Sensing device

Abstract

Provided herein is technology relating to sensing and particularly, but not exclusively, to fiber optic devices for sensing strain and related methods and systems for detecting contact between an apparatus and a person or other object.

Description

[0001]SENSING DEVICE CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application No. 63 / 531,477, filed August 8, 2023, which is incorporated by reference herein in its entirety. FIELD Provided herein is technology relating to sensing and particularly, but not exclusively, to fiber optic devices for sensing strain and related methods and systems for detecting contact between an apparatus and a person or other object. BACKGROUND Machines and apparatuses often have moving parts that may contact and injure a human or other animal, or that may contact and damage an object. Accordingly, the art is in need of technologies that sense contact between moving machine or apparatus components and a human, animal, or object to minimize the risk of injury and / or damage to the human, animal, or object. SUMMARY Accordingly, provided herein is technology relating to pressure and / or temperature sensing and particularly, but not exclusively, to fiber optic devices for sensing contact and / or temperature changes and related methods and systems for detecting contact between an apparatus or portion or component thereof and a person or other object. In particular, the technology described herein relates to a pressure and / or temperature sensing device for machine surfaces. In an exemplary embodiment, the sensing device comprises a fiber optic cable comprising a number of fiber Bragg gratings and the fiber optic cable is provided within a layered membrane comprising stiff and pliable layers, e.g., as further described below and shown in the figures. In some embodiments, the sensing device is approximately 4 mm thick. In some embodiments, the sensing device may be attached to a surface, e.g., a surface of a machine or apparatus. In some embodiments, the sensing device provides a contact-sensing (e.g., force-sensing, pressure-sensing) surface. In some embodiments, the sensing device provides a temperature-sensing surface. Accordingly, in some embodiments, the technology provides embodiments of a device (e.g., a sensing device). In some embodiments, the device comprises a layer of material; a fiber optic cable coupled to the layer of material, the fiber optic cable including a first portion, a second portion, and a Fiber Bragg Grating (FBG) portion positioned between the first portion and the second portion; and a protrusion positioned between the layer of material and the FBG portion. In some embodiments, the first portion and the second portion extend along a cable axis; and wherein the cable axis extends through the protrusion. In some embodiments, the device further comprises a substrate coupled to the layer of material, wherein the layer of material is positioned between the fiber optic cable and the substrate. In some embodiments, the device further comprises an adhesive positioned between the layer of material and the fiber optic cable. In some embodiments, the layer of material is elastically deformable. In some embodiments, the layer of material is a foam. In some embodiments, the device further comprises a first block coupled to the first portion and a second block coupled to the second portion. In some embodiments, the FBG portion and the protrusion are positioned between the first block and the second block. In some embodiments, the device further comprises an external layer coupled to the first block and the second block. In some embodiments, the protrusion is positioned between the external layer and the layer of material. In some embodiments, the protrusion includes a channel, and wherein the FBG portion is at least partially positioned within the channel. Further embodiments of the technology relate to an assembly. For example, in some embodiments, the technology provides an assembly comprising a component; a first sensing device coupled to the component, wherein the first sensing device includes a first fiber optic cable with a first Fiber Bragg Grating (FBG) portion; a second sensing device coupled to the component; wherein the second sensing device includes a second fiber optic cable with a second FBG portion, wherein at least one of the first FBG portion and the second FBG portion is strained in response to an external contact of the component. In some embodiments, the component includes a planar surface, and the first sensing device and the second sensing device are coupled to the planar surface. In some embodiments, the component includes a non-planar surface, and the first sensing device and the second sensing device are coupled to the non-planar surface. Additional embodiments relate to using sensing devices. For example, in some embodiments, methods are provided that comprise energizing a medical device; detecting a touch or a temperature change with a sensing device coupled to the medical device; and deenergizing the medical device in response to detecting the touch or the temperature change. In some embodiments, the medical device is a medical scanner. Some portions of this description describe the embodiments of the technology in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. Certain steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In some embodiments, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all steps, operations, or processes described. In some embodiments, systems comprise a computer and / or data storage provided virtually (e.g., as a cloud computing resource). In particular embodiments, the technology comprises use of cloud computing to provide a virtual computer system that comprises the components and / or performs the functions of a computer as described herein. Thus, in some embodiments, cloud computing provides infrastructure, applications, and software as described herein through a network and / or over the internet. In some embodiments, computing resources (e.g., data analysis, calculation, data storage, application programs, file storage, etc.) are remotely provided over a network (e.g., the internet; and / or a cellular network). Embodiments of the technology may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes and / or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. Additional embodiments will be apparent to persons skilled in the relevant art based on the teachings contained herein. BRIEF DESCRIPTION OF THE DRAWINGS The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. These and other features, aspects, and advantages of the present technology will become better understood with regard to the following drawings. FIG. 1A is a drawing of a sensing device. FIG. 1B is a drawing of a sensing device shown in an isometric view and showing a reference coordinate system. FIG. 1C is a drawing of a sensing device showing in the inset an enlarged portion of the sensing device. FIG. 1D is a drawing of a sensing device showing exemplary dimensions of sensing device components as described hereinbelow. FIG. 2A is a drawing of a sensing device. FIG. 2B is a drawing of a sensing device shown in an isometric view and showing a reference coordinate system. FIG. 2C is a drawing of a sensing device showing in the inset an enlarged portion of the sensing device. FIG. 2D is a drawing of a sensing device showing exemplary dimensions of sensing device components as described hereinbelow. FIG. 2E is a drawing of a sensing device comprising integrated components and a channel for the fiber optic cable. FIG. 3A is a drawing of a multi-sensor comprising a plurality of sensing devices. FIG. 3B is a drawing of a multi-sensor attached to a concave curved surface. FIG. 3C is a drawing of a multi-sensor attached to a convex curved surface. FIG. 4A is a drawing of a multi-sensor comprising a plurality of sensing devices. FIG. 4B is a drawing of a multi-sensor attached to a concave curved surface. FIG. 4C is a drawing of a multi-sensor attached to a convex curved surface. FIG. 5A is a drawing of a front view of a bore cover for a computerized tomography scanner. FIG. 5B is a drawing of a top view of a bore cover for a computerized tomography scanner. FIG. 5C is a drawing of a bottom view of a bore cover for a computerized tomography scanner. FIG. 5D is a drawing of a left view of a bore cover for a computerized tomography scanner. FIG. 5E is a drawing of a right view of a bore cover for a computerized tomography scanner. FIG. 5F is a drawing of a back view of a bore cover for a computerized tomography scanner. FIG. 5G is a drawing of a first isometric view of a bore cover for a computerized tomography scanner. FIG. 5H is a drawing of a second isometric view of a bore cover for a computerized tomography scanner. FIG. 5I is a drawing of a first isometric view of a bore cover for a computerized tomography scanner showing an internal surface and an external surface of the bore cover. FIG. 5J is a photograph of a bore cover for a computerized tomography scanner. FIG. 5K is a photograph of a bore cover for a computerized tomography scanner showing a multi-sensor affixed to an internal surface of the bore cover. FIG. 6 is a plot of sensor response to force. A multi-sensor is affixed to an internal surface and forces of 20, 40, and 56 pound-feet are applied opposite the sensors on the external surface. FIG. 7A is a drawing of a sensing device. FIG. 7B is a drawing of a sensing device shown in an isometric view and showing a reference coordinate system. FIG. 7C is a drawing of a sensing device showing in the inset an enlarged portion of the sensing device. FIG. 8A is a drawing of a sensing device. FIG. 8B is a drawing of a sensing device showing in the inset an enlarged portion of the sensing device. It is to be understood that the figures are not necessarily drawn to scale, nor are the objects in the figures necessarily drawn to scale in relationship to one another. The figures are depictions that are intended to bring clarity and understanding to various embodiments of apparatuses, systems, and methods disclosed herein. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Moreover, it should be appreciated that the drawings are not intended to limit the scope of the present teachings in any way. DETAILED DESCRIPTION Provided herein is technology relating to sensing and particularly, but not exclusively, to fiber optic devices for sensing contacts and / or temperature and related methods and systems for detecting contact between an apparatus and a person or other object. In this detailed description of the various embodiments, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the embodiments disclosed. One skilled in the art will appreciate, however, that these various embodiments may be practiced with or without these specific details. In other instances, structures and devices are shown in block diagram form. Furthermore, one skilled in the art can readily appreciate that the specific sequences in which methods are presented and performed are illustrative and it is contemplated that the sequences can be varied and still remain within the spirit and scope of the various embodiments disclosed herein. All literature and similar materials cited in this application, including but not limited to, patents, patent applications, articles, books, treatises, and internet web pages are expressly incorporated by reference in their entirety for any purpose. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which the various embodiments described herein belongs. When definitions of terms in incorporated references appear to differ from the definitions provided in the present teachings, the definition provided in the present teachings shall control. The section headings used herein are for organizational purposes only and are not to be construed as limiting the described subject matter in any way. Definitions To facilitate an understanding of the present technology, a number of terms and phrases are defined below. Additional definitions are set forth throughout the detailed description. Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment, though it may. Furthermore, the phrase “in another embodiment” as used herein does not necessarily refer to a different embodiment, although it may. Thus, as described below, various embodiments of the invention may be readily combined, without departing from the scope or spirit of the invention. In addition, as used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and / or” unless the context clearly dictates otherwise. The term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of “a”, “an”, and “the” include plural references. The meaning of “in” includes “in” and “on.” As used herein, the terms “about”, “approximately”, “substantially”, and “significantly” are understood by persons of ordinary skill in the art and will vary to some extent on the context in which they are used. If there are uses of these terms that are not clear to persons of ordinary skill in the art given the context in which they are used, “about” and “approximately” mean plus or minus less than or equal to 10% of the particular term and “substantially” and “significantly” mean plus or minus greater than 10% of the particular term. As used herein, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges. As used herein, the disclosure of numeric ranges includes the endpoints and each intervening number therebetween with the same degree of precision. For example, for the range of 6–9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0–7.0, the numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated. As used herein, the suffix “-free” refers to an embodiment of the technology that omits the feature of the base root of the word to which “-free” is appended. That is, the term “X-free” as used herein means “without X”, where X is a feature of the technology omitted in the “X-free” technology. For example, a “calcium-free” composition does not comprise calcium, a “mixing-free” method does not comprise a mixing step, etc. Although the terms “first”, “second”, “third”, etc. may be used herein to describe various steps, elements, compositions, components, regions, layers, and / or sections, these steps, elements, compositions, components, regions, layers, and / or sections should not be limited by these terms, unless otherwise indicated. These terms are used to distinguish one step, element, composition, component, region, layer, and / or section from another step, element, composition, component, region, layer, and / or section. Terms such as “first”, “second”, and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, composition, component, region, layer, or section discussed herein could be termed a second step, element, composition, component, region, layer, or section without departing from technology. As used herein, the word “presence” or “absence” (or, alternatively, “present” or “absent”) is used in a relative sense to describe the amount or level of a particular entity (e.g., component, action, element). For example, when an entity is said to be “present”, it means the level or amount of this entity is above a pre-determined threshold; conversely, when an entity is said to be “absent”, it means the level or amount of this entity is below a pre-determined threshold. The pre-determined threshold may be the threshold for detectability associated with the particular test used to detect the entity or any other threshold. When an entity is “detected” it is “present”; when an entity is “not detected” it is “absent”. As used herein, an “increase” or a “decrease” refers to a detectable (e.g., measured) positive or negative change, respectively, in the value of a variable relative to a previously measured value of the variable, relative to a pre-established value, and / or relative to a value of a standard control. An increase is a positive change preferably at least 10%, more preferably 50%, still more preferably 2-fold, even more preferably at least 5-fold, and most preferably at least 10-fold relative to the previously measured value of the variable, the pre- established value, and / or the value of a standard control. Similarly, a decrease is a negative change preferably at least 10%, more preferably 50%, still more preferably at least 80%, and most preferably at least 90% of the previously measured value of the variable, the pre- established value, and / or the value of a standard control. Other terms indicating quantitative changes or differences, such as “more” or “less,” are used herein in the same fashion as described above. As used herein, a “system” refers to a plurality of real and / or abstract components operating together for a common purpose. In some embodiments, a “system” is an integrated assemblage of hardware and / or software components. In some embodiments, each component of the system interacts with one or more other components and / or is related to one or more other components. In some embodiments, a system refers to a combination of components and software for controlling and directing methods. For example, a “system” or “subsystem” may comprise one or more of, or any combination of, the following: mechanical devices, hardware, components of hardware, circuits, circuitry, logic design, logical components, software, software modules, components of software or software modules, software procedures, software instructions, software routines, software objects, software functions, software classes, software programs, files containing software, etc., to perform a function of the system or subsystem. Thus, the methods and apparatus of the embodiments, or certain aspects or portions thereof, may take the form of program code (e.g., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, flash memory, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the embodiments. In the case of program code execution on programmable computers, the computing device generally includes a processor, a storage medium readable by the processor (e.g., volatile and non-volatile memory and / or storage elements), at least one input device, and at least one output device. One or more programs may implement or utilize the processes described in connection with the embodiments, e.g., through the use of an application programming interface (API), reusable controls, or the like. Such programs are preferably implemented in a high-level procedural or object-oriented programming language to communicate with a computer system. However, the program(s) can be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language, and combined with hardware implementations. As used herein, the term “structured to [verb]” means that the identified element or assembly has a structure that is shaped, sized, disposed, coupled, and / or configured to perform the identified verb. For example, a member that is “structured to move” is movably coupled to another element and includes elements that cause the member to move or the member is otherwise configured to move in response to other elements or assemblies. As such, as used herein, “structured to [verb]” recites structure and not function. Further, as used herein, “structured to [verb]” means that the identified element or assembly is intended to, and is designed to, perform the identified verb. As used herein, the term “associated” means that the elements are part of the same assembly and / or operate together or act upon / with each other in some manner. For example, an automobile has four tires and four hub caps. While all the elements are coupled as part of the automobile, it is understood that each hubcap is “associated” with a specific tire. As used herein, the term “coupled” refers to two or more components that are secured, by any suitable means, together. Accordingly, in some embodiments, the statement that two or more parts or components are “coupled” shall mean that the parts are joined or operate together either directly or indirectly, e.g., through one or more intermediate parts or components. As used herein, “directly coupled” means that two elements are directly in contact with each other. As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. Accordingly, when two elements are coupled, all portions of those elements are coupled. A description, however, of a specific portion of a first element being coupled to a second element, e.g., an axle first end being coupled to a first wheel, means that the specific portion of the first element is disposed closer to the second element than the other portions thereof. Further, an object resting on another object held in place only by gravity is not “coupled” to the lower object unless the upper object is otherwise maintained substantially in place. That is, for example, a book on a table is not coupled thereto, but a book glued to a table is coupled thereto. As used herein, the term “removably coupled” or “temporarily coupled” means that one component is coupled with another component in an essentially temporary manner. That is, the two components are coupled in such a way that the joining or separation of the components is easy and does not damage the components. Accordingly, “removably coupled” components is readily uncoupled and recoupled without damage to the components. As used herein, the term “operatively coupled” means that a number of elements or assemblies, each of which is movable between a first position and a second position, or a first configuration and a second configuration, are coupled so that as the first element moves from one position / configuration to the other, the second element moves between positions / configurations as well. It is noted that a first element is “operatively coupled” to another without the opposite being true. As used herein, the term “rotatably coupled” refers to two or more components that are coupled in a manner such that at least one of the components is rotatable with respect to the other. As used herein, the term “translatably coupled” refers to two or more components that are coupled in a manner such that at least one of the components is translatable with respect to the other. As used herein, the term “temporarily disposed” means that a first element or assembly is resting on a second element or assembly in a manner that allows the first element / assembly to be moved without having to decouple or otherwise manipulate the first element. For example, a book simply resting on a table, e.g., the book is not glued or fastened to the table, is “temporarily disposed” on the table. As used herein, the term “correspond” indicates that two structural components are sized and shaped to be similar to each other and is coupled with a minimum amount of friction. Thus, an opening which “corresponds” to a member is sized slightly larger than the member so that the member may pass through the opening with a minimum amount of friction. This definition is modified if the two components are to fit “snugly” together. In that situation, the difference between the size of the components is even smaller whereby the amount of friction increases. If the element defining the opening and / or the component inserted into the opening are made from a deformable or compressible material, the opening may even be slightly smaller than the component being inserted into the opening. With regard to surfaces, shapes, and lines, two, or more, “corresponding” surfaces, shapes, or lines have generally the same size, shape, and contours. As used herein, a “path of travel” or “path,” when used in association with an element that moves, includes the space an element moves through when in motion. As such, any element that moves inherently has a “path of travel” or “path.” As used herein, the statement that two or more parts or components “engage” one another shall mean that the elements exert a force or bias against one another either directly or through one or more intermediate elements or components. Further, as used herein with regard to moving parts, a moving part may “engage” another element during the motion from one position to another and / or may “engage” another element once in the described position. Thus, it is understood that the statements, “when element A moves to element A first position, element A engages element B,” and “when element A is in element A first position, element A engages element B” are equivalent statements and mean that element A either engages element B while moving to element A first position and / or element A either engages element B while in element A first position. As used herein, the term “operatively engage” means “engage and move.” That is, “operatively engage” when used in relation to a first component that is structured to move a movable or rotatable second component means that the first component applies a force sufficient to cause the second component to move. For example, a screwdriver is placed into contact with a screw. When no force is applied to the screwdriver, the screwdriver is merely “coupled” to the screw. If an axial force is applied to the screwdriver, the screwdriver is pressed against the screw and “engages” the screw. However, when a rotational force is applied to the screwdriver, the screwdriver “operatively engages” the screw and causes the screw to rotate. Further, with electronic components, “operatively engage” means that one component controls another component by a control signal or current. As used herein, the term “number” shall mean one or an integer greater than one (e.g., a plurality). As used herein, in the phrase “[x] moves between its first position and second position,” or, “[y] is structured to move [x] between its first position and second position,” “[x]” is the name of an element or assembly. Further, when [x] is an element or assembly that moves between a number of positions, the pronoun “its” means “[x],” i.e., the named element or assembly that precedes the pronoun “its.” As used herein, a “radial side / surface” for a circular or cylindrical body is a side / surface that extends about, or encircles, the center thereof or a height line passing through the center thereof. As used herein, an “axial side / surface” for a circular or cylindrical body is a side that extends in a plane extending generally perpendicular to a height line passing through the center. That is, generally, for a cylindrical soup can, the “radial side / surface” is the generally circular sidewall and the “axial side(s) / surface(s)” are the top and bottom of the soup can. As used herein, the term “optically coupled” refers to coupling, attaching, or adhering two or more components such that the intensity of light passing from one component to the other component is not substantially reduced (e.g., due to differences in refractive indices between the regions). Accordingly, when a first component is optically coupled to a second component, light may be transmitted from the first component to the second component. As used herein, the term “substantially close refractive index” refers to a refractive index that differs from another refractive index by approximately 0.3 or less, e.g., 0.2 or 0.1. As used herein, and when used in reference to communicating data or a signal, “in electronic communication” includes both hardline and wireless forms of communication. As used herein, “in electric communication” means that a current passes, or can pass, between the identified elements. Being “in electric communication” is further dependent upon an element’s position or configuration. For example, in a circuit breaker, a movable contact is “in electric communication” with the fixed contact when the contacts are in a closed position. The same movable contact is not “in electric communication” with the fixed contact when the contacts are in the open position. As used herein, “in optical communication” means that light passes, or can pass, between the identified elements. As used herein, the term “light” refers to visible and non-visible electromagnetic radiation. As used herein, the term “sensing light” refers to a spectrum of electromagnetic radiation (“light”) provided at the terminal of a sensing device or multi-sensor device as described herein. As used herein, the term “reflected light” refers to a spectrum of electromagnetic radiation (“light”) reflected by an FBG and detected at the terminal of the sensing device or multi-senor device as described herein. In some embodiments, the sensing light is provided by a broadband optical source (e.g., light emitting diode (LED), edge- emitting light emitting diode (ELED), laser diode (LD), super-luminescent diode (SLD), surface-emitting light emitting diode (SLED), amplified spontaneous emission (ASE) source, semiconductor optical amplifier (SOA), etc.) The sensing light is typically provided in a spectrum covering approximately 80 or 90 nm (e.g., approximately 50 to 100 nm (e.g., 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 nm). In some embodiments, the sensing light is provided by a tunable diode laser. As used herein, the term “optical signal” refers to information carried by light, e.g., by a variation in the intensity or frequency of light. Description Provided herein is technology relating to sensing and particularly, but not exclusively, to fiber optic devices for sensing contacts and / or temperature and related methods and systems for detecting contact between an apparatus and a person or other object. Embodiments of systems comprising the fiber optic devices and methods of using the fiber optic devices to sense or predict contact of a surface with another object or an animal (e.g., a mammal (e.g., a primate (e.g., a human))) are also provided. Fiber Bragg gratings A Fiber Bragg grating (FBG) is a Bragg reflector that is constructed (e.g., “written” or “inscribed”) in a short segment of a fiber optic cable. The FBG reflects a small wavelength band (e.g., “narrowband”) of light centered on a characteristic peak wavelength (the “Bragg wavelength” or “Bragg reflection wavelength”) and transmits all other wavelengths of light. See, e.g., Hill (1978) “Photosensitivity in optical fiber waveguides: Application to reflection filter fabrication” Appl. Phys. Lett. 32: 647, incorporated herein by reference. The full-width half-maximum (FWHM) or bandwidth of the reflected spectrum band is typically 0.05 to 0.3 nm (e.g., 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, or 0.30 nm) and depends on the physical characteristics of the FBG (e.g., the grating length). When sensing light (e.g., from a spectrally broadband light source) is provided at the fiber terminal, the small spectral band (narrowband) of light at the Bragg wavelength is reflected back to the fiber terminal by the FBG (reflected light). The reflected light can be detected as a peak in intensity of the wavelength spectrum corresponding to the band of light reflected by the FBG. The reflected light at the Bragg wavelength and thus the peak detected at the fiber terminal is provided by: where λB is the Bragg wavelength, ne is the effective refractive index of the Bragg grating (e.g., the velocity of light through the fiber relative to the velocity of light in a vacuum), and Λ is the grating period. Many FBG technologies operate with ne equal to approximately 1.5 and FBGs having Bragg wavelengths centered around 1520 nm to 1600 nm. Thus, Λ is a distance that typically ranges from 505 nm to 535 nm. However, the technology provided herein is not limited to ranges of Λ from 505 nm to 535 nm and includes embodiments where Λ is outside the range of from 505 nm to 535 nm. The grating period or “pitch” of the FBG changes with changes in temperature and / or strain (e.g., longitudinal deformation) applied to the FBG. Further, strain and / or temperature may also change ne by the photo-elastic effect and thermo-optic effect, respectively. Consequently, the wavelength band reflected by the FBG and thus the peak in intensity of the wavelength spectrum changes (linearly and / or substantially or effectively linearly) as a function of temperature or strain applied to the region of the fiber comprising the FBG. Thus, detecting a shift in the wavelength of the reflected peak (∆λB) indicates that a temperature change or strain has been applied to the FBG; further, the magnitude of the shift in the wavelength of the reflected peak is proportional (e.g., linearly and / or substantially or effectively linearly) to the magnitude of the change in temperature or strain applied to the FBG. A typical value for the sensitivity of an FBG to strain is approximately 1 nm per millistrain at 1300 nm and approximately 0.64 nm per millistrain at 820 nm. A typical value for the response to a change in temperature is 0.01 nm per degree Kelvin at 1550 nm. A FBG is wavelength-encoded. That is, a FBG is written into a fiber optic cable using methods that produce a Bragg grating that reflects a defined and specified narrow band of wavelengths (e.g., to produce a reflected peak at a known wavelength). Accordingly, a number of FBGs can be written into a single optical fiber such that each FBG reflects a different, specified narrow band of non-overlapping wavelengths. By providing a broad spectrum of light at the fiber terminal (e.g., sensing light comprising wavelengths reflected by all FBGs present in the fiber), a number of reflected peaks are detected at the terminal where each peak corresponds to one FBG present in the fiber optic cable that reflects a different spectral band corresponding to the Bragg wavelength of the FBG. The signal received by the detector is wavelength encoded and wavelength division multiplexing may be used to assign each characteristic wavelength to a FBG with one-to-one correspondence. A shift in a peak indicates a change in temperature or strain applied to the FBG associated with the wavelength of the shifted peak. Accordingly, one may identify the position on the fiber optic cable where the temperature change or strain is applied by identifying the wavelength of the shifted peak and thus identifying the FBG associated with the shifted wavelength and the known location of the identified FBG within the fiber. A fiber comprising a number of FBG thus provides a multiplex technology for sensing changes in temperature and / or strain applied to the fiber at multiple locations. In some embodiments, a fiber optic cable comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) FBGs. In some embodiments, a fiber comprises 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) FBGs. In some embodiments, a fiber comprises 1– 100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) FBGs. Spacing between each Bragg wavelength is typically approximately 2 nm (e.g., 1.5 to 3.0 nm (e.g., 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, or 3.00 nm)). The detector thus receives a spectrum comprising a combination of the individual FBG reflected spectra. Further, optical switches may be used (e.g., micro-electromechanical systems-based optical switches) to provide a multi-channel system. For instance, time-division- multiplexing may be used to interrogate multiple fibers comprising multiple FBGs and thus provide FBG sensing networks comprising hundreds and multiples hundreds of FBGs. In some embodiments, a MEMS switch is provided in a 1×2, 1×4, 1×8, 1×16, 1×32, or 1×64 format. The fundamentals of FBGs and methods for producing optical fibers comprising FBG that reflect a defined and specific wavelength band of light are described, e.g., in Hill and Meltz (1997) “Fiber Bragg Grating Technology Fundamentals and Overview” Journal of Lightwave Technology 15(8): 1263–76; Meltz et al. (1989) “Formation of Bragg gratings in optical fibers by a transverse holographic method” Optics Letters 14(15): 823–25, each of which is incorporated herein by reference. Applications of strain and temperature measurement with FBGs are described, e.g., in Kreuzer (2006) “Strain measurement with fiber Bragg grating sensors” HBM, Darmstadt, S2338-l.0, incorporated herein by reference. Methods for peak tracking are described in, e.g., Tosi (2017) “Review and Analysis of Peak Tracking Techniques for Fiber Bragg Grating Sensors” Sensors (Basel) 17(10): 2368, incorporated herein by reference. Sensing device In some embodiments, the technology provides a sensing device. For example, e.g., as shown in FIG. 1A, the technology provides a sensing device 100 comprising an external layer 110; a number of blocks 121, 122; a layer of material 130; a fiber optic cable 160 comprising a fiber Bragg grating (FBG) 170; and a protrusion 150. The fiber optic cable 160 extends along a cable axis 900, and the cable axis 900 extends through the protrusion 150. The fiber optic cable 160 includes a first portion and a second portion. The FBG 170 is positioned between the first portion and the second portion. The protrusion 150 is positioned between the layer of material 130 and the FBG 170. FIG. 1C shows a portion of the sensing device 100 shown in FIG. 1A and is enlarged to show the fiber optic cable 160, FBG 170, protrusion 150, layer of material 130, and blocks 121, 122. FIG.1C also shows the external layer 110. The layer of material 130 is compressible upon an application of a force to the layer of material 130 and the layer of material 130 returns to a non-compressed state after removal of the force. In some embodiments, the sensing device comprises an optional substrate 140. In some embodiments, the substrate 140 is the surface of an apparatus or machine. In some embodiments, the substrate 140 is a stiff layer that is a component of the sensing device 100. In some embodiments, the substrate 140 is attached to the surface of an apparatus or machine. As shown in FIG. 1A and FIG. 1B, a coordinate system is used for reference herein in which the layers of the sensing device lie (e.g., substantially lie or essentially lie) in an X- Y plane and the Z axis is defined as being normal (e.g., substantially normal or essentially normal) to the surface of the external layer 110. The long dimension (“length”) of the sensing device is along the Y axis, the short dimension (“width”) is in the X dimension, and the thickness is in the Z dimension. The cable axis 900 is parallel (e.g., substantially and / or essentially parallel) to the Y axis. In embodiments in which the sensing device is attached to a curved surface, the Z axis at a region of the sensing device comprising the FBG passes through or near the FBG and passes through or near the center of the radius of curvature of the curved surface (see, e.g., FIG.3B and FIG.3C). As shown in FIG. 1A and FIG. 1C, the external layer 110 is coupled (e.g., directly coupled) to the blocks 121, 122. The fiber optic cable 160 comprising the FBG 170 is provided between the layer of material 130 and the blocks 121, 122 coupled (e.g., directly coupled) to the external layer 110. The protrusion 150 is provided between the portion of the fiber optic cable 160 comprising the FBG 170 and the layer of material 130. The portion of the fiber optic cable 160 comprising the FBG 170 and the FBG 170 engage the protrusion 150. The fiber optic cable 160 is coupled to the layer of material 130, e.g., by an adhesive 180 as shown in FIG.1C. In some embodiments, the protrusion 150 is held in place by the fiber optic cable 160. In some embodiments, the protrusion 150 is coupled to the layer of material 130 (e.g., with an adhesive) to hold the protrusion 150 in place. As shown in FIG. 1A and FIG. 1C, the blocks 121, 122 laterally flank the protrusion 150 and the FBG 170. That is, the blocks 121, 122 are provided in positions that are displaced in the Y dimension (e.g., a first block 121 is displaced in the negative Y direction and a second block 122 is displaced in the positive Y direction) from the protrusion 150 and the FBG 170 such that the protrusion 150 and the FBG 170 are provided in a gap between a first block 121 and a second block 122. The long dimension of the fiber optic cable 160 is provided generally in the Y direction of the sensing device 100. Regions of the fiber optic cable 160 that comprise an FBG 170 are displaced in the Z direction (e.g., the positive or negative Z direction) by the protrusion 150 within the gap between the first block 121 and the second block 122. Accordingly, the blocks 121, 122 engage the fiber optic cable 160 in regions that do not comprise an FBG 170 (in “FGB-free” regions of the fiber optic cable); and the FBG 170 engages the protrusion 150. See FIG.1A and FIG. 1C. A force (e.g., a pressure) having a component in the Z direction applied to the external layer 110 is transferred through one or both block(s) 121, 122 to the fiber optic cable 160 and to the layer of material 130. Further, as shown by Example 1, a force (e.g., a pressure) having a component in the Z direction applied to the device on a surface opposite the external layer, e.g., a force applied to the substrate 140 (e.g., a surface of an apparatus or machine and / or a stiff layer that is a component of the sensing device 100) from “below” the device produces a strain in the FBG 170. Thus, a force having a component in the Z direction (e.g., the positive or negative Z direction) applied to device 100 produces a deflection of the fiber optic cable 160 in the Z direction (and may produce a compression of the layer of material 130 in the Z direction), which produces a strain in the FBG 170. In some embodiments, the protrusion 150 amplifies a bend of the fiber optic cable 160 and change of length of the FBG 170. In some embodiments, the deflection in the Z direction (e.g., the positive or negative Z direction) is approximately 1 mm (e.g., 0.1 to 5 mm (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm)). For any force that produces a strain in FBG 170, the strain in the FBG 170 is detectable as a signal at the terminal of the fiber optic cable. Further, a change in temperature of the FBG may produce a strain in the FBG 170 that is detectable as a signal at the terminal of the fiber optic cable. The signal comprises a shifted wavelength of the reflected peak associated with the strained FBG and a magnitude of the shift in the wavelength of the reflected peak that is proportional (e.g., linearly and / or substantially or effectively linearly proportional) to the magnitude of the strain applied to the FBG. FIG. 1D shows exemplary dimensions of an embodiment of the sensing device, its components, and their relationships to each other. The length (as indicated by a–b and / or g–h of FIG. 1D) of each of the blocks is approximately 20 mm (e.g., 15 to 25 mm (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mm)). The lengths a–b and g–h may be the same or different. The diameter of the bending object (as indicated by d–e in FIG. 1D) is approximately 1 mm (e.g., 0.25 to 4 mm (e.g., 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, 2.75, 3.00, 3.25, 3.50, 3.75, or 4.00 mm)). The length of the portion of the fiber optic cable comprising the FBG (as indicated by c–f in FIG.1D) is approximately 2 mm (e.g., 1 to 3 mm (e.g., 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 mm)). The spacing between the edge of the block and the nearest edge of the portion of the fiber optic cable comprising the FBG (as indicated by b–c and / or f– g in FIG. 1D) is approximately 3 mm (e.g., 1.5 to 5 mm (e.g., 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm)). The lengths b–c and f–g may be the same or different. The thickness of the exterior layer (as indicated by i–j in FIG. 1D) is approximately 1 mm (e.g., 0.5 to 2.0 mm (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm)). The thickness of each of the blocks (as indicated by j–k in FIG. 1D) is approximately 1.5 mm (e.g., 1 to 2 mm (e.g., 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm)). The thickness of the fiber optic cable is approximately 0.15 mm (e.g., 0.10 to 0.20 mm (e.g., 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.20 mm)). The thickness of the layer of material (as indicated by l–m in FIG. 1D) is approximately 1 mm (e.g., 0.25 to 3.00 mm (e.g., 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, or 3.00 mm)). Accordingly, the thickness of the sensing device is generally less than 5.0 mm. In some embodiments, the thickness of the sensing device is less than 2.0 mm. In some embodiments, the thickness of the sensing device is less than 7.5 mm. In some embodiments, the thickness of the sensing device is less than 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1, 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1, or 2.0 mm. In some embodiments, the technology provides a sensing device that does not comprise an external layer (e.g., an external layer 110 as shown in FIG.1A to 1C). For example, e.g., as shown in FIG. 2A, the technology provides a sensing device 200 comprising a number of blocks 221, 222; a layer of material 230; a fiber optic cable 260 comprising a fiber Bragg grating (FBG) 270; and a protrusion 250. The fiber optic cable 260 extends along a cable axis 900, and the cable axis 900 extends through the protrusion 250. The fiber optic cable 260 includes a first portion and a second portion. The FBG 270 is positioned between the first portion and the second portion. The protrusion 250 is positioned between the layer of material 230 and the FBG 270. FIG. 2C shows a portion of the sensing device 200 shown in FIG. 2A and is enlarged to show the fiber optic cable 260, FBG 270, protrusion 250, layer of material 230, and blocks 221, 222. The layer of material 230 is compressible upon an application of a force to the layer of material 230 and the layer of material 230 returns to a non-compressed state after removal of the force. In some embodiments, the sensing device comprises an optional substrate 240. In some embodiments, the substrate 240 is the surface of an apparatus or machine. In some embodiments, the substrate 240 is a stiff layer that is a component of the sensing device 200. In some embodiments, the substrate 240 is attached to the surface of an apparatus or machine. Further, some embodiments do not comprise the blocks 221, 222. Some embodiments do not comprise the external layer 110 and do not comprise the blocks 221, 222. In such embodiments, substrate 240 provides an external layer. See FIG.7A–7D; FIG. 8A and FIG. 8B. As shown in FIG. 2A and FIG. 2B, a coordinate system is used for reference herein in which the layers of the sensing device lie (e.g., substantially lie or essentially lie) in an X- Y plane and the Z axis is defined as being normal (e.g., substantially normal or essentially normal) to the surface of layer of material 230 (and, optionally to the substrate 240). The long dimension (“length”) of the sensing device is along the Y axis, the short dimension (“width”) is in the X dimension, and the thickness is in the Z dimension. The cable axis 900 is parallel (e.g., substantially and / or essentially parallel) to the Y axis. In embodiments in which the sensing device is attached to a curved surface, the Z axis at a region of the sensing device comprising the FBG passes through or near the FBG and passes through or near the center of the radius of curvature of the curved surface (see, e.g., FIG.4B and FIG. 4C). As shown in FIG. 2A and FIG. 2C, the fiber optic cable 260 comprising the FBG 270 is provided between the layer of material 230 and the blocks 221, 222. The protrusion 250 is provided between the portion of the fiber optic cable 260 comprising the FBG 270 and the layer of material 230. The portion of the fiber optic cable 260 comprising the FBG 270 and the FBG 270 engage the protrusion 250. The fiber optic cable 260 is coupled to the layer of material 230, e.g., by an adhesive 280 as shown in FIG. 1C. In some embodiments, the protrusion 250 is held in place by the fiber optic cable 260, e.g., as shown for protrusion 150 and optical fiber 160 of the sensing device 100 shown in FIG. 1C. In some embodiments, the protrusion 250 is coupled to the layer of material 230 (e.g., with an adhesive) to hold the protrusion 250 in place. As shown in FIG. 2A and FIG. 2C, the blocks 221, 222 laterally flank the protrusion 250 and the FBG 270. That is, the blocks 221, 222 are provided in positions that are displaced in the Y dimension (e.g., a first block 221 is displaced in the negative Y direction and a second block 222 is displaced in the positive Y direction) from the protrusion 250 and the FBG 270 such that the protrusion 250 and the FBG 270 are provided in a gap between a first block 221 and a second block 222. The long dimension of the fiber optic cable 260 is provided generally in the Y direction of the sensing device 200. Regions of the fiber optic cable 260 that comprise an FBG 270 are displaced in the Z direction (e.g., the positive or negative Z direction) by the protrusion 250 within the gap between the first block 221 and the second block 222. Accordingly, the blocks 221, 222 engage the fiber optic cable 260 in regions that do not comprise an FBG 270 (in “FGB-free” regions of the fiber optic cable); and the FBG 270 engages the protrusion 250. See FIG.2A and FIG. 2C. A force (e.g., a pressure) having a component in the Z direction applied to the sensing device 200 is transferred through one or both block(s) 221, 222 to the fiber optic cable 260 and to the layer of material 230. Further, as shown by Example 1, a force (e.g., a pressure) having a component in the Z direction applied to the device on a surface opposite the external layer, e.g., a force applied to the substrate 240 (e.g., a surface of an apparatus or machine and / or a stiff layer that is a component of the sensing device 200) from “below” the device produces a strain in the FBG 270. For any force that produces a strain in FBG 270, the strain in the FBG 270 is detectable as a signal at the terminal of the fiber optic cable. Thus, a force having a component in the Z direction (e.g., the positive or negative Z direction) applied to the sensing device 200 produces a deflection of the fiber optic cable 260 in the Z direction (and may produce a compression of the layer of material 230 in the Z direction), which produces a strain in the FBG 270. In some embodiments, the protrusion 250 amplifies a bend of the fiber optic cable 260 and change of length of the FBG 270. In some embodiments, the deflection in the Z direction (e.g., the positive or negative Z direction) is approximately 1 mm (e.g., 0.1 to 5 mm (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm)). For any force that produces a strain in FBG 270, the strain in the FBG 270 is detectable as a signal at the terminal of the fiber optic cable. Further, a change in temperature of the FBG may produce a strain in the FBG 270 that is detectable as a signal at the terminal of the fiber optic cable. The signal comprises a shifted wavelength of the reflected peak associated with the strained FBG and a magnitude of the shift in the wavelength of the reflected peak that is proportional (e.g., linearly and / or substantially or effectively linearly proportional) to the magnitude of the strain applied to the FBG. FIG. 2D shows exemplary dimensions of an embodiment of the sensing device, its components, and their relationships to each other. The length (as indicated by a–b and / or g–h of FIG. 2D) of each of the blocks is approximately 20 mm (e.g., 15 to 25 mm (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mm)). The lengths a–b and g–h may be the same or different. The diameter of the bending object (as indicated by d–e in FIG. 2D) is approximately 1 mm (e.g., 0.25 to 4 mm (e.g., 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, 2.75, 3.00, 3.25, 3.50, 3.75, or 4.00 mm)). The length of the portion of the fiber optic cable comprising the FBG (as indicated by c–f in FIG.2D) is approximately 2 mm (e.g., 1 to 3 mm (e.g., 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 mm)). The spacing between the edge of the block and the nearest edge of the portion of the fiber optic cable comprising the FBG (as indicated by b–c and / or f– g in FIG. 2D) is approximately 3 mm (e.g., 1.5 to 5 mm (e.g., 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 mm)). The lengths b–c and f–g may be the same or different. The thickness of each of the blocks (as indicated by j–k in FIG. 2D) is approximately 1.5 mm (e.g., 1 to 2 mm (e.g., 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm)). The thickness of the fiber optic cable is approximately 0.15 mm (e.g., 0.10 to 0.20 mm (e.g., 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.20 mm)). The thickness of the layer of material (as indicated by l–m in FIG. 2D) is approximately 1 mm (e.g., 0.25 to 3.00 mm (e.g., 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, or 3.00 mm)). Accordingly, the thickness of the sensing device is generally less than 5.0 mm. In some embodiments, the thickness of the sensing device is less than 2.0 mm. In some embodiments, the thickness of the sensing device is less than 7.5 mm. In some embodiments, the thickness of the sensing device is less than 5.0, 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4.0, 3.9, 3.8, 3.7, 3.6, 3.5, 3.4, 3.3, 3.2, 3.1, 3.0, 2.9, 2.8, 2.7, 2.6, 2.5, 2.4, 2.3, 2.2, 2.1, or 2.0 mm. As shown in FIG. 2E, in some embodiments, the sensing device 200 comprises an integrated component 290 that comprises the blocks and the protrusion. As shown in FIG. 2E, the sensing device 200 comprising the integrated component 290 comprises a protrusion comprising a channel 291 that is structured to accommodate the fiber optic cable 260 over the protrusion and a channel 292 structured to accommodate the fiber optic cable 260 under the blocks. While FIG. 2E shows the fiber optic cable layered over the blocks for clarity and to show the path of the fiber optic cable 260, the sensing device 200 comprising an integrated component 290 comprises the fiber optic cable 260 in the channel 292 and passing under the blocks. In some embodiments, the integrated component 290 is made from a bendable or pliable material so that the entire bottom surface of the sensing device comprising integrated component 290 or a multi-sensor device comprising a plurality of sensing devices 200 comprising an integrated component 290 can be adhered to a curved surface. As shown in FIG. 3A, embodiments provide a multi-sensor 300 comprising a plurality of sensing devices 100. While the multi-sensor 300 shown in FIG. 3A comprises three sensor devices 100, the technology is not limited to a multi-sensor 300 comprising three sensor devices 100. For example, in some embodiments, the multi-sensor 300 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) sensing devices 100. In some embodiments, the multi-sensor 300 comprises 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) sensing devices 100. In some embodiments, the multi-sensor 300 comprises 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensing devices 100. As discussed above, the spacing between each Bragg wavelength of the FBGs provided in the fiber optic cable is typically approximately 2 nm (e.g., 1.5 to 3.0 nm (e.g., 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, or 3.00 nm)). In some embodiments, a multi-sensor is pre-strained to improve sensitivity. In some embodiments, the technology provides a plurality of multi-sensors 300 and each multi-sensor 300 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensor devices 100 as described above. For example, in some embodiments, the technology provides 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) multi-sensors 300 and each multi-sensor 300 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensor devices 100 as described above. In some embodiments, the multi-sensor is attached to a flat, planar surface. In some embodiments, the multi-sensor is attached to a curved surface, e.g., as shown in FIG. 3B and FIG. 3C. In some embodiments, a multi-sensor is attached in a pre-strained state to improve sensitivity. Similarly, as shown in FIG. 4A, embodiments provide a multi-sensor 400 comprising a plurality of sensing devices 200. While the multi-sensor 400 shown in FIG. 4A comprises three sensor devices 200, the technology is not limited to a multi-sensor 400 comprising three sensor devices 200. For example, in some embodiments, the multi-sensor 400 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10) sensing devices 200. In some embodiments, the multi-sensor 400 comprises 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20) sensing devices 200. In some embodiments, the multi-sensor 400 comprises 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensing devices 200. As discussed above, the spacing between each Bragg wavelength of the FBGs provided in the fiber optic cable is typically approximately 2 nm (e.g., 1.5 to 3.0 nm (e.g., 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95, 2.00, 2.05, 2.10, 2.15, 2.20, 2.25, 2.30, 2.35, 2.40, 2.45, 2.50, 2.55, 2.60, 2.65, 2.70, 2.75, 2.80, 2.85, 2.90, 2.95, or 3.00 nm)). In some embodiments, a multi-sensor is pre-strained to improve sensitivity. In some embodiments, the technology provides a plurality of multi-sensors 400 and each multi-sensor 400 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensor devices 200 as described above. For example, in some embodiments, the technology provides 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) multi-sensors 400 and each multi-sensor 400 comprises 1–10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), 1–20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20), or 1–100 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100) sensor devices 200 as described above. In some embodiments, the multi-sensor is attached to a flat, planar surface. In some embodiments, the multi-sensor is attached to a curved surface, e.g., as shown in FIG. 4B and FIG. 4C. See also FIG. 5K. In some embodiments, a multi-sensor is attached in a pre- strained state to improve sensitivity. Embodiments provide that the multi-sensor 300 or 400 may be attached to an internal and / or to an external surface. See, e.g., FIG.5I showing an external surface 510 and an internal surface 520 of a bore cover 500 for a computerized tomography scanner. FIG. 5K is a photograph showing a multi-sensor 300 / 400 attached to an external surface of a bore cover 500 of a computerized tomography scanner. As shown by Example 1, embodiments of the technology provided herein were attached to the internal surface of a component of an apparatus and forces applied to the external surface of the component were detected by the multi-sensor, by translation of the force through the component to the multi-sensor. In some embodiments, the sensing devices provided herein (e.g., a sensing device 100 or a sensing device 200) comprises a fiber optic cable (e.g., a fiber optic cable 160 or a fiber optic cable 260) that comprises silica. In some embodiments, the sensing devices provided herein (e.g., a sensing device 100 or a sensing device 200) comprises a fiber optic cable (e.g., a fiber optic cable 160 or a fiber optic cable 260) that comprises plastic. Without being bound by theory it is contemplated that optical fibers comprising a plastic are more appropriate for use with x-ray technologies (e.g., such as computerized tomography) than are optical fibers comprising a silica material. In some embodiments, the blocks comprise a plastic; in some embodiments, the layer of material comprises an open or closed cell foam. In some embodiments, the protrusion comprises a plastic or a metal wire. As shown in FIG. 7A, embodiments of the technology provide a sensing device 700 comprising a layer of material 730; a fiber optic cable 760 comprising a fiber Bragg grating (FBG) 770; and a protrusion 750. The layer of material 730 is compressible upon an application of a force to the layer of material 730 and the layer of material 730 returns to a non-compressed state after removal of the force. In some embodiments, the sensing device comprises an optional substrate 740. In some embodiments, the substrate 740 is the surface of an apparatus or machine. In some embodiments, the substrate 740 is a stiff layer that is a component of the sensing device 700. In some embodiments, the substrate 740 is attached to the surface of an apparatus or machine. Similar to other embodiments described herein, FIG. 7B shows an embodiment of the technology and a coordinate system. FIG.7C shows an inset of the technology (e.g., showing an adhesive 780). In some embodiments, an adhesive component comprises both the adhesive 780 and the layer of material 730. See, e.g., the Examples. As shown in FIG. 8A, embodiments of the technology provide a sensing device 800 comprising a fiber optic cable 860 comprising a fiber Bragg grating (FBG) 870; a protrusion 850; and a substrate 840. In some embodiments, the substrate 840 is the surface of an apparatus or machine. In some embodiments, the substrate 840 is a stiff layer that is a component of the sensing device 800. In some embodiments, the substrate 840 is attached to the surface of an apparatus or machine. Similar to other embodiments described herein, FIG. 8C shows an inset of the technology (e.g., showing an adhesive 880 affixing the components of the sensing device 800 to the substrate). Embodiments as shown in FIG. 7A and 8A may be provided in a multi-sensor as described herein (e.g., as shown in FIG.3A–3C and 4A–4C, wherein the sensing device 700 or 800 replaces the sensing device 100 or 200). Systems In some embodiments, the technology provides systems comprising a sensing device. In some embodiments, systems comprise a sensing device 100 comprising an external layer 110; a number of blocks 121, 122; a layer of material 130; a fiber optic cable 160 comprising a fiber Bragg grating (FBG) 170; and a protrusion 150. In some embodiments, systems comprise a sensing device 200 comprising a number of blocks 221, 222; a layer of material 230; a fiber optic cable 260 comprising a fiber Bragg grating (FBG) 270; and a protrusion 250. In some embodiments, the technology provides systems comprising a multi-sensor 300 comprising a plurality of sensing devices 100 (e.g., a plurality of sensing devices 100, where each sensing device 100 comprises an external layer 110; a number of blocks 121, 122; a layer of material 130; a fiber optic cable 160 comprising a FBG 170; and a protrusion 150). In some embodiments, the technology provides systems comprising a multi-sensor 400 comprising a plurality of sensing devices 200 (e.g., a plurality of sensing devices 200, where each sensing device 200 comprises a number of blocks 221, 222; a layer of material 230; a fiber optic cable 260 comprising a FBG 270; and a protrusion 250). Embodiments of systems comprise an interrogator optically coupled to a sensing device as described herein or to a multi-sensor as described herein. The interrogator comprises a laser source (e.g., a tunable diode laser) and a photodetector (e.g., a spectrophotometer). The interrogator is configured to perform interferometry by shining a sensing light along the fiber optic cable and detecting reflected light reflected by the FBG. The interrogator outputs a signal based on interferometry performed on the reflected light. The interrogator may be configured to use wavelength division multiplexing to measure strain at different locations of the optical cable of the sensing device. Typically, interrogators provide a sensing light having a spectrum covering approximately 50–100 nm (e.g., 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, or 120 nm). Further, the reflected light comprises a peak having a full width at half maximum value (FWHM) of approximately 0.1 nm (e.g., 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, or 0.20 nm). In use, the interrogator or software monitors a number of ranges (windows) of wavelengths within which the peaks are present. Typically, each window is approximately 2 nm (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 nm). Each peak shifts within its respective window as the strain in the FΒG changes. Typically, a peak movement of approximately 1 pm (e.g., 0.5 to 5.0 pm (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 pm)) is caused by approximately 1 microns (e.g., 0.5 to 5.0 microns (e.g., 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 microns)) of strain sensitivity. Assuming a conventional interrogator provides a sensing light having a 100-nm spectrum and monitors 2-nm spectral windows, a fiber optic comprising multiple FBGs used with this interrogator can theoretically comprise 100 nm / 2 nm = 50 sensors and associated peak windows. However, a fiber optic comprising multiple FBGs typically provides space between windows to provide separation of peaks. Accordingly, in some embodiments, technologies provide a multi-sensor comprising approximately 20 FBGs in a fiber chain with 10 mm of space between each FBG. Exemplary commercially available interrogators include, e.g., a FAZT-I4G optical interrogator (Faz Technology) and Interrogator model number FBGX100, type SM800, wide band (Micronor FiSens). The FBG-Scan 90X (FBGS) can multiplex up to 40 sensors per channel with 0.8-nm spacing from 1510 nm to 1590 nm. The model I4G from Optics11 has four channels that can each multiplex 30 sensors. The WaveCapture FBG Interrogator (Advanced Energy) has either a 40-nm or 80-nm range with one, four, or sixteen channels. Most interrogator units are configured to operate using light in the third window for optical fiber transmission near 1500 nm. This range is also known as the “C-band” and is commonly used for communications. However, some interrogator units in the first window (near 800 nm) or second window (near 1300 nm). The first window finds use in technologies comprising plastic core fibers. In some embodiments, systems further comprise a signal processing device in communication with the interrogator. The signal processing device may be configured to process the signal output by the interrogator to determine a location on a fiber optic cable at which a strain is occurring or has occurred. The signal processing device may be configured to process the signal output by the interrogator to estimate a magnitude of the strain at the location. The signal processing device may be configured to process the signal output by the interrogator and monitor changes in frequency of the signal output by the interrogator. In some embodiments, systems comprise a surface (e.g., a component comprising a surface (e.g., a planar or curved surface)). In some embodiments, the sensing device is affixed directly to the surface. In some embodiments, the sensing device is affixed to an external surface (e.g., a surface exposed to the environment and / or that experiences contacts by other objects or humans (e.g., a patient-accessible surface)). In some embodiments, the sensing device is affixed to an internal surface (e.g., a surface that encloses an internal volume of an apparatus and that is substantially not exposed to the environment and does not usually experience contacts by other objects or humans (e.g., a patient-inaccessible surface)). In some embodiments, the component is a bore cover for a computerized tomography scanner. See, e.g., FIG. 5A to 5I and Example 1. In some embodiments, systems comprise an interlock. For example, in some embodiments, systems comprise an interlock that stops the movement of an apparatus, machine, device, or component thereof when a force is sensed by a sensor and / or multi- sensor described herein. Accordingly, embodiments provide a system comprising an apparatus (e.g., a computerized tomography scanner), a sensor and / or multi-sensor as described herein, and an interlock configured to stop movement of the apparatus (e.g., the computerized tomography scanner) when a force is applied to the sensor and / or multi- sensor. In some embodiments, the sensor and / or multi-sensor is affixed to a surface of the apparatus. In some embodiments, the sensor and / or multi-sensor is affixed to an internal surface of the apparatus. In some embodiments, the sensor and / or multi-sensor is affixed to an external surface of the apparatus. In some embodiments, systems comprise a motor engaged with an apparatus and configured to move the apparatus. In some embodiments, systems comprise a power supply configured to provide power to a motor engaged with the apparatus. See, e.g., U.S. Pat. App. Ser. No. 17 / 535,091 (MULTI-AXIS MEDICAL IMAGING), which is incorporated herein by reference. Embodiments of the technology comprise an apparatus as described in U.S. Pat. App. Ser. No.17 / 535,091 to which is affixed a sensor and / or multi-sensor as described herein. In some embodiments, an interlock is configured to stop the flow of electricity to a motor engaged with an apparatus when a force is applied to a sensor or a multi-sensor. In some embodiments, the force is measured and the interlock stops the movement of an apparatus or component thereof if the force is greater than a defined threshold. In some embodiments, systems comprise an alerting component (e.g., a sound-making device, a light, a vibration-creating device) that produces an alert (e.g., a sound, a light, a vibration) when a force is applied to a sensor or a multi-sensor. A plurality of fasteners may be used to affix the fiber optic cable directly to the surface. In some embodiments, an adhesive finds use in affixing the fiber optic cable to a surface. The surface may comprise a longitudinally extending linear channel or groov in which the fiber optic cable is positioned. In some embodiments, systems comprise a microprocessor (e.g., a computer). In some embodiments, systems comprise a storage device. In some embodiments, steps of a method are implemented in software code, e.g., a series of procedural steps instructing a computer and / or a microprocessor to produce and / or transform data. In some embodiments, software instructions are encoded in a programming language, e.g., BASIC, Java, C, C++, C#, Objective-C, MATLAB, Mathematica, Python, R, PHP, Ruby, Perl, Object Pascal, Swift, Scala, Common Lisp, .NET, Visual Basic, or Smalltalk. In some embodiments, one or more steps or components are provided in individual software objects connected in a modular system. In some embodiments, the software objects are extensible and portable. In some embodiments, the objects comprise data structures and operations that transform the object data. In some embodiments, the objects are used by manipulating their data and invoking their methods. Accordingly, embodiments provide software objects that imitate, model, or provide concrete entities, e.g., for numbers, shapes, data structures, that are manipulable. In some embodiments, software objects are operational in a computer or in a microprocessor. In some embodiments, software objects are stored on a computer readable medium. In some embodiments, a step of a method described herein is provided as an object method. In some embodiments, data and / or a data structure described herein is provided as an object data structure. Some embodiments provide an object-oriented pipeline for measuring a force applied to a sensor as described herein and / or locating the position of a force applied to a sensor as described herein. Embodiments comprise use of code that produces and manipulates software objects, e.g., as encoded using a programming language. Methods In some embodiments, the technology provides methods. For example, in some embodiments, methods comprise providing a sensing device, e.g., a sensing device 100 comprising an external layer 110; a number of blocks 121, 122; a layer of material 130; a fiber optic cable 160 comprising a fiber Bragg grating (FBG) 170; and a protrusion 150; or a sensing device 200 comprising a number of blocks 221, 222; a layer of material 230; a fiber optic cable 260 comprising a fiber Bragg grating (FBG) 270; and a protrusion 250. In some embodiments, methods comprise providing a multi-sensor, e.g., a multi-sensor 300 comprising a plurality of sensing devices 100; or a multi-sensor 400 comprising a plurality of sensing devices 200. In some embodiments, providing the sensing device or the multi-sensing device comprising constructing the sensing device or the multi-sensing device. In some embodiments, methods comprise affixing the sensing device or multi-sensor device to a surface. In some embodiments, methods comprise affixing the sensing device or multi- sensor device to an internal surface (see, e.g., Example 1). In some embodiments, methods comprise affixing the sensing device or multi-sensor device to an external surface. In some embodiments, affixing the sensing device or multi-sensor device to a surface comprising pre-straining the sensing device or multi-sensor device. Embodiments of methods find use in sensing a force that causes a strain in a sensing device or a multi-sensor device. For example, in some embodiments, methods comprise providing a sensing device or multi-sensor device as described herein; providing a sensing light at a terminal of the sensing device or multi-sensor device; and monitoring reflected light at the terminal (e.g., using an interrogator). In some embodiments, the sensing light provided at the terminal comprises a broad spectrum. In some embodiments, methods comprise identifying a peak in a spectrum of the reflected light. In some embodiments, methods comprise associating the peak in the spectrum of the reflected light with a sensor of a multi-sensor device, e.g., to identify a location at which a force was applied to the multi- sensor device. In some embodiments, methods comprise measuring a change in temperature that induces a strain in a sensing device or a multi-sensor device. In some embodiments, methods comprise stopping a movement of an apparatus or a component of an apparatus when a force is applied to a sensing device or a multi-sensor device. In some embodiments, methods comprise producing an alert (e.g., producing a sound, producing a light, and / or producing a vibration) when a force is applied to a sensing device or a multi-sensor device. For example, in some embodiments, electrical power is provided to a medical device to energize the medical device. Thus, in some embodiments, methods comprise energizing a medical device. In some embodiments, a sensing device or multi-sensor device finds use in detecting contact or proximity (e.g., by sensing a temperature change) to a person or other object and interrupting power to the medical device to deenergize the medical device. Thus, in some embodiments, methods comprise detecting a touch or a temperature change with a sensing device coupled to the medical device; and deenergizing the medical device in response to detecting the touch or the temperature change. In some embodiments, the medical device is a medical imaging device (e.g., a computerized tomography scanner). Uses In some embodiments, the technology described herein finds use in detecting or measuring a force and / or a pressure applied to a surface upon which the sensing device described herein is attached. See, e.g., FIG.7A–7C, FIG.8A, FIG. 8B. In some embodiments, the fiber optic cable is attached in a pre-stretched state and may be stretched further, e.g., to provide a signal upon providing a strain in the FBG. The protrusion amplifies a bend in the fiber optic cable and FBG relative to the change of length of the FBG. See, e.g., the Examples. In the exemplary device constructed and tested, the protrusion and blocks had sufficient stiffness to maintain a substantially and / or effectively unchanged cross-sectional shape with application of a reasonable force. The substrate stiffness (flexural modulus) was approximately 5 to 10 Gpa. In some embodiments, the sensing devices and multi-sensors described herein provide sensing of at least 200 Newtons of force applied on the substrate layer. In some embodiments, the technology comprises a substrate having a defined bending moment and / or having a defined shape. For example, in some embodiments, the material and / or dimensions of the substrate are controlled to provide a substrate upon which to affix a sensing device or multi-sensor so that the sensing device or multi-sensor affixed to one side of the substrate detects a force of at least 200 N applied to the other side of the substrate. In some embodiments, the technology finds use in detecting or measuring a force and / or a pressure applied to an external layer (e.g., a top surface such as external layer 110) of a sensing device or multi-sensor as described herein. For example, in some embodiments, a sensing device or multi-sensor described herein is affixed to a stiff substrate. Accordingly, in some embodiments, the layer of material is sufficiently pliable to allow the fiber to be strained when a force or pressure is applied to the external layer. The stiffness of the external layer may vary depending on the application. In some embodiments, the stiffness of the external layer is approximately the same as the stiffness of the substrate. Accordingly, when the external layer is approximately the same as the stiffness of the substrate the sensing device senses pressures and forces applied to the sensing device at distances relatively far from the FBG (e.g., 1 to 10 cm or 10 to 100 cm). In some embodiments, the stiffness (flexural modulus) of the substrate is greater than the stiffness of the external layer, which is approximately 1 to 3GPa. Embodiments provide controlling the stiffness of the external layer to provide a range of distances over which the sensing device would sense a force or pressure. For example, in embodiments comprising a substrate having a stiffness greater than the stiffness of the external layer, the sensing device provides sensitive local sensing. Accordingly, embodiments provide an array or mesh of closely arranged sensing devices that find use in providing a spatially precise localization of forces applied to the array. For example, embodiments find use in measuring a distribution of a person’s weight on a surface. In some embodiments, the external layer conducts heat. In particular, FBG sensors are nearly equally sensitive to both temperature induced strain and pressure induced strain. Accordingly, embodiments provide that the sensing devices described herein detect and / or measure temperature changes at the surface of the external layer that cause a strain in the FBG. Thus, in some embodiments, the sensing devices and multi-sensors detect proximity of a heat-irradiating body (e.g., a person) that causes a temperature change in the device and strain in the FBG without a force or pressure being applied to the sensing device or multi-sensor. Embodiments also provide sensing strains caused by both a temperature change and a force or pressure. Although the disclosure herein refers to certain illustrated embodiments, it is to be understood that these embodiments are presented by way of example and not by way of limitation. Examples Example 1 During the development of embodiments of the technology described herein, experiments were conducted to test a multi-sensor attached to an internal surface of a fiberglass bore cover for a computerized tomography scanner. A multi-sensor was constructed comprising 10 sensing devices. Each sensing device comprised two blocks made from approximately 1- mm thick polylactic acid; a layer of material made from polyurethane foam mounting tape with acrylic adhesive on both sides (open-cell, 0.5 inch wide, 0.031 inch thick; McMaster- Carr catalog number 7626A213); a fiber optic cable comprising a fiber Bragg grating (FBG); and a protrusion made from 1.75-mm acrylonitrile butadiene styrene (ABS) plastic. The blocks were printed using a three-dimensional printer. The protrusion was cut from a spool of three-dimensional printing filament. It is contemplated that a range of material types (e.g., plastic, metal) having a range of material properties would be useful for the protrusion. The foam mounting tape was used to affix each sensing device to the interior surface of the bore cover as shown in FIG.5K. The sensing devices were affixed approximately 10 cm apart. The adhesive of the foam mounting tape provided good adhesion to the fiberglass surface of the bore cover and was easily removed without damaging the glass fibers. The tape remains pliable over temperature range in which the sensors are used. The blocks were adhered to the tape and did not interfere with the fiber optic cable or FBG. The fiberglass bore cover was constructed from flame-retardant unsaturated polyester resin (Polynt Composites 752-4423). This material was cast as a 0.125 inch-thick 33 / 67 glass resin composite at 77 degrees Fahrenheit. Typical mechanical properties of this material are a flexural strength (ASTM D790) of 33,400 psi, a flexural modulus (ASTM D790) of approximately 9.5 GPa, a tensile strength (ASTM D638) of 22,000 psi, a tensile modulus of 1,535,900 (ASTM D638), a tensile elongation of 2.07% (ASTM D638), and a Barcol (934 / 1) hardness (ASTM D2583) of 55. The multi-sensor was pre-tensioned to improve the strain measurements. In particular, each sensing device was affixed to produce a reading offset of approximately 40°C ± 20°C of equivalent strain in each sensing device. While experiments were conducted in which the multi-sensor was pre-tensioned, embodiments of the technology are provided that do not comprise a pre-tensioned sensing device or that do not comprise a pre-tensioned multi-sensor. Sensor number 7 came loose while attaching the covers to the system; accordingly, measurements recorded by sensor number 7 are not considered to be accurate. The corresponding point for each sensor location was marked on the external (e.g., patient-accessible) surface of the bore cover (e.g., the surface opposite the surface onto which the multi-sensor was mounted). Force was applied at each measurement point. Applied forces were measured using a force gauge. Forces of 20, 40, and 56 pound-feet were applied. Measurements of the 20 pound-feet force were performed in duplicate. FIG. 6 shows the strain measurement at each of sensors 1–6 and 8–10 upon application of the force. The response is shown as the equivalent in thermal expansion strain expressed in degrees Celsius. All publications and patents mentioned in the above specification are herein incorporated by reference in their entirety for all purposes. Various modifications and variations of the described compositions, methods, and uses of the technology will be apparent to those skilled in the art without departing from the scope and spirit of the technology as described. Although the technology has been described in connection with specific exemplary embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are obvious to those skilled in the art are intended to be within the scope of the following claims.

Claims

CLAIMS WE CLAIM:

1. A device comprising: a layer of material; a fiber optic cable coupled to the layer of material, the fiber optic cable including a first portion, a second portion, and a Fiber Bragg Grating (FBG) portion positioned between the first portion and the second portion; and a protrusion positioned between the layer of material and the FBG portion.

2. The device of claim 1, wherein the first portion and the second portion extend along a cable axis; and wherein the cable axis extends through the protrusion.

3. The device of claim 1, further comprising a substrate coupled to the layer of material; wherein the layer of material is positioned between the fiber optic cable and the substrate.

4. The device of claim 1, further comprising an adhesive positioned between the layer of material and the fiber optic cable.

5. The device of claim 1, wherein the layer of material is elastically deformable.

6. The device of claim 5, wherein the layer of material is a foam.

7. The device of claim 1, further comprising a first block coupled to the first portion and a second block coupled to the second portion.

8. The device of claim 7, wherein the FBG portion and the protrusion are positioned between the first block and the second block.

9. The device of claim 7, further comprising an external layer coupled to the first block and the second block.

10. The device of claim 9, wherein the protrusion is positioned between the external layer and the layer of material.

11. The device of claim 1, wherein the protrusion includes a channel, and wherein the FBG portion is at least partially positioned within the channel .

12. An assembly comprising: a component; a first sensing device coupled to the component; wherein the first sensing device includes a first fiber optic cable with a first Fiber Bragg Grating (FBG) portion; a second sensing device coupled to the component; wherein the second sensing device includes a second fiber optic cable with a second FBG portion; wherein at least one of the first FBG portion and the second FBG portion is strained in response to an external contact of the component.

13. The assembly of claim 12, wherein the component includes a planar surface, and the first sensing device and the second sensing device are coupled to the planar surface.

14. The assembly of claim 12, wherein the component includes a non-planar surface, and the first sensing device and the second sensing device are coupled to the non- planar surface.

15. A method comprising: energizing a medical device; detecting a touch or a temperature change with a sensing device coupled to the medical device; and deenergizing the medical device in response to detecting the touch or the temperature change.

16. The method of claim 15, wherein the medical device is a medical scanner.

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