System and method for detecting potential loss of integrity in flexible bags for biopharmaceuticals

Abstract

The integrity of the flexible bag is verified by a testing system (1) that uses helium to detect the presence of possible holes. The flexible bag (2) is preliminarily placed in a vacuum chamber (CH) of a liquid-tight isolated enclosure (10). After connecting the bag's port (11) to a helium supply pipe (3a), a vacuum is applied to evacuate the outside of the bag within the enclosure. A first amount of helium is then diffused through the gas-permeable wall into the internal volume (10a), increasing the helium partial pressure outside the flexible bag. Subsequently, during a testing phase while the vacuum is still applied, the bag is filled with a second amount of helium. A helium detection means (9) of the system (1) detects information representative of the helium partial pressure in the internal volume (10a) and allows helium escaping from the bag to be detected by analyzing the helium partial pressure drop.

Description

[Technical Field]

[0001] The present invention relates to a system and method for detecting the potential loss of integrity of flexible packaging, such as flexible bags intended to receive biopharmaceutical fluids.

[0002] The term “biopharmaceutical fluid” is understood to mean products resulting from biotechnology (culture media, cell cultures, buffers, artificial nutrients, blood products, and derivatives of blood products), or pharmaceuticals, or more generally, products intended for use in the medical field. Such products may be in the form of liquids, pastes, or occasionally powders. The present invention also applies to other products that are subject to similar requirements regarding their packaging. Such products are usually of high added value, and it is important to ensure the integrity of the packaging containing such products, particularly that it is free from contamination. [Background technology]

[0003] For storage and transport purposes, such biopharmaceutical liquids are typically placed in bags with flexible, sealed, and sterile plastic walls. Such bags must be liquid-tight when receiving the biopharmaceutical fluid before or during use, or at least when they have a sufficient level of liquid-tightness, to ensure that their possible contents are preserved from degradation occurring outside the bag, such as contamination. Therefore, it is necessary to be able to easily detect any loss of bag integrity before, during, or after use.

[0004] Various methods are currently known for verifying the integrity of bags suitable for containing biopharmaceutical fluids. The first known method consists of physical tests to determine whether there are leaks or holes in the bag walls. European Patent No. EP2238425 describes a method in which the pressure inside an empty sterile bag increases between two plates and limits its expansion.

[0005] A porous material is placed between the bag walls and each plate to prevent contact between the walls and the expansion limiting plates from concealing leakage. After inflating the bag, the change in pressure inside the bag (with the bag sandwiched or constrained between the two plates) is measured. The pressure drop inside the bag is analyzed. If there is leakage in the bag, under such a suppressed state, the measured pressure will fall below a given threshold over time, and a loss of integrity can be concluded.

[0006] U.S. Patent No. US2014 / 0165707 discloses an alternative method for testing the integrity of a bag. The bag is placed in a compartment, and a structured, permeable receiving layer is placed between the bag and the compartment. The bag is then connected to a source of filling fluid to generate a predetermined positive pressure within it.

[0007] Next, the pressure fluctuations within the bag are analyzed to determine whether the bag is liquid-tight and therefore intact. Similarly, U.S. Patent No. US8910509 or U.S. Patent No. US2014 / 0083170 are known to describe portable equipment for verifying the integrity of bags. Here, before measuring the pressure within the bag to detect loss of integrity, the bag is preferably filled with sterile air.

[0008] Other known methods exist for verifying integrity using inert tracer gases. For example, in an integrity test using helium as a gas tracer, the entire bag is placed in a liquid-tight enclosure, which is then sealed around the bag, and a vacuum is created inside the enclosure. A specific amount of helium (He) is then introduced into the bag. If there is leakage from the bag, a mass spectrometer detects the presence of helium outside the bag within the enclosure volume.

[0009] These physical testing methods are suitable for testing the integrity of flexible containers or bags, provided they can demonstrate the absence of leakage pathways of a size that would prevent microbiological intrusion. At the time, the most sensitive method known and suitable for flexible containers was the gas tracer method.

[0010] Current gas tracer measuring instruments (mass spectrometers) can detect low partial pressures representing micro-leaks far below 2 μm. However, there are other limitations in detecting leak sizes smaller than 2 μm. To obtain a sufficient signal-to-noise ratio, the residual He level in the vacuum chamber should be 1000 mbar (5.10) for a 2 μm leak size. -3 The sample must be processed at a level below the natural concentration / partial pressure of He in air (mbar). When actually performing the test, residual He in the vacuum chamber will generate background noise that masks any detected leakage.

[0011] In the case of flexible plastic containers, measuring conforming products is affected by several noise sources that increase the signal amplitude (one of which is the natural He concentration / partial pressure). Therefore, it is not easy to determine the leakage rate (the signal representing the rate measured for a good bag that needs to pass the test may resemble a kind of signal representing a defective product).

[0012] Noise can be caused by a variety of conditions, depending on the humidity level inside the enclosure, flexibility, and / or the physicochemical state of the bag. Despite the gas barrier film typically present in the flexible bag or similar device under test, helium penetration through the plastic film can produce leakage rates even in rigid products.

[0013] To obtain quantifiable and reliable results, a very high level of sensitivity (10 -8 A method is needed to provide up to mbar.L / sec. Additionally, the process can be partially or fully automated and, upon request, directly integrated into the manufacturing line.

[0014] Current physical methods are ineffective in detecting micro-leaks within bags, such as pores smaller than 2 microns in diameter. Furthermore, detecting leaks through pores smaller than 2 microns is difficult because the leakage rate is often too low to distinguish from background leakage rates or bag-specific noise (even using oxygen barrier layers such as EVOH cannot prevent helium penetration). However, it is known that some microorganisms can pass through pores smaller than this size, particularly sub-micrometer sized pores under certain conditions, such as during immersion bacteriological loading tests. Therefore, the use of the above physical testing methods does not guarantee that microbial intrusion into the bag will not occur under such specific conditions. [Overview of the Initiative] [Problems that the invention aims to solve]

[0015] Therefore, in certain areas of the present invention, there is a need to efficiently test bags intended to be filled with biopharmaceutical fluids while detecting pores as small as possible in micrometers and submicrometers. When testing the integrity of such bags before use, it is possible to easily test them with the same level of reliability as, or even higher than, currently known or used methods. [Means for solving the problem]

[0016] To improve the situation, embodiments of the present invention provide a test system for verifying the integrity of a flexible bag using a gas tracer, the system of which: - A housing that partitions a vacuum chamber, wherein in the operating configuration of the housing, the internal volume is liquid-tightly isolated from the outside of the housing, and the housing; -A first helium supply device, equipped with a supply pipe for filling the flexible bag with helium in a filling step, when the flexible bag is placed in a vacuum chamber so as to be surrounded by an internal volume, via the outlet of the supply pipe; - In the suction mode, a vacuum suction assembly for performing vacuum suction and extracting gas from the internal volume outside the flexible bag; - At least one pressure measurement member for detecting the helium partial pressure within the detection area of the internal volume, the detection area being in communication with the suction inlet of the vacuum suction assembly, said pressure measurement member; - At least one source of pressurized helium adapted to be introduced into the flexible bag and intended for introduction.

[0017] The test system further comprises the following: - A second helium supply device for adding helium (e.g., from at least one source of pressurized helium) to the internal volume of the vacuum chamber outside the flexible bag, comprising: - Different from the supply pipe, - Communicating with a gas source, which can be at least one source of pressurized helium, A supply member, said second helium supply device; - A control unit for controlling the first helium supply device and the second helium supply device, said control unit being adapted to trigger the second helium supply device before the first helium supply device; - An analysis module that uses information representing the change over time of the helium partial pressure detected by the pressure measurement member before and after the filling step, said analysis module being configured to detect helium leakage based on said information.

[0018] The information representing the change over time of the helium partial pressure may be the time derivative and / or the leakage rate (each expressed in mbar.L.s -2 or mbar.L.s -1 ). Such information can be analyzed taking into account similar information recorded for an integrated (defect-free) test sample.

[0019] Typically, the analysis module is adapted to use information representing the change over time of the helium partial pressure detected by the pressure measurement member before and after the filling step, in order to obtain test results representing the helium partial pressure drop in the detection area, and the analysis module: - When the vacuum suction assembly is in the suction mode, use information representing the helium partial pressure detected by the pressure measurement member after the addition of helium by the second helium supply device during a period including the period after the filling step; - When the vacuum suction assembly is in the suction mode, after identifying the background value identified based on the information representing the helium partial pressure detected by the pressure measurement member before the filling step, subtract the background value identified from the raw measurement value; and - Is configured to compare the test results with at least one reference result to identify whether the flexible bag filled with helium passes the integrity verification.

[0020] The subtraction of the determined background value can be performed after adding the tracer gas to the internal volume. Assuming that helium is the tracer gas, the injection of helium may be a step that depends on the value of the first derivative of the helium partial pressure in the detection area. The injection is usually executed after a calculation routine and only when the conditions are met (such conditions may usually reflect inappropriate situations for direct analysis).

[0021] In fact, for each test, the analysis module calculates the first derivative of the helium partial pressure in the detection area. When the partial pressure of helium measured in the detection area reaches the trigger point (i.e., it means that the noise is small enough to trigger the measurement stage), it is checked whether the first derivative of the helium partial pressure is within a predetermined range (between the lower limit and the upper limit). If the "slope" (within the leakage rate graph) is outside the appropriate range (i.e., the range that does not represent a reproducible measurement value), the helium injection is executed by the second supply device. Thereby, due to the stabilization effect, a lower leakage rate can be detected.

[0022] Conversely, if the first derivative of the partial pressure of helium is within a given range, injection is not necessary (no stabilization effect is needed). The subtraction of the determined background value can be performed without such injection, and the conclusions of the test can be obtained by a more conventional method. The test results may indicate the end of the helium partial pressure drop in the detection region. Therefore, it can be determined at the end of the normal duration of the partial pressure fluctuation due to bag inflation (e.g., a period of about 2.5 seconds).

[0023] If the test results reflect a sufficient decrease in helium partial pressure, such a decrease in helium partial pressure is observed when there is no leakage in the bag under test. This configuration mitigates the impact of the following limitations on the test system: i) The flexibility of the bag or similar container, which artificially increases the helium velocity (leakage rate) when measured during helium filling (the decrease in internal volume around an inflated bag causes an increase in the pressure (partial pressure of helium) in the chamber). ii) The release of varying tracer gases during the test period due to the desorption of tracer gases from the tested material and the vacuum chamber walls.

[0024] In fact, injecting helium around the flexible bag before the filling step while the test system is in suction mode allows for more uniform desorption (from the chamber surface and the surface of the bag material) and adjusts the background value of the helium leakage rate remaining in the vacuum chamber (despite the vacuum).

[0025] The second supply device can be considered as part of a control system for adjusting the amount of helium that can be removed from the internal volume immediately before the filling step. The inventors have found that when a specific amount of helium is added to the internal volume, a low leakage rate (typically 10) is desirable. -8We observed that the time required to have a threshold of less than mbar.L / sec increased, and such times were, for example, about 2 or 4 minutes, resulting in less variation due to the movement of the bag wall when it expanded during the desorption and / or filling steps. The measurements were accurate and formed reproducible measurements.

[0026] For flexible bags with volumes ranging from 50 mL to 50 L, the test system has been advantageously observed to efficiently detect leaks with a size of less than 2 micrometers within the flexible bag. This means the test system is also efficient at efficiently detecting micrometer-sized leaks or leaks of approximately 1 or 2 micrometers for larger capacity bags.

[0027] More generally, such testing systems improve the efficiency of testing pouches with a wide range of capacities, including, for example, pouches with larger capacities from 50L to 650L (e.g., using specially sized testing systems for pouch capacities greater than 50L). In some cases, if leak detection (for micrometer-sized leaks) is sufficient to enable / disable the bag's integrity, the time required to reach the threshold may be reduced.

[0028] If a subtraction step is performed to subtract a background value determined in the preparation phase (before the filling step), the analysis module can typically use information representing the change over time of the helium partial pressure detected by the pressure measuring member before the filling step to determine such a background value (e.g., a leak rate value) to be subtracted from the raw measurement (for leak rate) obtained immediately after the filling step.

[0029] In some embodiments, prior to the filling step, the specific injection of helium around the bag can be carried out via a porous material. The porous material can be selected to have a background descent rate similar to that typically observed for helium desorption from the material of the bag under test. Optionally, there is an acceptable threshold to determine whether the bag passes the integrity test, which is 2.00·10. -8 mbar.Ls -1 It may be lower than that.

[0030] Because the helium partial pressure is selectively injected around the flexible bag in a controlled manner after the initial suction phase and before reaching a low threshold for the leakage rate, the helium background value related to the helium remaining in the vacuum chamber (despite the vacuum) cannot vary in various profiles as in previous methods. In other words, the test method is suitable for reducing the standard deviation of the leakage rate measurement after subtracting the background value from the raw measurement.

[0031] Furthermore, the test system can be operated for a very short test time (e.g., about 3-4 seconds after the start of the filling step) to avoid adverse effects from helium penetration through the plastic film of the bag under test. The regulating effect of injecting helium into the internal volume around the bag prevents the drawback that measuring the leakage rate of a suitable flexible container (within such a short test time) would be randomly affected by the flexibility of the bag (i) and tracer gas desorption (ii).

[0032] Ultimately, if no detectable increase in helium leakage rate is observed at the end of the test, the flexible bag (which may have a single package) is considered fit to prevent microorganisms from moving from the outside to the inside of the bag. More precisely, improved accuracy allows for ensuring that there are no pores larger than the smallest detectable sub-micrometer size when adjusting the amount of helium present in the internal volume immediately before the filling step.

[0033] Comparison of test results with reference results can be made based on test results that reflect the change in helium partial pressure over time within a time slot consisting of 1 to 10 seconds, preferably 3 to 10 seconds, from the start of the filling step. In such a time slot, the influence of permeation is sufficiently low or insignificant, thus increasing the accuracy of the test. Needless to say, the steps can be controlled in a time series, and the addition of a certain amount of helium can usually be performed before the filling step, with a time interval (between introducing the amount of helium into the internal volume and starting the filling step), at a predetermined moment, which is adapted to adjust for bumps or pressure drops present in the leakage rate graph within the vacuum chamber. A bump is a short-term increase in helium partial pressure due to the expansion of the bag.

[0034] Furthermore, to replicate the background rate typically observed due to helium desorption from the bag material, a certain amount of helium can be injected through a porous material, such as a thin silicone tube (under compatible conditions to observe the same desorption phenomenon as after the filling step). This may be interesting for performing a background value subtraction with respect to raw measurements obtained over a suitable period after the filling step.

[0035] In fact, even if the desorption rate can vary within the range of the same bag with exactly the same conditions before the test, such a desorption rate is proportional to a given physical constant of the given bag. As a result, if the pressure drop representing the physical constant (the desorption constant of the bag under test) is determined first, and if it has a background value corresponding to the same bag, then the deviation effect and the leakage effect of the leakage rate reduction can be better distinguished in the test phase before the filling step.

[0036] Optionally, the control unit can be configured to control the following: - A first valve that allows helium to circulate in the supply pipe during the filling step; and - A second valve that allows for the circulation of helium within the supply member.

[0037] In another embodiment, the second helium supply device includes a valve, preferably a solenoid valve, upstream of the supply member, which has a gas-permeable wall for limiting the rate at which helium is added to the internal volume.

[0038] According to one embodiment, the second helium supply device further includes an additional valve, preferably a solenoid valve, downstream of the supply member. Such an additional valve, which may allow communication between the adjustment chamber or similar compartment and the vacuum chamber, is important to avoid prolonging the cycle when not needed.

[0039] In various embodiments of the present invention, one and / or the other of the following details may also be used separately or in combination as appropriate. - A second helium supply device for adding helium to the internal volume is isolated from the mechanical connector for connecting to the flexible bag (the second helium supply device has no opening for communicating with the internal volume of the chamber, and the first helium supply device includes a connector that demarcates the supply pipe outlet, forming a free end of the supply member in a cut state). - The port is typically a port that connects the flexible bag to a pressurized system, including the primary helium supply device, using a supply pipe. - The gas-permeable wall (included in the supply member) comprises a microporous and / or mesoporous membrane of silicone rubber or glass.

[0040] - The supply member includes a silicone tube and is adapted to supply helium by diffusion through the silicone wall of the tube. - At least one source of pressurized helium is a helium source including a single tank located outside the internal volume for containing all the helium to be injected into the chamber, the single tank being operably coupled to a first helium supply device and a second helium supply device. - A helium supply source, preferably pressurized helium, extends adjacent to the bag and / or is embedded as part of the bag (the operation of valves associated with such embedded helium supply source may optionally be performed by remote control means). - The test system includes two spaced-apart, preferably parallel, plates and a housing between the two plates for receiving a flexible bag, the plates preferably forming restraint plates to restrain the expansion of the flexible bag when filled with helium during the filling step. -The two plates are fixed plates.

[0041] In various embodiments of the present invention, one or more of the following may be used separately or in combination as appropriate. - The bag has an outer packaging / wall that divides the bag's single internal space. - The outer wall of the bag includes a port suitable for being sealed or connected in a liquid-tight and removable manner to a gas or fluid supply source. - The bag comes with a filling tube and / or discharge tube located on the outside of the outer packaging / wall. - The bag may contain one or more connectors, filters, and sensors.

[0042] Furthermore, an optional system for verifying the integrity of the bag according to the present invention is provided, which includes: -Bag according to the present invention, - A source of pressurized gas intended to be introduced into the intermediate space of the bag. - A component for measuring the gas pressure in the intermediate space in order to compare the pressure drop in the expanded intermediate space with a predefined pressure drop threshold, and - Two fixed expansion limiting plates facing each other with a gap between them (suitable so as not to obstruct leakage of the second packaging wall positioned relative to them).

[0043] According to the specifications, each expansion limiting plate is covered with a lining that is porous to gas (helium). The present invention also relates to a test method for verifying the integrity of a flexible bag using a tracer gas to detect the presence of possible pores, the test method being as follows: -During the preparation phase: To provide a test system that includes a housing that separates a vacuum chamber adapted to be liquid-tightly isolated from the outside of the housing in the housing's operating configuration; To provide an injection device suitable for supplying a tracer gas into a vacuum chamber, the tracer gas being preferably helium; A flexible bag is placed inside a vacuum chamber, and the bag's port is connected to a supply pipe that communicates with a tracer gas source, which is typically helium. Performing vacuum suction to obtain a vacuum outside the flexible bag within the internal volume of the vacuum chamber; Gas tracer injection is performed by injecting a fixed amount of tracer gas (typically helium) into the internal volume outside the flexible bag using an injection device;

[0044] -During the testing phase, while the vacuum suction is still being performed: The filling step involves filling the flexible bag with helium; To enable the detection of helium escaping from the flexible bag, information representing the partial pressure of helium outside the flexible bag in the internal volume is detected by using at least one pressure measuring element; Next, in order to determine whether the flexible bag has passed the integrity verification, the next step is to compare the test results, which represent the helium partial pressure drop in the internal volume outside the flexible bag and are obtained using at least one pressure measuring member, with at least one reference result. Includes.

[0045] This method offers greater sensitivity because the conditions are more stable. All steps can be performed in the same measurement cycle (e.g., with substantially constant suction performed by at least one vacuum pump or similar vacuum means). Thus, a 1 μm leak detection limit (and sub-micrometer leak detection) can be efficiently utilized, for example, to ensure / verify microbial integrity under immersion BCT (Bacterial Challenge Testing) conditions.

[0046] Unlike previous methods involving pressure drop analysis, the detection method poses no risk for larger containers (such as 3D bags, typically with capacities of 10L, 50L, or more) by reducing the standard deviation of the leakage rate measurement after subtracting background values ​​from the raw measurement.

[0047] Using this method, the leakage rate can be calculated (usually using a mass spectrometer) based on the determination of the partial pressure of helium in the test chamber to determine whether the tested flexible bag passes or fails the test, and then such calculated leakage rate can be compared to an acceptable standard (threshold).

[0048] Subtracting background noise to sufficiently increase the sensitivity of the measurement improves the efficiency and reliability of the test. Furthermore, the second supply device may be configured to add helium slowly, thus mimicking / reproducing the background descent rate typically observed for helium desorption from the plastic material of the bag under test. A silicone tube may be placed in the tube prior to the solenoid valve to prevent unnecessary lengthening of the cycle.

[0049] According to a particular embodiment, during the testing phase: - The comparison between the test results and the reference results is performed based on the helium partial pressure measured in a time slot between 3 and 10 seconds from the start of the filling step, preferably between 3 and 6 seconds. - And / or the comparison of the test results with the reference results is performed after injecting the determined gas tracer into the internal volume outside the flexible bag, taking into account the pressure drop background value obtained before the filling step, and the test results are determined based on the raw measurement values obtained in the time slot included between 3 seconds and 10 seconds after the start of the filling step.

[0050] The tracer gas is helium and the test method is, in the preparation stage: - Performing vacuum suction inside the flexible bag to empty the internal space of the flexible bag; - Measuring the partial pressure of helium in the detection area of the internal volume (outside the bag); - Calculating the first derivative of the partial pressure of helium in the detection area (using a sensor, a mass spectrometer, or a similar pressure measuring member); including When the partial pressure of helium measured in the detection area reaches the trigger point (i.e., such pressure has dropped sufficiently (high vacuum) and the noise is small enough to trigger the measurement stage), it is checked whether the first derivative of the partial pressure of helium is within a predetermined range between the lower limit and the upper limit, and helium injection is performed by the injection device in the chamber only if the first derivative of the partial pressure of helium is outside the predetermined range.

[0051] According to a specific embodiment, in the preparation stage, after the partial pressure of helium is measured in the internal volume below a predetermined threshold value, a certain amount of helium is supplied to the internal volume outside the flexible bag. Such a threshold is less than 5.10 -3 mbar (usually 4.10 -5 mbar or less), which means that the threshold usually corresponds to a helium pressure lower than the partial pressure of helium in the ambient air.

[0052] This means that, prior to the test phase (i.e., before the measurements are used for helium integrity testing), some of the helium (including the helium most recently injected in the supply step) is discharged by suction from the chamber of the housing where the flexible bag is located. Optionally, the reference result is either a predefined pressure drop threshold, or a reflection thereof, obtained by calculating the time derivative of the helium leakage rate detected by at least one pressure measuring element within the internal volume sensing area.

[0053] When helium leaks from a bag, the partial pressure drop (a sudden drop in pressure) that would normally be present when there is no leak decreases or disappears, which may allow the leak to be detected. According to certain embodiments, the filling step is performed to maintain the flexible bag between two expansion limiting plates, keeping them spaced apart and facing each other so as not to obstruct leakage of the walls of the flexible bag positioned against them. This may be interesting for controlling the expansion of the internal space of the bag. A porous layer can be used to form contact with the outer wall of the bag.

[0054] According to a particular embodiment, the flexible bag constitutes or is part of a device under test intended to receive a biopharmaceutical, comprising several flexible pipes, each connected to a respective port of the device under test, and the device under test is placed in the chamber before vacuum aspiration is performed.

[0055] Optionally, performing vacuum suction during the preparation phase means removing gas from different suction areas of the housing to obtain a vacuum inside and outside the flexible bag within the housing.

[0056] According to the specifications, the amount of helium injected when performing gas tracer injection into the internal volume outside the flexible bag is a first amount of helium, and the flexible bag is filled with a second amount of helium in the filling step, with the first amount of helium being less than the second amount of helium.

[0057] The present invention also relates to a system for verifying the integrity of a bag according to the present invention, which includes a gas detection member. In various embodiments of the present invention, one and / or the other of the following may also be used separately or in combination as appropriate. -The system is: A bag according to the present invention A source of pressurized gas intended for introduction into an intermediate space. Includes a control unit including gas pressure control and management components, and - The system is adapted to accommodate the entire bag, and further includes the intended outer container or housing. [Brief explanation of the drawing]

[0058] [Figure 1] Figure 1 is a schematic diagram of a test system according to an embodiment of the present invention. [Figure 2] Figure 2 is a top view of an exemplary flexible bag that can be used to form the device under test when carrying out the test method according to the present invention. [Figure 3] Figure 3 is a timing chart showing the operation of the test system, demonstrating that there are limitations to efficiently identifying leaks when the leak size is the same as or slightly smaller than 2 micrometers. [Figure 4] Figure 4 is a timing chart similar to Figure 3, illustrating the operation of the test system according to an embodiment of the present invention by opening a valve and injecting a certain amount of helium.

[0059] [Figure 5] Figure 5 is a schematic diagram of another embodiment of a system for verifying the integrity of a bag as shown in Figure 2, which includes a source of pressurized helium intended to be introduced on the one hand into the internal space of the bag and on the other hand around the bag, and valve assemblies and components provided for managing and controlling the helium injected into and around the bag.

[0060] [Figure 6] Figure 6 shows the waveforms of leakage rate and time obtained using the same conventional leakage rate test cycle. All bags are fit (no leakage, considering subsequent testing / investigation), and in particular, it shows four situations where deviations in the measured leakage rate prevent efficient differentiation between intact bags and bags with micrometer or submicrometer-sized leakage. [Modes for carrying out the invention]

[0061] A detailed description of several embodiments of the present invention, along with examples, is provided below with reference to the drawings. In various diagrams, the same reference is used to indicate identical or similar elements. Referring to Figure 1, a test system 1 for verifying the integrity of a flexible bag 2 is shown, which comprises a housing 10, one or more pressurized helium 4 supply sources and a pressure measuring member 9, which is typically suitable for providing a measurement that reflects the partial pressure of helium in a chamber CH separated by the housing 10. The chamber CH forms an airtight (and thus isolated from ambient air) space.

[0062] The housing 10 may have opposite sides that demarcate the receiving compartment for the flexible bag 2. Optionally, two plates 12, 14, for example, two rigid plate members, are provided to demarcate the compartment in which the bag 2 is located. The bag 2 is typically introduced into the chamber CH, in this case the compartment, in an unexpanded / unfilled state.

[0063] Bag 2, introduced into chamber CH, may initially contain only a small amount of air for pressure balance. This is advantageous in limiting the amount of gas discharged. At least one port, in this case only one port 11 of bag 2, can provide communication between the internal space SP of bag 2 and the source of pressurized helium 4.

[0064] When the housing 10 is tightly closed, the outer wall W of the bag 2 can be considered a partition wall made of plastic material (usually plastic without mineral or metal layers) between the internal space SP inside the bag 2 and the internal volume 10a around the bag 2, which is liquid-tightly isolated from the outside of the housing 10.

[0065] The enclosure 10 has at least two supply ports to allow the tracer gas to be introduced into the internal space SP and the chamber CH of internal volume 10a outside the bag 2, respectively. The expression "outside the flexible bag 2" means that the gas tracer is injected into the area around the outermost wall of the flexible bag: typically, the outer wall W of the bag 2 is the wall that expands directly when the bag is filled with helium, and this outer wall W directly separates the internal space SP from the internal volume 10a.

[0066] For example, as shown particularly in Figures 1 and 5, the test system 1 may include a first helium supply device 3 having a supply pipe 3a or similar injection line 27 to connect a source of pressurized helium 4 to a given port 11 of the flexible bag 2.

[0067] In the embodiment shown in Figure 1, at least one valve V1 is included in the first helium supply device 3, such valve V1 is located between the tank of the pressurized helium 4 supply source and the outlet 3b for connection to the port 11 of the bag 2. The pressurized helium 4 supply source includes or is itself a helium supply source including a single tank (outside the chamber CH) for containing all the helium to be injected into the chamber CH. The single tank is operably coupled to the first helium supply device 3, preferably to a supply member 5 (e.g., a pipe or similar duct) of the second helium supply device 6. In modifications, several tanks or separate helium supply sources may be used.

[0068] The test system 1 comprises a pressure measuring member 9, a housing 10, a control unit 13, and a leak detection assembly including a control and management assembly 28 coupled to the control unit 13, and valves V1, V2, V3, V5 which are operated during the measurement cycle by the control and management assembly 28 and / or the control unit 13. The control unit 13 may also include an analysis module 15 that uses information representing the helium partial pressure detected by the pressure measuring member 9 during the measurement cycle as shown in Figure 4.

[0069] A mass spectrometer is typically provided to form a pressure measuring member 9, such a mass spectrometer having or communicating with a detection region 10d, which can measure and analyze the pressure drop PD (the drop due to a rapid change in the partial pressure of helium in the chamber CH around the newly inflated bag 2). Since a pressure difference is obtained between the internal space SP of bag 2 and the internal volume 10a around bag 2, the pressure drop PD is systematically created after helium has started to fill bag 2 (as the concentration in the internal volume 10a increases).

[0070] The mass spectrometer is suitable for tracer gas detection (helium detection), and is particularly suitable when a vacuum is generated inside the housing 10 before the stage in system 1 where bag 2 is tested. In the embodiments shown in Figures 1 and 5, the test system 1 is used to detect the integrity of the outer wall W of bag 2, such wall W extends entirely within the chamber, typically between two plates 12, 14 located inside the chamber CH.

[0071] The housing 10 of the test system 1 is, in this case, an outer container on which the bag 1 according to the present invention can be placed. The outer container is larger than the bag 2 (or symmetrically, the bag 2 is smaller than such an outer container) so that the inflated bag 2 remains inside the chamber CH. Optionally, the housing 10 may include a porous lining for gases in the chamber 10, such lining being at least a contact portion that comes into contact with the bag 2 when the bag is in an inflated state after the filling step in which the bag 2 is filled with helium (an inert tracer gas). The lining on which the bag 2 is placed does not block leakage of the outer wall W when the bag 2 under test is placed inside the chamber CH.

[0072] The outer casing forming the housing 10 can consist, in particular, of a box or a rigid or semi-rigid fluid-tight shell. More specifically, in one configuration, the housing has a parallelepiped shape. The housing 10 may include an opening for introducing a bag 1 that can be selectively opened and closed. For this purpose, the outer casing of the housing 10 may include, for example, a removable cover or door with members for gripping and handling. Preferably, grip members are provided for quickly locking the cover in a closed position and capping the opening.

[0073] Referring to Figure 1, the test system 1 includes a source 4 for pressurized gas (here, pressurized helium in this non-limiting embodiment) which can be associated with fluid communication or with the outlet of port 11 of bag 1, and a line including a supply pipe 3a for injecting pressurized helium. The first helium supply device 3 is connected to the housing 10 at a location separate from / away from the pipe connecting the port 30 or the pressure measuring member 9 to the chamber CH.

[0074] A certain amount of helium is intended to be introduced into the internal space SP of bag 2 via port 11 and appropriate connecting elements of the first helium supply device 3. It is understood that the helium (or equivalent inert gas) is a neutral and non-toxic gas to the biopharmaceutical fluid that can form the contents of bag 2, so as not to contaminate the biopharmaceutical fluid. Figure 1 shows the outer wall W below the single-wall configuration of the bag, but in a modified example, bag 2 may have one or more external components that partially cover the outer wall W and are spaced apart from the outer wall W.

[0075] As shown in Figure 2, the folded flexible bag 2 has two opposing flat surfaces, with ports 11 and 12a-12 provided on one of these main surfaces. The other two surfaces are folded. The bag portions forming these other two surfaces are sheets of plastic material, having a flat bellows shape (forming two opposite gussets), with two initials forming the opposite surfaces inserted between the flat sheets.

[0076] The flat state of the flexible bag 2 obtained immediately after manufacturing is made possible by the overlapping of the weld seams 61, 61' and 62, 62'. The free ends 2e and 2f may be the straight edges of the bag 2. Thanks to the typical hexagonal shape of the opposite face, the bag 2 can easily reach a parallelepiped shape by expanding the gussets and folding along parallel fold lines FL1, FL2 (where L1 is the distance separating the fold lines FL1, FL2 of the same plastic sheet of the bag 2).

[0077] This is a non-limiting example of a 3D flexible pouch or bag 2. The parallel fold lines FL1, FL2 obtained in the inflated / filled state of bag 2 are predetermined fold lines formed on the opposite main surface of bag 2 (unlike a 2D container).

[0078] Such a bag 2 includes a bottom wall, a top wall, and flexible side walls that can be in two extreme states—flattened or unfolded—and is reshaped to change from one of these states to the other or to any intermediate state. When the flexible bag 2 is filled with a biopharmaceutical fluid or gas during testing, it expands more or less. It may form a parallelepiped container. Its bottom wall can rest on the inner surface of the base of the housing 10 or on the inner surfaces of the restraint plates 12, 14, while its side walls unfold toward the inner surfaces of the side walls of the housing.

[0079] The flexible bag 2 is shown here as having a hexagonal shape in its unfilled state. Each sheet forming the bag 2 may have a length L1 that is longer than the long side L2 of the hexagonal flexible bag 2 in its unexpanded / unfilled state (the shape clearly visible in Figure 2). It is understood that the length L1 of the flexible bag 2 in its initial state before filling, when measured from the lower end 2a to the upper end 2b, is greater than the height of the flexible bag or pouch 2 in the unfolded and filled state (for example, this height is substantially equal to the length L2).

[0080] The flexible pouch or bag 2 here has one or more inlets or filling or supply openings, particularly in the form of ports 12a-12b (which may form an upper port), particularly on the upper wall, and one or more outlets or discharge or discharge openings, particularly in the form of port 11, particularly on the bottom wall. Thus, the outer wall W of the bag 2 may have at least two orifices, in other words, two passages, at least one for filling with a biopharmaceutical fluid and at least one for discharging the biopharmaceutical fluid.

[0081] Preferably, any lines 7, 9a, 9b, and 2b connected to the same side of the bag 2 are called flexible supply lines. Furthermore, each of the flexible lines 7 and 9a-9b is preferably equipped with a clamping member such as clamps C1, C2, and C3.

[0082] The inlet openings are adapted to be closed as needed, and / or clamp members C1-C2 are used to block access to the interior of the flexible pouch 2. Similarly, one or more outlet openings are adapted to be opened as needed, and / or clamp member C3 is used to allow passage through the flexible line 7. The filling orifices and discharge orifices of the wall W are associated with the filling pipes by liquid-tight connections, respectively. For example, the filling orifices of ports 12a-12b are associated with flexible lines 9a and 9b (usually clamps C1 and C2 are shifted away from ports 12a-12b).

[0083] The illustrated embodiment shows the use of port 11 for filling with helium, but when the other flexible lines are closed and connected to a pressurized helium source 4 by the corresponding flexible lines, the internal space SP of the flexible bag 2 can be filled with helium using either the filling orifice or the outlet opening. In Figure 5, the port 11 into which helium is injected into the internal space of the flexible bag 2 may be the outlet orifice. The other lines can be attached using fixing devices 39, while clamps (here clamps C1, C2) prevent the helium present in the bag 2 from escaping into the chamber CH in the internal volume 10a around the bag 2.

[0084] Referring to Figure 5, it can be seen that clamps C1, C2, and C3 can be used to seal the flexible bag 2 when it is placed in the housing 10. In a modified example, the flexible lines 7, 9a, and 9b of the bag 2 can each be connected to a vacuum circuit, for example, the same vacuum circuit.

[0085] In some variations, bag 2 may include packaging that is 2D in which two wall members are directly joined to each other. Bag 2 may also have a 3D type, in other words, three-dimensional packaging. The wall W then typically includes two parts that form a main surface, and such two parts are fixed and sealed together to two side gussets by four longitudinal liquid-tight weld seams 61, 61' and 62, 62' (and two transverse weld seams).

[0086] As shown in Figure 3-4, it can be seen that suction needs to be performed to reduce the pressure in chamber CH. If the residual pressure is sufficiently low, the monitoring phase (test phase) of the measurement cycle can be performed. The test phase starts here from t0. At the start of the measurement cycle, the test system 1 may be similar to a known system in that it needs to reach a low pressure threshold after a waiting period T1. Valve V1 is activated at t0 to obtain the inflated bag 2 that is suitable for the test.

[0087] The control and management assembly 28 may include, for example, a pressure controller for the pressurized expansion gas in the supply pipe 3, commanding the injection of gas (helium) as needed (here at t0) and controlling the injection at the desired pressure. Such an assembly 28 may include a pressure gauge, an adjustable valve, and / or a control line between them. The control line 28a can link the control and management assembly 28 to the control unit 13 to coordinate steps during the measurement cycle. The assembly 28 may form part of the control unit 13.

[0088] In a preferred embodiment, as shown in Figure 4, valve V2 for the operation of the second helium supply device 6 allows helium to circulate toward the internal volume 10a and can be temporarily opened before opening valve V1 to fill bag 2. Unlike a conventional preparation stage (as shown in Figure 3) in which no helium is added around bag 2, while bag 2 is not filled with helium, a specific injection 18 is performed using a vacuum pump P1 for a period of suction. Such an injection 18 increases the partial pressure of helium in the internal volume 10a.

[0089] Referring to Figures 3 and 6, a comparison of several leakage rate curves of the conforming product under test reveals that after t0, the leakage rate measured by the pressure measuring member 9 may deviate (not forming a pressure drop PD with the expected significant leakage rate). Therefore, the curve 51 of a completely intact bag 2 may be similar to the curve 52 that reflects a situation where the bag 2 has a hole of about 1 or 2 micrometers in size, causing leakage. By using a specific injection 18 as shown in Figure 4, such deviations are significantly minimized, and / or conclusions regarding the testing of conforming products are easier to reach.

[0090] Since injection 18 provides an overview of the background value profile (as it causes a reference descent profile), it is straightforward to extract background values ​​relevant to the improvements made in the test phase performed after the start of the filling step. The end of the descent in the preparation phase (reference descent profile over time) may reflect background values ​​to consider. Consequently, the problematic case reflected by curve 51 in Figure 3 can be arbitrarily resolved by subtracting the background values ​​from the raw measurements obtained based on the descent caused by injection 18 (for example, taking into account the level of the final leakage rate in the reference descent profile).

[0091] Referring here to Figure 1, it is understood that a specific injection 18 is possible before the gas, in this case helium, flows through the supply pipe 3a of the first supply device 3. The vacuum pump P1 is involved in draining the gas from the chamber CH. Pump P1 performs vacuum suction and functions as, or is part of, a vacuum suction assembly for extracting gas from the internal volume 10a outside the flexible bag 2 in suction mode.

[0092] A vacuum pump P2 may be associated with the first supply device 3. The vacuum pump P2 communicates with the supply pipe 3a, for example, via a lateral passage downstream of the position of valve V1. This vacuum pump P2 is not used during the test phase of the measurement cycle (valve V5 is just closed at t0, and immediately after such closing, valve V1 is opened). The vacuum pump P2 is important for removing air from the flexible bag 2 to have a reproducible test gas volume or concentration (He) in the bag 2, otherwise the helium from the supply source 4 would mix with the remaining air in the bag 2.

[0093] In a preferred optional configuration, as shown in Figure 4, pump P2 can be activated immediately during the preparation phase after suction by the main vacuum pump P1 has started to prevent excessive inflation of bag 2. Suction by pump P2 is stopped well before t0 by closing the associated valve V5. Vacuum pump P2 can optionally be used for suction before the measurement cycle and, if applicable, after the measurement cycle.

[0094] The pressure measuring member 9 includes one or more mass spectrometers, typically a mass spectrometer suitable for detecting the helium concentration (partial pressure) in a detection region 10d of the internal volume 10a. Here, the detection region 10d is in direct communication with the suction inlet of a vacuum suction assembly, which is the inlet of a vacuum pump P1 in the embodiment shown in Figure 1.

[0095] At least one vacuum pump P3 can be associated with the mass spectrometer. Another pump (secondary pump, not shown) can be embedded in the mass spectrometer to form member 9. The valve V3 may be a conventional valve for such a mass spectrometer. This typically comprises a turbopump assembly or similar pumping means. The detection assembly forming or including the pressure measuring member 9 can be selected from several commercially available products and may be improved in some cases to increase the accuracy of the measurement.

[0096] In a modified configuration, the main vacuum pump P1 may be located downstream of valve V3 in a line that communicates directly with duct 30a. The principle of the leak detector in such a detection assembly can be based on a sector-field mass spectrometer. The analyzed entry gas (helium in this case) is ionized in a vacuum. The helium ions are accelerated using an added voltage and further separated in a magnetic field. For example, the ion current is converted into a current using a special detector (which is known in itself). This current is accelerated and displayed on a screen using a leak detection unit. Since the measured current is directly proportional to the helium partial pressure, it is equal to the measured leak.

[0097] Next, embodiments of the second supply device 6, and optionally the second helium supply device, will be described in reference to Figures 1 and 5. A second helium supply device 6 for adding helium to the internal volume 10a includes, here, a supply member 5 separate from the supply pipe 3a, a tube 32, or a similar part for the diffusion of helium through the outer surface of the wall inside the chamber CH of the internal volume 10a, or for demarcating all or part of an area that is in direct communication with the internal volume 10a, from a supply source of pressurized helium 4.

[0098] The tube 32 is typically made of silicone adapted to supply helium by diffusion through the silicone wall or porous glass wall of the tube 32. The surface of the tube 32, preferably the inner surface, demarcates a region that communicates with at least one source of pressurized helium 4 via the pipe of the supply member 5. The valve V2 may be a solenoid valve controlled by the control unit 13 via the control line 28a. Using the routines of the control unit 13, the valve V2 can be selectively opened to cause helium injection 18 and increase the partial pressure of helium in the internal volume 10a around the bag 2.

[0099] In the embodiment shown in Figure 1, the second helium supply device 6 includes at least one valve V2, preferably a solenoid valve, upstream of the diffusion portion of the supply member 5 or the tube 32 ("upstream" should be considered in relation to the flow of gas tracer from the gas tracer supply source toward the interface where the tracer gas reaches the internal volume 10a around the bag 2). The diffusion portion of the supply member 5 is understood to typically have a gas-permeable wall to limit the rate at which helium is added to the internal volume 10a.

[0100] In the modified example shown in Figure 5, the second helium supply device 6 includes at least one valve V2', preferably a solenoid valve, upstream of the tube, tube 32', or similar diffusion portion of the supply member 5. The second helium supply device 6 also includes an additional valve V2'', preferably a solenoid valve, downstream of the supply member 5. The valve V2'' may be adjacent to or extend into the chamber CH. In tube 32', the supply member 5 has a gas-permeable wall. Optionally, as in the embodiment of Figure 1, the permeable wall is adapted to limit the rate at which helium is added to the regulating chamber CR before it is injected into the internal volume 10a (using a helium-porous material).

[0101] An additional valve V2'' that may allow communication between the adjustment chamber CR or a similar compartment and the vacuum chamber CH is important to prevent the cycle from becoming longer when not needed. The silicone or glass tube that forms the gas permeable wall of the supply member 5 is located in the tube before the additional valve V2'' while it extends into the adjustment chamber / compartment CR, so that helium is not supplied to the vacuum chamber CH when the additional valve V2'' is closed.

[0102] In Figure 5, the control and management assembly 28 may be suitable for controlling the helium circulation in line 27 of the first helium supply unit 3 and the second helium supply unit 6. In this particular embodiment, the control unit 13 is linked to the control and management assembly 28 so that adjustment with measurements is possible. Needless to say, many other options are suitable for forming and controlling the first helium supply unit 3 and the second helium supply unit 6.

[0103] The second helium supply device 6 may include a gas-permeable wall containing a microporous and / or mesoporous membrane of silicone rubber (or optionally a porous glass material) suitable for diffusing helium toward the internal volume 10a.

[0104] The second helium supply unit 6 can be activated by a command from the control unit 13, depending on the results of calculations performed in the initial stage when a low vacuum is reached. Typically, the first derivative of the helium partial pressure in the detection region 10d is analyzed. If such a slope is too high or too low, the measurement is not considered reproducible. Here, helium injection by using the second helium supply unit 6 is performed when the analyzed / determined slope does not reflect the appropriate conditions for a reproducible measurement. Such analysis is performed when the helium partial pressure is low, as low as 4E-5mbar (see, for example, the slope on the left in Figures 3 and 4).

[0105] When the partial pressure of helium measured in the detection region 10d reaches the trigger point (meaning the noise is small enough to trigger the measurement stage), it is checked whether the first derivative of the partial pressure of helium is within a predetermined range between the lower and upper limits. Only if the slope observed in the leakage rate graph (e.g., Figure 3-4) is outside the appropriate range is a specific injection 18 (helium injection) performed by the second helium supply device 6. A calculation routine for detecting the need for injection 18 is performed in each test, which is interesting in some tests, as accurate results can be obtained quickly without injection 18 and without an additional waiting period until the partial pressure of helium decreases.

[0106] The following section describes several options for the preparation phase. These options are preferable to use only when the initial slope is determined to be outside the appropriate range (the situation in Figure 4).

[0107] Referring to Figure 1, the control unit 13 is configured to trigger the second helium supply unit 6 before the first helium supply unit 3, so that during the measurement cycle of a given bag 2 under test, valve V1 is activated after valve V2. The control unit 13 also triggers pumps, e.g., vacuum pumps P1 and P2, in a conventional manner if necessary. If pump P1 is activated to draw gas present in chamber CH (in step a / ), a waiting period T1' is usually required before initiating the filling step to inflate bag 2. In fact, it is usually necessary to wait for the stabilization period to end before proceeding with the test itself.

[0108] During this waiting period T1', as shown in Figure 4, valve V2 is opened when the helium partial pressure is sufficiently low, and as a result, helium injection 18 is carried out around bag 2. This is done well before the filling step (i.e., well before t0) in order to generate a reference drop.

[0109] Next, in the following step, the pressure drop in the intermediate space or internal volume 10a is compared to a predefined pressure drop threshold by a pressure measuring member 9 coupled to the control unit 13. This threshold is, for example, the pressure drop value of a bag 2 that has undergone integrity verification and is considered intact.

[0110] However, if the pressure drop PD is detected to be greater than the threshold (at the end of the normal period), the outer wall W is considered to have failed the integrity verification (bag 2 fails the test).

[0111] The measurement is optionally performed during the preparation phase and is used to determine the background value of the reference descent due to injection 18. Such options can be implemented in the case of a series of bags where pressure deviations cause problems in properly detecting leaks, and / or in situations where it is necessary to systematically find sub-micrometer-sized leaks that form pathways for specific bacteria.

[0112] The background value can be determined at the end of the reference drop (end of the peak) when the decrease in helium partial pressure is sufficiently low. Such background values ​​are interesting because they reflect the physical conditions of chamber CH around bag 2 and how helium is released under such conditions. In fact, such conditions show the profile of the helium leakage rate when the helium partial pressure in the internal volume 10a is increased instantaneously.

[0113] The testing phase can begin when the helium partial pressure level falls below a threshold. In some cases, the same or similar threshold may be used, e.g., 4.10. -5 When a value of mbar or less is used by the control unit 13, the second helium supply device 6 and the first second helium supply device 3 can be triggered only after the leakage rate reaches a predetermined threshold of such a threshold.

[0114] Measurements taken during the test phase reflect the end of the pressure loss PD profile. The analysis module 15 uses such measurements (helium partial pressure detected by the pressure measuring member 9) to generate information representing the change in the detected helium partial pressure over time. The analysis module 15 includes a comparison routine for detecting helium leakage based on such information. Typically, a reference result corresponding to a predefined threshold (predefined pressure drop threshold) is also used by the comparison routine.

[0115] In some embodiments, the reference result is a predefined pressure drop threshold obtained by calculating the time derivative of the helium leakage rate detected by the pressure measuring member in the detection region 10d. In a modified example, the reference result can be determined taking into account the duration of the pressure drop PD and compared with test results obtained at simultaneous or similar times reflecting the end of the peak / pressure drop.

[0116] More generally, it can be understood that analysis module 15 may be structured as follows: -When the suction mode is active, the information representing the partial pressure of helium detected by the pressure measuring member 9 after the addition of helium by the second helium supply device 6 is used for a period including the period following the filling step; and -Compare the test results with at least one reference result to determine whether the helium-filled flexible bag 2 has passed the integrity verification.

[0117] The analysis module 15 may include, or be part of, a control unit 13 configured as, for example, a computer unit, which includes a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), flash memory for storing backup data, an input interface, and an output interface. Typically, the control unit 13 is an electronic control unit (ECU) that electrically controls valves V1, V2, V3, and V5, for example, by including control and management members 28. The control and management members 28 may include control lines 28a that enable the activation and / or transmission of commands to the valves.

[0118] The ROM of the control unit 13 stores a program for operating the computer unit as the control unit 13. By using RAM as a workspace, the computer unit functions as the control unit 13 in this embodiment when the CPU executes the program stored in ROM. A mass spectrometer or similar pressure measuring device 9 for detecting gases within the housing 10 is connected to the input interface of the control unit 13 to provide data to the analysis module 15. Various control objects, including valves, are connected to the output interface of the control unit 13.

[0119] Referring to Figure 1, test system 1 may be a complete system comprising one or more sources 4 of pressurized tracer gas (here, helium or SF6), a housing 10, and the following modules: A helium mass spectrometer leak detector, comprising a mass spectrometer 9 designed to function as a pressure measuring member, and optionally an inlet interface 19 for communication between chamber CH and port 30, or a pipe for circulating gas toward the pressure measuring member 9. • A vacuum system coupled to the housing 10 to maintain a sufficiently low pressure within the mass spectrometer.

[0120] A vacuum pump, including a pump P2 for discharging the tested flexible bag 2 (typically step b / shown in Figures 3 and 4), another pump P3 for circulating helium toward the mass spectrometer forming the pressure measuring member 9 (if the mass spectrometer is located outside the chamber CH, as in the embodiment shown in Figure 1), and optionally a main pump P1 used to discharge the internal volume 10a around the bag 2. • Controlling individual steps of the measurement cycle, from discharge to testing and ventilation (the preparation and testing phases are part of such a measurement cycle), valves V1, V2, V3, V5.

[0121] • An electronic measurement and control system designed to function as a control unit 13. • Valves, circuits, etc. - Power supplies for individual components, In particular, the test product, in this case the fixing and positioning members (which may include a supply pipe 3, a fixing device 39, and two plates 12, 14) that connect the flexible bag 2 to the chamber CH of the housing 10.

[0122] Such a test system 1 is a complete system suitable for detecting leakage by simply continuously measuring the helium partial pressure and analyzing the change over time of the information representing such helium partial pressure by the analysis module 15 of the control unit 13, thereby detecting leakage from the outer wall W of bag 2.

[0123] The test method uses so-called tracer gas - helium, which is used to fill bag 2 placed in chamber CH, and the internal volume 10a around / outside bag 2 is connected to a detection assembly equipped with a pressure measuring member 9.

[0124] If helium rapidly leaks from the test bag 2 into the detection area 10d where the helium partial pressure is measured (and possibly displayed on the screen), the analysis module 15 will not be able to identify a significant pressure drop PD, which means that the detected helium is helium coming from the internal space SP through the hole in the bag 2. In fact, the permeability through the bag 2 (which typically has a plastic wall W with a thickness of 150 or 200 micrometers or more) allows helium to escape only after a minimum period that may be better than 4 seconds.

[0125] Referring to Figures 3-4 and 6, it can be seen that after time t0, which reflects the moment when helium is filled into bag 2 (in step c / , valve V1 opens and such filling becomes possible), there is a pressure drop PD even though the minimum period has not elapsed. The duration of the pressure drop PD can usually be considered to be shorter than the minimum period and substantially constant. In fact, in all experiments, the start and end of the pressure drop PD are substantially the same. The duration of the pressure drop PD is approximately 2.5 seconds or 2.6 seconds here, and not longer than 3 seconds, depending on the arrangement of the housing 10 and the type of detection means used in the test system 1.

[0126] During the first few seconds of the test, after helium is injected into bag 2, the flexible bag 2 expands, compressing the remaining air in the vacuum chamber CH outside bag 2 accordingly (i.e., the internal volume 10a decreases).

[0127] As a result, the partial residual helium pressure in chamber CH increases briefly due to continuous discharge before decreasing again. This is read by the mass spectrometer as an increase and subsequent decrease in leakage rate, which is usually called pressure loss PD; on the other hand, bag 2 is completely liquid-tight. In Figure 6, all bags 2 under test are completely liquid-tight, but there is no helium injection into the internal volume 10a. It can be seen that this creates an artifact (bump) that reduces the separation force to 1 / 1000 for leakage detection. The leakage rate curve 38 is an exemplary curve (worst case for bag 2, which should be identified as conforming to the test) that reflects a high deviation and causes a large loss of separation force.

[0128] In several tests, it was surprisingly found that when helium was injected by the second helium supply device 6, if suction was efficiently performed after such a particular injection, the curve 38 did not actually collide (or collided very little) (this means that the period during which the mass spectrometer measures the partial pressure of helium remaining in the vacuum chamber CH before the helium is filled into bag 2 is longer compared to the situation in which no helium has been specifically added to the internal volume 10a).

[0129] As a result, if there are only curves with a slow increase after the pressure drop period has elapsed, such as curve 50 in Figure 6 with a slow increase in leakage rate after the pressure drop PD, or curve 50' in Figure 6 with a relatively rapid increase in leakage rate after the pressure drop PD, the analysis module 15 can use a comparison with a pre-set reference result that reflects a state without leakage, for example, a reference result similar to the case of curve 50'. In fact, if the leakage rate is measured to be lower than or below an appropriate threshold, for example, at approximately 3.5 seconds after t0 (or within the time slot before or after that moment) 10 -7 When the helium level is mbar.L / sec, it can be efficiently concluded that the flexible bag 2, filled with helium, has passed the integrity verification.

[0130] In Figure 3-4, step d / corresponds to the period starting at t0 or immediately following, during which monitoring is performed based on measurements (measurements taken at least after t0) to analyze the pressure loss. The horizontal scale may be exaggerated in such steps d / to better illustrate the pressure drop PD. Step e / shows that after the end of the pressure drop PD in bag 2 under normal conditions without leakage (see curve 50 in particular), the helium partial pressure typically increases after some time.

[0131] Needless to say, the method for calculating the final leakage rate value may vary. For example, the analysis module 15 may first determine the turn-up points (down points) of curve 50, 50' as the pressure drop PD has elapsed, and then estimate whether the leakage rate level at such turn-up points is sufficiently low (below the acceptable standard / threshold). If no such turn-up points exist or are found to be higher than the acceptable threshold, it is concluded that the tested bag 2 has failed the test.

[0132] For the sake of convenience, the acceptable threshold is 2.00·10, at the discretion of the user. -8 mbar.Ls -1 It can be lower. The above method for verifying the integrity of bag 2 may include a preparation phase that is longer than the test phase, particularly due to the time required to have a low helium partial pressure before and after injection 18.

[0133] In the preparation phase, a bag 2 and a system 1 as described are provided, as shown in Figure 5. Bag 2 is empty (without biopharmaceutical fluid) and may initially be flat. The housing 10 has a single injection line 27 or similar connection, which is part of the first helium supply device 3, so that at time t0, pressurized gas, in this case helium, can be delivered to inflate the flexible bag 2. Prior to t0, the second helium supply device 6 has already been used to perform the injection 18, and bag 2 is already inside the housing 10 (the measurement cycle is started before the injection 18).

[0134] In some embodiments, the test system 1 uses a two-stage suction, i.e.: - The first stage in which the helium leakage rate measured around bag 2 under test reaches an initial (low) threshold (in this first stage, the initial removal of adsorbed helium becomes possible); and - Second stage after new helium injection 18: Remaining adsorbed helium and new helium are removed in order to reach a second (lower) threshold (or a second identical threshold). To implement this, it may include any suitable helium injection means.

[0135] This two-stage suction method favorably reduces the background noise deviation effect (background noise that may mask detected leaks), particularly the background during pressure drop following the filling step performed at the beginning of the test phase.

[0136] While the detailed embodiments described above typically illustrate the use of a pressurized helium 4 source containing helium of normal purity suitable for medical applications, the amount of helium injected around the flexible bag 2 may be increased, depending on the type of source used, and may be supplemented, depending on the gas mixture or helium of a different purity. Helium is preferable to use for many reasons. It is: • It is non-toxic, • It is inert and non-condensable, • Normally, it does not exist in the atmosphere, and only exists in trace amounts. • Due to its small atomic weight, even a very small leak can easily cause a flow. It is non-combustible.

[0137] This test method is suitable for detecting leaks of micrometer and submicrometer size, even in large-capacity bags 2. The housing 10 may be suitable for receiving bags having a capacity of at least 2L, and possibly close to 500 or 650L. In some embodiments, the bag 2 has a capacity ranging from 20 to 50L. In such cases, a single outer wall W can be provided to partition the internal space SP, which can be filled with a biopharmaceutical fluid.

[0138] Needless to say, the present invention is not limited to the embodiments described above, but is provided only as examples. It encompasses various modifications, alternative forms, and other variations that can be conceivable to those skilled in the art within the context of the present invention, in particular any combination of the various modes of operation described above that can be taken individually or in combination.

[0139] In particular, the flexible bag 2 may contain more than four plastic sheets for containing the biopharmaceutical fluid, and presumably, each additional sheet would enhance the integrity of bag 2 and prevent contamination of the biopharmaceutical fluid it contains.

Claims

1. A test system (1) for verifying the integrity of a flexible bag (2) using a gas tracer, wherein: - A housing (10) that separates a vacuum chamber (CH), wherein, in the operating configuration of the housing (10), the internal volume (10a) is liquid-tightly isolated from the outside of the housing (10), and the housing (10); - When the flexible bag (2) is placed in the vacuum chamber (CH) such that it is surrounded by an internal volume (10a), a first helium supply device (3) is provided with a supply pipe (3a) for filling the flexible bag (2) with helium in a filling step, via the outlet (3b) of the supply pipe (3a); - In suction mode, a vacuum suction assembly (P1, P3) is provided for performing vacuum suction and extracting gas from the internal volume (10a) outside the flexible bag (2); - At least one pressure measuring member (9) for detecting the partial pressure of helium in a detection region (10d) of the internal volume (10a), wherein the detection region (10d) is in communication with the suction inlets of the vacuum suction assemblies (P1, P3); - comprising at least one source (4) of pressurized helium intended to be introduced into a flexible bag (2); The test system (1) further includes the following: - A second helium supply device (6) for adding reference helium (18) into the external internal volume (10a) of the flexible bag (2): - Unlike the supply pipe (3a), - Communicating with the gas supply source, The second helium supply device (6), including the supply member (5); - A control unit (13) for controlling a first helium supply device (3) and a second helium supply device (6), wherein the control unit (13) is adapted to trigger the second helium supply device (6) before the first helium supply device (3); - The test system (1) further comprises an analysis module (15) that uses information representing the change over time of the partial pressure of helium detected by a pressure measuring member (9) before and after the filling step, and the analysis module (15) is configured to detect helium leakage based on the information.

2. The analysis module (15) is adapted to use information representing the change over time of the helium partial pressure detected by the pressure measuring member (9) after the filling step in order to obtain a test result representing the helium partial pressure drop (PD) in the detection region (10d), and the analysis module (15) is: - When the vacuum suction assemblies (P1, P3) are in suction mode, information representing the partial pressure of helium detected by the pressure measuring member (9) after the addition of helium by the second helium supply device (6) is used during the period including the period after the filling step; - When the vacuum suction assemblies (P1, P3) are in suction mode, before the filling step, a background value is identified based on information representing the partial pressure of helium detected by the pressure measuring member (9), and then the identified background value is subtracted from the raw measurement; and - The system according to claim 1, wherein the test results are configured to be compared with at least one reference result in order to determine whether the helium-filled flexible bag (2) has passed integrity verification.

3. The system according to claim 1 or 2, wherein a second helium supply device (6) includes a valve (V2'), preferably a solenoid valve, upstream of the supply member (5), and the supply member (5) has a gas-permeable wall for limiting the rate at which helium is added to the internal volume (10a).

4. The system according to claim 3, wherein the second helium supply device (6) includes an additional valve (V2''), preferably a solenoid valve, downstream of the supply member (5).

5. The control unit (13) - In the filling step, a first valve (V1) that allows the circulation of helium in the supply pipe (3); and - A second valve (V2; V2') that enables the circulation of helium within the supply member (5) The system according to claim 1 or 2, configured to control a

6. The system according to claim 3, 4, or 5, wherein the gas-permeable wall comprises a microporous and / or mesoporous membrane of silicone rubber or glass (32;32').

7. The system according to any one of claims 1 to 6, wherein the supply member (5) includes a silicone or glass tube (32) adapted to supply helium by diffusion through the silicone wall of the tube (32).

8. The system according to any one of claims 1 to 7, wherein at least one source of pressurized helium (4) is a helium source comprising a single tank outside of an internal volume (10a) for containing all the helium to be injected into a vacuum chamber (CH), the single tank being operably coupled to a first helium supply device (3) and a second helium supply device (6).

9. - Two plates (12, 14) that are spaced apart, preferably parallel; - A housing for receiving a flexible bag (2) between two plates (12, 14), wherein the plates form restraint plates for restraining the expansion of the flexible bag (2) when filled with helium during a filling step, the housing The system according to any one of claims 1 to 8, including the following.

10. A test method using a tracer gas to verify the integrity of a flexible bag (2) in order to detect the presence of possible pores, the following: - During the preparation phase: To provide a test system (1) that includes a housing (10) that separates a vacuum chamber (CH) adapted to be liquid-tightly isolated from the outside of the housing in the operating configuration of the housing; To provide an injection device suitable for supplying a tracer gas into a vacuum chamber, the tracer gas being preferably helium; The flexible bag (2) is placed inside the vacuum chamber (CH), and the port (11) of the bag is connected to a supply pipe that communicates with a source of inert tracer gas, preferably helium; Perform vacuum suction to obtain a vacuum outside the flexible bag (2) within the internal volume (10a) of the vacuum chamber (CH); Performing a reference gas tracer injection (18) by supplying a certain amount of tracer gas to the internal volume (10a) outside the flexible bag (2) using an injection device; -During the testing phase, while the vacuum suction is still being performed: In the filling step, a certain amount of tracer gas is filled into the flexible bag (2); By using at least one pressure measuring member (9), information representing the partial pressure of the tracer gas outside the flexible bag in the internal volume (10a) is detected, enabling the detection of this tracer gas escaping from the flexible bag; Next, in order to determine whether the flexible bag has passed the integrity verification, the next step is to compare the test results obtained using at least one pressure measuring member (9), which represent the tracer gas partial pressure drop (PD) in the internal volume (10a) outside the flexible bag (2), with at least one reference result. The test method, including the above.

11. The test method according to claim 10, wherein, during the testing phase, the comparison between the test result and the reference result is performed in a time slot that falls within 3 to 10 seconds from the start of the filling step.

12. The tracer gas is helium, and the test method, in the preparation stage: - To empty the internal space (SP) of the flexible bag (2), perform vacuum suction inside the flexible bag (2); - Measure the partial pressure of helium in the detection region (10d) of the internal volume (10a); - Calculate the first derivative of the helium partial pressure in the detection region (10d); It further includes, The test method according to claim 10 or 11, wherein when the helium partial pressure measured in the detection region (10d) reaches a trigger point, it is checked whether the first derivative of the helium partial pressure is within a predetermined range between a lower limit and an upper limit, and the injection (18) is performed by the injection device only if the first derivative of the helium partial pressure is outside the predetermined range.

13. The test method according to claim 10, 11, or 12, wherein the gas tracer is helium, and in the preparation stage, after the partial pressure of helium is measured in an internal volume (10a) below a predetermined threshold, a certain amount of helium is supplied into the internal volume (10a) outside the flexible bag (2).

14. The gas tracer is helium, and the reference result is: - A predefined pressure at a given time after the start of the filling step, or The test method according to claim 10, 11, 12, or 13, wherein a predefined pressure drop threshold is obtained at a given time after the start of the filling step by calculating the time derivative of the helium leakage rate detected by at least one pressure measuring member (9) in a detection region (10d) of the internal volume (10a).

15. The test method according to claim 10, 11, 12, 13 or 14, wherein the filling step is performed to hold the flexible bag (2) between two expansion limiting plates (12, 14) that are spaced apart from each other and are suitable not to interfere with leakage in the walls (W) of the flexible bag (2) positioned relative to them.

16. The flexible bag (2) constitutes or is part of a device under test intended to receive a biopharmaceutical, and comprises several flexible pipes (7, 9a, 9b), each connected to a respective port (11, 12a, 12b) of the device under test, the device under test being placed in a chamber (CH) before vacuum aspiration is performed. The test method according to claim 10, 11, 12, 13, 14 or 15, wherein performing vacuum suction in the preparation stage means removing gas in different suction areas of the housing (10) in order to obtain a vacuum inside and outside the flexible bag (2) inside the housing (10).

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