Apparatus, system and method for foam detection using stereoscopic imaging

Abstract

A bioreactor system includes a housing configured to receive and support a container, a stereoscopic imaging device having first and second imagers secured to the housing, the stereoscopic imaging device configured to image surfaces of foam and liquid exposed to a headspace of the container. The system also includes a controller operatively connected to the stereoscopic photographing device, and the stereoscopic photographing device and the controller are configured to create an image of the exposed surface and identify foam on the surface based on the image.

Description

Technical Field

[0001] Embodiments of the present invention relate generally to bioprocessing apparatus, systems and methods, and more particularly to observing and analyzing fluids in bioreactors using stereoscopic imaging to detect foam. Background Art

[0002] Bioreactors are often used to perform biochemical and / or biological processes and / or manipulate fluids and other products of such processes. Such bioreactors typically include a flexible or collapsible, single-use, disposable bag supported by an external rigid structure such as a stainless steel shell or frame. The bag is made of a thin, flexible plastic film and is located within a rigid shell and filled with the desired fluid for processing.

[0003] Growing biological material (such as mammalian cells, bacteria or yeast) in a bioreactor often results in the generation of an unwanted foam layer that floats on top of the fluid in the bioreactor, for example in the headspace of a bioreactor bag. This foam layer is the result of several factors, including the addition of pressurized air to maintain aerobic microorganisms, nutrients and growth factors present in the liquid growth medium, and waste products generated by the microorganisms. Over time, this foam layer can become unacceptably thick and, if not addressed, can potentially contaminate the exhaust ports and filters of the bioreactor, preventing CO from escaping and escaping. 2 The foam also forms a barrier to liquid injection from above the flow in the bioreactor and is problematic even at low fluid volume levels.

[0004] In order to reduce the foam layer to a reasonable thickness, chemical solutions such as defoaming compounds are usually employed. With such compounds, several applications may be required during a single production run to ensure effectiveness. Conversely, too much defoaming compound may be harmful to the biomaterial in the reactor. Mechanical solutions also exist, such as thermal probes and defoamers, however, they are more effective in reducing the amount of existing foam rather than inhibiting foam formation.

[0005] In view of the above, accurate detection and monitoring of foam in bioreactor bags is important for determining when intervention is necessary. While foam detection solutions exist, they only detect foam levels in small areas, or in some instances, at a single point in a bioreactor bag, rather than evaluating the entirety of the exposed fluid surface in the bag. Furthermore, it has been found that many such systems are generally only effective for the detection of extreme foam events, in which the structure of the biological material or the bag itself may have been compromised. Known solutions are also relatively large and expensive and do not provide for ensuring, for example, that the required amount of antifoam compound is applied in response to the actual foam level in the bag, and do not have the ability to quantify the amount of foam present.

[0006] In view of the above, a need exists for an apparatus and system for viewing fluids in a bioreactor bag that provides improved detection, monitoring, and mitigation of foam in the bag. Summary of the invention

[0007] Certain embodiments comparable in scope to the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed subject matter, but rather these embodiments are intended only to provide an overview of possible embodiments. In fact, the present disclosure may include various forms that may be similar or different from the embodiments set forth below.

[0008] In an embodiment, a foam identification system includes a stereo camera having first and second imagers configured to image the surface of foam and liquid in a container exposed to a headspace of the container. The system also includes a controller operatively connected to the stereo camera, and the stereo camera and the controller are configured to create an image of the exposed surface and identify foam on the surface based on the image.

[0009] In another embodiment, a bioreactor system includes a housing configured to house and support a container, a stereo camera having first and second imagers secured to the housing, the stereo camera configured to image a surface of foam and liquid exposed to a headspace of the container. The system also includes a controller operatively connected to the stereo camera, and the stereo camera and the controller are configured to create an image of the exposed surface and identify foam on the surface based on the image.

[0010] In yet another embodiment, a method for identifying foam on a surface of liquid in a container includes the steps of generating an image of a surface of liquid exposed to a headspace of the container via a stereoscopic imaging capture device having first and second imagers, and identifying foam on the exposed surface based on the image. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be better understood from reading the following description of non-limiting embodiments with reference to the accompanying drawings, of which the following are:

[0012] Figure 1 is a front view of a bioreactor system suitable for use with a foam identification system according to an embodiment of the present invention.

[0013] Figure 2 is a simplified diagram of a foam identification system according to an embodiment of the present invention.

[0014] Figure 3 is a perspective view of a stereoscopic imaging camera according to an embodiment of the present invention.

[0015] Figure 4 is a simplified schematic diagram illustrating the operation of a stereoscopic imaging camera according to an embodiment of the present invention.

[0016] Figure 5 is an exemplary depth image of foam (rendered without color) created in accordance with an embodiment of the present invention.

[0017] Figure 6 is an exemplary RGB image of foam (reproduced without color) created according to an embodiment of the present invention.

[0018] Figure 7 is a side cross-sectional view of a portion of a container wall configured for use with embodiments of the present invention.

[0019] Figure 8 is a side cross-sectional view of a viewport of a container configured for use with embodiments of the present invention.

[0020] Fig. 9 is an isometric view of an air curtain configured for use with embodiments of the present invention.

[0021] Fig.10 is a simplified diagram of a foam identification system in combination with an air curtain according to an embodiment of the present invention.

[0022] Fig.11 is a side view of a foam identification system according to an alternative embodiment of the present invention.

[0023] Fig.12 is a top view of a foam identification system according to an alternative embodiment of the present invention.

[0024] Fig.13 yes Fig.10 Side view of the foam identification system. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts.

[0026] As used herein, the terms "flexible" or "foldable" refer to structures or materials that are pliable or capable of bending without breaking, and may also refer to compressible or expandable materials. An example of a flexible structure is a bag formed from a polyethylene film. The terms "rigid" and "semi-rigid" are used interchangeably herein to describe a "non-foldable" structure, that is, a structure that does not fold, fold, or otherwise deform to significantly reduce its extended dimension under normal forces. Depending on the context, "semi-rigid" may also refer to a structure that is more flexible than a "rigid" element, for example, a bendable tube or conduit, but still a structure that does not fold longitudinally under normal conditions and forces.

[0027] The term "container" as used herein means a flexible bag, a flexible vessel, a semi-rigid vessel, or a rigid vessel, as appropriate. The term "container" as used herein is intended to include bioreactor containers having flexible or semi-rigid walls or portions of walls, disposable flexible bags, and other vessels or conduits typically used in biological or biochemical processes, including, for example, cell culture / purification systems, fermentation systems, mixing systems, media / buffer preparation systems, and filtration / purification systems.

[0028] As used herein, the term "bag" means a flexible or semi-rigid vessel or container that is used, for example, as a bioreactor or mixer for the contents therein. Although embodiments of the present invention are described for use with bioprocessing bags, including but not limited to bioreactor bags and mixer bags, embodiments may also be configured for use with other bags or containers. Similarly, embodiments may be used to image, assess, and mitigate / treat other characteristics or conditions in addition to the accumulation of foam in a bioreactor.

[0029] Furthermore, while embodiments are described in conjunction with single-use stirred tank bioreactors and bioreactor systems, they are not limited thereto and may be used with a variety of containers and associated equipment used in biological or biochemical processes. Furthermore, embodiments may be suitable for use in identifying foam in other non-biological / biochemical contexts. Certain embodiments may be useful in detecting other non-foam related conditions or events on a surface that may be identified via stereoscopic imaging as described herein.

[0030] refer to Figure 1, a bioreactor system 10 suitable for use with embodiments of the present invention is illustrated. The bioreactor system 10 includes a generally rigid bioreactor housing 12 mounted on top of a frame 14. The rigid housing 12 can be formed of, for example, stainless steel, polymers, composites, glass, or other metals, and can be cylindrical in shape, although other shapes can also be utilized without departing from the broader aspects of the present invention. As will be appreciated, the housing is configured to house and support a container, such as a bioreactor bag 15. In certain embodiments, the housing 12 can be a substantially rectangular mixer housing.

[0031] As shown, a disposable flexible bioreactor bag 15 is disposed within the housing 12. As mentioned, the housing 12 can be of any size (or shape) as long as it is capable of supporting a container such as a disposable flexible bioprocessing bag 15. For example, according to one embodiment, the housing 12 is capable of accepting and supporting a 10-2000L flexible or collapsible bioprocessing bag.

[0032] The bioreactor system 10 also includes a support structure 18 to which various devices utilized in the biochemical and / or biological process are attached. The support structure 18 may also be used to lift the bag 15 and hold it in place within the housing 12. The support structure 18 is shown as having a plurality of legs 19, but other configurations may be employed.

[0033] The housing 12 includes an opening or aperture 20 wherein, among other things, a temperature probe 24 may be inserted into a thermowell or port in the vessel 15 and then coupled via, for example, a cable to an instrument tower 22. As will be appreciated, the temperature probe 24 provides the temperature of the fluid in the vessel 15.

[0034] Reference now Figure 2 , depicting a foam identification system 100 according to an embodiment of the present invention. As shown, the foam identification system 100 includes a stereoscopic imaging camera 220 and a controller 130 operatively connected to the stereoscopic imaging camera 220. In an embodiment, the stereoscopic imaging camera 220 is fixed to the support structure 18 ( Figure 1 ). As described in more detail below, the stereoscopic imaging camera 220 images the surface 142 of the liquid 144 in the container (e.g., bag) 15. In particular, the camera 220 images the surface 142 exposed to the head space 146 of the container 15. The head space 146 is the volume within the container 140 that is not occupied by the liquid 144 or the foam 148. The head space 146 includes a gas 147, such as air, retained within the container 15, which is in contact with the exposed surface 142 of the liquid 144.

[0035] In an embodiment, the stereoscopic imaging camera 220 uses visible wavelengths (380nm to 700nm) to image and calculate foam depth without requiring illumination. In certain embodiments including an infrared projector, as discussed in more detail below, the camera 220 may include a sensor that measures infrared wavelengths up to about 865nm.

[0036] Notably, the stereoscopic imaging camera 220 sees a wide field of view V as opposed to a point source, which is important due to the unpredictable nature of foam accumulation. In embodiments, the field of view V is substantially the entirety of the exposed surface 142. In certain embodiments, the stereoscopic imaging camera 220 may utilize a wide angle lens and may include autofocus functionality. In embodiments, the camera 220 may image from a viewing angle / field of view of about 70° to about 120°.

[0037] Reference now Figure 3 , the stereoscopic imaging camera 220 includes a first sensor / imager 222 (e.g., a right imager) and a second sensor / imager 224 (e.g., a left imager). The two sensors 222, 224 are located on the same plane and are separated by a distance D, so that the object distance perpendicular to the plane is the same distance for the two sensors 222, 224. The stereoscopic imaging camera 220 captures two images, a left image L and a right image R. Since the distance S between the sensors is known, a comparison of the left image L and the right image R can provide depth information. In particular, the imagers 222, 224 send data to a processor, which can be inside or outside the camera 220. The processor in turn calculates a depth value for each pixel in the image by the principle of parallax, for example, evaluating a point from the right image R to the left image L (e.g., Figure 4 The disparity between points 1 and 2 depicted in FIG.

[0038] The stereo imaging camera 220 then outputs a depth image where each pixel has an associated depth (distance from a parallel plane of the imager). Figure 5 An example of a depth image is shown at Figure 5 , but the depth image is colored, where each color represents the depth from the camera 220. As will be appreciated, various colors can be used to represent different depths.

[0039] In an embodiment, the camera 220 also includes an RGB module 228, which, as will be appreciated, can capture RGB data and output an RGB image. Figure 6An exemplary RGB image (decolorized) is shown at . The RGB image can be used to supplement the depth data. In particular, the RGB image can be used to determine the percentage of the surface 142 that contains foam and / or the density of the foam present. The image can be manually inspected by an operator to assess / mitigate foam, or the RGB image can be output to a controller that automates foam assessment / mitigation via machine learning, etc. In an embodiment, the camera 220 can also output a single file with pixels having all four values ​​(RGBD).

[0040] Camera 220 may also output stereoscopic image data in a format that also includes color image data (pixel location, RGBD data, and intensity data). This data may be used to assess the percentage of surface 142 that contains foam and / or the density of foam present.

[0041] In some embodiments, camera 220 may also include infrared projector 226. While stereo cameras generally have good low light sensitivity and do not require supplemental ambient lighting, in some cases, such as when imaging scenes or objects with low texture or visual detail (e.g., smooth surfaces), infrared light may be used to illuminate the object to collect depth data.

[0042] In an embodiment, the camera 220 can be USB powered, although other power supply mechanisms are possible without departing from the scope of the invention. In some embodiments, the camera 220 can be fixed in a reinforced housing that can be waterproof and / or padded to protect the camera 220.

[0043] As will be appreciated, embodiments of the present invention are useful in determining when chemical or mechanical defoaming should occur, the amount of defoaming required given the amount / rate of foam formation, and the efficacy of the defoaming treatment. In other words, for example, if the distance (i.e., depth) of the foam to the camera 220 exceeds a certain minimum or threshold, defoaming can be automatically initiated.

[0044] Reference now Figure 2 and Figure 8 In an embodiment, the foam identification system 100 includes a container 15 having a viewport 50 that allows the stereoscopic imaging camera 220 to image the exposed surface 142 of the liquid 144. In some embodiments, the viewport 50 may be heated to reduce condensation, or may be equipped with an air curtain, as described in more detail below.

[0045] In an embodiment, the container 15 has a multilayer film construction including an innermost layer of a wetting material 200 (e.g., polyethylene) in contact with the liquid in the container. The viewport 50 can be formed on or combined with the wetting material 200. In certain embodiments, the viewport 50 is made of low-density polyethylene (LDPE), which is a material that has been found to have excellent transmittance within the spectral range of interest (e.g., 380nm-900nm). As will be appreciated, the thickness of the viewport 50 can vary depending on material properties. Without departing from the scope of the present invention, other materials with the necessary transmittance can be utilized. In certain embodiments, polypropylene and polystyrene can be utilized.

[0046] In some embodiments, the viewport 50 may be a single or multiple layers of the same material as the container 15 itself. In other words, the container 15 may not have a dedicated viewport having a configuration that faces away from the viewport of the container 15. For example, a 15 to 20 mil thick LDPE sheet may provide suitable transmittance and structure for such an embodiment. In still other embodiments, the port 50 may be an internal wetted material 200 layer and may be formed by simply removing a layer that is on top of the wetted material 200.

[0047] In some embodiments, the viewport 50 is circular and is substantially wider / larger in diameter than the lens of the stereoscopic imaging camera 220. Other viewport 50 sizes and shapes may be employed without departing from the invention.

[0048] As mentioned above, the stereoscopic imaging camera 220 may be mounted on the support structure 18 so that it is located above the container 15 and aimed vertically downward so that substantially the entirety of the exposed surface 142 can be imaged. In this regard, the viewport 50 may be located on the upper or top surface of the container 15. As will be appreciated, the viewport 50 may be in a variety of locations as long as substantially the entirety of the exposed surface 142 can be imaged.

[0049] In one embodiment, the foam identification system 100 includes an air curtain 52, such as Fig. 9 and Fig.10 . The air curtain 52 reduces container condensation to facilitate stereoscopic imaging of the exposed surface 142. In an embodiment, the air curtain 52 is located within the container (e.g., bag) 15 and is aimed at the viewport 50 or other optically clear viewing area of ​​the container 15. The air curtain 52 can be removable or fixedly attached to the wall of the container 15 and can utilize gas (e.g., air, O) from the existing head-sweep gas flow of the mass flow controller 180. 2 or N 2As will be appreciated, in embodiments where the air curtain 52 utilizes existing airflow, no additional hardware is required, only that the air curtain 52 be added to the vessel 15. Furthermore, the existing head purge airflow provides a supply of gas with a very low dew point (less than -40°C) that is ideal for condensate prevention.

[0050] Specific reference Fig. 9 , the exemplary air curtain 52 includes a nozzle or outlet portion 53 and a threaded base portion 55 through which the gas / air flow is directed. The threaded base portion 55 can be directly attached to the mass flow controller 180 ( Fig.10 ) or otherwise connected to the mass flow controller 180 fluid.

[0051] In use, the air curtain 52 directs the gas / air flow F toward the viewport 50 to clear the condensate area. In certain embodiments, the air curtain 52 may be selectively positionable so that the gas flow F may be directed by an operator to maximize condensate removal. Additionally, the velocity of the gas / air flow F may vary depending on the moisture content of the air in the headspace, the air temperature in the headspace, or other variables. In this regard, the air curtain 52 may be paired with a sensor or meter to measure moisture content, etc.

[0052] As will be appreciated, the air curtain 52 may be used to clear a portion of the condensate from the container / bag for purposes other than imaging, such as for various external optical measurements.

[0053] In certain other embodiments, an air knife may be employed, although additional pressurized air and flow control may be required in such a configuration.

[0054] Reference now Figure 11-13 , alternative arrangements of stereo cameras may be employed. In one embodiment, the stereo imaging camera 220 may be positioned so that it images one side of the headspace of the container 15. Such an arrangement may be suitable for containers (e.g., bags) made entirely of materials that are substantially transparent within the spectral range of the camera 220, or containers with side viewports.

[0055] In another embodiment, the system may include a plurality of stereo imaging cameras 220 spaced around the periphery of the container 15 and aimed at the headspace. In certain embodiments, one or more stereo cameras may be built into the rigid bioreactor housing 12. In still other embodiments, the stereo cameras may be integrated into the container / bag itself. In an embodiment, where one or more cameras are built into the container / bag, a lower resolution stereo imaging camera may be used to reduce costs.

[0056] In use, the system 100 identifies the presence and / or amount of foam 148 on the surface 142 of the liquid 144 exposed to the headspace 146 in several ways. In one embodiment, the system 100 detects the difference between the depth of the surface 142 without foam and the depth measurement during use of the container / reactor, which indicates a potentially problematic foam level. In other embodiments, the rate of change of depth can be evaluated via multiple measurements by the stereo imaging camera 220.

[0057] A method for identifying foam 148 on a surface of a liquid 144 in a container 15 is provided. The method includes obtaining a depth measurement D of a surface 142 of the liquid 144 via a stereoscopic imaging camera 220 and then obtaining at least one depth measurement D' of the surface 142 to detect a change in depth of the exposed surface 142 of the liquid 144, and identifying foam 148 on the exposed surface 142 based on the detected depth change, in the absence of foam 148 in the container 15. In some embodiments, the depth measurement D is compared to a separately calculated fluid volume calculation (e.g., independently measuring the height of the surface of the liquid 144). This can be performed to ensure that the surface 142 of the liquid 144 is accurately measured when no foam is present. In one example, the volume, and therefore the depth D, is calculated based on the measured mass of the container 15 and the liquid 144 and the size of the container 15. In this way, when no foam is present, erroneous measurements are made by the stereoscopic imaging camera 220 (e.g., to mitigate issues with imaging featureless surfaces (no foam)).

[0058] In yet another embodiment, the step of identifying the foam 148 on the exposed surface 142 includes obtaining multiple depth measurements of a set area on the exposed surface 142 of, for example, the liquid 144, determining a rate of change of depth of the area on the exposed surface 142 based on the multiple depth measurements of the exposed surface 142, and identifying the presence and / or amount of foam 148 on the surface of the liquid 144 by comparing the rate of change of depth to a predetermined value indicative of foam.

[0059] In one embodiment, the method of identifying foam 148 also includes mitigating the detected foam 148 on the exposed surface 142 of the liquid 144 , for example, by applying a defoaming agent into the container 15 .

[0060] In an embodiment, the method of identifying the bubble 148 further includes removing condensation from the viewport 50 of the container 15 via an anti-condensation system (eg, air curtain 52 , etc.) to facilitate identifying the bubble 148 by the stereoscopic imaging camera 220 .

[0061] In some embodiments, in addition to chemical defoamers, the foam identification system 100 provides defoamer injection feedback by analyzing the amount of foam during and after using mechanical or gas solutions. The stereo imaging camera 220 provides data quantifying the input of defoamers and / or the response of the foam 148 to the defoamers.

[0062] As used herein, the element or step recorded in singular form and beginning with the word "one" or "an" should be understood as not excluding a plurality of said elements or steps, unless such exclusion is explicitly stated. In addition, the reference to "one embodiment" of the present invention is not intended to be interpreted as excluding the existence of additional embodiments also in conjunction with the recorded features. In addition, unless explicitly stated to the contrary, the embodiment of "including", "comprising" or "having" an element or multiple elements with a specific attribute may include additional such elements without that attribute.

[0063] This written description uses examples, including the best mode, to disclose several embodiments of the invention, and also enables one of ordinary skill in the art to practice embodiments of the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to one of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if such other examples include equivalent structural elements that have insubstantial differences from the literal language of the claims.

Claims

1. A bioreactor system comprising: a housing configured to receive and support the container; a stereo camera secured to the housing, the stereo camera having first and second imagers, the stereo camera configured to image the surface of the foam and liquid exposed to the headspace of the container; a controller operatively connected to the stereo camera; as well as The stereo camera and the controller are configured to create an image of the exposed surface and identify foam on the surface based on the image.

2. The bioreactor system according to claim 1, wherein: The image of the exposed surface is a depth image.

3. The bioreactor system according to claim 1, wherein: The stereoscopic camera device further includes an RGB module, and the image is an RGB image.

4. The bioreactor system according to claim 3, wherein: The image is a composite depth and RGB image.

5. The bioreactor system according to claim 1, wherein: The stereo camera also includes an infrared projector to facilitate depth imaging of surfaces with low texture or visual detail.

6. The bioreactor system according to claim 5, wherein: The stereo camera detects light having a wavelength from about 400 nm to about 865 nm.

7. The bioreactor system according to claim 1, wherein: The stereo camera has a field of view from about 70° to about 120°.

8. The bioreactor system according to claim 1, wherein: The stereo camera provides data quantifying the input of an anti-foaming agent and / or the response of the foam to the anti-foaming agent.

9. The bioreactor system of claim 1, further comprising: A container having a viewport configured to allow the stereo camera to image the exposed surface.

10. The bioreactor system according to claim 9, wherein: The viewport is heated to reduce condensation.

11. The bioreactor system of claim 1 , further comprising: An air curtain is configured to reduce container condensation to facilitate imaging of the exposed surface.

12. The bioreactor system of claim 11, further comprising the container; and The air curtain is located inside the container.

13. The bioreactor system according to claim 1, wherein: The camera is mounted on the support structure of the housing so that it is located above the container and is aimed vertically downward so that substantially the entirety of the exposed surface can be imaged.

14. The bioreactor system according to claim 1, wherein: The container is a collapsible bioreactor bag.

15. A method of identifying foam on the surface of a liquid in a container, comprising the steps of: generating an image of a surface of liquid exposed to a headspace of the container via a stereoscopic imaging camera having first and second imagers; Foam is identified on the exposed surface based on the image.

16. The method according to claim 15, wherein: The image of the exposed surface is a depth image.

17. The method according to claim 16, wherein: The steps of identifying foam on the exposed surface include: A first depth image of the surface of the liquid without foam is compared to a second depth image of the surface to determine if the depth has changed.

18. The method according to claim 16, wherein: The steps of identifying foam on the exposed surface include: obtaining a plurality of depth images of the exposed surface of the liquid, determining a rate of change of depth across the exposed surface from the plurality of depth images of the exposed surface, and The presence and / or amount of foam on the surface is identified by comparing the rate of change of depth to a predetermined value indicative of foam.

19. The method according to claim 15, wherein: The stereoscopic camera device further includes an RGB module, and the image is an RGB image.

20. The method according to claim 19, wherein: The image is a composite depth and RGB image.

21. The method according to claim 15, wherein: The stereo camera also includes an infrared projector to facilitate depth imaging of surfaces with low texture or visual detail.

22. The method of claim 15, further comprising providing data quantifying input of an anti-foaming agent and / or the response of the foam to the anti-foaming agent.

23. The method according to claim 15, further comprising the steps of: Foam detected on the exposed surface of the liquid is mitigated.

24. The method according to claim 15, further comprising the steps of: Condensate is removed from the container via a condensate prevention system to facilitate identification of foam by the stereo camera.

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