Fiber optic based sensing film layout

Abstract

This application relates to fiber optic based sensing film layouts. According to an example, a fiber optic based sensing film can include at least one optical fiber and a substrate. The at least one optical fiber can be integrated in the substrate. The fiber optic based sensing film can include a fiber optic based sensing film layout based on a specified geometry of the at least one optical fiber. The substrate can include a thickness and material properties specified to determine, via the at least one optical fiber and based on the fiber optic based sensing film layout, a thermal and / or mechanical property associated with a device, or a radiation level associated with a device environment.

Description

[0001] Priority

[0002] This application claims priority to co-assigned and co-pending European Patent Application No. EP21305505.6, filed April 16, 2021, entitled “OPTICAL FIBER-BASED SENSING MEMBRANE LAYOUT,” and co-assigned and co-pending European Patent Application No. EP21305506.4, filed April 16, 2021, entitled “OPTICAL FIBER-BASED SENSING MEMBRANE,” the disclosures of each of which are hereby incorporated by reference in their entirety. BACKGROUND

[0003] Optical fibers can be used in various industries, such as communications, medical, military, broadcasting, etc., to transmit data and for other related applications. Examples of applications can include sensing temperature, mechanical strain, vibration, and / or radiation dose by utilizing optical fibers. In this regard, principles of Raman scattering, Rayleigh scattering, and / or Brillouin scattering can be implemented for sensing of temperature, mechanical strain, vibration, and / or radiation dose. BRIEF DESCRIPTION OF DRAWINGS

[0004] Features of the present disclosure are illustrated by way of example in the following figures. In the following figures, like numbers refer to like elements, in which:

[0005] Figure 1 An electric vehicle including an optical fiber-based sensing membrane according to an example of the present disclosure is shown;

[0006] Figure 2 An electric vehicle according to an example of the present disclosure, in which the optical fiber-based sensing membrane is removed; Figure 1

[0007] Figure 3 A schematic diagram showing the optical fiber-based sensing membrane in use according to an example of the present disclosure is shown; Figure 1

[0008] Figure 4 A schematic diagram showing an embedded distributed temperature sensor utilizing the optical fiber-based sensing membrane according to an example of the present disclosure is shown; Figure 1

[0009] Figure 5A and Figure 5B showing a temperature spatial resolution plot and an example of spatial resolution, respectively, according to an example of the present disclosure.​​​

[0010] Figure 6 Further details of spatial resolution are shown in accordance with examples of the present disclosure;

[0011] Figure 7 Fiber optic based sensing film layouts including loops with multiple layers are shown in accordance with examples of the present disclosure;

[0012] Figure 8 And Figure 9 Further examples of fiber optic based sensing film layouts are shown in accordance with examples of the present disclosure;

[0013] Figure 10 Fiber optic based sensing film layouts including sliding loops are shown in accordance with examples of the present disclosure;

[0014] Figure 11 Fiber optic based sensing film layouts including fiber optic based sensing films embedded in battery cell inserts are shown in accordance with examples of the present disclosure;

[0015] Figure 12 Fiber optic based sensing film layouts including loops in series are shown in accordance with examples of the present disclosure;

[0016] Figure 13 Further examples of fiber optic based sensing film layouts are shown in accordance with examples of the present disclosure;

[0017] Figure 14 Fiber optic based sensing film layouts including fiber optics embedded in battery molded parts are shown in accordance with examples of the present disclosure;

[0018] Figures 15 to 17 Dynamic temperature sensing measurements and associated calibration are shown in accordance with examples of the present disclosure;

[0019] Figure 18 Fiber optic grid coverage is shown in accordance with examples of the present disclosure; and

[0020] Figure 19 Methods of manufacturing fiber optic based sensing films are shown in accordance with examples of the present disclosure. DETAILED DESCRIPTION

[0021] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples thereof. In the following description, numerous specific details are set forth to provide an understanding of the examples herein. However, it will be apparent to one skilled in the art that the examples described herein can be practiced without the specific details. In other instances, well-known methods and structures have not been described in detail in order to avoid obscuring the examples described herein.

[0022] In the present disclosure, the terms "a" and "an" are intended to denote at least one of a particular element. As used herein, the term "includes" means includes but not limited to, the term "including" means including but not limited to. The term "based on" means based at least in part on.

[0023] According to examples disclosed herein, a fiber optic based sensing film can include at least one optical fiber and a flexible substrate. The at least one optical fiber can be integrated in the flexible substrate. The fiber optic based sensing film can include a fiber optic based sensing film layout based on a specified geometric pattern of the at least one optical fiber. The flexible substrate can include a thickness and material properties specified to determine thermal and / or mechanical properties associated with a device via the at least one optical fiber and based on the fiber optic based sensing film layout. Examples of the mechanical properties can include strain, vibration, and other such properties. The device can include, for example, a battery pack of an electric vehicle, or any other type of flat or curved structure to be monitored. Applications can include, but are not limited to, monitoring of battery based energy storage plants, monitoring of nuclear power plants, and monitoring of defense equipment. Further, the substrate can be flexible or rigid. For example, for a surface application of the sensing film on the device or an embedded application of the sensing film in the device, the optical fiber can be embedded in a rigid sensing film formed by a rigid substrate. According to another example, for an optical fiber integrated in a molded part of a device such as a battery pack, the optical fiber can be embedded in a rigid sensing film formed by a rigid substrate.

[0024] For fiber optic sensing, generally in some applications, an optical fiber can be used to monitor thermal and / or mechanical properties of a device. A device as used herein can be any type of machine, component, structure, etc. to be monitored. For example, for a device such as an electric vehicle battery pack including a plurality of battery cells, an optical fiber can be used to monitor thermal and / or mechanical properties of the battery pack. In this regard, due to technical challenges related to laying, winding, and / or attaching optical connectors each time a separate element of the device (e.g., a battery cell of the battery pack) needs to be handled, it can not be feasible to directly embed the optical fiber in the device.

[0025] To address at least the above technical challenges, a fiber-based sensing film disclosed herein can include at least one optical fiber integrated in a flexible substrate and include a fiber-based sensing film layout based on a specified geometry of the at least one optical fiber. According to examples disclosed herein, the fiber-based sensing film can utilize, for example, a polyimide flex or other such material. In this regard, the fiber-based sensing film can also house components such as electrical tracks, sensors, and optical connectors to reduce electrical harnessing associated with use of the fiber-based sensing film.

[0026] According to examples disclosed herein, the fiber-based sensing film layout can include various types of layouts. For example, the layout can include a single or multiple optical fibers, single or double ended access to the optical fibers, coils with multiple layers, slip rings, fiber-based sensing films embedded in battery cell inserts, rings in series, optical fibers embedded in battery molded components, and other types of layouts.

[0027] According to examples disclosed herein, the fiber-based sensing film layout can include optical fiber loops to compensate for spatial resolution. Alternatively or additionally, the fiber-based sensing film layout can include path folding or partial path folding to compensate for optical fiber losses. For example, full and perfect path folding can be achieved by a multi-core fiber and a loopback optical element that connects two cores in series at the far end of the interrogator. Path folding techniques can provide for use of a Raman distributed temperature sensor that is single ended, uses single source, and Anti-Stokes power information. Such an optical engine configuration can utilize one laser, one photodiode, and one three-port multiplexer. Based on implementation of path folding techniques, the optical configuration can distinguish between loss changes and temperature changes.

[0028] According to examples disclosed herein, the fiber-based sensing film can sense various types of parameters associated with a device. For example, the parameters can include temperature, strain, vibration, radiation dose, and other such parameters.

[0029] According to examples disclosed herein, different types of parameters sensed by the fiber-based sensing film can be used to generate different types of notifications or alerts. For example, a temperature change that exceeds a specified temperature threshold can be used to generate a first type of notification or alert. Similarly, a strain change that exceeds a specified strain threshold (e.g., due to device damage) can be used to generate a second type of notification or alert. By analyzing the time evolution and, in particular, the rate of change of temperature or strain, it is also possible to classify the occurrence of a so-called thermal runaway of a battery element.

[0030] According to examples disclosed herein, the number of elements of a device being monitored can be scaled without requiring the addition of optical connections. For example, the length or configuration of the fiber optic based sensing film can be modified as needed in view of an increase or decrease in the number of monitored elements. In this regard, one or more optical connections can be used with the fiber optic based sensing film, and the size of the fiber optic based sensing film can be increased or decreased as needed to accommodate multiple devices without requiring the inclusion of an optical connection for each device. Accordingly, a single optical connection can be implemented for multiple devices being monitored, thereby reducing the likelihood of failure associated with the operation of the fiber optic based sensing film.

[0031] According to examples disclosed herein, a device being monitored can remain accessible, e.g., for maintenance and other such activities, without being restricted by optics associated with the fiber optic based sensing film. For example, the fiber optic based sensing film can be configured to address a specified area of the device being monitored, while leaving other areas of the device available for maintenance and other activities.

[0032] According to examples disclosed herein, the fiber optic based sensing film itself can remain accessible, e.g., for maintenance and other such activities. In this regard, the fiber optic based sensing film can be configured to address a specified area of the device being monitored, while leaving other areas of the fiber optic based sensing film available for maintenance and other activities.

[0033] According to examples disclosed herein, the fiber optic based sensing film can be implemented in relatively harsh environments. For example, the environment of the fiber optic based sensing film can include relatively significant temperature variations of approximately -40°C to 140°C. The materials used for the fiber optic based sensing film can replace standard fiber optic coatings and continue to mechanically protect the optical fibers beyond the melting point of the coating.

[0034] According to examples disclosed herein, the fiber optic based sensing film layout can include two-dimensional or three-dimensional configurations. A two-dimensional configuration can include a plurality of optical fibers embedded in a substrate and configured as a two-dimensional planar structure to match a corresponding two-dimensional surface of a device to be monitored for temperature and / or strain changes and / or vibrations. A three-dimensional configuration can include a plurality of optical fibers embedded in a substrate and configured as a three-dimensional structure to match a corresponding three-dimensional shape of a device to be monitored for temperature and / or strain changes and / or vibrations. Depending on the size of the structure to be monitored, the budget loss of the fiber optic system, and the dynamic range of the interrogator, the distance can be covered with a single strand, or with multiple parallel fibers that can be sequentially accessed from a single interrogator through an optical switch.

[0035] According to examples disclosed herein, a fiber optic based sensing film can be used with an optical time domain reflectometer (OTDR) to determine a temperature and / or a strain associated with a device. An OTDR can represent an optoelectronic instrument used to characterize an optical fiber, e.g., a fiber optic based sensing film. An OTDR can inject a series of optical pulses into an optical fiber under test. Based on the injected optical pulses, the OTDR can extract light scattered or reflected back from points along the optical fiber from the same end of the optical fiber into which the optical pulses were injected. The backscattered or reflected light can be used to characterize the optical fiber. For example, the backscattered or reflected light can be used to detect, locate, and measure events at any location of the optical fiber. Events can include a fault at any location of the optical fiber. Other types of features that can be measured by an OTDR include attenuation uniformity and attenuation rate, segment length, and location and insertion loss of connectors and splices.

[0036] An OTDR can be used to determine a Brillouin trace and a Rayleigh trace for an optical fiber, e.g., a fiber optic based sensing film. In one example, in an initial acquisition, a Brillouin frequency shift and a Brillouin power can be used to achieve an absolute reference of a Rayleigh reference trace (or more traces). The Rayleigh reference trace can represent a reference point for subsequent measurements of Rayleigh frequency shifts. In this regard, the absolute reference of the Rayleigh reference trace (or more traces) can subsequently be used to determine a temperature and / or a strain associated with the optical fiber by using the Brillouin frequency shift and the Rayleigh frequency shift in subsequent acquisitions.

[0037] According to examples disclosed herein, a fiber optic based sensing film can be used with an OTDR to determine a temperature, a strain, and / or a vibration associated with a device, such as a battery pack, based on distributed measurements.

[0038] According to examples disclosed herein, a fiber optic based sensing film can include at least one optical fiber and a substrate. The at least one optical fiber can be integrated in the substrate. The fiber optic based sensing film can include a fiber optic based sensing film layout based on a specified geometry of the at least one optical fiber. The substrate can include a thickness and a material property. The thickness and the material property can be specified to determine, via the at least one optical fiber and based on the fiber optic based sensing film layout, a thermal property and / or a mechanical property associated with a device or a radiation level associated with a device environment.

[0039] For the fiber optic based sensing film described above, the device can include a battery pack of an electric vehicle.

[0040] For the fiber optic based sensing film described above, the mechanical property can include a strain and / or a vibration.

[0041] For the above-described fiber optic-based sensing film, the fiber optic-based sensing film layout can include a two-dimensional (2D) layout to match a corresponding 2D monitoring area layout of the device. Alternatively or additionally, the fiber optic-based sensing film layout can include a three-dimensional (3D) layout to match a corresponding 3D monitoring area layout of the device.

[0042] For the above-described fiber optic-based sensing film, the substrate can include polyimide.

[0043] For the above-described fiber optic-based sensing film, the fiber optic and the substrate can include a combined weight of between approximately 200 g / m 2 and 500 g / m 2 .

[0044] For the above-described fiber optic-based sensing film, the fiber optic and the substrate can include a combined thickness of less than approximately 0.5 mm.

[0045] For the above-described fiber optic-based sensing film, the specified geometric pattern of the at least one fiber optic can include a circular geometric pattern, a spiral geometric pattern, and / or a grid geometric pattern. Alternatively or additionally, the specified geometric pattern of the at least one fiber optic can include a plurality of loops, and at least one loop of the plurality of loops can be designated for calibrating the fiber optic-based sensing film.

[0046] For the above-described fiber optic-based sensing film, the fiber optic-based sensing film layout can include a folded layout including at least one fold line.

[0047] According to examples disclosed herein, a method can include determining a geometric pattern for integrating a fiber optic in a substrate, and feeding the fiber optic toward a consolidation roller. The method can also include integrating the fiber optic onto the substrate based on the geometric pattern and through the consolidation roller.

[0048] For the above-described method, the method can also include heating the substrate by a heat source to integrate the fiber optic onto the substrate.

[0049] For the above-described method, the geometric pattern can include a circular geometric pattern, a spiral geometric pattern, or a grid geometric pattern.

[0050] According to examples disclosed herein, a method can include embedding a fiber optic-based sensing film in a device or continuously engaging the fiber optic-based sensing film with the device. The fiber optic-based sensing film can include at least one fiber optic and a substrate. The at least one fiber optic can be integrated in the substrate. The fiber optic-based sensing film can include a fiber optic-based sensing film layout based on a specified geometric pattern of the at least one fiber optic. The substrate can include a thickness and a material property. The method can also include determining a thermal property or a mechanical property associated with the device through the embedded or continuously engaged fiber optic-based sensing film.

[0051] Figure 1 An electric vehicle 100 including a fiber optic based sensing film 102 (hereinafter “sensing film 102”) according to examples of the present disclosure is shown. Referring to Figure 1 , the electric vehicle 100 can include the sensing film 102 disposed on a device such as a battery pack 104. As disclosed herein, the sensing film 102 can include a fiber optic based sensing film layout (hereinafter “sensing film layout 122”) to accurately detect and measure temperature and / or strain changes, and / or vibrations, particularly for relatively smaller devices or for applications requiring relatively smaller spatial resolution.

[0052] The electric vehicle 100 can include other known components such as a thermal system 106 for cooling the vehicle, an auxiliary battery 108, an on-board battery charger 110, a vehicle transmission 112, a charging port 114 for the battery pack 104, a converter 116, a power electronics controller 118, and a power traction motor 120.

[0053] Figure 2 An electric vehicle 100 according to examples of the present disclosure is shown Figure 1 with the fiber optic based sensing film 102 removed.

[0054] Referring to Figure 2 , the battery pack 104 is shown with the sensing film 102 removed. In this regard, the battery pack 104 can include a plurality of battery cells 200 as shown. The sensing film 102 can be configured to sense thermal and / or strain changes, and / or vibrations associated with one, several, or all of the battery cells 200 of the battery pack 104.

[0055] Figure 3 A diagram showing the fiber optic based sensing film 102 in use according to examples of the present disclosure is shown.

[0056] Referring to Figure 3 , the fiber optic based sensing film 102 can include at least one optical fiber integrated in an adhesive substrate. In Figure 3 examples, a plurality of optical fibers 300 can be integrated in an adhesive substrate 302 as shown in the magnified view.

[0057] In Figure 3 examples, the sensing film can be disposed on the upper and lower surfaces of the battery pack 104 in an orientation of Figure 3 . The battery pack 104 can include a plurality of battery cells. In the example shown, the battery cells can include in Figure 3cooling system 304 between the upper set of battery cells and the lower set of battery cells in the orientation shown. Figure 3

[0058] For the example of Figure 3 For the example of

[0059] The adhesive base can include a polyimide or other such material. The polyimide material can provide the necessary durability for vibrations associated with the battery pack 104 and / or other components that can be engaged with the sensing film 102. Similarly, the polyimide material can provide the necessary durability for temperature changes associated with the battery pack 104 and / or other components, which can be approximately -40°C to 140°C, or include a range greater than -40°C to 140°C. Further, the polyimide material can provide the necessary flexibility associated with surface changes associated with the battery pack 104 and / or other components that can be engaged with the sensing film 102. The polyimide material can also be transparent and thus provide sufficient transmission of light into the optical fibers for detecting light or abnormalities (e.g., high temperature events) associated with the battery pack 104.

[0060] The sensing film 102 can be lightweight (e.g., 200-500 g / m 2 In this regard, the sensing film 102 can add minimal weight to the device being monitored for thermal and / or strain changes and / or vibrations.

[0061] The sensing film 102 can be approximately 0.5 mm, thus minimizing integration challenges with respect to the device being monitored for thermal and / or strain changes and / or vibrations. In this regard, the thickness of the optical fibers embedded in the sensing film 102 can be approximately 0.25 mm. For a geometric pattern of optical fibers that includes an optical fiber cross-over, such optical fibers can be treated after the sensing film is assembled, for example, by the combined effect of pressure and temperature above the melting point of the optical fiber coating, while the sensing film material is not affected. Thus, the overall thickness of 0.5 mm can thus add minimal thickness associated with the battery pack 104.

[0062] With continued reference to Figure 4 ​, shows one example of a test setup for evaluating the performance of a distributed temperature sensing system based on a distributed temperature sensing interrogator (DTS) 318 (also referred to herein as a distributed temperature sensor) and a fiber optic sensing film 320, and which can be used to sense temperature, but can also use a distributed strain sensing interrogator in place of the DTS to sense strain changes. In this regard, a distributed temperature sensing interrogator 318, which can include an OTDR, can be used with the various examples of sensing films 102 disclosed herein.

[0063] Figure 4 shows a schematic diagram showing an embedded distributed temperature sensor (eDTS) utilizing a sensing film 102, in accordance with examples of the present disclosure.

[0064] Referring to Figure 4 , the embedded distributed temperature sensor 400 can be positioned as shown for temperature sensing in association with an optical fiber 402. For the example of Figure 5A , the optical fiber 402 can include any path as shown at 404, and a common path as shown at 406. With respect to the common path, a minimum configuration can include one common path coupling two fiber ends, but higher accuracy in loss compensation can be obtained with multiple common paths distributed evenly over the total sensing length, and even higher accuracy can be obtained with a full fold through the entire fiber. The embedded distributed temperature sensor 400 can provide continuous monitoring of a device such as a battery pack 104.

[0065] Figure 5B and Figure 5A shows a temperature spatial resolution plot and an example of spatial resolution, respectively, in accordance with examples of the present disclosure.

[0066] Referring to Figure 5BThe spatial resolution can represent the minimum length of the temperature-affected fiber sensor for which the distributed fiber system can measure a reference temperature of a hotspot fiber condition within a specified temperature measurement error of the distributed temperature sensor system. For example, a spatial resolution on the order of millimeters and including increments of 0.1 °C can be used for a monitoring unit, a spatial resolution on the order of centimeters and including increments of 0.1 °C can be used for a monitoring module, and a spatial resolution on the order of meters and including increments of 1 °C can be used for a monitoring system. In this regard, an example of a 1.5 m temperature spatial resolution for the sensing fiber 500 is shown at 502. Examples of spatial resolutions are shown for different fiber coil lengths, such as 1.0 m at 504, 1.5 m at 506, and 6.0 m at 508. As shown at 504, since the temperature spatial resolution is specified as 1.5 m, the measured values at 504 show temperature measurements below 90%. The measured values at 506 show temperature measurements above 90%, and the measured values at 508 show 100% temperature measurements.

[0067] Referring to Figure 6 For fiber sensing solutions having a particular spatial resolution, it can not be possible to monitor discrete temperature changes occurring on elements of a smaller size, and loss calibration along the fiber can also be relatively complex. In this regard, as shown at 510, if the length of the fiber that is contacted is less than the spatial resolution, the associated distributed temperature sensor can not accurately measure the amplitude. For example, as shown at 510, if the length of the fiber 512 that is contacted is less than the darkened region at 514 representing a temperature spike, the associated distributed temperature sensor can not accurately measure the amplitude. In this regard, a spatial resolution of approximately 1.0 m can be specified to determine a full measurement of the temperature spike.

[0068] Figure 6 Further details of spatial resolution in accordance with examples of the present disclosure are shown.

[0069] Referring to Figure 7 For another example of spatial resolution, the spatial resolution can represent the shortest length of the fiber that must be subjected to a local temperature step in order for the system (e.g., a distributed temperature sensor) to return approximately 90% of the response (e.g., as shown at 600). The 90% response criterion can be applied to determine the spatial resolution, taking into account the length required to monitor 80% of the step change. Thus, as shown at 602, if the temperature stimulus is shorter than the spatial resolution, the temperature event can be detected but not accurately measured. Thus, it is technically challenging to accurately detect and measure temperatures, particularly for applications including a relatively small spatial resolution, such as on the order of millimeters or centimeters.

[0070] Figure 7 A sensing film layout 122 including coils with multiple layers is shown in accordance with examples of the present disclosure.

[0071] Referring to Figure 8 To address the aforementioned technical challenges associated with accurate detection and measurement of temperature and / or strain changes and / or vibrations, particularly for relatively small devices or for applications requiring relatively small spatial resolution, in some examples, the sensing film layout 122 can include a total length of optical fiber that is increased to a value higher than the spatial resolution of an associated optical fiber sensing solution. In this regard, in some examples, the sensing film layout 122 can include optical fiber patterned with coils having single or multiple layers as shown at 700. The coils can be constructed according to different winding techniques. As disclosed herein, the sensing film layout 122 can include one or more optical fibers having other geometric patterns. For example, as shown at 700, if the optical fiber is folded back on common paths, these common paths sharing seam temperature can allow for accurate measurement of optical fiber loss, which is required for the accuracy of the optical fiber sensing solution. Thus, the winding as shown at 700 can provide accurate temperature measurement as shown at 702. The number of coils can be based on the total length required for a specified spatial resolution as disclosed herein. For example, n coils including a total length of x m can be utilized to provide a response of 90% or higher. Thus, the number of coils can be determined based on the total length required for a particular response and the diameter of each coil. In this regard, each coil in a set of coils can include equal or unequal diameters.

[0072] Figure 9 And Figure 8 A further example of a sensing film layout 122 in accordance with examples of the present disclosure is shown.

[0073] Referring to Figure 9As disclosed herein, the sensing film layout 122 can include one or more optical fibers having other geometric patterns. For example, the geometric patterns can include a ring as shown in 800, a serpentine coil as shown in 802, and a spiral as shown in 804 and 806. The ring as shown in 800 can represent a quasi-distributed two-dimensional shape. The serpentine coil as shown in 802 can represent a distributed shape. Other types of shapes can include a repeating shape with multiple rings, a stack of optical fiber rings, a geometric pattern including optical fiber crossings, a square spiral, a two-dimensional spiral, a three-dimensional spiral, etc. For the geometric pattern shown at 806, various temperature or strain events can be detected, for example, at 808, 810, and 812. In this regard, for the geometric pattern shown at 806, various temperature or strain events can be detected across a single length of the optical fiber (e.g., at 808) or across multiple lengths of the optical fiber (e.g., at 810 and 812).

[0074] Referring to Figure 10 , the sensing film layout 122 can include other types of geometric patterns including an optical fiber without crossings as shown in 900, an optical fiber with crossings as shown in 902, a bundle of optical fibers with optical fiber crossings as shown in 904, and a replicated layout as shown in 906.

[0075] Figure 1 A sensing film layout 122 including a sliding ring is shown in accordance with examples of the present disclosure.

[0076] Referring to Figure 10 and Figure 10 , with respect to the geometric pattern of the sensing film layout 122, the sensing film 102 can include a sliding ring arrangement as shown in 1000. An additional lateral triangular sliding motion with an amplitude of the order of a few millimeters and a slope that exceeds the diameter of one optical fiber for each ring can be applied to avoid the accumulation of several optical fiber layers that are apparent at the top and bottom of 1000. Another solution for the accumulation of optical fibers can include a hybrid concentric spiral and sliding layout, for example, where N concentric turns and N times the sliding step length are applied (compared to the step length selected for a pure sliding ring pattern and thus with equivalent spatial resolution). The repeating pattern can cover the entire surface to be monitored with a single layer, but as shown at 1002, the sensing film 102 can include multiple layers with a horizontal offset in the orientation of Figure 11 , which can further increase the density of optical fibers and the associated spatial resolution of the sensor.

[0077] Figure 1 A sensing film layout 122 including a sensing film 102 embedded in a battery cell insert is shown in accordance with examples of the present disclosure.

[0078] Referring to Figure 11 and Figure 11The various geometric patterned sensing films 102 disclosed herein can be embedded in a battery cell insert of a battery pack 104. For example, for a battery cell 1100, a battery cell insert 1102 can be positioned on an upper surface of the battery cell in an orientation of Figure 12 and a battery cell insert 1104 can be positioned on a lower surface of the battery cell. The battery pack 104 can also include a current collector plate 1106 positioned on an upper surface of the battery cell insert 1102, and a current collector plate 1108 positioned on a lower surface of the battery cell insert 1104. In this way, the sensing film 102 can be embedded in the battery cell inserts 1102 and 1104 as shown at 1110.

[0079] Figure 1 A sensing film layout 122 including a series of loops is shown in accordance with examples of the present disclosure.

[0080] Referring to Figure 12 and Figure 13 for monitoring of the battery pack 104, the sensing film layout 122 can include a series of loops as shown at 1200. In this regard, each loop can be used to address a single battery cell 1202 of the battery pack 104. In this way, when a temperature, strain, and / or vibration event occurs at a battery cell such as battery cell 1204, 1206, or 1208, the associated loop can be used to detect the temperature, strain, and / or vibration event.

[0081] Figure 1 A further example of a sensing film layout 122 in accordance with examples of the present disclosure is shown.

[0082] Referring to Figure 13 and Figure 14 the sensing film layout 122 can be applied to various cell types. For example, as shown at 1300, the sensing film layout 122 can include a serpentine coil layout applied to a single soft pack battery (pouch cell). As shown at 1302, for a cell stack forming a module, the sensing film layout 122 can include a ribbon-layout applied to the cell stack as shown at 1304. As shown at 1306, for the ribbon-layout shown at 1304, the layout is shown in an unfolded configuration at 1306, and the layout includes a sensing film 102 that includes a folded region 1308.

[0083] Figure 14 A sensing film layout 122 including an optical fiber embedded in a battery molded component is shown in accordance with examples of the present disclosure.

[0084] Referring to Figures 15 to 17The sensing film layout 122 can include optical fibers embedded in a device such as a molded component of the battery pack 104. For example, the optical fibers can be inserted into an insert or thermally conductive gap filler of the battery pack 104. An example of an optical fiber inserted into an insert or thermally conductive gap filler of the battery pack 104 is shown at 1400. Other components of the insertable optical fiber or sensing film 102 associated with the battery pack 104 can include a battery pack seal assembly at 1402, a thermally conductive adhesive at 1404, a structural adhesive at 1406, and / or a thermally conductive gap filler at 1408.

[0085] Figure 15 Dynamic temperature sensing measurements and associated calibrations are shown in accordance with examples of the present disclosure.

[0086] Referring to Figure 16 The sensing film layout 122 as disclosed herein can include various loops and other geometric patterns. In this regard, depending on the geometric pattern, different calibration techniques can be needed to be applied for loss distribution. For example, distributed temperature sensing measurements can produce errors due to differential attenuation. The same temperature can be interpreted as different temperatures depending on the location along the optical fiber. In this regard, calibration can be performed, for example, by utilizing a reference region that is subjected to the same temperature or to a known absolute temperature. Different calibration methods can differ depending on the measurement setup (e.g., single-ended, dual-source, etc.).

[0087] Referring to Figure 17 For distributed temperature sensor temperature calibration, for example, to compensate for losses, multiple (e.g., two) reference loops can be superimposed and thus subjected to the same temperature as shown at 1600. In this regard, absolute values (offsets) can be calibrated during the start of temperature, strain, and / or vibration sensing.

[0088] Referring to Figure 18 For distributed temperature sensor temperature calibration, for example, to compensate for losses, multiple (e.g., two) reference loops can be superimposed and thus subjected to the same temperature as shown at 1700. In this regard, calibration can be based on readings of a dedicated sensor (e.g., a thermocouple as shown at 1702).

[0089] Figure 18 Optical fiber mesh coverage is shown in accordance with examples of the present disclosure.

[0090] Referring to Figure 19 For optical fiber mesh coverage (e.g., temperature, pressure, strain, vibration sensing), a sensing film layout 122 that includes multiple optical fiber crossings can be used to detect pressure, strain, vibration, and / or mechanical impact using distributed loss or strain. In this regard, for a pressure point as shown at 1800, multiple optical fiber crossings can increase the detection capability for pressure, strain, vibration, and / or mechanical impact.

[0091] Figure 1 A method of manufacturing a sensing film 102 according to examples of the present disclosure is shown.

[0092] Referring to Figure 19 and ​ Sensing films 102 including various examples of sensing film layouts 122 disclosed herein can be manufactured as shown. For example, a sensing film 102 can include a substrate 1900 including at least one optical fiber 1902 provided in a geometric pattern as shown at 1904. The optical fiber 1902 can be fed at 1906. A consolidation roller 1908 can place the optical fiber 1902 uniformly on the substrate 1900. A heat source 1910 can heat the substrate to a specified temperature to allow the optical fiber 1902 to be embedded in the substrate 1900. In this manner, various geometric patterns as disclosed herein can be formed with respect to the sensing film layout 122.

[0093] Described and illustrated herein are examples and some variations thereof. The terms, descriptions and drawings used herein are set forth by way of illustration only and are not meant as limitations. There can be many variations within the spirit and scope of the present subject matter, which is defined by the appended claims and their equivalents, where all terms are meant in their broadest reasonable sense unless otherwise indicated.

Claims

1. A sensing film based on optical fiber, comprising: optical fiber; and a substrate, wherein the optical fiber is integrated into the substrate in a pattern of a plurality of coils, and wherein, to form the pattern of the plurality of coils, the optical fiber is placed on the substrate multiple times in a first circular shape to form a first coil, and continues to be placed multiple times in a second circular shape to form a second coil, and After forming the second coil, the optical fiber is doubled back onto a common path with the first coil and then continues to be placed on the substrate in an additional circular shape to form an additional coil having an additional common path, wherein the common path of the first coil and the second coil and the additional common path of the additional coil enable the optical fiber-based sensing film to provide accurate temperature measurement of the device.

2. The optical fiber-based sensing film according to claim 1, wherein The apparatus includes a battery pack for an electric vehicle.

3. The optical fiber-based sensing film of claim 1 , wherein: The total number of the plurality of coils to be formed on the substrate is determined based on the total length of the optical fiber required for a specific response.

4. The optical fiber-based sensing film of claim 1 , wherein: The fiber-optic-based sensing film includes a two-dimensional (2D) layout to match the corresponding 2D monitoring area layout of the device.

5. The optical fiber-based sensing film of claim 1 , wherein: The fiber-optic-based sensing film includes a three-dimensional (3D) layout to match the corresponding 3D monitoring area layout of the device.

6. The optical fiber-based sensing film of claim 1 , wherein: The substrate includes polyimide.

7. The optical fiber-based sensing film of claim 1 , wherein: The optical fiber and the substrate comprise a 200 g / m 2 Up to 500g / m 2 The combined weight between.

8. The optical fiber-based sensing film of claim 1 , wherein: The optical fiber and the substrate comprise a combined thickness of less than about 0.5 mm.

9. A method for forming an optical fiber-based sensing film, comprising: placing optical fibers in a pattern of a plurality of coils on a substrate of the fiber-based sensing film, comprising: placing the optical fibers multiple times in a first circular shape to form a first coil, continuing to place the optical fibers multiple times in a second circular shape to form a second coil, and after forming the second coil, folding the optical fibers back onto a common path with the first coil, and then continuing to place the optical fibers on the substrate in additional circular shapes to form additional coils having additional common paths, wherein the common paths of the first and second coils and the additional common paths of the additional coils enable the fiber-based sensing film to provide accurate temperature measurements; rolling a consolidation roller on the substrate to uniformly press the optical fiber onto the substrate in the pattern of the plurality of coils; and The substrate is heated to a predetermined temperature to integrate the optical fiber onto the substrate in the pattern of the plurality of coils.

10. The method according to claim 9, wherein: The optical fiber and the substrate comprise a combined thickness of less than about 0.5 mm.

11. The method according to claim 9, wherein The optical fiber and the substrate comprise a 200 g / m 2 Up to 500g / m 2 The combined weight between.

12. A method comprising: Embedding an optical fiber-based sensing membrane into a device, wherein the optical fiber-based sensing membrane comprises: optical fiber; and a substrate, wherein the optical fiber is integrated in the substrate in a pattern of a plurality of coils, wherein, to form the pattern of the plurality of coils, the optical fiber is placed on the substrate multiple times in a first circular shape to form a first coil, and continues to be placed multiple times in a second circular shape to form a second coil, and After forming the second coil, the optical fiber doubles back onto a common path with the first coil and then continues to be placed on the substrate in additional circular shapes to form additional coils having additional common paths, wherein the common paths of the first and second coils and the additional common paths of the additional coils enable the optical fiber-based sensing film to provide accurate temperature measurements; and A thermal or mechanical property associated with the device is determined via the fiber-optic based sensing film.

13. The method according to claim 12, wherein: The total number of the plurality of coils to be formed on the substrate is determined based on the total length of the optical fiber required for a specific response.

14. The method according to claim 12, wherein: The apparatus includes a battery pack of an electric vehicle, and the mechanical characteristic includes at least one of strain or vibration of the battery pack.

15. The method according to claim 12, wherein: The fiber-optic-based sensing film includes a three-dimensional (3D) layout to match the corresponding 3D monitoring area layout of the device.

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