Patent Description:
Optical fibers may be utilized in various industries such as communications, medical, military, broadcast, etc., to transmit data and for other related applications. Examples of applications may include sensing of temperature, mechanical strain, vibrations, and/or radiation dosage by utilizing an optical fiber. In this regard, principles of Raman, Rayleigh, and/or Brillouin scattering may be implemented for sensing of the temperature, mechanical strain, vibrations, and/or radiation dosage. <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose optical fiber based sensing arrangements.

The invention is defined by an optical fiber-based sensing membrane as recited in claim <NUM>. The invention is further defined by a method as recited in claim <NUM>.

According to one aspect, there is provided an optical fiber-based sensing membrane comprising: at least one optical fiber; and a substrate, wherein the at least one optical fiber is integrated in the substrate, the optical fiber-based sensing membrane includes, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout, the substrate includes a thickness and a material property, and the thickness and the material property are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, at least one of a thermal or a mechanical property associated with a device, or a radiation level associated with a device environment.

The device may include a battery pack of an electric vehicle.

The mechanical property may include at least one of strain or vibration.

The optical fiber-based sensing membrane layout may include a two-dimensional (2D) layout to match a corresponding 2D monitoring area layout of the device.

The optical fiber-based sensing membrane layout may include a three-dimensional (3D) layout to match a corresponding 3D monitoring area layout of the device.

The at least one optical fiber and the substrate may include a combined weight of between approximately <NUM>/m<NUM> to <NUM>/m<NUM>.

The at least one optical fiber and the substrate may include a combined thickness of less than approximately <NUM>.

The specified geometric pattern of the at least one optical fiber may include a circular geometric pattern.

The specified geometric pattern of the at least one optical fiber may include a spiral geometric pattern.

The specified geometric pattern of the at least one optical fiber may include a grid geometric pattern.

The specified geometric pattern of the at least one optical fiber may include a plurality of loops, and the at least one loop of the plurality of loops may be designated for calibration of the optical fiber-based sensing membrane.

The optical fiber-based sensing membrane layout may include a folding layout including at least one fold line.

According to a second aspect, there is provided a method comprising: determining a geometric pattern for integration of an optical fiber in a substrate; feeding the optical fiber towards a consolidation roller; and integrating, based on the geometric pattern and by the consolidation roller, the optical fiber onto the substrate
The method may further comprise: heating, by a heat source, the substrate to integrate the optical fiber onto the substrate.

The geometric pattern may include a circular geometric pattern, a spiral geometric pattern, or a grid geometric pattern.

According to a third aspect, there is provided a method comprising: embedding an optical fiber-based sensing membrane in a device or contiguously engaging the optical fiber-based sensing membrane with the device, wherein the optical fiber-based sensing membrane includes: at least one optical fiber; and a substrate, wherein the at least one optical fiber is integrated in the substrate, the optical fiber-based sensing membrane includes, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout, and the substrate includes a thickness and a material property; and ascertaining, via the embedded or the contiguously-engaged optical fiber-based sensing membrane, a thermal or a mechanical property associated with the device.

The geometric pattern may include a plurality of loops, and at least one loop of the plurality of loops may be designated for calibration of the optical fiber-based sensing membrane.

Features of the present disclosure are illustrated by way of examples shown in the following figures. In the following figures, like numerals indicate like elements, in which:.

For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples thereof. In the following description, details are set forth in order to provide an understanding of the present disclosure. It will be readily apparent however, that the present disclosure may be practiced without limitation to these details.

According to examples disclosed herein, an optical fiber-based sensing membrane may include at least one optical fiber, and a flexible substrate. The at least one optical fiber may be integrated in the flexible substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The flexible substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device. Examples of mechanical properties may include strain, vibration, and other such properties. The device may include, for example, a battery pack of an electric vehicle, or any other type of flat or curved structure that is to be monitored. Applications may include and not be limited to the monitoring of an energy storage plant based on batteries, monitoring of a nuclear power plant, and monitoring of defense equipment. Yet further, the substrate may be flexible or rigid. For example, with respect to a surface application of the sensing membrane on a device or an embedded application of the sensing membrane in a device, the optical fiber may be embedded in a rigid sensing membrane formed of a rigid substrate. According to another example, with respect to an optical fiber integrated in a molded part of a device such as a battery pack, the optical fiber may be embedded in a rigid sensing membrane formed of a rigid substrate.

With respect to fiber sensing generally, in some applications, an optical fiber may be utilized to monitor thermal and/or mechanical properties of a device. The device as utilized herein may be any type of machine, component, structure, etc., that is to be monitored. For example, for a device such as an electric vehicle battery pack that includes a plurality of battery cells, an optical fiber may be utilized to monitor thermal and/or mechanical properties of the battery pack. In this regard, embedding of an optical fiber directly into the device may not be feasible due to technical challenges related, for example, to laying, coiling, and/or attaching optical connectors each time an independent element (e.g., battery cell of the battery pack) of the device needs to be addressed.

In order to address at least the aforementioned technical challenges, the optical fiber-based sensing membrane disclosed herein may include at least one optical fiber integrated in a flexible substrate, and include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. According to examples disclosed herein, the optical fiber-based sensing membrane may utilize, for example, a Polyimide flex, or other such materials. In this regard, the optical fiber-based sensing membrane may also house components such as electrical tracks, sensors, and optical connectors to reduce an electrical harness associated with utilization of the optical fiber-based sensing membrane.

According to the invention, the optical fiber-based sensing membrane includes a layout with a coil with multiple layers.

According to examples disclosed herein, the optical fiber-based sensing membrane layout may include various types of layouts. For example, the layouts may include single or multiple optical fibers, single-end or dual-end access to the optical fibers, sliding loops, an optical fiber-based sensing membrane embedded in a battery cell insert, loops in series, an optical fiber embedded in battery molded parts, and other types of layouts.

According to examples disclosed herein, the optical fiber-based sensing membrane layout may include fiber loops to compensate for spatial resolution. Alternatively or additionally, the optical fiber-based sensing membrane layout may include path folding or partial path folding to compensate for optical fiber losses. A complete and perfect path folding may be achieved, for example, with a multicore fiber and a loopback optical element connecting the two cores in series at a distal end from an interrogator. The path folding technique may provide for the use of a Raman distributed temperature sensor that is single-ended, uses a single-source, and Anti-Stokes power information. This optical-engine configuration may utilize one laser, one photodiode and a three port multiplexer. This optical configuration may distinguish changes of losses from temperature based on implementation of the path-folding technique.

According to examples disclosed herein, the optical fiber-based sensing membrane may sense various types of parameters associated with a device. For example, the parameters may include temperature, strain, vibration, radiation dosage and other such parameters.

According to examples disclosed herein, different types of parameters sensed by the optical fiber-based sensing membrane may be used to generate different types of notifications or alarms. For example, a temperature variation that exceeds a specified temperature threshold may be used to generate a first type of notification or alarm. Similarly, a strain variation that exceeds a specified strain threshold (e.g., due to damage to the device) may be used to generate a second type of notification or alarm. The occurrence of so-called thermal runaway of a battery element may also be classified through the analysis of the temporal evolution and in particular the rate of change of temperature or strain.

According to examples disclosed herein, a number of elements of the device being monitored may be scaled without the need to add optical connections. For example, a length or configuration of the optical fiber-based sensing membrane may be modified as needed to account for an increased or a decreased number of elements being monitored. In this regard, one or more optical connections may be utilized for an optical fiber-based sensing membrane, and a size of the optical fiber-based sensing membrane may be increased or decreased as needed to address a plurality of devices, without the need to include an optical connection for each device. Thus a single optical connection may be implemented for a plurality of devices being monitored, thus reducing the potential of a fault associated with operation of the optical fiber-based sensing membrane.

According to examples disclosed herein, the devices that are being monitored may remain accessible, for example, for maintenance and other such activities, without being restricted by optics associated with the optical fiber-based sensing membrane. For example, the optical fiber-based sensing membrane may be configured to address a specified area of the device being monitored, leaving other areas of the device accessible for maintenance and other activities.

According to examples disclosed herein, the optical fiber-based sensing membrane may itself remain accessible, for example, for maintenance and other such activities. In this regard, the optical fiber-based sensing membrane may be configured to address a specified area of the device being monitored, leaving other areas of the optical fiber-based sensing membrane accessible for maintenance and other activities.

According to examples disclosed herein, the optical fiber-based sensing membrane may be implemented in a relatively harsh environment. For example, the environment of the optical fiber-based sensing membrane may include relatively significant temperature variations on the order of -<NUM> to <NUM>. The material used for the optical fiber-based sensing membrane may supersede a standard coating of optical fibers and continue to protect the optical fiber mechanically beyond the melting point of coating.

According to examples disclosed herein, the optical fiber-based sensing membrane layout may include a two-dimensional or a three-dimensional configuration. The two-dimensional configuration may include a plurality of optical fibers embedded in a substrate and configured as a two-dimensional plane structure to match a corresponding two-dimensional surface of a device that is to be monitored for temperature and/or strain variations, and/or vibrations. The three-dimensional configuration may 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 that is to be monitored for temperature and/or strain variations, and/or vibrations. Depending on the dimensions of the structure to be monitored, the budget loss of the fiber system and the dynamic range of the interrogator, distances may be covered in a single chain, or with multiple fibers in parallel that may be accessed sequentially from a single interrogator by means of an optical switch.

According to examples disclosed herein, the optical fiber-based sensing membrane may be utilized with an optical time-domain reflectometer (OTDR) to determine temperature and/or strain associated with a device. The OTDR may represent an optoelectronic instrument used to characterize an optical fiber, for example, of the optical fiber-based sensing membrane. The OTDR may inject a series of optical pulses into an optical fiber under test. Based on the injected optical pulses, the OTDR may extract, from the same end of the optical fiber in which the optical pulses are injected, light that is scattered or reflected back from points along the optical fiber. The scattered or reflected light that is gathered back may be used to characterize the optical fiber. For example, the scattered or reflected light that is gathered back may be used to detect, locate, and measure events at any location of the optical fiber. The events may include faults at any location of the optical fiber. Other types of features that may be measured by the OTDR include attenuation uniformity and attenuation rate, segment length, and location and insertion loss of connectors and splices.

The OTDR may be used to determine both Brillouin and Rayleigh traces for an optical fiber, for example, of the optical fiber-based sensing membrane. In one example, in an initial acquisition, Brillouin frequency shift and Brillouin power may be used to implement an absolute referencing of a Rayleigh reference trace (or traces). The Rayleigh reference trace may represent a reference point for subsequent measurements of the Rayleigh frequency shift. In this regard, the absolute referencing of the Rayleigh reference trace (or traces) may then be used to determine temperature and/or strain associated with an optical fiber by using the Brillouin frequency shift and the Rayleigh frequency shift in subsequent acquisitions.

According to examples disclosed herein, the optical fiber-based sensing membrane may be utilized with the OTDR to determine, based on distributed measurement, temperature, strain, and/or vibrations associated with a device, such as a battery pack.

According to examples disclosed herein, an optical fiber-based sensing membrane may include at least one optical fiber and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property. The thickness and the material property may be specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

For the optical fiber-based sensing membrane described above, the device may include a battery pack of an electric vehicle.

For the optical fiber-based sensing membrane described above, the mechanical property may include strain and/or vibration.

For the optical fiber-based sensing membrane described above, the optical fiber-based sensing membrane layout may include a two-dimensional (2D) layout to match a corresponding 2D monitoring area layout of the device. Alternatively or additionally, the optical fiber-based sensing membrane layout may include a three-dimensional (3D) layout to match a corresponding 3D monitoring area layout of the device.

For the optical fiber-based sensing membrane described above, the substrate may include Polyimide.

For the optical fiber-based sensing membrane described above, the optical fiber and the substrate may include a combined weight of between approximately <NUM>/m<NUM> to <NUM>/m<NUM>. The
For the optical fiber-based sensing membrane described above, the optical fiber and the substrate may include a combined thickness of less than approximately <NUM>.

For the optical fiber-based sensing membrane described above, the specified geometric pattern of the at least one optical fiber may 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 optical fiber may include a plurality of loops, and at least one loop of the plurality of loops may be designated for calibration of the optical fiber-based sensing membrane.

For the optical fiber-based sensing membrane described above, the optical fiber-based sensing membrane layout may include a folding layout including at least one fold line.

According to examples disclosed herein, a method may include determining a geometric pattern for integration of an optical fiber in a substrate, and feeding the optical fiber towards a consolidation roller. The method may further include integrating, based on the geometric pattern and by the consolidation roller, the optical fiber onto the substrate.

For the method described above, the method may further include heating, by a heat source, the substrate to integrate the optical fiber onto the substrate.

For the method described above, the geometric pattern may include a circular geometric pattern, a spiral geometric pattern, or a grid geometric pattern.

According to examples disclosed herein, a method may include embedding an optical fiber-based sensing membrane in a device or contiguously engaging the optical fiber-based sensing membrane with the device. The optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property. The method may further include ascertaining, via the embedded or the contiguously-engaged optical fiber-based sensing membrane, a thermal or a mechanical property associated with the device.

<FIG> illustrates an electric vehicle <NUM> including an optical fiber-based sensing membrane <NUM> (hereinafter referred to as "sensing membrane <NUM>"), according to an example of the present disclosure. Referring to <FIG>, the electric vehicle <NUM> may include the sensing membrane <NUM> disposed on a device, such as a battery pack <NUM>. As disclosed herein, the sensing membrane <NUM> may include an optical fiber-based sensing membrane layout (hereinafter referred to as "sensing membrane layout <NUM>") to accurately detect and measure temperature and/or strain variations, and/or vibrations, particularly for relatively small devices or for applications that need a relatively small spatial resolution.

The electric vehicle <NUM> may include other known components such as a thermal system <NUM> for cooling the vehicle, an auxiliary battery <NUM>, an onboard battery charger <NUM>, a vehicle transmission <NUM>, a charge port <NUM> for the battery pack <NUM>, a converter <NUM>, a power electronics controller <NUM>, and an electric traction motor <NUM>.

<FIG> illustrates the electric vehicle <NUM> of <FIG>, with the optical fiber-based sensing membrane <NUM> removed, according to an example of the present disclosure.

Referring to <FIG>, the battery pack <NUM> is shown with the sensing membrane <NUM> removed. In this regard, the battery pack <NUM> may include, as shown, a plurality of battery cells <NUM>. The sensing membrane <NUM> may be configured to sense thermal and/or strain variations, and/or vibrations associated with one, a few, or all of the battery cells <NUM> of the battery pack <NUM>.

<FIG> illustrates a diagrammatic view illustrating the optical fiber-based sensing membrane <NUM> in use, according to an example of the present disclosure.

Referring to <FIG>, the optical fiber-based sensing membrane <NUM> may include at least one optical fiber integrated in an adhesive substrate. In the example of <FIG>, as shown in the enlarged view, a plurality of optical fibers <NUM> may be integrated in an adhesive substrate <NUM>.

In the example of <FIG>, sensing membranes may be disposed on upper and lower surfaces of the battery pack <NUM> in the orientation of <FIG>. The battery pack <NUM> may include a plurality of battery cells. The battery cells may include, in the example shown, a cooling system <NUM> between upper and lower sets of battery cells in the orientation of <FIG>. The upper and lower sensing membranes, and the battery pack <NUM> may be enclosed in an enclosure, with upper and lower layers <NUM> and <NUM> of the enclosure shown in the orientation of <FIG>.

For the example of <FIG>, the sensing membrane <NUM> at <NUM> may be used to sense thermal and/or strain variations, and/or vibrations of upper battery cells at <NUM>, and the sensing membrane <NUM> at <NUM> may be used to sense thermal and/or strain variations, and/or vibrations of lower battery cells at <NUM>.

The adhesive substrate may include Polyimide, or another such material. The Polyimide material may provide the requisite durability with respect to vibrations associated with the battery pack <NUM> and/or other components that may be engaged with the sensing membrane <NUM>. Similarly, the Polyimide material may provide the requisite durability with respect to temperature variations associated with the battery pack <NUM> and/or other components, which may be on the order of -<NUM> to <NUM>, or include a greater range than -<NUM> to <NUM>. Further, the Polyimide material may provide the requisite flexibility associated with surface variations associated with the battery pack <NUM> and/or other components that may be engaged with the sensing membrane <NUM>. The Polyimide material may also be transparent, and thus provide sufficient transmission of light into the optical fiber for detection of light or an anomaly (e.g., a high temperature event) associated with the battery pack <NUM>.

The sensing membrane <NUM> may be of a light weight (e.g., <NUM> - <NUM>/m<NUM>). In this regard, the sensing membrane <NUM> may add minimal weight with respect to the device being monitored for thermal and/or strain variations, and/or vibrations.

The sensing membrane <NUM> may be approximately <NUM>, to thus minimize integration challenges with respect to the device being monitored for thermal and/or strain variations, and/or vibrations. In this regard, the optical fibers embedded in the sensing membrane <NUM> may be on the order of <NUM> in thickness. For the geometric patterns of optical fibers that include optical fiber crossings, such optical fibers may be treated after the sensing membrane is assembled, for example, by a combined action of pressure and temperature above the melting point of the optical fiber coating while the sensing membrane material is unaffected. Thus, the overall thickness of <NUM> may thus add minimal thickness associated with the battery pack <NUM>.

With continued reference to <FIG>, one example of a test set-up to evaluate performances of distributed temperature sensing systems based on distributed temperature sensing interrogator (DTS) <NUM> (also referred to herein as distributed temperature sensor) and fiber sensing membrane <NUM> is shown, and may be utilized to sense temperature, but also strain variations using a distributed strain sensing interrogator in place of the DTS. In this regard, the distributed temperature sensing interrogator <NUM>, which may include an OTDR, may be utilized with the various examples of the sensing membrane <NUM> as disclosed herein.

<FIG> illustrates a diagrammatic view illustrating an embedded distributed temperature sensor (eDTS) that utilizes the sensing membrane <NUM>, according to an example of the present disclosure.

Referring to <FIG>, an embedded distributed temperature sensor <NUM> may be positioned as shown for temperature sensing associated with an optical fiber <NUM>. For the example of <FIG>, the optical fiber <NUM> may include arbitrary paths as shown at <NUM>, and common paths as shown at <NUM>. Regarding common paths, the minimal configuration may include one common path joining the two optical fiber ends, but higher accuracy may be obtained in the loss compensation with multiple common paths evenly distributed over the total sensing length, and an even higher accuracy may be obtained with a complete folding of the entire optical fiber. The embedded distributed temperature sensor <NUM> may provide for continuous monitoring of a device, such as the battery pack <NUM>.

<FIG> and <FIG> respectively illustrate a temperature spatial resolution graph, and an example of spatial resolution, according to an example of the present disclosure.

Referring to <FIG>, spatial resolution may represent a smallest length of the temperature affected fiber optic sensor for which a distributed fiber optic 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, for a spatial resolution on the order of millimeters and including a delta of <NUM> may be utilized for monitoring cells, a spatial resolution on the order of centimeters and including a delta of <NUM> may be utilized for monitoring modules, and a spatial resolution on the order of meters and including a delta of <NUM> may be utilized for monitoring systems. In this regard, an example of a <NUM> temperature spatial resolution for a sensing fiber <NUM> is shown at <NUM>. Examples of spatial resolution are illustrated for different fiber coil length, for example, of <NUM> and <NUM>, <NUM> at <NUM>, and <NUM> at <NUM>. As shown at <NUM>, since the temperature spatial resolution is specified as <NUM>, the measurement at <NUM> shows a lower than <NUM>% temperature measurement. The measurement at <NUM> shows a greater than <NUM>% temperature measurement, and the measurement at <NUM> shows a <NUM>% temperature measurement.

Referring to <FIG>, with fiber sensing solutions of a specified spatial resolution, it may not be possible to monitor discrete temperature variations occurring on elements with smaller dimensions, and the loss calibration along an optical fiber may also be relatively complex. In this regard, as shown at <NUM>, if an optical fiber is in contact over a length that is less than the spatial resolution, an associated distributed temperature sensor may not measure an amplitude accurately. For example, as shown at <NUM>, if optical fiber <NUM> is in contact over a length that is less than the darkened area at <NUM> that represents a temperature spike, an associated distributed temperature sensor may not measure an amplitude accurately. In this regard, a spatial resolution of approximately <NUM> may be specified to ascertain a complete measurement of the temperature spike.

<FIG> illustrates further details of spatial resolution, according to an example of the present disclosure.

Referring to <FIG>, with respect to another example of spatial resolution, spatial resolution may represent a shortest length of an optical fiber which has to be subjected to a localized temperature step in order that a system (e.g., a distributed temperature sensor) returns approximately <NUM>% of the response (e.g., as shown at <NUM>). The <NUM>% response criteria may be applied to determine spatial resolution to thus consider a length required to monitor <NUM>% of a step change. Thus, as shown at <NUM>, if a temperature stimulus is shorter than the spatial resolution, the temperature event may be detected but not accurately measured. Thus, it is technically challenging to accurately detect and measure temperature, particularly for applications that include a relatively small spatial resolution, for example, on the order of millimeters or centimeters.

<FIG> illustrates the sensing membrane layout <NUM> including a coil with multiple layers according to the present invention as defined by the independent claims.

Referring to <FIG>, in order to address the aforementioned technical challenges associated with accurate detection and measurement of temperature and/or strain variations, and/or vibrations, particularly for relatively small devices or for applications that need a relatively small spatial resolution, in some examples, the sensing membrane layout <NUM> may include a total length of an optical fiber that is increased to a value that is higher than a spatial resolution of the associated fiber sensing solution. In this regard, in some examples, the sensing membrane layout <NUM> may include an optical fiber that is patterned in a coil as shown at <NUM> with single or multiple layers. The coils may be built according to different spooling techniques. As disclosed herein, the sensing membrane layout <NUM> may include an optical fiber or fibers with other geometric patterns. For example, as shown at <NUM>, if a fiber is folded back onto a common path, then these common paths where a seam temperature is shared, may allow for a precise measurement of the optical fiber loss that is needed for accuracy of a fiber sensing solution. Thus, the coiling as shown at <NUM> may provide for accurate temperature measurement, as shown at <NUM>. A number of the coils may be based on a total length that is needed for a specified spatial resolution as disclosed herein. For example, n coils that include a total length of x m may be utilized to provide a <NUM>% or higher response. Thus a number of the coils may be determined based on a total length needed for a specified response, and a diameter of each coil. In this regard, each coil of a set of coils may include equal or unequal diameters.

<FIG> and <FIG> illustrate further examples of the sensing membrane layout <NUM>, according to an example of the present disclosure.

Referring to <FIG>, as disclosed herein, the sensing membrane layout <NUM> may include an optical fiber or fibers with other geometric patterns. For example, geometric patterns may include loops as shown at <NUM>, a meander-line coil as shown at <NUM>, and spirals as shown at <NUM> and <NUM>. The loops as shown at <NUM> may represent a quasi-distributed two dimensional shape. The meander-line coil as shown at <NUM> may represent a distributed shape. Other types of shapes may include repetitive shapes with multiple loops, stacks of fiber loops, geometric patterns that include fiber crossing, square spirals, two dimensional spiral, three-dimensional spiral, etc. For the geometric pattern shown at <NUM>, various temperature or strain events may be detected, for example, at <NUM>, <NUM>, and <NUM>. In this regard, for the geometric pattern shown at <NUM>, various temperature or strain events may be detected across a single length of an optical fiber (e.g., at <NUM>) or across multiple lengths of the optical fiber (e.g., at <NUM> and <NUM>).

Referring to <FIG>, the sensing membrane layout <NUM> may include other types of geometric patterns that include an optical fiber without crossing as shown at <NUM>, an optical fiber with crossing as shown at <NUM>, fiber strands with optical fiber crossing as shown at <NUM>, and a replicated layout as shown at <NUM>.

<FIG> illustrates the sensing membrane layout <NUM> including sliding loops, according to an example of the present disclosure.

Referring to <FIG> and <FIG>, with respect to the geometric patterns of the sensing membrane layout <NUM>, the sensing membrane <NUM> may include a sliding loops arrangement as shown at <NUM>. An additional transverse triangle sliding movement with an amplitude of the order of several mm and a slope exceeding one optical fiber diameter for each loop may be applied to avoid accumulation of several optical fiber layers as apparent at top and bottom at <NUM>. Another solution to fiber accumulation may include a hybrid concentric spiral and sliding layout, with, for example, N concentric turns applied and a N times larger sliding step (compared to one chosen for the pure sliding loop pattern, and therefore with an equivalent spatial resolution). The repeated pattern may cover the entire surface to be monitored with a single layer, but as shown at <NUM>, the sensing membrane <NUM> may include multiple layers with an horizontal offset in the orientation of <FIG>, which may further increase the density of the optical fiber and associated spatial resolution of the sensor.

<FIG> illustrates the sensing membrane layout <NUM> including the sensing membrane <NUM> embedded in a battery cell insert, according to an example of the present disclosure.

Referring to <FIG> and <FIG>, the sensing membrane <NUM> of the various geometric patterns disclosed herein may be embedded in a battery cell insert of the battery pack <NUM>. For example, for the battery cells <NUM>, a battery cell insert <NUM> may be positioned on an upper surface of the battery cells in the orientation of <FIG>, and a battery cell insert <NUM> may be positioned on the lower surface of the battery cells. The battery pack <NUM> may further include a collector plate <NUM> positioned on an upper surface of the battery cell insert <NUM>, and a collector plate <NUM> positioned on a lower surface of the battery cell insert <NUM>. In this manner, as shown at <NUM>, the sensing membrane <NUM> may be embedded in battery cell inserts <NUM> and <NUM>.

<FIG> illustrates the sensing membrane layout <NUM> including loops in series, according to an example of the present disclosure.

Referring to <FIG> and <FIG>, with respect to monitoring of the battery pack <NUM>, the sensing membrane layout <NUM> may include loops in series as shown at <NUM>. In this regard, each loop may be used to address a single battery cell <NUM> of the battery pack <NUM>. In this manner, when a temperature, strain, and/or vibration event occurs at a battery cell such as battery cell <NUM>, <NUM>, or <NUM>, an associated loop may be used to detect a temperature, strain, and/or vibration event.

<FIG> illustrates further examples of the sensing membrane layout <NUM>, according to an example of the present disclosure.

Referring to <FIG> and <FIG>, the sensing membrane layout <NUM> may be applied to a variety of cell types. For example, as shown at <NUM>, the sensing membrane layout <NUM> may include a meander-line coil layout applied to a single pouch cell. As shown at <NUM>, for a stack of cells that form a module, the sensing membrane layout <NUM> may include a ribbon-layout applied to a stack of cells as shown at <NUM>. As shown at <NUM>, for the ribbon-layout shown at <NUM>, this layout is shown in an unfolded configuration at <NUM> and includes the sensing membrane <NUM> including fold areas <NUM>.

<FIG> illustrates the sensing membrane layout <NUM> including an optical fiber embedded in battery molded parts, according to an example of the present disclosure.

Referring to <FIG>, the sensing membrane layout <NUM> may include an optical fiber embedded in a device, such as molded parts of the battery pack <NUM>. For example, an optical fiber may be inserted in an insert or thermally conductive gap filler of the battery pack <NUM>. An example of an optical fiber inserted in an insert or thermally conductive gap filler of the battery pack <NUM> is shown at <NUM>. Other components associated with the battery pack <NUM> where an optical fiber or sensing membrane <NUM> may be inserted may include a battery pack sealing assembly at <NUM>, a thermal conductive adhesive at <NUM>, a structural adhesive at <NUM>, and/or a thermally conductive gap filler at <NUM>.

<FIG> illustrate dynamic temperature sensing measurements and associated calibrations, according to an example of the present disclosure.

Referring to <FIG>, the sensing membrane layout <NUM> as disclosed herein may include various loops and other geometric patterns. In this regard, depending on the geometric pattern, different calibration techniques may need to be applied with respect to loss distribution. For example, distributed temperature sensing measurements may incur errors due to differential attenuation. The same temperature may be interpreted as different temperatures depending on a position along an optical fiber. In this regard, calibration may be performed, for example, by utilizing reference zones, subjected to the same temperature, or subjected to a known absolute temperature. Different calibration methods may vary with measurement setup (e.g., single-ended, dual source, etc.).

Referring to <FIG>, with respect to distributed temperature sensor temperature calibration, for example, to compensate for loss, as shown at <NUM>, a plurality (e.g., two) reference loops may be superimposed, and are therefore subjected to the same temperature. In this regard, an absolute value (offset) may be calibrated during initiation of the temperature, strain, and/or vibration sensing.

Referring to <FIG>, with respect to distributed temperature sensor temperature calibration, for example, to compensate for loss, as shown at <NUM>, a plurality (e.g., two) reference loops may be superimposed, and are therefore subjected to the same temperature. In this regard, the calibration may be based on the reading of a dedicated sensor (e.g., a thermocouple as shown at <NUM>).

<FIG> illustrates a fiber grid overlay, according to an example of the present disclosure.

Referring to <FIG>, with respect to fiber grid overlay (e.g., temperature, pressure, strain, vibration sensing), the sensing membrane layout <NUM> including multiple optical fiber crossings may be utilized to either detect pressure, strain, vibration, and/or mechanical shock using distributed loss or strain. In this regard, for a pressure spot as shown at <NUM>, the multiple optical fiber crossings may increase a detection capability with respect to pressure, strain, vibration, and/or mechanical shock.

<FIG> illustrates a method of manufacturing the sensing membrane <NUM>, according to an example of the present disclosure.

Referring to <FIG> and <FIG>, the sensing membrane <NUM> that includes various examples of the sensing membrane layout <NUM> as disclosed herein may be manufactured as shown. For example, the sensing membrane <NUM> may include a substrate <NUM> that includes at least one optical fiber <NUM> provided in a geometric pattern as shown at <NUM>. The optical fiber <NUM> may be fed at <NUM>. A consolidation roller <NUM> may uniformly place the optical fiber <NUM> onto the substrate <NUM>. A heating source <NUM> may heat the substrate to a specified temperature to allow for embedding of the optical fiber <NUM> into the substrate <NUM>. In this manner, various geometric patterns as disclosed herein may be formed with respect to the sensing membrane layout <NUM>.

Claim 1:
An optical fiber-based sensing membrane (<NUM>) comprising:
at least one optical fiber (<NUM>); and
a substrate (<NUM>), wherein
the at least one optical fiber (<NUM>) is integrated in the substrate (<NUM>),
the optical fiber-based sensing membrane (<NUM>) includes, based on a specified geometric pattern of the at least one optical fiber (<NUM>), an optical fiber-based sensing membrane (<NUM>) layout, the specified geometric pattern includes a coil with multiple layers (<NUM>),
the substrate (<NUM>) includes a thickness and a material property, and
the thickness and the material property are specified to ascertain, via the at least one optical fiber (<NUM>) and based on the optical fiber-based sensing membrane layout (<NUM>), at least one of a thermal or a mechanical property associated with a device, or a radiation level associated with a device environment.