Displacement sensor, sensor tape, and sensor tape system

Abstract

A displacement sensor includes: a base including a fixed input mount; the displacement arm comprises a fixed end, and the fixed end fixes the displacement arm to the base; and a free end comprising: a displaceable input mount aligned with the fixed input mount wherein the displacement arm has one degree of freedom along a displacement axis perpendicular to the displacement arm to allow substantially linear translation of the free end of the displacement arm along the displacement axis; and a sensor configured to determine a displacement of the free end of the displacement arm along the displacement axis. The displacement sensor may be part of a sensor strip, such as a sensor strip for monitoring a state of a human subject, such as monitoring a breathing state. The sensor tape may be part of a sensor tape system.

Description

Background Technology

[0001] Currently, methods such as respiratory rate measurement and end-tidal carbon dioxide measurement are used to assess the health status, especially respiratory status, of human subjects. For subjects in certain clinical settings (such as postoperative care and / or intensive care), respiratory status is primarily monitored by pulse oximetry, which involves measuring peripheral oxygen saturation (SpO2) using a pulse oximeter probe suitable for the earlobe or fingertip.

[0002] These monitoring techniques come with some drawbacks and limitations. For example, end-tidal carbon dioxide measurement can be useful for monitoring anesthetized or oxygen-supplied subjects, but is quite inaccurate when used on non-oxygen-supplied subjects. Respiratory volume measurement, like the use of a respiratory rate meter, is somewhat unreliable because the results depend largely on the subject's effort during the test, and thus on other highly variable factors, such as the instructions received, understood, or able to follow during the measurement. Measuring peripheral oxygen saturation is relatively accurate and reproducible; however, decreased oxygen saturation is a marker only appearing at a relatively late stage in a series of events associated with the development of often fatal respiratory problems, limiting the possibility of applying effective therapeutic interventions with low side effects to the subjects.

[0003] Therefore, there is a need for technologies and devices for monitoring the respiratory status of subjects, enabling earlier and more reliable detection of respiratory deterioration episodes than currently possible. Furthermore, there is a need for improved devices for monitoring the respiratory status of human subjects with enhanced sensitivity. These and other needs are addressed through various aspects and embodiments of this disclosure, as described below.

[0004] Invention Summary A sensor band is provided, adapted to sense signals characterizing one or more respiratory parameters of a human subject performing at least one respiratory action. The sensor band includes: (a) a band having a longitudinal dimension adapted to encircle the chest of the subject, wherein the band is substantially inelastic. The band further includes: (b) a fastening device for directly or indirectly connecting a first point of the band to a second point of the band to secure the band around the chest of the subject; and (c) a sensing device, referred to herein as a first sensing device, attached to the band, the first sensing device being adapted to acquire and transmit signals characterizing one or more respiratory parameters of the subject, including tidal volume (Vt), inspiratory time (Ti), expiratory time (Te), total cycle time (Ttot), respiratory rate (RR), and / or work of breathing (WoB). The first sensing device is further characterized in that it is capable of sensing forces acting on the band, wherein said forces are generated by the expansion of the subject's chest caused by the subject's respiratory action.

[0005] Optionally, the sensor band includes a second sensing device adapted to sense the electrical activity of one or more muscles involved in the subject's breathing movements.

[0006] On the other hand, this disclosure provides the use of the sensor strip, such as for acquiring and transmitting signals characterizing one or more respiratory parameters selected from Vt, Ti, Te, Ttot, RR, WoB and / or any derivative thereof; and / or signals characterizing the electrical activity of one or more muscles involved in the respiratory movements of a subject.

[0007] On another front, methods for the use of sensor strips are provided.

[0008] In one aspect of the first sensing device of the sensor band, this disclosure provides a displacement sensor comprising: a base including a fixed input mount; a displacement arm including: a fixed end that secures the displacement arm to the base; and a free end including: a displaceable input mount aligned with the fixed input mount, wherein the displacement arm has one degree of freedom along a displacement axis perpendicular to the displacement arm to allow the free end of the displacement arm to perform substantially linear translation along the displacement axis; and a sensor configured to determine the displacement of the free end of the displacement arm along the displacement axis.

[0009] In another aspect, the sensor strip includes a displacement sensor and further includes a strap fastened at one end to a fixed input mount of the displacement sensor and at the opposite end to a displaceable input mount, wherein the strap is configured to transmit forces acting on the strap to the displaceable input mount, thereby causing translation of the free end of the displacement arm along the displacement axis. Preferably, according to this aspect, the sensor strip includes a displacement sensor configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the forces acting on the strap translated to the displaceable input mount.

[0010] In another aspect, the sensor band for monitoring a subject's respiration includes a displacement sensor. The sensor band also includes a strap configured to be applied around the subject's chest, the strap being fastened at one end to a fixed input mount of the displacement sensor and at the opposite end to a displaceable input mount. When the subject breathes, the strap is configured to transmit the force of expansion from the subject's chest to the displaceable input mount, thereby causing translation of the free end of the displacement arm along a displacement axis. Preferably, according to this aspect, the sensor band for monitoring respiration includes a displacement sensor configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the force acting on the strap translated to the displaceable input mount.

[0011] In another aspect, the sensor strip system includes a sensor strip, and further includes: a processor connected to a displacement sensor; and a power supply connected to the displacement sensor. Preferably, according to this aspect, the sensor strip system includes: a processor configured to determine one or more respiratory parameters based on the output of the displacement sensor and / or an electrical sensor.

[0012] Further aspects and features are disclosed in the detailed embodiments, drawings, and patent claims. Brief description of the attached diagram Figure 1 This is a simplified depiction of a human subject wearing a sensor band that is securely fastened around the chest.

[0014] Figure 2 A cross-section of a sensor belt according to one aspect is depicted, which includes a fastening device and a pretensioner.

[0015] Figure 3 An example of a first sensing device is shown, based on certain aspects.

[0016] Figure 4 A cross-section of a strap according to another aspect of a sensor belt is depicted, which includes a fastening device and a pretensioner; an EMG sensor as part of an example of a second sensing device is also shown.

[0017] Figure 5A , Figure 5B and Figure 5C One aspect of a first sensing device, which serves as an exemplary displacement sensor, is described.

[0018] Figure 6A and Figure 6B An example of a displacement sensor is depicted.

[0019] Figure 7A and Figure 7B An example of a displacement sensor is depicted.

[0020] Figure 8A and Figure 8B An example of a displacement sensor is depicted.

[0021] Figure 9 An example depicting one or more planar coils is shown.

[0022] Figure 10 An example of a sensor aspect of a displacement sensor is described.

[0023] Figure 11A and Figure 11B An example of a displacement sensor is depicted.

[0024] Figure 12An example of a sensor aspect of a displacement sensor is described.

[0025] Figure 13 An exemplary strain gauge is depicted.

[0026] Figure 14 This is a diagram of an exemplary bridge circuit.

[0027] Figure 15 The sensor belt system is described.

[0028] The accompanying figures in this article are not drawn to scale.

[0029] Detailed description In a first aspect, a sensor band is provided. The sensor band is adapted to sense signals characterizing one or more respiratory parameters of a human subject performing at least one respiratory action. The band includes: (a) a strap having a longitudinal dimension adapted to encircle the chest of the subject, wherein the strap is substantially inelastic. The band also includes: (b) a fastening device for directly or indirectly connecting a first point of the strap to a second point of the strap to secure the strap around the chest of the subject; and (c) a sensing device, referred to herein as a first sensing device, attached to the strap, the first sensing device being adapted to acquire and transmit signals characterizing one or more respiratory parameters of the subject, including tidal volume (Vt), inspiratory time (Ti), expiratory time (Te), total cycle time (Ttot), respiratory rate (RR), and / or work of breathing (WoB). The first sensing device is further characterized in that it is capable of sensing forces acting on the strap, wherein said forces are generated by the expansion of the subject's chest caused by the subject's respiratory action.

[0030] The sensor bands described herein enable highly accurate assessment of the health status of human subjects, particularly their lung and / or respiratory function, and allow for very early detection of any deterioration in a patient's respiratory system, as explained in more detail below.

[0031] The band includes a strap that is long enough to be worn around the chest of a human subject. Typically, the strap is flexible, allowing it to conform to the shape of the chest. Furthermore, due to its material, its structure, and / or its size, the strap is essentially non-elastic. This differs from elastic sensor bands and allows for more accurate measurement of the mechanical forces exerted by the subject during the inspiratory phase of breathing, during which the chest undergoes expansion. Because the strap is essentially non-elastic, these mechanical forces can be selectively measured by a first sensing device adapted to sense such forces acting on the strap.

[0032] In this context, essentially inelastic means that the length of the band does not increase significantly when it is tightened around the chest of a human subject during breathing. In some aspects, the length of the band between the first and second points increases by no more than about 5% during breathing, wherein the percentage is based on the resting length of the band between the first and second points. In some preferred aspects, the length increase does not exceed about 3%, or about 2%, or about 1%, respectively. It is also preferred that the length increase between the first and second points does not exceed about 3 cm, or about 2 cm, or about 1 cm, respectively, as measured as described above. This does not preclude the possibility of bands having a higher elongation rate (particularly when subjected to high tensile forces) than that that occurs when the band, as part of the band described herein, is tightened around the chest of a human subject performing breathing.

[0033] Potentially suitable strap materials are generally known to those skilled in the art. For example, woven polyester fibers used in automotive or aircraft seat belts can be used.

[0034] The strap can have any suitable width, for example, in the range of about 20 mm to about 100 mm. In other respects, the width is about 30 mm to about 80 mm, or about 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm or 70 mm respectively. In the context of strap width, the expression "about" preferably means ±5 mm.

[0035] The thickness of the strap can be selected with reference to the strap material and its structure. For some useful strap materials, a thickness in the range of about 0.5 mm to about 3 mm is considered useful. Other examples of potentially useful thicknesses are about 1 mm, about 1.2 mm, about 1.4 mm, about 1.6 mm, about 1.8 mm, or about 2 mm. In the context of strap thickness, the expression "about" should preferably be understood as ±0.2 mm.

[0036] As described above, the band includes a fastening device for directly or indirectly connecting a first point of the band to a second point of the band, allowing the band to be fastened around the chest of a human subject. In some aspects, the first or second point is located at or near one end of the band, and the other point is located at or near the other end of the band. Thus, the length of the band from the first point to the second point is sufficient to constitute a significant portion (e.g., about 60% or more, or about 70% or more) of the chest circumference of the fastening band.

[0037] For example, the fastening device may be directly attached to the first point at the first end of the strap, and near or at the opposite end, the fastening device may optionally be indirectly attached via one or more components of the first sensing device, or vice versa.

[0038] Any suitable type of fastening device can be used, including any combination of different types of fastening devices. For example, the fastening device may include a tongue-shaped member attached to a strap and a buckle member integrated into a housing that also holds the first sensing device.

[0039] As described above, the first sensing device is adapted to acquire and transmit signals characterizing one or more respiratory parameters of the subject. In particular, the sensing device is adapted to sense forces acting on the straps, generated by the expansion of the subject's chest caused by the subject's breathing movements. These forces generally act longitudinally on the straps relative to their orientation.

[0040] Respiratory parameters can be any of tidal volume (Vt), inspiratory time (Ti), expiratory time (Te), total cycle time (Ttot), respiratory rate (RR), and / or work of breathing (WoB). As used herein, Vt is understood as the volume of air moved into or out of the subject's lungs during each respiratory movement when breathing normally (i.e., without any effort to perform a deep breath, etc.). Ti is preferably understood as the time interval from the start of inspiratory flow to the start of expiratory flow during a respiratory movement. The primary duration of inspiratory time is the time it takes for actual positive airflow to enter the lungs, typically followed by a very short inspiratory pause without airflow that forms the second phase of Ti. Similarly, Te is preferably understood as the time interval from the start of expiratory flow to the start of inspiratory flow during a respiratory movement, including the short expiratory pause without airflow following the expiratory flow time. Ttot should be interpreted as the total time of a respiratory movement, measured, for example, from the start of expiratory flow in a given respiratory movement to the start of inspiratory flow in a subsequent respiratory movement. RR refers to the number of respiratory movements per minute. Work of breath, or WoB (sometimes also called work of breathing), in the case of non-oxygenated human subjects, should preferably be understood as the energy required for the subject's respiratory activity (i.e., for inhaling and exhaling air or breathing gases). WoB can be expressed as work per volume unit, such as joules per liter. Alternatively, WoB can be expressed as power, such as joules per minute.

[0041] In some preferred aspects, the signal obtained by the first sensing device relates to a combination of respiratory parameters. In some cases, optionally after appropriate calibration, the same raw signal as the signal obtained by the sensing device can be used to derive or characterize more than one respiratory parameter. In some preferred aspects, the first sensing device is adapted to obtain a signal characterizing WoB and at least one additional parameter selected from Vt, Ti, Te, Ttot, and RR. Such a signal can be generated in response to changes in force, deflection, motion, or any of these over time.

[0042] In some additional aspects, the first sensing device includes a member that is movable or deformable by force acting on a band due to the expansion of the subject's chest during a breathing action. In this context, the expression "movable or deformable" should be interpreted as movable and / or deformable; in other words, the corresponding member can be both movable and deformable by force. To make the movable or deformable member responsive to force, it is arranged between a first point and a second point of the band. More specifically, the movable or deformable member has a first end fixed to the first point of the band and a second end fixed to the second point of the band. In this context, the fixing can be direct or indirect. In other words, the first and second points are connected by means of the main portion of the substantially inelastic band and also via the movable or deformable member of the first sensing device to form a band capable of being securely fastened around the subject's chest, wherein the movable or deformable member moves or deforms in response to the expansion of the chest during a breathing action. Preferably, the movement or deformation of the movable or deformable member is reversed during the exhalation phase of the subject's breathing action.

[0043] In a further preferred embodiment, the first sensing device includes a housing that holds or accommodates a movable or deformable member. For example, the housing may hold the movable or deformable member such that one end (e.g., a first end or a second end) is immovably attached to the housing, while the other end is movable relative to the housing. For instance, a first point of the strap, a first end of the movable or deformable member, and the housing of the first sensing device may all be fixed to each other, while a second point of the strap may be fixed to a second end of the movable or deformable member but movable relative to the housing.

[0044] Optionally, the movable or deformable member is completely enclosed by the housing, such that the point of the strap movable relative to the housing can be at least partially inserted into the housing, for example, through an opening arranged in the housing. The shape and size of such an opening can be designed to guide the insertable portion of the strap and restrict or prevent lateral movement of the strap. Optionally, a guide member can be arranged within the housing to further restrict or prevent lateral movement of the inserted portion of the strap.

[0045] In some aspects, the movable or deformable component is or includes springs, such as disc springs, helical springs, compression springs, torsion springs, gas springs, or leaf springs. Optionally, two or more springs of the same or different types may be combined into the movable or deformable component. One or more springs may be made of any suitable material, such as metals, polymers, or composite materials, such as fiber-reinforced composites.

[0046] In some further preferred aspects, the movable or deformable member is a leaf spring or includes a leaf spring. In some preferred forms of the leaf spring, there are at least two leaves, particularly two metal leaves. In another aspect, the movable or deformable member is a leaf spring comprising two stainless steel leaves.

[0047] Furthermore, the movable or deformable component can be a leaf spring comprising two or more metal (such as stainless steel) leaves attached to each other to form a four-bar linkage. As used herein, a four-bar linkage is a closed-loop movable linkage mechanism comprising four components, sometimes referred to as links or links, connected in a loop by four joints. In the context of this invention, the joints are preferably configured such that the links move in a parallel plane, thereby forming a planar four-bar linkage. Two of the four links or bars can be represented by two leaves of a leaf spring, and the other two are auxiliary links. The advantage of this type of assembly is that it prevents or minimizes lateral movement of the leaves.

[0048] Furthermore, the first sensing device preferably includes a transducer adapted to generate an electrical signal in response to movement or deformation of a movable or deformable member. A transducer is generally understood as a device capable of converting a signal in one form of energy into a signal in another form of energy. For example, in this context, a transducer may be adapted to convert mechanical signals based on the movement and / or deformation of a leaf spring into electrical signals, which can then be transmitted and processed.

[0049] In some preferred aspects, the transducer is adapted to generate electrical signals without friction with the movable or deformable member. This arrangement offers the advantage of reducing noise associated with the electrical signals generated by the transducer. In some aspects, the electrical signals are generated without direct contact between the transducer and the movable or deformable member.

[0050] This can be achieved, for example, by a non-contact transducer device with a sensing sensor comprising at least one coil, wherein each coil is configured with a helical conductor arranged on a plane and having two flat surfaces, one of which forms a measuring surface that covers a measuring object arranged at a certain distance, depending on the movement of the measuring object parallel to the measuring surface. Furthermore, the sensor electronics supply alternating current to the sensing sensor and evaluate changes in alternating current caused by the measuring object. The measuring object is guided at a constant distance on the surface of the flat coil. The sensor electronics of the device are configured to detect attenuation changes caused by variations in the area of ​​the flat coil covered by the measuring object. Additionally, the measuring object affecting the measuring surface is conductive, or has a conductive target or measuring loop, and covers a coil area of ​​the flat coil, which can be geometrically predetermined based on the position of the target or measuring loop. The device is further characterized in that the rectangular measuring surface is diagonally divided into two triangular flat coils, whereby their inductance and ohmic resistance form one half of a bridge circuit, the other half of which is supplemented by resistors, thus creating a full bridge.

[0051] A potentially useful alternative type of transducer in the first sensing device is based on one or more strain gauges fixed to a movable or deformable member. In some aspects, the movable or deformable member is or includes a leaf spring, such as a spring comprising two or more metal plates, wherein at least one of the plates is equipped with at least one strain gauge. The strain gauges are not non-contact, but they do not generate undesirable friction when operating. Moreover, the strain gauges primarily respond to the deformation of the part to which they are attached (e.g., a leaf spring).

[0052] In some respects, two or more strain gauges are fixed to the surface of a movable or deformable member, such as to the surface of a metal leaf spring included in a leaf spring. In particular, the strain gauges should be arranged or fixed such that they respond to longitudinal deformation of the leaf spring. In this context, the longitudinal direction is the same as the longitudinal direction of the straps and the same direction in which the force generated by the expansion of the subject's chest due to respiratory movements acts on the movable or deformable member.

[0053] If one or more strain gauges are used as transducers to generate electrical signals in response to the mechanical deformation of one or more metal reeds, these strain gauges can also be arranged in a double-bending beam configuration. In such an assembly, two spring elements (i.e., reeds or beams) are connected via a rigid element. The strain gauges can be fixed to the surface of at least one reed, optionally at the location of the reed's maximum strain, but more preferably at a location not exceeding the maximum strain of the strain gauge.

[0054] In some further preferred aspects, the first sensing device includes a transmitter adapted to transmit the electrical signal generated by the transducer via wired or wireless means. The signal can be transmitted directly or after initial signal processing (i.e., amplification or filtering), which can be performed by additional electronic components arranged as part of the sensing device, for example, within an optional housing.

[0055] Signal transmission can typically occur from the sensing device to an external control unit that is not part of the sensor band claimed herein. Alternatively, the control unit can actually be incorporated into the sensor band. For example, the control unit can be integrated within the housing of the first sensing device. The control unit may include a central processing unit and other electronics necessary to perform further signal processing to calculate the aforementioned respiratory parameters or any parameters derived from them. The control unit may also include a display or associated with a display for displaying one or more parameters (which change over time) or messages related to the subject's state or the functionality of the sensor band.

[0056] In some aspects, the first sensing device may be arranged as part of a strip, such that it bridges or connects a first point and a second point. In related aspects, a fastening device is arranged for connecting the first point to the second point via the first sensing device. The fastening device may be associated with or integrated within the housing of the first sensing device.

[0057] In some preferred aspects, for example, the housing of the first sensing device includes: a first end fixed relative to a first point of the strap and a first end of the movable or deformable member; and a second end movable relative to a second point of the strap and a second end of the movable or deformable member. The second point of the strap can be connected to the second end of the movable or deformable member, for example, by a fastening device or a component thereof. For example, a tongue-shaped member can be fixed to the second point of the strap, and a buckle member can be fixed to the second end of the movable or deformable member, wherein the tongue-shaped member and the buckle member are securely but reversibly connected.

[0058] In some respects, the buckle component is secured to a movable or deformable component via a portion of a non-elastic strap. In other words, the strap can be interrupted by a fastening device.

[0059] In some further preferred aspects, the sensor band includes a pretensioner for adjusting the longitudinal extension of the band to the subject's chest circumference. The pretensioner can be a simple, manually adjustable device for pre-adjusting the effective length of the band, such as a slider, like a webbing buckle slider.

[0060] Providing power to the first sensing device can be achieved by connecting the sensing device to an external power source (e.g., using a suitable power cord). Alternatively, according to some preferred aspects, the sensor strip is arranged to house an internal power source. For example, the sensor strip may include a battery holder. Such a battery holder can be advantageously arranged within a housing that also holds a movable or deformable component, namely the housing of the first sensing device.

[0061] In some additional aspects, the sensor band includes a second sensing device, preferably adapted to sense the electrical activity of one or more muscles involved in the subject's breathing movements. This additional sensing device preferably includes at least one electronic amplifier and at least three skin electrodes arranged for performing surface electromyography (EMG). The electrodes are connected to the amplifier via wires sized to allow the electrodes to be positioned on the subject's skin independently of the band (i.e., independently of the band's exact location on the chest). The amplifier may optionally be housed within the housing of the first sensing device.

[0062] Electromyography (EMG) involves detecting the electrical potential generated when muscle cells are electrically activated or nerves are activated. EMG can be performed using needle sensors, but in the context of this invention, skin electrodes or surface electrodes are preferred.

[0063] The inclusion of a sensor band for a second sensing device is particularly advantageous because it allows for the simultaneous analysis and correlation of respiratory parameters derived from mechanical signals obtained through the first sensing device with electrical signals from the muscles involved in respiration, reflecting the degree of physiological stimulation required to generate the respiratory parameters. This analysis and correlation has been found to allow for a more accurate assessment of the health status of human subjects, particularly the respiratory system. Furthermore, the inventors have discovered that it enables the earlier detection of deterioration in health compared to conventional monitoring techniques.

[0064] In this context, human subjects may preferably be patients receiving postoperative care and / or intensive care. In particular, subjects may be patients at risk of developing pulmonary complications, such as postoperative pulmonary complications. As used herein, being at risk should be understood as being at increased risk compared to healthy human subjects.

[0065] In another aspect, this disclosure relates to the use of a sensor strip for monitoring a subject. More specifically, the sensor strip as described above can be used to acquire and transmit signals characterizing one or more respiratory parameters of a human subject. In particular, the respiratory parameters can be selected from Vt, Ti, Te, Ttot, RR, WoB, and / or any derivative thereof. Moreover, some preferred aspects relate to the use of a sensor strip including a second sensing device as disclosed above for acquiring and transmitting signals related to muscle electrical activity, particularly the electrical activity of one or more muscles involved in respiration.

[0066] In another aspect, this disclosure relates to a method for evaluating signals generated by a sensor band. This method includes: continuously and simultaneously (i) receiving from a first sensing device and / or a second sensing device and (ii) processing a plurality of signals characterizing one or more respiratory parameters and / or electrical muscle activity selected from Vt, Ti, Te, Ttot, RR, WoB. In other words, the signals are processed simultaneously while they are continuously received from the first sensing device and / or the second sensing device. This processing includes calculating one or more statistical variability measures of Vt, Ti, WoB, electrical muscle activity, or any ratio thereof. As used herein, continuous processing should be broadly interpreted to include both continuous and repetitive or iterative processing, such as when a particular calculation step is repeated at specific time intervals (e.g., every second or every 5 seconds).

[0067] The duration of continuous and simultaneous signal reception and processing can be selected based on the specific circumstances. Typically, this duration is at least about one minute. For example, the duration can be set in the range of about one minute to about 14 days. In some further preferred aspects, the duration is about one hour to about 7 days. If the method is performed during postoperative care and / or intensive care, the duration of the method can substantially cover the period during which the subject receives postoperative care and / or intensive care. Alternatively, the duration of the method may be at least about 50%, 60%, 70%, 80%, or 90% of the duration of postoperative care and / or intensive care.

[0068] In some aspects, continuous processing of the signal received from the first sensing device includes continuous calculation of a measure of variability of Vt and / or a ratio Vt / Ti (such as a coefficient of variation). Optionally, the method further includes the step of continuously displaying the one or more measures of variability on an electronic display, for example, in numerical form or in the form of a graph depicting the one or more measures of variability over time.

[0069] In a further preferred aspect, the continuous processing of the signals includes performing a Fast Fourier Transform (FFT) on one or more signals received from the first sensing device. Preferably, it may also include the continuous calculation of a correlation metric, which indicates the degree of correlation between the FFT-transformed signal and a previously acquired and FFT-transformed reference signal. The results of the continuous calculation can be displayed on a display in real time or with minimal delay. The inventors have found that this use of FFT can significantly enhance the ability of an informed observer to identify the onset of deterioration in the condition of a monitored human subject compared to conventional monitoring techniques.

[0070] In some other preferred aspects, the continuous processing includes calculating a ratio of at least one of the respiratory parameters to a parameter describing the electrical activity, based on signals received from the first sensing device and signals received from the second sensing device. For example, a particularly relevant ratio reflecting the state of the monitored subject could be the ratio of the WoB calculated based on signals from the first sensing device to a parameter describing the electrical activity of one or more muscles involved in breathing, based on signals from the second sensing device, or vice versa. The inventors have found that such a ratio is particularly sensitive in assessing the state of human subjects or in the early detection of changes in state.

[0071] The following list of numbered items represents the embodiments included in this disclosure: 1. A sensor strip for sensing signals characterizing one or more respiratory parameters of a human subject performing at least one respiratory action, the strip comprising: (a) A band having a longitudinal dimension suitable for wrapping around the chest of the subject, wherein the band is substantially non-elastic; (b) A fastening device for directly or indirectly connecting a first point of the strap to a second point of the strap to secure the strap around the subject's chest; and (c) A first sensing device attached to the strap, the first sensing device being adapted to acquire and transmit signals characterizing one or more respiratory parameters of the subject, including tidal volume (Vt), inspiratory time (Ti), expiratory time (Te), total cycle time (Ttot), respiratory rate (RR), and / or work of breathing (WoB), wherein the first sensing device is capable of sensing forces acting on the strap, said forces being generated by the expansion of the subject's chest caused by the subject's breathing movements.

[0072] 2. The sensor band according to item 1, wherein the first sensing device includes a movable or deformable member by the force, the member having a first end and a second end, wherein the first end is fixed to a first point of the band and the second end is fixed to a second point of the band; and wherein the first sensing device optionally includes a housing for holding the movable or deformable member.

[0073] 3. The sensor band according to item 1 or 2, wherein the movable or deformable member is or includes a leaf spring, which preferably includes one or more leaflets, and wherein two or more leaflets are preferably attached to each other, for example forming a four-bar linkage.

[0074] 4. The sensor strip according to any of the preceding claims, wherein the first sensing device includes a transducer adapted to generate an electrical signal in response to movement or deformation of a movable or deformable member, and wherein the transducer is preferably adapted to generate the electrical signal without directly contacting the movable or deformable member.

[0075] 5. The sensor strip according to item 4, wherein the transducer comprises: an inductive sensor including at least one coil, wherein each coil is configured with a helical conductor arranged on a plane and having two flat surfaces, one of the two flat surfaces forming a measuring surface, the measuring surface covering a measuring object arranged at a certain distance according to the movement of the measuring object parallel to the measuring surface; wherein the sensor electronics system provides alternating current to the inductive sensor and evaluates the change in alternating current caused by the measuring object; wherein the measuring object is guided at a constant distance on the surface of the flat coil; wherein the sensor electronics system is configured to detect attenuation changes caused by changes in the area of ​​the flat coil covered by the measuring object; wherein the measuring object affecting the measuring surface is conductive, or the measuring object has a conductive target or measuring loop and covers a coil area of ​​the flat coil, the coil area being geometrically predetermined according to the position of the target or measuring loop; and wherein the rectangular measuring surface is diagonally divided into two triangular flat coils, whereby their inductance and ohmic resistors form one half of a bridge circuit, the other half of which is supplemented by resistors, thereby producing a full bridge.

[0076] 6. The sensor band according to item 4 or 5, wherein the transducer comprises one or more strain gauges fixed to a movable or deformable member.

[0077] 7. The sensor strip according to any of the preceding items, wherein the first sensing device includes a transmitter adapted to transmit electrical signals generated by the transducer via wired or wireless means.

[0078] 8. The sensor strip according to any of the preceding items, wherein the fastening device is arranged for connecting the first point to the second point via the first sensing device.

[0079] 9. The sensor strip according to any one of items 2 to 8, wherein the housing of the first sensing device includes: a first end fixed relative to a first point of the strip and a first end of a movable or deformable member; and a second end movable relative to a second point of the strip and a second end of the movable or deformable member.

[0080] 10. The sensor band according to any one of the preceding items further includes: a pretensioner for adjusting the longitudinal extension of the band to the subject's chest circumference; and / or a battery retainer, wherein the battery retainer is optionally disposed in a housing that holds a movable or deformable member.

[0081] 11. A sensor band according to any of the preceding claims, comprising a second sensing device adapted to sense the electrical activity of one or more muscles involved in the respiratory movements of a subject; and wherein the second sensing device preferably comprises at least one electronic amplifier and at least three skin electrodes arranged for performing surface electromyography (EMG), wherein the electrodes are connected to at least one amplifier via wires sized to allow the electrodes to be positioned on the subject's skin independently of the band, wherein the amplifier is preferably disposed within the housing of the first sensing device.

[0082] 12. The sensor band according to any of the preceding items, wherein the subject is a patient receiving postoperative care and / or intensive care, and wherein the subject is at risk of developing pulmonary complications, such as postoperative pulmonary complications.

[0083] 13. The use of the sensor band according to any one of items 1 to 12 for acquiring and transmitting signals characterizing one or more respiratory parameters selected from Vt, Ti, Te, Ttot, RR, WoB and / or signals characterizing muscle electrical activity or any derived parameters thereof.

[0084] 14. A method for evaluating signals generated by a sensor band according to any one of items 1 to 12, the method comprising: continuously and simultaneously (i) receiving from a first sensing device and / or a second sensing device and (ii) processing a plurality of signals characterizing one or more respiratory parameters [and / or electrical muscle activity] selected from Vt, Ti, Te, Ttot, RR, WoB, wherein the processing includes calculating one or more statistical variability measures of Vt, Ti, WoB, electrical muscle activity, or any ratio thereof.

[0085] 15. The method of claim 14, wherein the processing includes: performing a fast Fourier transform (FFT) on one or more signals received from a first sensing device, and calculating a correlation metric indicating the degree of correlation between the FFT-transformed signal and a previously acquired and FFT-transformed reference signal; and optionally calculating a ratio of at least one of the respiratory parameters to a parameter describing the electrical activity based on the signals received from the first sensing device and the signals received from the second sensing device.

[0086] In one aspect of the first sensing device described in detail above, the first sensing device may be a displacement sensor. The physical structure and arrangement of the displacement sensor offer numerous advantages, which are also described in detail above with respect to the first sensing device. In one aspect, since there is no inter-component friction between the structures of the displacement sensor, the displacement sensor is able to output a highly accurate and low-noise signal for measuring displacement. Furthermore, again due to the physical structure and arrangement of the displacement sensor, the mechanical isolation of the relevant input forces allows the system to have no or negligible mechanical hysteresis. These aspects, individually and cumulatively, allow the sensor to output a highly accurate and low-noise signal for measuring displacement. The structure and various related aspects of the displacement sensor are further described in detail below.

[0087] The displacement sensor includes: a base including a fixed input mount; a displacement arm including: a fixed end that secures the displacement arm to the base; and a free end including: a displaceable input mount aligned with the fixed input mount, wherein the displacement arm has one degree of freedom along a displacement axis perpendicular to the displacement arm to allow the free end of the displacement arm to perform substantially linear translation along the displacement axis; and a sensor configured to determine the displacement of the free end of the displacement arm along the displacement axis.

[0088] The base of the displacement sensor provides a reference frame for various features of the displacement sensor (including the orientation of these features) and a physical structure to which other features are attached or integrally formed. The base can be part of the aforementioned housing or a separate structure disposed within the housing. Since the base is the reference frame for the displacement sensor, it can be formed of a material that will not undergo plastic deformation due to forces acting on the input of the displacement sensor or forces typically acting on the displacement sensor. Considering the various applications of the displacement sensor, the base can be formed of one or more metals, plastics, ceramics, and / or composite materials. The base includes a fixed input mounting element. The fixed input mounting element can be a separate structure attached to the base or integrally formed with the base, i.e., integrally formed such that it is stationary and has a fixed position relative to the base. An external input that transmits physical forces can be attached (e.g., releasably or irreversibly fastened) to the fixed input mounting element. A releasably fastened external input can be a structure that allows for a secure and fixed connection upon attachment, but has a structure that allows for reversible disconnection of the external input from the fixed input mounting element. Conversely, an irreversibly secured external input cannot be removed without causing physical damage to the external input or the fixed input mounting.

[0089] The displacement sensor also includes a displacement arm, also referred to herein as a movable or deformable member of the first sensing device. The displacement arm extends from a fixed end (also referred to herein as the first end of the movable or deformable member) to a free end (also referred herein as the second end of the movable or deformable member).

[0090] The fixed end of the displacement arm fixes the displacement arm to the base, so that the displacement arm (i.e. the free end of the displacement arm) has one degree of freedom along the displacement axis perpendicular to the displacement arm, so as to allow the free end of the displacement arm to perform a basically linear translation along the displacement axis.

[0091] For reference, one degree of freedom refers to the six degrees of freedom of the body about the X, Y, and Z axes, including translation along or relative to any corresponding axis and rotation along or relative to any corresponding axis. Thus, as used herein, the free end of the displacement arm has only one translational degree of freedom along a single axis referred to herein as the displacement axis. Since the displacement arm is an elongated structure extending from the free end to the fixed end, the structure can have an overall deflection profile that will have an arcuate or curvilinear shape (elastic or plastic) from one point of maximum deflection to another; however, the fundamental linear translation of the free end of the displacement arm is directed towards the target region for displacement measurement, where the movement of the free end of the displacement arm follows a fundamentally linear path, for example, the deflection profile within the target region has a sufficiently large radius of curvature such that the movement of the free end is practically linear for measurement purposes. Thus, the physical parameters of the displacement arm (e.g., size, shape, and material properties, and their interactions) ensure that the free end of the displacement arm translates substantially linearly along the displacement axis within the target region. The target region can be determined by a predetermined maximum displacement length that the displacement sensor is configured to measure / determine. In this configuration, no guide structure is required, which will depict a single axis by physically blocking the non-axial movement of the measurement target (thus causing friction between the measurement target and the guide structure).

[0092] Additionally, the displacement sensor may have one or more stops that prevent the free end of the displacement arm from translating beyond the target measurement area and / or to locations that may cause plastic deformation of the displacement arm. One or more stops may be fixed to a base, fixed to a housing, and / or integrally formed with the base and / or housing. One or more stops are configured to physically block or limit the movement of the free end of the displacement arm along the displacement axis in one or both directions.

[0093] The free end of the displacement arm includes a displaceable input mount aligned with the fixed input mount. The alignment of the displaceable and fixed input mounts ensures that forces acting on one or both mounts do not generate torque that could cause torque or rotation in the displacement sensor, thus reducing its accuracy. The displacement and fixed input mounts can also be aligned so that forces acting on one or both mounts are aligned with the displacement axis.

[0094] The displaceable input mount can be a separate structure attached to the free end of the displacement arm, or it can be integrally formed with the free end, i.e., integrally formed so that it is stationary and has a fixed position relative to the free end of the displacement arm. An external input that transmits physical forces can be attached (e.g., releasably or irreversibly fastened) to the displaceable input mount. A releasably fastened external input can be a structure that allows for a secure and fixed connection upon attachment, but has a structure that allows for reversible disconnection of the external input from the displaceable input mount. Conversely, an irreversibly fastened external input cannot be removed without causing physical damage to either the external input or the displaceable input mount.

[0095] Since the fixed end of the displacement arm is the only part of the displacement arm attached to the base, the free end of the displacement arm does not physically contact any other structure of the displacement sensor. That is, there is a gap between the free end of the displacement arm and any other structure of the displacement sensor; physical contact would cause friction during movement. This allows the free end of the displacement arm to move frictionlessly due to the force acting on the displaceable input mount (excluding internal friction). Thus, the mechanical force acting on the displaceable input mount is accurately transmitted as translation of the free end of the displacement arm without any loss due to friction.

[0096] The displacement arm may include a leaf spring extending from a fixed end to a free end (also discussed elsewhere herein), with the leaf spring overhanging at the fixed end, i.e., along the longitudinal axis / longest dimension of the leaf spring, only one end of the leaf spring (the fixed end) is fixed relative to the base, wherein the free end does not physically contact any other structure of the displacement sensor, physical contact would result in friction during movement, and wherein the planar shape of the leaf spring is oriented perpendicular to the displacement axis. With the planar shape of the leaf spring oriented perpendicular to the displacement axis and overhanging at the fixed end, the free end of the leaf spring can translate along the displacement axis, wherein the leaf spring geometry is oriented to allow deflection in the direction of the leaf spring's highest elasticity, while suppressing or preventing deflection in other directions (e.g., perpendicular to the displacement axis and aligned with the planar shape of the leaf spring). As the free end of the leaf spring translates along the displacement axis, the overall planar shape of the leaf spring deflects in an "S" shape when viewed along its planar shape. The leaf spring parameters (e.g., spring constant, shape, dimensions, and their interactions) are selected to minimize or negligibly affect the input force to the displaceable input mount, ensuring that the mechanical force acting on the displaceable input mount is accurately transmitted as translation of the free end of the displacement arm along the displacement axis, thereby eliminating or reducing components of force in other directions. As an example, the leaf spring may have the following dimensions: a length ranging from 10 to 200 mm, optionally from 50 to 150 mm, preferably 80 mm; a width ranging from 1 to 50 mm, optionally from 10 to 20 mm, preferably 16 mm; and a thickness ranging from 0.1 to 1.0 mm, optionally from 0.1 to 0.3 mm, preferably 0.25 mm. The leaf spring may have a linear spring constant. Alternatively, the leaf spring may have a nonlinear spring constant, for example, a variable stiffness spring constant that varies based on the deflection of the leaf spring. The nonlinear spring stiffness can be increasing (i.e., increasing with deflection) or decreasing (i.e., decreasing with deflection). As an example, the spring constant can have a nonlinear spring constant according to Table 1, and the leaf spring can include one or more metals and / or metal alloys, such as spring steel, such as spring steel conforming to one or more of the standards BS 1449, CS 80 and BS 970.

[0097] Table 1

[0098] In another aspect described elsewhere herein, for example as a four-bar linkage, the displacement arm may further include: a mounting member fixed to a base; a plurality of leaf springs extending from a fixed end to a free end, the leaf springs cantilevered from the mounting member at the fixed end of the displacement arm, wherein the planar shape of each of the leaf springs is perpendicular to the displacement axis and oriented parallel to each other; and a connecting member attached to the free ends of the leaf springs for coherent translation of the free ends of the leaf springs. The leaf springs may be spaced apart from each other; for example, each leaf spring may be considered to be in a parallel plane, i.e., the planar shapes of the leaf springs are aligned substantially parallel. The leaf springs may be spaced from each other in the range of 1 to 100 mm, optionally in the range of 10 to 30 mm, and preferably in the range of 26 mm.

[0099] The mounting member can be a separate structure attached to the base, or it can be integrally formed with the base, i.e., integrally formed so that it is stationary and has a fixed position relative to the base. The mounting member is constructed such that it is the only structure that contacts the base or other structure of the displacement arm with the displacement sensor, and this structure causes friction when the displacement arm moves. The mounting member can be made of a rigid or substantially inflexible material, i.e., forces acting on the displacement arm should not cause deflection or other movement of the mounting member.

[0100] A connecting member attaches the free ends of multiple leaf springs together, allowing the free ends of the multiple leaf springs to translate uniformly. Thus, similar to the mounting member, the connecting member can be constructed of a rigid or substantially inflexible material; that is, forces acting on the displacement arms should not cause deflection or other movement of the connecting member. In this configuration, multiple cantilever leaf springs are constructed as a structure of displacement arms designed to deflect with the substantially linear translation of the free ends of the multiple leaf springs. As the free ends of the multiple leaf springs translate along the displacement axis, overall, when viewed along the planar shape of the leaf springs, the planar shape of each leaf spring deflects in a parallel "S" shape.

[0101] In a configuration of multiple leaf springs, each leaf spring has a planar shape perpendicular to the displacement axis and is oriented parallel to each other, with a cantilever at the fixed end. The free end of the leaf spring can translate along the displacement axis, where the leaf spring geometry is oriented to allow deflection in the direction of highest elasticity while suppressing or preventing deflection in other directions (e.g., perpendicular to the displacement axis and aligned with the planar shape of the leaf spring). Additionally, this configuration also suppresses or prevents torsional / rotational movement of the displacement arm and is more stable than with a single leaf spring. Leaf spring parameters (e.g., spring constant, shape, size, and their interactions) are selected to minimize or negligibly affect the input force to the displaceable input mount, ensuring that the mechanical force acting on the displaceable input mount is accurately transmitted as translation of the free end of the displacement arm along the displacement axis, thereby eliminating or reducing linear and torsional components along other directions.

[0102] The displacement sensor also includes a sensor configured to determine the displacement of the free end of the displacement arm along the displacement axis. The sensor may include, but is not limited to, any sensor circuitry mentioned elsewhere herein, such as transducers, non-contact transducers, transmitters, electronic components, sensing elements, and / or core components; that is, the sensor refers to any circuitry described elsewhere herein configured to output an electrical signal based, for example, the displacement of the free end of the displacement arm of the displacement sensor and the overall mechanical input to the displacement sensor from any circuitry implementing this function. For example, the sensor may also include: a controller; integrated circuits; electrical hardware and components, such as, but not limited to, one or more resistors, one or more capacitors, one or more coils, one or more diodes, one or more amplifiers, one or more regulators, etc.; software, firmware, and any combination thereof.

[0103] While the various advantages of the physical structure of the displacement sensor have already been described above in terms of accurately transmitting the mechanical force acting on the displaceable input mount as translation of the free end of the displacement arm along the displacement axis (where linear and / or torsional components and / or friction in other directions are eliminated or reduced), these advantages also benefit the accuracy of the sensor. In particular, the overall friction caused by the structural components of the displacement sensor will increase the noise level of the sensor's output signal. Furthermore, nonlinear movement of the free end of the displacement arm can also lead to less accurate displacement measurements, as the sensor can be configured to determine linear movement of the free end of the displacement arm along the displacement axis, thereby ignoring or taking into account the input forces that cause other movements, resulting in less accurate measurements. Additionally, the physical structure of the displacement sensor allows it to be configured to convert the input force into a substantially linear electrical signal.

[0104] The sensor may include: a measurement target attached to the free end of the displacement arm so that the measurement target translates substantially linearly along the displacement axis; a sensing circuit attached to the base and spaced apart from the free end of the displacement arm and the measurement target to form a gap between the sensing circuit and the measurement target and the free end of the displacement arm, wherein the sensing circuit is configured to determine the translation of the measurement target along the displacement axis.

[0105] The measurement target can be a separate structure or a predetermined portion of the free end of a displacement arm. The sensing circuit is capable of sensing (i.e., determining and / or measuring) any translation of the measurement target. The measurement target is attached (i.e. fixed) to the free end of the displacement arm such that any translation of the free end of the displacement arm also results in a substantially linear common translation of the measurement target along the displacement axis.

[0106] Because the sensing circuit is attached to the base and spaced apart from the free end of the displacement arm and the measurement target, a gap is formed between the sensing circuit and the measurement target and the free end of the displacement arm. Therefore, the sensing circuit does not physically contact the measurement target or the free end of the displacement arm, and thus no friction occurs when the displacement arm moves. Consequently, the measurement target can move relative to the sensing circuit along the displacement axis in a frictionless manner. The gap can be in the range of 0.1 to 10 mm, optionally 0.1 to 1.0 mm or 0.5 to 1.0 mm, preferably 0.5 mm or 1.0 mm.

[0107] The sensing circuit is configured to determine the movement of the target in a frictionless manner (i.e., without direct physical contact with the target). The sensing circuit can be an optical sensor capable of optically distinguishing the target and determining its movement via a photosensitive receiver. The sensing circuit can be an electric field sensor with a target that causes a measurable change in the electric field between the sensing circuit and the target to determine the target's movement. The sensing circuit can be a magnetic field sensor with a target that causes a measurable change in the magnetic field between the sensing circuit and the target to determine the target's movement. The sensing circuit can be a combination of optical, electric, and / or magnetic field sensors. For example, the sensing circuit can be an electromagnetic sensor with a target that causes a measurable change in the magnetic field due to the interaction of a magnetic and an electrical system to determine the target's movement. The sensing circuit can be, for example, an eddy current sensor or an inductive sensor.

[0108] Therefore, the measurement target may include optical patterns and / or optically distinguishable materials and / or colors, such as contrasting colors and / or phosphorescent materials. The measurement target may include conductive materials. The measurement target may include electrical components, for example, having an electrically configured structure to capacitively interact with another electrically configured structure in the sensing circuit, such as capacitor plates or a capacitor comb. The measurement target may include metals (e.g., aluminum) and / or metal alloys (e.g., brass). The measurement target may include ferromagnetic materials, such as steel.

[0109] The sensing circuit may include one or more planar coils arranged parallel to the displacement axis, with one or more planar coils positioned at a fixed distance from the displacement axis. The target to be measured is configured to translate along the displacement axis along with the free end of the displacement arm. Thus, the size of the gap between the sensing circuit, the target to be measured, and the free end of the displacement arm is constant along the displacement axis. The area covered by the one or more planar coils can define a target region along the displacement axis, on which the displacement sensor is configured to measure displacement. Since the free end of the displacement arm, where the target to be measured is located, has one degree of freedom along the displacement axis, the physical structure of the displacement sensor ensures that the target to be measured moves along the displacement axis to a fixed distance from the one or more planar coils, thereby ensuring a constant influence on the one or more planar coils. In the configuration of the sensing circuit with one or more planar coils, the target to be measured may include a ferromagnetic material.

[0110] One or more planar coils may include a conductive material. The conductive material may include one or more metals, such as copper, or may include alloys, such as copper alloys. One or more planar coils may be arranged on a substrate or carrier, which may include a material that is non-conductive relative to the conductive material of the one or more planar coils. The material of the substrate or carrier may include, for example, resins (such as epoxy resin), silicon, ceramics, glass, and / or composite materials (such as FR4).

[0111] One or more planar coils may comprise multiple planar coils arranged in a parallel plane. These multiple planar coils arranged in a parallel plane can be electrically isolated from each other and vertically aligned with a corresponding coil stacked above another coil (i.e., stacked). Because of the higher impedance of the stacked coil system, it can reduce the power required to input to the sensing circuit. This is particularly advantageous, for example, when the displacement sensor is connected to a power source with a fixed amount of power (e.g., a battery), thereby extending the operating time of the displacement sensor.

[0112] The windings of one or more planar coils can be arranged in a triangular shape, and the measuring target can have a right-angled quadrilateral prism shape. In another aspect of this disclosure, two or more planar coils have windings arranged in a triangular shape, wherein the corresponding hypotenuses and sides of the triangular shapes of the two or more planar coils are arranged parallel to each other, forming an overall quadrilateral shape. The measuring target can have a narrow rectangular profile facing one or more planar coils, wherein the maximum length of the measuring target is arranged perpendicular to the displacement axis, and the minimum dimension of the right-angled quadrilateral prism shape is arranged parallel to the displacement axis. The maximum length of the measuring target may extend beyond the maximum width of the planar coils (i.e., as one or more planar coils or two or more planar coils) to compensate for any curvature in the fundamental linear path of the free end of the displacement arm by ensuring that the maximum width of the planar coils is always covered by the measuring target. For example, the narrow rectangular profile may have adjacent sides, such as length and width, in a ratio of approximately 4:1. The length of the narrow rectangular profile can range from 1 to 100 mm, optionally from 10 to 30 mm, preferably 20 mm, and the width can range from 1 to 25 mm, optionally from 1 to 10 mm, preferably 5 mm. The sensing circuit can include a bridge circuit, such as a Wheatstone bridge circuit, wherein the planar coil forms a half-bridge of the bridge circuit. The planar coil can be configured to generate a high-frequency electromagnetic field that induces eddy currents in a measuring target moving above the planar coil, thereby causing a damping effect in the high-frequency electromagnetic field determined by the sensing circuit. Utilizing the triangular shape of the planar coil and the right-angled quadrilateral prism shape of the measuring target, and using a linear output signal from the sensing circuit including the bridge circuit, path-dependent damping caused by the translation of the measuring target on the planar coil becomes possible.

[0113] The sensing circuit may also include a ferromagnetic structure on the side of the planar coil opposite to the measurement target. The ferromagnetic structure reduces interference from electromagnetic fields opposite the side of the planar coil in the planar coil and improves the accuracy of the sensing circuit.

[0114] In an alternative aspect of this disclosure, the sensor may include one or more strain gauges attached to the displacement arm (described in further detail above). One or more strain gauges may be attached to the leaf spring of the displacement arm, preferably to the planar surface of the leaf spring. A first strain gauge may be attached to the leaf spring closer to the fixed end than the free end, and a second strain gauge may be attached to the leaf spring closer to the free end than the fixed end. In this configuration, during the deflection of the leaf spring, i.e., during the relevant translation along the displacement axis at the free end, one of the first and second strain gauges is attached to the compressed region of the leaf spring, and the other strain gauge is attached to the tensile region of the leaf spring. The measuring areas of the first and second strain gauges may be arranged equidistant from the neutral region of the leaf spring. The neutral region of the leaf spring is the leaf spring region where compressive and tensile stresses transition. In a configuration with multiple leaf springs, the first and second strain gauges may be attached to different leaf springs among the multiple leaf springs.

[0115] The sensor may include a bridge circuit, such as a Wheatstone bridge circuit, wherein a first strain gauge and a second strain gauge form a half-bridge of the bridge circuit. In another aspect of this disclosure, the bridge circuit (e.g., a Wheatstone bridge circuit) may be formed by four strain gauges, wherein a third and fourth strain gauge are attached to another leaf spring of a plurality of leaf springs in a mirror image of the first and second strain gauges.

[0116] Similar to the sensors described above that have a measurement target and one or more planar coils, sensors including one or more strain gauges attached to a displacement arm allow for frictionless translation of the free end of the displacement arm because the free end of the displacement arm does not contact other structures of the displacement sensor, which would cause friction during movement if contact were present. While the one or more strain gauges may have wires connecting the respective strain gauges to additional sensing circuitry, the geometry and characteristics of the wires can be selected to have a negligible impact on the movement of the displacement arm; for example, thin or small-gauge wires.

[0117] As described above, displacement sensors according to various aspects of this disclosure can be incorporated into a sensor band. The sensor band may further include a strap (described in further detail elsewhere) fastened at one end to a fixed input mount of the displacement sensor and at the opposite end to a displaceable mount at the free end of a displacement arm of the displacement sensor. The strap is configured to transmit forces acting on the strap to the displaceable input mount, thereby causing translation of the free end of the displacement arm along the displacement axis. The displacement sensor is configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the forces acting on the strap translated to the displaceable input mount.

[0118] As discussed in detail above, an advantageous aspect of this disclosure is the application of a sensor band for monitoring a subject's respiration and / or respiratory parameters. The band is thus configured for application around the subject's chest, wherein the band is secured at one end to a fixed input mount of a displacement sensor and at the opposite end to a displaceable input mount. When the subject breathes, the band is configured to transmit the force of expansion from the subject's chest to the displaceable input mount, causing translation of the free end of the displacement arm along the displacement axis; during exhalation, the subject's chest contracts, and the force acting on the band decreases, and the displacement arm of the displacement sensor returns to its initial position. The displacement sensor is configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the force acting on the band that translates to the displaceable input mount due to the subject's breathing. Thus, when the subject breathes, the displacement sensor can output a sinusoidal waveform dependent on the subject's respiratory input.

[0119] The sensor band may also include an electrical sensor, also referred to herein as a second sensing device. The electrical sensor includes multiple electrodes and can be configured to determine the potential difference between the multiple electrodes. As described elsewhere herein, the electrical sensor may be an electromyography (EMG) sensor. The electrical sensors may coexist within a housing that also includes a displacement sensor. Alternatively, the electrical sensors may be located at a different position on the band than the displacement sensor.

[0120] A sensor strip can be part of a sensor strip system. The sensor strip system may also include a processor connected to a displacement sensor. The processor is configured to receive outputs from the displacement sensor and / or an electrical sensor, and / or determine one or more respiratory parameters (discussed in detail elsewhere) based on the outputs of the displacement sensor and / or the electrical sensor. The processor may be configured to perform the processing methods described herein.

[0121] The sensor belt system may also include a power supply connected to the displacement sensor. The power supply may be directly or indirectly connected to the displacement sensor and / or the processor. The power supply may be a finite source, such as a battery, or it may be directly or indirectly connected to the power grid, such as being "plugged" into an electrical system that provides power on demand.

[0122] Detailed description of the attached diagram Figure 1 A sensor band (10) according to some aspects disclosed herein is depicted, which is worn by a subject (1) optionally representing a human patient. The sensor band (10), which is only partially visible, is fastened around the chest of the subject (1). The sensor band (10) includes a strap (12) and a first sensing device (20) (e.g., a displacement sensor (20)).

[0123] Figure 2A portion of a sensor band according to some aspects disclosed herein is depicted, having a strap (12) and a fastening device (15) connecting a first point (17) of the strap to a second point (18) of the strap. The first point (17) and the second point (18) may represent opposite ends of a single continuous strap segment, or they may be positioned on different segments (i.e., the first and second segments) of the strap (10) such that the fastening device also connects these two segments of the strap (12). Furthermore, the sensor band (10) includes a pretensioner (16) for adjusting the longitudinal extension of the strap (12) to the chest circumference of a subject (not shown).

[0124] Figure 3 An example of a first sensing device (20) (e.g., a displacement sensor (20)) according to some aspects of this disclosure is depicted. Sections of a strap (12) are visible, which are connected to the first sensing device (20) (e.g., the displacement sensor (20)) via connectors (14), one of which secures the strap (12) to the housing (22) of the sensing device (20), and another connector secures the strap (12) to a movable structure, in this case, a core element (30) (which could be an example of a measurement target, such as a measurement target (141)). If the function of the fastening device is integrated into the first sensing device (20), the strap section connected via the sensing device (20) potentially represents a first point (17) and a second point (18) of a single strap segment, e.g., opposite ends. Alternatively, if the fastening device is arranged separately from the first sensing device (20), the strap section thus connected via the sensing device (20) represents two distinct segments of the strap (12) of the sensor band.

[0125] Within the housing (22), functional sensor components (e.g., sensors (140)) are arranged, including an inductive sensing element (28) (which may be an example of a sensing circuit, such as sensing circuit (142)), the inductive sensing element slidably receiving a core member (30), the core member being at least partially insertable into the inductive sensing element (28). Movement of the inductive sensing element (28) and the core member (30) relative to each other (the direction of which (38) is shown in the figure) is caused by the expansion of the strap (12) in response to the breathing movements of a subject (not shown). Movement of the core member (30) relative to the inductive sensing element (28) generates an electrical signal that can be transmitted to an electronic component (32), which may include, for example, one or more amplifiers and / or transducers.

[0126] Moreover, a leaf spring (24) is shown, for example, having two metal springs attached to each other to form a four-bar linkage (which may be an example of a displacement arm (120) comprising multiple leaf springs (121, 122)). Thus, the leaf spring (24) represents part of a deformable member (e.g., displacement arm (120)) that responds to the movement of the strap (12). As shown, one end of the leaf spring (24) (e.g., the fixed end (125)) is immovable relative to the housing (22) (e.g., relative to a base (100) that may be part of the housing (22)) by means of its fastener (26) (which may be an example of a mounting member (124)) and thus immovable relative to the first point (17) or segment of the strap (12); while the other end of the leaf spring (24) (e.g., the free end (126)) is movable relative to the housing (22) (e.g., relative to a base (100) that may be part of the housing (22)) and is connected via a core member (30) to the second point (18) or segment of the strap (12) (as discussed elsewhere, the free end (126) of the displacement arm (120) includes a displaceable input mount (130) to which the strap (12) may be attached, and a measuring target (141) may be attached to the free end (126) of the displacement arm (120)). A guide member (36) is arranged to guide the movement of the movable connector (14) and the associated strap portion at its second point (18) or segment. At the second point (18) of the strap (12), which is movable relative to the housing (22) and capable of partially sliding into and out of the housing (22), a gasket (34) is arranged to protect the interior of the housing (22) from contamination.

[0127] Figure 4 An example of a second sensing device (40) (e.g., an electrical sensor (40)) according to some aspects of this disclosure is depicted. A segment of a sensor band having a strap (12), a fastening device (15), and a pretensioner (16) as previously described is also shown. In this example, the second sensing device (40) includes three electromyography (EMG) sensor patches (42), each patch including an electrode (44) adapted for surface EMG. Each electrode (44) is connected via a wire (52) to a signal distributor (40), which is electrically connected via a wire (52) to, for example, an amplifier (not shown).

[0128] Figure 5A , Figure 5B and Figure 5C An aspect of a first sensing device, which is an exemplary displacement sensor (20), is depicted. Figure 5A The displacement sensor (20) is shown from above. Figure 5B and Figure 5CThe displacement sensor (20) is shown in a side view. The displacement sensor (20) includes a base (100), which may be part of the housing (22) or may be a separate structure. A fixed input mount (110) is fixed to the base (100).

[0129] A displacement arm (120) extends from a fixed end (125) to a free end (126). The fixed end (125) is fixed to a base (100). The free end (126) includes a displaceable input mount (130) aligned with the fixed input mount (110) (e.g., aligned along the displacement axis (150)). As described above, the displacement arm (120) has one degree of freedom along the displacement axis (150). The displacement axis (150) is oriented perpendicular to the displacement arm (120), and the free end (126) of the displacement arm (120) translates substantially linearly along the displacement axis (150) as described above. For illustrative purposes, the displacement axis (150) can be considered as the x-axis; the y-axis is perpendicular to and coplanar with the displacement axis (150), for example, the longitudinal axis of the displacement arm (120), or parallel to the longitudinal axis of the displacement arm (120); the z-axis is perpendicular to the plane formed by the x-axis and the y-axis.

[0130] The displacement sensor (20) includes a sensor (140). The sensor (140) is configured to determine the displacement of the free end (126) of the displacement arm (120) along the displacement axis (150). The sensor (140) may be configured to determine the displacement of the free end (126) of the displacement arm (120) along the displacement axis (150) within a target area (151), which may also correspond to the area where the free end (126) of the displacement arm (120) travels substantially linearly along the displacement axis (150). One or more stops (160) may be fixed to the base (100) and limit the translation of the free end (126) of the displacement arm (120), for example, limiting the translation to the target area (151).

[0131] Figure 5B and Figure 5C A side view of the displacement sensor (20) is shown. Various components are omitted for illustrative purposes. Figure 5C and Figure 5B The difference lies in that it shows the fixed end (125) of the displacement arm (120) can be fixed to the base (100) in any orientation, and is not limited to, for example, an arrangement in which the displacement arm (120) is parallel to the base (100). Thus, the displacement arm (120) can extend directly from the base (100), rather than the fixed end (125) orienting the displacement arm (120) to a specific arrangement. Alternatively, the fixed end (125) can orient the displacement arm (120) as... Figure 5B The specific orientation shown.

[0132] Figure 6A and Figure 6B An example of a displacement sensor (20) is depicted. Figure 6A The displacement sensor (20) is shown from above. Figure 6B The displacement sensor (20) is shown in the side view. Various components are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0133] Figure 6A and Figure 6B A displacement arm is shown comprising a leaf spring (121) extending from a fixed end (125) to a free end (126), wherein the leaf spring (121) is suspended at the fixed end (125), and the planar shape of the leaf spring (121) is oriented perpendicular to the displacement axis (150). The displacement arm (120) may also include a mounting member (124) that secures and suspends the fixed end (125) of the leaf spring (121) to a base (100). In this aspect of the disclosure, the mounting member (124) may orient the displacement arm (120) into a particular arrangement.

[0134] Figure 7A and Figure 7B An example of a displacement sensor (20) is depicted. Figure 7A The displacement sensor (20) is shown from above. Figure 7B The displacement sensor (20) is shown in the side view. Various components are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0135] Figure 7A and Figure 7B A displacement arm (120) is shown, comprising a mounting member (124), a plurality of leaf springs (121, 122), and a connecting member (123). The mounting member (124) is fixed to a base (100). The plurality of leaf springs (121, 122) extend from a fixed end (125) to a free end (126) and cantilever from the mounting member (124) at the fixed end (125) of the displacement arm (120). The planar shape of each of the plurality of leaf springs (121, 122) is oriented perpendicular to the displacement axis (150) and parallel to each other. The connecting member (123) is attached to the free end (126) of the plurality of leaf springs (121, 122) so that the free end (126) of the plurality of leaf springs (121, 122) translates uniformly along the displacement axis (150).

[0136] Figure 8A and Figure 8B An example of a displacement sensor (20) is depicted. Figure 8A The displacement sensor (20) is shown from above. Figure 8BThe displacement sensor (20) is shown in the side view. Various components are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0137] Figure 8A and Figure 8B A displacement sensor (20) is shown, comprising a sensor (140) including a measuring target (141) and a sensing circuit (142). The measuring target (141) is attached to the free end (126) of a displacement arm (120) such that the measuring target (141) undergoes a substantially linear co-translation along a displacement axis (150). The sensing circuit (142) is attached to a base (100) and spaced apart from the free end (126) of the displacement arm (120) and the measuring target (141) to form a gap (170) between the sensing circuit (142) and the measuring target (141) and the free end (126) of the displacement arm (120). The sensing circuit (142) is configured to determine the translation of the measuring target (141) along the displacement axis (150). The sensing circuit (142) can be arranged in the target area (151) to determine the translation of the measurement target (141) attached to the free end (126) of the displacement arm (120).

[0138] The sensing circuit (142) may include one or more planar coils (143) arranged parallel to the displacement axis (150), with one or more planar coils (143) arranged at a fixed distance from the displacement axis (150), and the measuring target (141) configured to translate along the displacement axis together with the free end (126) of the displacement arm (120). Figure 8B As shown, one or more planar coils (143) can be coplanar.

[0139] Alternatively, such as Figure 9 As shown, one or more planar coils (143) may include a plurality of planar coils (143-1, 143-2) arranged in a parallel plane. The plurality of planar coils (143-1, 143-2) are electrically isolated from each other on respective substrates (142-1, 142-2); for example, the substrates may be formed of different layers or may be monolithically formed as a single substrate, in which one or more planar coils are embedded. The sensing circuit (142) may also include a ferromagnetic structure (148) on the side of one or more planar coils opposite to the measurement target (141).

[0140] Figure 10 Examples of various aspects of a sensor (140) including a measurement target (141) and one or more planar coils (143) are depicted. Various elements are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0141] Figure 10 A sensing circuit (142) is depicted, comprising one or more planar coils (143) corresponding to a target region (151) and a measurement target (141) aligned on the target region (151) and the displacement axis (150). For illustrative purposes, a two-dimensional profile of the measurement target (141) is provided. The planar coils (143) may also include one or more contact points (144).

[0142] The windings of one or more planar coils (143) can be arranged in a triangular shape, and the measuring target (141) can have a right-angled quadrilateral prism shape, such as... Figure 10 As exemplarily illustrated. Furthermore, as shown in [the text]. Figure 10 As exemplarily shown, the sensing circuit (142) may include two or more planar coils (143) having windings arranged in a triangular shape, wherein the hypotenuses and sides of the triangular shapes of the two or more planar coils arranged in parallel form an overall quadrilateral shape.

[0143] Figure 11A and Figure 11B An example of a displacement sensor (20) is depicted. Figure 11A The displacement sensor (20) is shown from above. Figure 11B The displacement sensor (20) is shown in the side view. Various components are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0144] exist Figure 11A and Figure 11B In this configuration, the sensor (140) can be attached to one side of the displacement arm (120). Although Figure 11A and Figure 11B A sensor (140) is depicted on a specific side of the displacement arm (120), but the position of the sensor (140) is not limited to this, but may be located, for example, on the opposite side of the displacement arm (120) or on... Figure 11A and Figure 11B On the adjacent side of the depicted side. In this aspect of the displacement sensor (20), the sensor (140) may include one or more strain gauges attached to the displacement arm (120). Since the strain gauges can directly determine the compressive and tensile forces on the displacement arm (120), it is not necessary to arrange the components of the sensor (140) within the target area with aligned sensing circuitry and measurement targets. However, the free end (126) of the displacement arm (120) is still configured to travel along the displacement axis (150) and may be restricted by one or more stops (160).

[0145] Figure 12Examples of various aspects of a sensor (140) including one or more strain gauges (145, 146) attached to a displacement arm (120) including a leaf spring (121) are depicted. Various elements are omitted for illustrative purposes, and for the sake of brevity, the same or similar features are not repeated here.

[0146] like Figure 12 As shown, the sensor (140) includes one or more strain gauges (145, 146) attached to the displacement arm (120). A first strain gauge (145) may be attached to a leaf spring (121) of a plurality of leaf springs (121, 122) closer to the fixed end (125) than the free end (126), and a second strain gauge (146) may be attached to a leaf spring (121) of a plurality of leaf springs (121, 122) closer to the free end (126) than the fixed end (125). The first strain gauge (145) and the second strain gauge (146) may be positioned equidistant from the neutral zone (147) of the leaf spring (121).

[0147] Figure 13 Exemplary strain gauges, such as a first strain gauge (145) and / or a second strain gauge (146), are depicted. The strain gauge includes a contact pad (181) and an active region (182) having a conductive pattern configured to elastically deform based on stress applied to the strain gauge, the stress changing the resistivity of the conductive pattern.

[0148] Figure 14 This is a diagram of an exemplary bridge circuit (300). For example, the sensing circuit (142) of the sensor (140) may include a bridge circuit (300) having two or more planar coils (e.g., 143-1, 143-2) forming a half-bridge of the bridge circuit (300). Alternatively, the sensor (140) may include a bridge circuit (300) in which two or more strain gauges (e.g., 145, 146) form a half-bridge of the bridge circuit (300).

[0149] The bridge circuit (300) is attached to the power supply, such as Figure 14 As shown, the power supply is exemplarily an AC power supply. The diagram of the bridge circuit (300) depicts contact nodes (370), representative resistors (310, 320, 330, and 340), and representative inductors (350, 360). Thus, a half-bridge formed by two or more planar coils or two or more strain gauges can be represented by representative resistors and inductors (330, 350) and (340, 360), respectively.

[0150] In one aspect of this disclosure, as follows is provided Figure 15The depicted sensor strip system includes a sensor strip (10) comprising a displacement sensor (20); a processor (80) connected to the displacement sensor (20) and an optional electrical sensor (40); and a power supply (90). The processor (80) is configured to receive outputs from the displacement sensor (20) and / or the electrical sensor (40) and to determine one or more respiratory parameters based on the outputs of the displacement sensor (20) and / or the electrical sensor (40).

[0151] The accompanying figures in this article are not drawn to scale.

[0152] Figure Label Overview 1 subject 10 sensor bands 12 straps 14 connectors 15 Fastening devices 16 Preload The first point of the 17-band The second site of the 18-band 20 First sensing device / displacement sensor 22 Housing of the first sensing device / displacement sensor 24 leaf springs 26 Leaf Spring Fixing / Mounting Components 28 Inductive sensing elements / sensing circuits 30 iron core components / measurement target 32 electronic components 34 Washer 36 guiding components 38 directions of movement 40 Second sensing device / electrical sensor 42 EMG sensor patch 44 electrodes 50 EMG signal distributor 52 EMG wires

Claims

1. A displacement sensor, comprising: The base includes a fixed input mounting component; Displacement arm, comprising: The fixed end, which secures the displacement arm to the base; and The free end includes: A movable input mounting component, which is aligned with the fixed input mounting component. The displacement arm has one degree of freedom along a displacement axis perpendicular to the displacement arm, allowing the free end of the displacement arm to perform a substantially linear translation along the displacement axis; and A sensor is configured to determine the displacement of the free end of the displacement arm along the displacement axis.

2. The displacement sensor according to claim 1, wherein, The displacement arm includes a leaf spring extending from the fixed end to the free end, the leaf spring being suspended at the fixed end, and the planar shape of the leaf spring being oriented perpendicular to the displacement axis.

3. The displacement sensor according to claim 1, wherein, The displacement arm also includes: Mounting components are fixed to the base; A plurality of leaf springs extending from the fixed end to the free end, the leaf springs being cantilevered from the mounting member at the fixed end of the displacement arm, each of the leaf springs having a planar shape oriented perpendicular to the displacement axis and parallel to each other; and A connecting member is attached to the free ends of the plurality of leaf springs so that the free ends of the plurality of leaf springs translate uniformly.

4. The displacement sensor according to any one of claims 1 to 3, wherein, The sensor includes: A measurement target is attached to the free end of the displacement arm so that the measurement target can be translated substantially linearly along the displacement axis. A sensing circuit is attached to the base and spaced apart from the free end of the displacement arm and the measurement target to form a gap between the sensing circuit, the measurement target, and the free end of the displacement arm. The sensing circuit is configured to determine the translation of the measurement target along the displacement axis.

5. The displacement sensor according to claim 4, wherein, The sensing circuit includes one or more planar coils arranged parallel to the displacement axis, the one or more planar coils being a fixed distance from the displacement axis, and the measurement target being configured to translate along the displacement axis together with the free end of the displacement arm.

6. The displacement sensor according to claim 5, wherein, The one or more planar coils include a plurality of planar coils arranged in a parallel plane.

7. The displacement sensor according to any one of claims 5 or 6, wherein, The windings of the one or more planar coils are arranged in a triangular shape, and The measurement target has a right-angled quadrilateral prism shape.

8. The displacement sensor according to any one of claims 5 to 7, wherein, The sensing circuit includes a bridge circuit, wherein the one or more planar coils form a half-bridge of the bridge circuit.

9. The displacement sensor according to any one of claims 5 or 6, wherein, The sensing circuit includes two or more planar coils having windings arranged in a triangular shape, wherein the corresponding hypotenuses and sides of the triangular shape of the two or more planar coils are arranged parallel to each other, forming an overall quadrilateral shape. The measurement target has a right-angled quadrilateral prism shape.

10. The displacement sensor according to claim 9, wherein, The sensing circuit includes a bridge circuit, wherein the two or more planar coils form a half-bridge of the bridge circuit.

11. The displacement sensor according to any one of claims 5 to 10, wherein, The sensing circuit also includes a ferromagnetic structure on the side of the one or more planar coils opposite to the measurement target.

12. The displacement sensor according to any one of claims 1 to 3, wherein, The sensor includes: One or more strain gauges are attached to the displacement arm.

13. The displacement sensor according to any one of claims 2 or 3, wherein, The sensor includes one or more strain gauges attached to the leaf spring or one of the leaf springs.

14. The displacement sensor according to claim 13, wherein, The one or more strain gauges include: A first strain gauge, attached to a leaf spring closer to the fixed end than the free end of the plurality of leaf springs; and The second strain gauge is attached to the leaf spring that is closer to the free end than the fixed end among the plurality of leaf springs.

15. A sensor strip comprising a displacement sensor according to any one of claims 1 to 14, the sensor strip further comprising: A strap, which is fastened at one end to the fixed input mount of the displacement sensor and at the opposite end to the displaceable input mount. in, The strap is configured to transmit the force acting on the strap to the displaceable input mount, thereby causing the free end of the displacement arm to translate along the displacement axis.

16. The sensor strip according to claim 15, wherein, The displacement sensor is configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the force acting on the strap that translates to the displaceable input mount.

17. The sensor strip according to claim 15 or 16, wherein the sensor strip further comprises: An electrical sensor comprising a plurality of electrodes, the electrical sensor being configured to determine a potential difference between the plurality of electrodes.

18. The sensor strip according to claim 17, wherein, The electrical sensor is an electromyography (EMG) sensor.

19. A sensor band for monitoring the respiration of a subject, the sensor band comprising a displacement sensor according to any one of claims 1 to 14, the sensor band further comprising: A strap, configured for application around the chest of a subject, is fastened at one end to the fixed input mount of the displacement sensor and at the opposite end to the displaceable input mount. in, When the subject breathes, the strap is configured to transmit the force of expansion from the subject's chest to the displaceable input mount, thereby causing the free end of the displacement arm to translate along the displacement axis.

20. The sensor strip according to claim 19, wherein, The displacement sensor is configured to determine the displacement of the free end of the displacement arm along the displacement axis based on the force acting on the strap that translates to the displaceable input mount.

21. The sensor strip according to claim 19 or 20, wherein the sensor strip further comprises: An electrical sensor comprising a plurality of electrodes, the electrical sensor being configured to determine a potential difference between the plurality of electrodes.

22. The sensor strip according to claim 21, wherein, The electrical sensor is an electromyography (EMG) sensor.

23. A sensor strip system comprising a sensor strip according to any one of claims 15 to 22, the sensor strip system further comprising: A processor connected to the displacement sensor, the processor being configured to receive outputs from the displacement sensor and / or the electrical sensor; as well as A power supply is connected to the displacement sensor.

24. The sensor strip system according to claim 23, wherein, The processor is configured to determine one or more respiratory parameters based on the output of the displacement sensor and / or the electrical sensor.

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