Patent Publication Number: US-2023151320-A1

Title: Optical cell culture monitoring and analyte measuring system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/US2018/049459 filed on Sep. 5, 2018, which claims the benefit of priority to U.S. Provisional Application Serial No. 62/555,338 filed on Sep. 7, 2017, both applications being incorporated herein by reference. 
    
    
     BACKGROUND 
     The following relates generally to cell culture monitoring, and more specifically to a non-invasive monitoring system designed to take measurements in an adherent cell vessel. 
     Cell cultures are widely used to provide an artificial environment for cell growth. In some cases, a stacked cell culture vessel may provide an increased area for cell growth over single layer dishes. Cells may grow in suspension or attached to a cell culture vessel surface. The processing of cell cultures includes two principal activities, monitoring cell growth and health (confluence and morphology) and ensuring a suitable environment for cell growth (e.g., pH, glucose, and lactate levels). Production cost of cell cultures is extremely high due to low yield, high labor cost, intensive manual work flow, and costly clean room environments where processing is often performed. Monitoring methods of cell cultures are a significant factor for increasing yield and decreasing costs. 
     Current methods for both viewing cells and measuring analytes can be time consuming and require direct access to the vessel, which risks breaking the sterility of the vessel’s environment. Scientists often utilize the naked eye or microscopes to view the confluence of cells. Unfortunately, these methods require direct access to the vessel, which often slows or stops cell growth. Moreover, direct access methods make it difficult or impossible to automate the process. For example, when a stacked cell culture vessel is used, only the exterior layers or near-exterior layers can be monitored, and the status of the interior layers must be estimated without direct measurements. 
     Cell culture processing is presently monitored (e.g., the presence of certain analytes) through invasive and semi-invasive methods which utilize components such as probe sensors or patches. These methods require some type of contact with the invasive or semi-invasive components within the cell growth environment even though it is desired to allow the systems to operate as a closed system. Monitoring methods are often insufficient and production environments rely on process development techniques for timing the feeding and harvest of cells, which still require manual monitoring. 
     A closed system with non-invasive monitoring may allow for use of automation to better control cell culture media compositions and cell growth and health. Closed systems can maintain sterility throughout growth, which reduces the requirements and cost of a clean room. Further, real-time monitoring data may be transmitted to a user in a remote location, which can reduce the need of manual labor. 
     SUMMARY 
     The described techniques relate to improved methods, systems, devices, or apparatuses that support non-invasive monitoring of cell cultures. Generally, the described techniques provide for closed-system operation of an adherent cell culture vessel with a monitoring layer external to cell growth layers. The monitoring layer may include a confluence monitor and an analyte monitor. Cell status may be transmitted from the monitoring layer to a user in a remote location. The monitoring layer may be positioned between cell growth layers within a stacked cell culture vessel, and take measurements of the interior layers of the stack. The closed system remains sterile and able to continuously grow cells, for example by remaining in an incubator, while taking real-time cell status data. 
     A remote monitoring system for non-invasive measurement of a cell culture is described. The system may include a cell culture vessel including at least one cell culture chamber configured for cell growth and for closed-system operation, the at least one cell culture chamber having at least one surface to which cells adhere, at least one monitoring layer including at least one measurement device, wherein the monitoring layer is external to the at least one cell culture chamber, and a communication component configured to transmit data from the monitoring layer to a remote location. 
     A method for non-invasive measurement of cell cultures is described. The method may include positioning an external monitoring layer between two or more cell culture chambers of a cell culture vessel configured for closed-system operation, the two or more cell culture chambers having at least one surface each to which cells adhere, measuring cell status of the two or more cell culture chambers while allowing continuous cell growth, and transmitting cell status data from the external monitoring layer to a remote location. 
     In some examples of the system and method described above, the monitoring layer is positioned between two or more cell culture chambers and is configured for inter-layer monitoring. In some cases, the monitoring layer may include at least two measurement devices and may be configured to measure both the cell culture chamber above and below the monitoring layer simultaneously. 
     In some examples of the system and method described above, the at least one measurement device includes one or both of a confluence monitor or an analyte monitor. 
     In some examples of the system and method described above, the confluence monitor includes an optical device configured to capture an image of at least one cell culture chamber. In one example, the optical device includes: at least one lens, a mirror, a camera, and the communication component. In another example, the optical device includes: a fiber probes, a mirror, a camera, and the communication component. 
     In some examples of the system and method described above, the analyte monitor includes a spectral element configured to emit excited light and capture emission light from a media layer within the cell culture chamber. In some cases, the spectral element includes: a light gate, a diffraction grating, a lens, a detector, and the communication component. In some examples of the system and method described above, the spectral element is configured to perform Raman spectroscopy on the media layer. 
     In some examples of the system and method described above, the monitoring layer comprises polystyrene. In some examples of the system and method described above, the at least one measurement device is removable from the monitoring layer. 
     In some examples of the system and method described above, the communication component is configured to transmit the data in real time or on demand. 
     Some examples of the system and method described above may further include processes, features, or means for measuring at least one cell culture chamber above the monitoring layer and at least one cell culture chamber below the monitoring layer simultaneously. 
     In some examples of the system and method described above, measuring the at least one cell culture chamber above the monitoring layer includes taking a confluence measurement of cells, and measuring the at least one cell culture chamber below the monitoring layer includes taking an analyte measurement of media. 
     In some examples of the system and method described above, transmitting cell status data is in real-time. In some examples of the system and method described above, transmitting cell status data is on a wireless network. 
     In some examples of the system and method described above, positioning the external monitoring layer includes positioning one or more measurement devices in the monitoring layer. In some cases, positioning the external monitoring layer further includes positioning the one or more measurement devices at different points on the monitoring layer. 
     Further scope of the applicability of the described methods and systems will become apparent from the following detailed description, claims, and drawings. The detailed description and specific examples are given by way of illustration only, since various changes and modifications within the spirit and scope of the description will become apparent to those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label. 
         FIG.  1    illustrates a perspective view of an example of a system for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. 
         FIG.  2    illustrates a perspective view of an example of a stacked cell culture vessel system for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. 
         FIG.  3    illustrates a perspective view of an example of a monitoring layer that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. 
         FIG.  4    illustrates a side view of an example of a confluence monitor that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. 
         FIG.  5    illustrates a side view of an example of an analyte monitor that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. 
         FIG.  6    illustrates a side view of an example of another analyte monitor that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. 
         FIG.  7    illustrates a top view of an example of a monitoring layer that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. 
         FIG.  8    illustrates a side view of an example of a system for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. 
         FIG.  9    illustrates a method for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. The endpoints of all ranges reciting the same characteristic are independently combinable and inclusive of the recited endpoint. All references are incorporated herein by reference. 
     As used herein, “have,” “having,” “include,” “including,” “comprise,” “comprising” or the like are used in their open ended sense, and generally mean “including, but not limited to.” 
     All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure. 
     The present disclosure is described below, at first generally, then in detail on the basis of several exemplary embodiments. The features shown in combination with one another in the individual exemplary embodiments do not all have to be realized. In particular, individual features may also be omitted or combined in some other way with other features shown of the same exemplary embodiment or else of other exemplary embodiments. 
     In practice, cell culture systems that allow for certain measurements to be completed in real time without disturbing the cells, or in other words, a closed system, may facilitate maintaining a sterile cell growth environment. For example, a monitoring system that is external to a cell culture chamber may provide a non-invasive method for measuring cell status, such as cell growth and health, without directly contacting the cells and without contaminating the growth environment. As used herein, the term “closed system” refers to a system wherein the contents of the system are not open to the surrounding atmosphere. The system may include a closure apparatus, such as a cap, which limits or prevents the introduction of contaminants from the surrounding atmosphere. The system may be, but is not necessarily, sealed to ensure sterility of the contents of the system. 
     As described herein, a cell culture vessel may include a monitoring layer including at least one of optical technology (e.g., micro lens arrays and waveguides) and spectral analytical technology integrated into any of the walls of the cell culture vessel. As will be described in more detail below, according to embodiments of the present disclosure, a monitoring layer including one of optical technology and spectral analytical technology may be integrated into one of the walls of the cell culture vessel, and the other of optical technology and spectral analytical technology may be integrated into another of the walls of the cell culture vessel. The cell culture vessels described herein may be an adherent cell culture vessel generally including a planar surface on which cells adhere while being cultivated. 
     Alternatively, the monitoring layer as described herein may include a tray positioned external to the cell culture vessel, the tray including at least one of optical technology and spectral analytical technology. As will be described in more detail below, according to embodiments of the present disclosure, a first tray including one of optical technology and spectral analytical technology may be positioned one of above or below the cell culture vessel, and a second tray including the other of optical technology and spectral analytical technology may be positioned at the other of above or below of the cell culture vessel. According to embodiments of the present disclosure, a monitoring layer may be inserted between, but external to, cell growth layers in a stacked vessel utilizing optical technology and spectral analytical technology. This configuration enables the monitoring of cell confluence and measuring analytes with spectral interrogation that illuminates, receives, and processes the signature wavelengths. A communication component may be utilized to transmit monitoring data from the monitor or monitoring layer to a user in a remote location. This configuration may be implemented in single use or multi-use stacked vessels. 
     Having a monitoring layer positioned external to a cell culture chamber may maintain sterility and enable remote and automated control of the process. By remotely monitoring cell confluence, embodiments of the present disclosure enable the operator to increase the yield in cell processing by optimizing the timing of next steps in cell production, thus reducing handling and reducing operating costs. This disclosure provides a mechanism to automate system controls allowing the operator to be a less skilled technician, lowering labor costs. With the external and remote implementation, the disclosure provides the main component to a closed cell production system that may now be operated in a less costly environment. 
     The monitoring layer as described herein may be made of polystyrene. This monitoring layer enables two monitoring functions of the cell growth areas: cell confluence and analyte measurement. The confluence monitor may employ a dual lens system with a mirror formed within the monitoring layer, and an attached camera may provide light, image capture, magnification, and image delivery to a user. The analyte monitor may include a spectral analytical technology system and may further include a waveguide system with diffraction grating and lens in the monitoring layer, fibers for excitation and emission may be attached to the monitoring layer and may also be connected to a spectral sensor system. 
     An exemplary confluence monitor may employ a dual lens system with a mirror for reflecting light at right angles to the cell growth surface for illumination and image capture. The camera may provide the light and image capture function. Light waves or beams may travel through the lens to the mirror where it is focused on an area within the cell growth area. The illuminated image is then received by the camera once passing through the lens. 
     An exemplary analyte monitor may include a waveguide array that may be located above, below, or in-between stacked cell culture chambers. The monitor may employ dual optical ports where one port may be for excitation light and the other port may be for emission light. The excitation light may travel along the light guide (e.g., waveguide) to the diffraction grating and lens where it reflects off the diffraction grating into the media of a cell culture chamber. The emission fiber may receive the light from the excitation state of the media and deliver the excitation light to the spectral sensor (e.g., detector) to produce an emission or adsorption spectrum. The spectral sensor may include a 2D detector array system. The lens and diffraction grating system may be fabricated in a monitoring layer inserted between the cell culture chambers in stacked adherent cell vessels. 
     In some examples, micro lenses may be used in combination with the analyte monitor. For example, a micro lens array may be positioned on the top or bottom of the monitoring layer. Micro lens arrays are useful for refracting waves similar to a full-size lens. For example, micro lens arrays may be used for fiber couplings and optical switching. A micro lens may be manufactured in fused silica or silicon by photolithography to produce precise lenses. 
     Aspects of the disclosure are initially described in the context of a cell culture system. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to non-invasive remote measurements. 
       FIG.  1    shows a perspective view of one example of a system  100  for non-invasive measurement of a cell culture chamber  110  that supports remote monitoring in accordance with various aspects of the present disclosure. The non-invasive measurement system  100  includes a monitoring layer  105 , a cell culture chamber  110 , a confluence monitor  115 , an analyte monitor  120 , and cells  125 . In some aspects, the system  100  may be configured to operate in a wide temperature range, for example the system  100  may operate in an incubator configured for cell growth. In some examples, the non-invasive measurement system  100  may be part of a stacked cell culture vessel as shown in  FIG.  2   . 
     In one example, the monitoring layer  105  may be integrated into one or more sides of the cell culture chamber  110 . As illustrated, the monitoring layer  105  may be integrated into the side of the cell culture chamber  110  with the surface that the cells adhere to. The one or more sides that include a monitoring layer  105 , may be the same thickness or different in thickness than sides that do not include a monitoring layer. The monitoring layer  105  may include at least one of a confluence monitor  115  or an analyte monitor  120 . In some aspects, when more than one monitor is present, the monitors may be on the same edge of the monitoring layer  105 . In another aspect, the monitors may be on different edges of the monitoring layer  105 . When more than one monitor is present, each monitor may be positioned at different heights on the same or different edges of the monitoring layer  105 . In some examples, the monitors may be aligned on the edge of monitoring layer  105 . As described herein, a monitoring layer  105  below a cell culture chamber  110  may refer to the bottom side of the cell culture chamber  110 , a monitoring layer  105  above a cell culture chamber  110  may refer to the top side of the cell culture chamber  110 , etc. 
     In another example, the monitoring layer  105  may be positioned adjacent to the cell culture chamber  110 . For example, the monitoring layer  105  may be positioned below the cell culture chamber  110  such that the adherent cells would be on the side of the cell culture chamber  110  adjacent to the monitoring layer  105  as shown in  FIG.  1   . In another example, the monitoring layer  105  may be positioned above the cell culture chamber  110  such that the adherent cells would be on the side of the cell culture chamber  110  furthest from the monitoring layer  105 . The monitoring layer  105  may include at least one of a confluence monitor  115  or an analyte monitor  120 . In some aspects, when more than one monitor is present, the monitors may be on the same edge of the monitoring layer  105 . In another aspect, the monitors may be on different edges of the monitoring layer  105 . When more than one monitor is present, each monitor may be positioned at different heights on the same or different edges of the monitoring layer  105 . In some examples, the monitors may be aligned on the edge of monitoring layer  105 . The configuration of the confluence monitor  115  and the analyte monitor  120  illustrated in  FIG.  1    shows an example of when the two monitors are aligned on the same edge of the monitoring layer  105 . In some examples, the monitoring layer  105  may be composed of polystyrene or a similar polymer. 
     The confluence monitor  115  and the analyte monitor  120  may optically capture the cell status of the cells  125  in the cell culture chamber  110 . In some aspects, the confluence monitor  115  and the analyte monitor  120  may include a communication component for transmitting data, such as cell status data, from the monitors to a remote location via a wired communication network or a wireless communication network. For example, the communication component of each monitor may include a Wi-Fi transceiver. 
       FIG.  2    shows a perspective view of one example of a stacked cell culture vessel system  200  that can be used for non-invasive measurement of a cell culture  210  with support for remote monitoring in accordance with aspects of the present disclosure. The stacked cell culture vessel system  200  may include a plurality of monitoring layers  205 , a plurality of cell culture chambers  210 , a plurality of confluence monitors  215 , and a plurality of analyte monitors  220 . 
     As illustrated, the stacked cell culture vessel system  200  may be configured with a cell culture chamber  210   a  on top, a monitoring layer  205   a  below the cell culture chamber  210   a  and above a cell culture chamber  210   b , another monitoring layer  205   b  below the cell culture chamber  210   b  and above a cell culture chamber  210   c , a cell culture chamber  210   d  below the cell culture chamber  210   c  and above a monitoring layer  205   c , and a cell culture chamber  210   e  below the monitoring layer  205   c . In some examples, the plurality of monitoring layers  205  are dispersed between the plurality of cell culture chambers  210 . The stacked cell culture vessel is not limited to this arrangement. For example, one cell culture chamber  210  (e.g.,  210   a  and  210   b ) may be positioned on both the top and bottom of a monitoring layer  205  (e.g.,  205   a ) or more than one cell culture chamber  210  may be positioned on both the top and bottom of a monitoring layer  205 . The number of cell culture chambers  210  above the monitoring layer  205  may be different from the number of cell culture chambers  210  below the monitoring layer  205  (e.g.,  205   b  and  205   c ). 
     Additionally, the stacked cell culture vessel system  200  may be configured to operate over a wide temperature range such as in an incubator at a temperature designed for cell growth. 
     The confluence monitors  215  and the analyte monitors  220  may capture the cell status of the cells  225  in all cell culture chambers  210 , including inter-layer measurements and monitoring. In some cases, the confluence monitors  215  and the analyte monitors  220  may measure the cell status of multiple stacked cell culture chambers  210  with a single monitor. The confluence monitors  215  and the analyte monitors  220  may take measurements of the cell status of the cell culture chambers above and below the monitoring layer  205  that includes the monitors. For example, the confluence monitor  215   a  may measure the cell growth of the cell culture chamber  210   a , the confluence monitor  215   b  may measure the cell growth of the cell culture chamber  210   b , and the confluence monitor  215   c  may measure the cell growth of the cell culture chambers  210   c ,  210   d , and  210   e . In one example, the analyte monitor  220   a  may measure the cell health of the cell culture chambers  210   a  and  210   b , the analyte monitor  220   b  may measure the cell health of the cell culture chambers  210   c  and  210   d , and the analyte monitor  220   c  may measure the cell health of the cell culture chamber  210   e . 
     In some aspects, each confluence monitor  215  and each analyte monitor  220  may include a communication component for transmitting data, such as cell status data, from the monitors to a remote location via a wired communication network or a wireless communication network. For example, the communication component of each monitor may include a Bluetooth transceiver. In other aspects, each monitoring layer  205  may include a communication component for transmitting data, such as cell status data, from the monitoring layer to a remote location via a wired communication network or a wireless communication network. For example, the communication component of each monitoring layer may include a Bluetooth transceiver. 
       FIG.  3    illustrates an example of a perspective view of a monitoring layer  305  that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. The monitoring layer  305  may include one or more confluence monitors  315  and one or more analyte monitors  320 . In some cases, the monitors  315  and  320  are removable and positionable in different configurations within the monitoring layer  305 . 
     In one example, the monitoring layer  305  may be integrated into one or more sides of a cell culture chamber. In another example, the monitoring layer  305  may be positioned adjacent to a cell culture chamber. 
     Each confluence monitor  315  and analyte monitor  320  may take measurements of cell status in one direction, such as up or down, once the monitors are positioned in the monitoring layer  305 . The confluence monitors  315  and analyte monitors  320  may take measurements in the same direction or in different directions. For example, the confluence monitor  315   a  and the analyte monitor  320   b  may monitor the cell culture chamber(s) above the monitoring layer  305 , and the confluence monitor  315   b  and the analyte monitor  320   a  may monitor the cell culture chamber(s) below the monitoring layer  305 . In another example, the confluence monitors  315   a ,  315   b  may monitor the cell culture chamber(s) above the monitoring layer  305 , and the analyte monitors  320   a ,  320   b  may monitor the cell culture chamber(s) below the monitoring layer  305 . 
     When a confluence monitor  315  is integrated into a side of the cell culture chamber, image magnification to monitor cell growth may occur external to the monitoring layer  305 . For example, a light pipe may be used within the confluence monitor  315  to transfer the cell surface image to the wall of the monitoring layer  305  without magnification. The image may then be magnified by an external microscope, which may be aimed at the outside edge of the cell culture chamber that includes a confluence monitor  315 . In this example, the thickness of the monitoring layer  305  integrated within the side of a cell culture chamber may be decreased. 
     When an analyte monitor  320  is integrated into a side of the cell culture chamber, light may be transmitted into the cell culture chamber from a light source external to the monitoring layer  305  to monitor cell health by measuring the composition of the media in the cell culture vessel. The light source may extend from the outer edge of the analyte monitor  320  relative to the monitoring layer  305 . In this example, the thickness of the monitoring layer  305  integrated within the side of a cell culture chamber may be decreased. 
     In some aspects, when more than one monitor is present, the monitors may be on the same edge of the monitoring layer  305  as shown. In another aspect, the monitors may be on different edges of the monitoring layer  305 . When more than one monitor is present, each monitor may be positioned at different heights on the same or different edges of the monitoring layer  305 . In some examples, the monitors may be aligned on the edge of monitoring layer  305 . The configuration of the confluence monitors  315  and analyte monitors  320  illustrated in  FIG.  3    shows an example of when the monitors are positioned at different heights on the same edge of monitoring layer  305 . The analyte monitors  320  are positioned closer to the top of the monitoring layer  305  than the confluence monitors  315 . In some cases, the monitoring layer  305  may be composed of polystyrene or a similar polymer. Monitors of the monitor tray  305  are not limited to confluence or analyte monitors and may include other external cell monitors. The shape of monitoring layer  305  may include a rectangular prism or other geometric shapes. 
       FIG.  4    shows a side view of an example of a confluence monitoring system  400  that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. The confluence monitoring system  400  may include a monitoring layer  405 , a cell culture chamber  410 , a confluence monitor  415 , cells  425 , media  430 , lenses  435 ,  440 , mirror  445 , and light beams  450 . The confluence monitoring system  400  may include one or more monitoring layers  405 , one or more cell culture chambers  410  including cells  425  and media  430 , and one or more confluence monitors  415  per monitoring layer  405 . The monitoring layer  405  may be integrated within a wall of the cell culture chamber  410 . 
     The confluence monitor  415  may take measurements of the cells  425  in the cell culture chamber  410  above the monitoring layer  405  by any optical means. In one example, the confluence monitor  415  uses a 2D imaging array to measure the cell growth above or below the monitoring layer  405 . In another example, the confluence monitor  415  may employ a multi-lens (e.g., dual lens  435 ,  440 ) system with at least one mirror  445  and camera  455 . The confluence monitor  415  may include a sheath or lumen that allows the lens and mirror system to move within the monitoring layer  405  in order to image different sections of the cell culture chamber  410 . 
     Confluence monitor  415  including light beams  450 , lenses  435 ,  440 , and mirror  445  may be configured to use a number of illumination options (e.g., reflected light illumination, epi-illumination, dark field illumination, light field illumination, etc.) to observe the cells  425 . Light beams  450  may be transmitted from the camera  455  through the first lens  435 , where the light beams  450   a  and  450   c  may be refracted and focused towards mirror  445 . Once the light beams  450  contact the mirror  445 , the light beams may be reflected at any angle, for example 90 degrees, to be directed through the second lens  440  into the cell culture chamber  410  to measure the growth of cells  425 . The camera  455  may capture the illuminated cells to produce an image of their real-time confluency that may be used to monitor growth over time. As discussed above, the confluence monitor  415  may be designed to image at least one cell culture chamber  410  above or below the monitoring layer  405 . The confluence monitor  415  may take measurements of the cell culture chamber  410  above the monitoring layer  405  in order to image the cells on the side with less media  430 , which may affect image quality. 
     The confluence monitor  415  may also include a communication component that transmits cell data to a user, such as the captured image of at least a portion of the cells  425 . In some cases, the user may be in a remote location relative to the cell culture, such as a separate room, nearby building, across the world, or on the go. Real-time data related to the cell growth may be transmitted to the user at any remote location. Data transmissions may occur over a wired communication network (e.g., digital subscriber line) or a wireless communications network (e.g., Wi-Fi, Bluetooth, or LTE). 
     A fiber probe, described in  FIG.  6   , may be used for confluence monitoring to replace the free space optical system as described in  FIG.  4   . For example, a multicore fiber or a fiber bundle may be used for transmitting cell images to the camera. 
       FIG.  5    shows a side view of one example of an analyte monitoring system  500  that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. The analyte monitoring system  500  may include a monitoring layer  505  and a cell culture chamber  510 . The cell culture chamber  510  may include cells  525  and media  530 . The analyte monitor  520  may include a sheath or lumen that allows the system to move within the monitoring layer  505  in order to monitor different sections of the cell culture chamber  510 . The monitoring layer  505  may be integrated within a wall of the cell culture chamber  510 . 
     In some examples, the monitoring layer  505  may include the analyte monitor  520 . The analyte monitor  520  may take measurements of the health of the cells  525  by measuring the composition of the media  530  below the monitoring layer  505  by any spectral means (e.g., Raman spectroscopy). The analyte monitor  520  may include a waveguide  535  (e.g., a light pipe), a diffraction grating and lens  540 , light beam  545 , and detector  550 . The waveguide  535  may direct excited light to the diffraction grating and lens  540 , which then directs the light beam  545  into the media  530  within the cell culture chamber  510 . Excited light may be produced in a number of ways. Based on the composition of the media  530 , distinct emission spectrums will be given off and captured by the detector  550 . The detector  550  may transmit the captured emission or adsorption spectrum to a user. The user may use software to determine the composition of the media  530  based on the emission or adsorption spectrums. Some examples of analytes that may be measured by analyte monitor  520  include glucose, lactose, and glutamine. 
     In one example, a light emitting diode (LED) or laser may be in the analyte monitor  520 . The LED or laser may be paired with a photodiode detector within the monitoring layer  505 . This example may allow the LED or laser and the photodiode detector to be housed inside the analyte monitor  550  partially or completely within the monitoring layer  505 . 
     As discussed above, the analyte monitor  520  may be designed to monitor at least one cell culture chamber  510  above or below the monitoring layer  505 . It is preferable for the analyte monitor  520  to take measurements of the cell culture chamber  510  below the monitoring layer  505  in order to transmit excited light into the media  530 , while passing through as few other materials as possible in order to produce a clean emission spectrum. 
     The analyte monitor  520  may also include a communication component that transmits cell data to a user, such as the captured emission spectrum or adsorption spectrum of at least a portion of the media  530 . In some cases, the user may be in a remote location relative to the cell culture, such as a separate room or on the go. Real-time data related to the cell health may be transmitted to the user at any remote location. Data transmissions may occur over a wired communication network (e.g., digital subscriber line) or a wireless communications network (e.g., Wi-Fi, Bluetooth, or LTE). 
       FIG.  6    shows a side view of another example of an analyte monitoring system  600  that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. The analyte monitoring system  600  may include a monitoring layer  605  and a cell culture chamber  610 . The cell culture chamber  610  may include cells  625  and media  630 . The analyte monitor  620  may include a sheath or lumen that allows the system to move within the monitoring layer  605  in order to monitor different sections of the cell culture chamber  610 . The monitoring layer  605  may be integrated within a wall of the cell culture chamber  610 . 
     In some examples, the monitoring layer  605  may include the analyte monitor  620 . The analyte monitor  620  may take measurements of the health of the cells  625  by measuring the composition of the media  630  in the cell culture chamber  610  below the monitoring layer  605  by any spectral means (e.g., Raman spectroscopy). The analyte monitor  620  may include a fiber probe  635  (e.g., a dual clad fiber two multi-mode fibers (MMFs), or a multicore fiber), a mirror  640 , a lens  641 , light beam  645 , and detector  650 . The fiber probe  635  may direct excited light to the mirror  640 , which then directs the light beam  645  into the media  630  within the cell culture chamber  610 . In some examples, the fiber probe  635  may be bent 90 degrees to direct the light beam  645  through the lens  641  into the media  630  within the cell culture chamber  610  and the mirror  640  may be omitted. In some examples, the lens  641  may be integrated to the fiber end using a fiber lens making process. In some cases, the fiber probe may be straight and extend from the detector  650  to the mirror  640 . When the fiber probe  635  is configured with a dual clad structure, the central inner core may be used to transmit light beam  645  to the media  630 , and the outer core may be used to capture the Raman-scattered light from the media  630 . The central inner core may be a single-mode or a multimode core. When the fiber probe  635  includes two MMFs, one MMF may be for transmitting light beam  645  to the media, and the other MMF may be for capturing the Raman-scattered light from the media  630 . When the fiber probe  635  is configured with a multicore fiber, one core (e.g., the core in the center) may be used for transmitting light beam  645  to the media  630 , and the other cores may be for capturing the Raman-scattered light from the media  630 . In some cases, the mirror  640  may include a diffraction grating. In other cases, the mirror  640  may not include a diffraction grating. 
     Excited light may be produced in a number of ways. In one example, a light emitting diode (LED) or laser may be in the analyte monitor  620  as described above. Based on the composition of the media  630 , distinct emission spectrums are given off and captured by the detector  650 . Emissions from the cell media  610  may be directed through the fiber probe  635  to the detector  650 . Detector  650  may transmit the captured emission or adsorption spectrum to a user. The user may use software to determine the composition of the media  630  based on the emission or adsorption spectrums. Some examples of analytes that may be measured by the analyte monitor  620  include glucose, lactose, and glutamine. 
     Fiber probe  635  may include two MMFs used for the input and output of light to and from media  630 . The MMFs may have a 90 degree bend near the input/output end. In some examples, one MMF may be for directing light beam  645  into the media  630  while the other MMF may be for capturing Raman-scattered light from the media  630 . The distance of the input/output end of the fiber probe  635  from the media  630  may be adjusted for different light beam  645  powers and media  630  illumination areas. 
     In some examples when the fiber probe  635  is straight, mirror  640  may be omitted. In this example, the input/output end of the fiber probe  635  (e.g., two MMFs) may be polished at a 45 degree angle. Then, the input/output end may be coated with metal to create a mirror on the input/output end of the fiber probe  635 . 
     A fiber probe may also be used for confluence monitoring to replace free space optical system as described in  FIG.  4   . A multicore fiber or a fiber bundle may be used for transmitting cell images to the camera. In some examples, both the confluence monitoring and the analyte monitoring may be done through fiber probes. 
       FIG.  7    shows a top view of an example of a monitoring layer system  700  that supports non-invasive measurement and remote monitoring of a cell culture in accordance with aspects of the present disclosure. The monitoring layer system  700  may include a monitoring layer  705  that houses a plurality of analyte monitors  720   a - 720   e . A plurality of lenses  715  may be arranged on the top of the monitoring layer  705  to form a lens array  710  that assists with coupling light into and out of the cell and media samples of a cell culture chamber. In some examples, the lenses may be micro lenses. 
     The micro lens array  710  may include micro lenses  715  which are not used when the monitoring layer  705  is configured as shown. The micro lens array  710  may also include micro lenses  725  which are used when the monitoring layer  705  is configured as shown. As mentioned above, the analyte monitors  720  may be moved and arranged to monitor different areas of a cell culture chamber. Thus, an array system may be helpful when different points within a cell culture chamber are to be monitored. A micro lens  715  or  725  may be helpful for capturing the emitted light from the media of a cell culture chamber. 
       FIG.  8    shows a side view of an example of a system  800  for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. The system  800  may include two monitoring layers  805   a ,  805   b  and a cell culture chamber  810 . The monitoring layer  805   a  may include an analyte monitor  820  that is configured to measure the health of cells  825  by measuring the composition of the media  830  of the cell culture chamber  810  located below the monitoring layer  805   a . The monitoring layer  805   b  may include a confluence monitor  815  that is configured to measure the growth of cells  825  by capturing images of the cells  825  over time. 
     In some cases, the confluence monitor  815  and the analyte monitor  820  may operate simultaneously or at separate time periods. The confluence monitor  815  and the analyte monitor  820  may also each include a communication component that transmits the captured data in real time to a user. In some examples, the user may be remote. 
     The system  800  may be configured to operate at a wide temperature range. For example, the system  800  may operate in an incubator at a temperature designed for cell growth. Since the system can operate in an incubator, continuous cell growth with accurate cell culture monitoring in real time is possible. Moreover, real time monitoring may allow for optimized cell growth through improvements in control of the cell culture system, such as an automated feeding schedule. 
       FIG.  9    shows a flowchart illustrating a method for non-invasive measurement of a cell culture that supports remote monitoring in accordance with aspects of the present disclosure. The operations of method  900  may be implemented by any of the systems described above. For example, the operations of method  900  may be performed by systems  100 ,  200 , and  800  as described with reference to  FIGS.  1 ,  2 , and  8   . 
     At block  905  the external monitoring layer  205  may be positioned between two or more cell culture chambers  210  of a cell culture vessel configured for closed system operation. 
     At block  910  the monitoring layer  205  including monitors  215  and  220  may measure the cell status of the two or more cell culture chambers  210  while allowing continuous growth of the cells  225 . In certain examples, aspects of the operations of block  910  may be performed by a confluence monitor  215  or an analyte monitor  220  as described with reference to  FIGS.  1 - 8   . 
     At block  915  the one or more communication components may transmit cell status data from the external monitoring layer to a remote location. In certain examples, aspects of the operations of block  915  may be performed by a communication component as described with reference to  FIGS.  1 - 8   . 
     According to an aspect (1) of the present disclosure, a remote monitoring system configured to non-invasively measure a cell culture is provided. The system includes a cell culture vessel comprising at least one cell culture chamber configured to operate as a closed-system, the at least one cell culture chamber having at least one surface to which cells adhere; at least one monitoring layer comprising at least one measurement device, wherein the monitoring layer is external to the at least one cell culture chamber; and a communication component configured to transmit data from the monitoring layer to a remote location. 
     According to an aspect (2) of the present disclosure, the remote monitoring system of aspect (1) is provided, wherein the monitoring layer is integrated into a wall of the at least one cell culture chamber. 
     According to an aspect (3) of the present disclosure, the remote monitoring system of aspect (1) is provided, wherein the monitoring layer is positioned between two or more cell culture chambers and is configured for inter-layer monitoring. 
     According to an aspect (4) of the present disclosure, the remote monitoring system of aspect (3) is provided, wherein the monitoring layer comprises at least two measurement devices and is configured to measure both the cell culture chamber above and below the monitoring layer simultaneously. 
     According to an aspect (5) of the present disclosure, the remote monitoring system of any of aspects (1)-(4) is provided, wherein the at least one measurement device comprises one or both of a confluence monitor or an analyte monitor. 
     According to an aspect (6) of the present disclosure, the remote monitoring system of aspect (5) is provided, wherein the confluence monitor comprises an optical device configured to capture an image of at least one cell culture chamber. 
     According to an aspect (7) of the present disclosure, the remote monitoring system of aspect (6) is provided, wherein the optical device comprises: at least one lens; a mirror; a camera; and the communication component. 
     According to an aspect (8) of the present disclosure, the remote monitoring system of aspect (6) is provided, wherein the optical device comprises: a fiber probe; a mirror; a camera; and the communication component. 
     According to an aspect (9) of the present disclosure, the remote monitoring system of aspect (5) is provided, wherein the analyte monitor comprises a spectral element configured to emit one or more excitation wavelengths of light and capture emitted light from a media layer within the cell culture chamber. 
     According to an aspect (10) of the present disclosure, the remote monitoring system of aspect (9) is provided, wherein the spectral element comprises: a waveguide; a diffraction grating; a lens; a detector; and the communication component. 
     According to an aspect (11) of the present disclosure, the remote monitoring system of aspect (9) is provided, wherein the spectral element comprises: a fiber probe; a mirror; a detector; and the communication component. 
     According to an aspect (12) of the present disclosure, the remote monitoring system of aspect (9) is provided, wherein the spectral element is configured to perform Raman spectroscopy on the media layer. 
     According to an aspect (13) of the present disclosure, the remote monitoring system of any of aspects (1)-(12) is provided, wherein the monitoring layer comprises polystyrene. 
     According to an aspect (14) of the present disclosure, the remote monitoring system of any of aspects (1)-(13) is provided, wherein the at least one measurement device is removable from the monitoring layer. 
     According to an aspect (15) of the present disclosure, the remote monitoring system of any of aspects (1)-(14) is provided, wherein the communication component is configured to transmit the data in real time or on demand. 
     According to an aspect (16) of the present disclosure, a method for non-invasive measurement of cell cultures is provided. The method includes positioning an external monitoring layer between two or more cell culture chambers of a cell culture vessel configured to operate as a closed-system; measuring cell status of the two or more cell culture chambers while allowing continuous cell growth; and transmitting cell status data from the external monitoring layer to a remote location. 
     According to an aspect (17) of the present disclosure, the method of aspect (16) is provided, wherein measuring the cell status of the two or more cell culture chambers further comprises: measuring at least one cell culture chamber above the monitoring layer and at least one cell culture chamber below the monitoring layer simultaneously. 
     According to an aspect (18) of the present disclosure, the method of aspect (17) is provided, wherein measuring the at least one cell culture chamber above the monitoring layer comprises taking a confluence measurement of cells. 
     According to an aspect (19) of the present disclosure, the method of aspect (17) is provided, wherein measuring the at least one cell culture chamber below the monitoring layer comprises taking an analyte measurement of media. 
     According to an aspect (20) of the present disclosure, the method of any of aspects (16)-(19) is provided, wherein the cell status data is transmitted in real-time. 
     According to an aspect (21) of the present disclosure, the method of any of aspects (16)-(20) is provided, wherein the cell status data is transmitted over a wireless network. 
     According to an aspect (22) of the present disclosure, the method of any of aspects (16)-(21) is provided, wherein positioning the external monitoring layer comprises positioning one or more measurement devices in the monitoring layer. 
     According to an aspect (23) of the present disclosure, the method of aspect (22) is provided, wherein positioning the external monitoring layer further comprises positioning the one or more measurement devices at different points on the monitoring layer. 
     It should be noted that the methods describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Furthermore, aspects from two or more of the methods may be combined. 
     The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples. 
     Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an exemplary step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.” 
     The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein, but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.