sensor 124 is positioned is at one of the flow lines 24′ to provide output signals corresponding to detected levels of the sterilant at the select location of the flow line. Preferably, and as previously noted, the sensor chamber 120 is joined in fluid communication with an outermost one of the flow lines 24′ of the supply manifold 25, with the step of generating output signals including generating output signals from the sterilant sensor 124 which correspond to detected levels of sterilant within the sensor chamber 120.

[0062] In accordance with the present invention, the method can be performed during actual processing of the articles C by the sterilization apparatus, either continuously throughout at least a portion of the sterilization cycle, or periodically as desired. Additionally, it should be understood that the data collection and monitoring steps of the method can be performed at any time before or after the sterilization processing cycle for system verification and maintenance purposes. Additional sterilant sensors also can be provided external of the sterilization apparatus to monitor environmental sterilant concentration levels if desired.

[0063] 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.