Patent Application
20240197188
This disclosure relates, generally, to sensing of signals and, more particularly, to sensor assemblies for sensing signals relating to at least one physiological parameter of a subject.
Non-invasive patient or subject monitoring of physiological parameters through the use of sensors is important in the field of medicine. Apparatuses with different sensors coupled have been developed to gain multiple signals or data to accomplish monitoring of a few physiological characteristics of the subject at once. While these apparatuses with different sensors coupled have been developed, the specific combination of different sensors is in view of the intended purpose, which can be different or unsuitable for different types of physiological monitoring compared to the original intended purpose. For example, when the original intended purpose is to determine the pulse and the oxygen saturation in the blood of a subject, a pulse oximeter sensor will be able to sense the pulse rate and measure the oxygen level of the blood. However, blood pressure information will be omitted from reading as it is beyond the intended purpose, which limits what combination of sensors are needed in the apparatus.
There is always a need to optimise specific coupling of specific sensors that would be optimal for sensing relevant signals pertaining to the target organs and/or physiological parameters. There is a real felt need for an apparatus that has at least a force sensing resistor and a piezoelectric sensor coupled together to enable continuous and non-invasive monitoring of mechanical physiological events such as volumetric changes of blood in circulation of the subject, blood pressure and oxygen saturation in blood. There is also a need to increase sensitivity and accuracy in sensing physiological parameters as the efficient detection of irregular signals are vital for early diagnosis and treatment. Further, by optimising configuration of the sensors so as improve the contact with the subject will also allow for better signal to be obtained.
While a variety of sensors and systems exist to measure signals when placed about a volume, in particular, to measure and monitor physiological parameters of a living subject, providing a useful output signal representative of the parameter being measured, continuously and reliably, remains a challenge. In addition, to do so while a living subject can comfortably accommodate the sensor/system measuring the parameter is also challenging, particularly where the subject needs to wear the sensor/system for an extended period of time.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.
It may be an advantage to provide a force sensor that can be initially calibrated against a gold standard blood pressure measuring device such as a cuff or a finger device such as a Biopac. This step would allow an ongoing calibrated value for a measurement of the force to the sensor and therefore an ongoing measurement of blood pressure.
It may be an advantage to include a force sensor and an optical sensor and/or displacement sensor to provide additional signals related to the volumetric changes of blood in circulation of the subject. Having additional signals would provide more accurate about the physiological condition of the subject.
It may be an advantage for the apparatus to have a force-sensing resistor (FSR) together with a piezoelectric sensor such as a displacement sensor. Having different kinds of sensors together further provides crucial information about the physiological parameters of the subject.
It may be an advantage to operate the piezoelectric sensor to detect bodily sounds which can advantageously also used to monitor the health of the subject via sounds made from the normal functioning of organs, for example but is not limited to lungs (for breathing sounds) and heart (for monitoring heartbeat sounds) and determine whether the sounds heard are irregular or not.
It may be an advantage to use a coupler that have a maximum planar surface area which is less than a maximum planar surface area of the force sensor. This advantage with the planar configuration will allow the force sensor and the displacement sensor which are mechanically coupled to a coupler will ensure mechanical transfer of force from a subject to each sensors. It may be a further advantage that with the force and displacement sensors mechanically coupled to the coupler and the coupler mechanically coupled to the surface of the subject, the sensor assembly is configured to generate simultaneous force displacement and displacement velocity signals. These signals are, in turn, used to enable continuous and non-invasive monitoring of mechanical physiological events.
It may be an advantage to arrange the force sensor and the displacement sensor concentrically on the operatively rear surface of the coupler so that the displacement sensor can effectively sense body sounds generated by the organ of the subject.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
According to a first aspect of the present invention, there is provided an apparatus for sensing a physiological parameter of a subject, the apparatus comprising: a force sensor having a force sensing surface, wherein the force sensor is configured to generate a first signal representing force displacement of an organ of the subject; a displacement sensor associated with the force sensor, the displacement sensor having a displacement sensing surface, wherein the displacement sensor is configured to generate a second signal representing displacement velocity of the organ of the subject; and a coupler arranged on one of the force sensor and the displacement sensor, the coupler configured to mechanically couple the force sensor and the displacement sensor with the organ; and wherein the displacement sensing surface is congruent or smaller in size relative to the force sensing surface.
Preferably, the force sensor can be initially calibrated against a gold standard blood pressure measuring device such as a cuff or a finger device such as a Biopac. This step would allow an ongoing calibrated value for a measurement of the force to the sensor and therefore an ongoing measurement of blood pressure.
Preferably, the apparatus can include a force sensor and an optical sensor, the latter being used instead of, or as well as, the displacement sensor, to provide additional signals related to the volumetric changes of blood in circulation of the subject.
Preferably, The first force sensor may be measuring the signal on the chest of the patient and the second force sensor may be on the finger or wrist of the user. The second force sensor may also be on the upper chest eg at the suprasternal notch
Preferably, the force sensor may comprise a first force-sensing resistor (FSR). The displacement sensor may comprise a piezoelectric sensor. Operating the displacement sensor may allow detecting bodily sounds.
Preferably, the coupler may have a maximum planar surface area which is less than a maximum planar surface area of the force sensor. Further, the maximum planar surface area of the coupler may approximate a maximum planar surface area of the displacement sensor.
Preferably, the force sensor may be mounted to the displacement sensor.
Preferably, the force sensor may comprise an operatively front surface coupled to an operatively rear surface of the coupler and an operatively rear surface coupled to an operatively front surface of the displacement sensor.
Preferably, the force sensor and the displacement sensor may each have an operatively front surface coupled to an operatively rear surface of the coupler. The force sensor and the displacement sensor may be arranged concentrically on the operatively rear surface of the coupler. The displacement sensor may be configured such that the second signal represents body sounds generated by the organ of the subject.
Preferably, the apparatus may also include at least one optical sensor configured to generate a third signal representative of volumetric changes of blood in circulation of the subject. In such embodiments, the at least one optical sensor may be configured to be arranged on the subject separately from the force sensor, the displacement sensor and the coupler. Alternatively, the at least one optical sensor may be secured relative to, including adjacent, the force sensor.
Preferably, the coupler may be shaped to at least partially surround the optical sensor such that the coupler is mechanically uncoupled from the optical sensor.
Preferably, he apparatus may include a plurality of the optical sensors operable together to generate a fourth signal representative of blood oxygen saturation level.
Preferably, the coupler may be configured as a conductive electrode which is electrically coupled to processing circuitry configured to measure biopotential when the coupler is arranged against the subject. In such embodiments, the processing circuitry may be configured to measure an electrocardiogram (ECG) of the subject, and generate a fourth signal representative of the ECG.
Preferably, the coupler may include a temperature sensor and is electrically coupled to processing circuitry configured to measure temperature responsive to the coupler being arranged against the subject.
Preferably, an annular conductive electrode may be configured around the apparatus. The annular conductive electrode is electrically coupled to processing circuitry configured to measure biopotential when the coupler is arranged against the subject. In such embodiments, the processing circuitry may be configured to measure an electrocardiogram (ECG) of the subject, and generate a fourth signal representative of the ECG.
Preferably, the apparatus may include a first conductive electrode configured as an annular ring, the annular ring being electrically coupled to processing circuitry configured to measure a biopotential when the annular ring is arranged against the subject.
Preferably, the apparatus may include a second conductive electrode arranged to be spaced from, and isolated from, the first conductive electrode to allow arranging against another part of the subject, the second conductive electrode being coupled to the processing circuitry to allow measuring a further biopotential when the first conductive electrode and the second conductive electrode are arranged against the subject.
Preferably, the apparatus may include a third conductive electrode arranged to be spaced from, and isolated from, the first and second conductive electrodes to allow arranging against another part of the subject, the third conductive electrode coupled to the processing circuitry to allow measuring a further biopotential when the first, second and third conductive electrodes are arranged against the subject. The third conductive electrode may be movable relative to the first electrode and the second electrode.
Preferably, the processing circuitry may be configured to measure an electrocardiogram (ECG) of the subject responsive to any conductive electrode being arranged against the subject, and configured to generate a fourth signal representative of the ECG.
Preferably, where a second and third ECG electrode is incorporated in the apparatus, this may be isolated from the first electrode and arranged to allow the subject's hand to complete the ECG circuit while holding the second electrode, or arranged on a second sensor which is attached to the subject and connected to the processing circuitry.
Preferably, the coupler may comprise a front surface configured to contact the organ. The front surface may be dome shaped or mushroom shaped or cone shaped or pyramid shaped. Instead, the coupler may be cylindrical or cuboid. The coupler may comprise at least one of a rigid plastics material, such as acrylic resin, and a conductive material.
Preferably, the apparatus may further comprise a second force sensor configured to measure a force applied to an operatively rear surface of the apparatus. The second force sensor may be calibrated to known forces in production allowing the signals from the first force sensor, to be quantified leading to an estimate of blood pressure. The second force sensor may be a force-sensing resistor (FSR). The second force sensor may be coupled to an operatively rear surface of the displacement sensor.
Preferably, the apparatus may further comprise a fixing device configured to secure the apparatus to the organ of the subject. The fixing device may comprise at least one of: a) a strap; b) a belt; c) an adhesive patch.
Preferably, the apparatus may further comprise at least one processor configured to determine the physiological parameter based on the first signal and the second signal. The at least one processor may be configured to: calibrate the second signal received from the displacement sensor based on the first signal.
Preferably, the physiological parameter may comprise at least one of a cardiac parameter, such as a cardiac impulse, a blood pressure, such as central blood pressure or peripheral blood pressure, a uterine contraction, foetal activity, respiration, body sounds such as heart sounds, an opening time of a heart valve of the subject, a closure time of a heart valve of the subject, a contractility level of a heart of the subject, elasticity of blood vessels, a stroke volume of a heart of the subject, a cardiac output, and a blood pulse transit time. Preferably, the apparatus further comprises a first morphic sensor configured to generate a respiratory signal representing the chest volume changes, and wherein the morphic sensor is in communication with the sensors. Preferably, the apparatus further comprises a second morphic sensor configured to detect physiological signals for allowing the identification of the subject. Preferably, the first morphic sensor or the second morphic sensor comprise an accelerometer for detecting the position and movement of the subject.
In another aspect there is provided a method for enhancing signal to noise ratio of a signal generated by a sensor assembly, the assembly including a force sensor and a displacement sensor, the method including: arranging the displacement sensor at a location on the subject, the displacement sensor configured to generate a first signal representing displacement; arranging the force sensor at the same location on the subject, the force sensor configured to generate a second signal representing force displacement; and operating at least one processor coupled to the displacement sensor and the force sensor and configured to process the force and displacement signals.
Preferably, the processing may include multiplying the first signal and the second signal.
In another aspect, there is provided a method of measuring a physiological parameter of a subject, the method comprising: receiving a first signal from a first force sensor mechanically coupled to a first location on the subject; receiving a second signal from a second force sensor mechanically coupled a second location on the subject, the second location being separated from the first location; and determining the physiological parameter based on a comparison of the first and second signals.
Preferably, The first force sensor may be measuring the signal on the chest of the patient and the second force sensor may be on the finger or wrist of the user. The second force sensor may also be on the upper chest eg at the suprasternal notch
Preferably, the comparison may comprise a difference between the first signal and the second signal. The comparison may further comprise the timing between the first and second signal where this timing is equal to the pulse transit time (PTT) from the first to the second location. PTT is a measurement which is representative of blood pressure. It may be appreciated that the PTT can be measured at any different predetermined locations.
Preferably, one or more of the first force sensor and the second force sensor may be a force-sensing resistor (FSR).
Preferably, the physiological parameter may comprise at least one of a cardiac parameter, such as a cardiac impulse, a pulse transit time, a pulse arrival time, a blood pressure, such as central blood pressure or peripheral blood pressure, a uterine contraction, foetal activity, respiration, body sounds such as heart sounds, an opening time of a heart valve of the subject, a closure time of a heart valve of the subject, a contractility level of a heart of the subject, a stroke volume of a heart of the subject, a cardiac output, and a blood pulse transit time.
Preferably, the first location may be on an upper thorax of the subject, such as at or near the xiphoid process. The second location may be on a lower thorax of the subject. The physiological parameter to be measured may be central blood pressure.
In another aspect of the present invention, the first location may be on a thorax of the subject. The second location may be proximate to one of a femoral artery and a subclavian artery, or other peripheral artery, of the subject. The physiological parameter to be measured in such cases may be peripheral blood pressure.
In another aspect of the present invention, the first and second forces sensors may be on the one assembly with the back force sensor disconnected from the front force sensor. A user's finger can be applied to the coupler to the second force sensor when the assembly is placed over the user's heart. The timing difference of the cardiac signal from the heart to the finger is the pulse transit time.
Preferably, he method may further comprise receiving a third signal from a third force sensor mechanically coupled to the subject at a third location separated from the first location and the second location and determining the physiological parameter based on a comparison of the first signal, the second signal and the third signal. The third force sensor may be an FSR.
Preferably, the method may further comprise mechanically coupling one or more of the first sensor and the second sensor to the subject.
Preferably, the method may further comprise using the apparatus with both a force and displacement sensor, where the signal from the displacement sensor is multiplied by signal from the force sensor to avoid the need for modulation of the signal from the displacement sensor.
According to another aspect there is provided a system for measuring a physiological parameter of a subject, the system comprising: a first force sensor configured to generate a first signal representing force displacement at a first location on the subject; a second force sensor configured to generate a second signal representing force displacement at a second location on the subject; and at least one processor configured to determine the physiological parameter of the subject based on a comparison between the first signal and the second signal.
Preferably, the comparison may comprise a difference between the first signal and the second signal. Furthermore, the comparison may comprise a timing difference between the first and second signal.
Preferably, at least one of the first force sensor and the second force sensor may be a force-sensing resistor (FSR).
Preferably, the physiological parameter may comprise a cardiac parameter, such as a cardiac impulse, a pulse transit time, a pulse arrival time or a blood pressure, such as central blood pressure or peripheral blood pressure, a uterine contraction, foetal activity, respiration, body sounds such as heart sounds, an opening time of a heart valve of the subject, a closure time of a heart valve of the subject, a contractility level of a heart of the subject, a stroke volume of a heart of the subject, a cardiac output, and a blood pulse transit time.
Preferably, the first location may be on an upper thorax of the subject, such as at or near the xiphoid process. The second location may be on a lower thorax of the subject. The physiological parameter to be measured may be central blood pressure.
In another aspect of the present invention, the first location may be on a thorax of the subject. The second location may be proximate to one of a femoral artery and a subclavian artery, or other peripheral artery, of the subject. The physiological parameter to be measured in such cases may be peripheral blood pressure.
Preferably, the system may further comprise third force sensor configured to generate a first signal representing force displacement at a third location on the subject separated from the first location and the second location. The physiological parameter may then be determined based on a comparison of the first signal, the second signal and the third signal. The third force sensor may be an FSR.
Preferably, one or more of the first force sensor and the second force sensor may be the first force sensor of an apparatus as described above.
According to another aspect there is provided an apparatus for sensing at least one parameter of a subject, the apparatus comprising: a flexible sensor member having an impedance which changes with flexure; and a flexible carrier surrounding the flexible sensor member and configured to maintain a contact surface of the flexible sensor member proximate a surface of the subject such that a change of shape, such as radius, of the surface of the subject causes the flexible sensor to flex.
Preferably, the flexible sensor member may comprise force-sensing resistor (FSR).
Preferably, the carrier may be at least one of a fabric carrier and an elastomeric carrier. The carrier may comprise a strap or an adhesive patch. The carrier may comprise a garment worn by the subject. The garment may comprise a shirt, or a vest, or a jacket, or a coat.
Preferably, the surface of the subject may be skin, such as the skin at a thorax of the subject. The flexible carrier may be configured to maintain the contact surface proximate to the skin such that expansion and contraction of the skin (e.g. expansion and contraction of the thorax due to respiration) causes the flexible sensor to flex.
Preferably, the apparatus may further comprise at least one processor configured to generate the at least one parameter based on the impedance of the flexible sensor member.
Preferably, the parameter may comprise a cardiac parameter, such as a cardiac impulse, or a blood pressure, such as central blood pressure or peripheral blood pressure, or uterine contraction, foetal activity, respiration, body sounds such as heart sounds, an opening time of a heart valve of the subject, a closure time of a heart valve of the subject, a contractility level of a heart of the subject, a stroke volume of a heart of the subject, a cardiac output, and/or a blood pulse transit time.
According to another aspect there is provided a method of sensing at least one parameter of a subject, the method comprising: locating a flexible sensor as described above at a first location proximate an organ of a subject; and determining the at least one parameter based on the impedance of the flexible sensor member.
According to another aspect there is provided apparatus for sensing a physiological parameter of a subject, the apparatus including: a force sensor configured to generate a first signal representing force displacement of an organ of the subject; at least one optical sensor configured to generate a second signal representing volumetric changes of blood in circulation of the subject; and a coupler arranged on the force sensor, the coupler configured to mechanically couple the force sensor with the organ.
Preferably, the at least one optical sensor of any of the above described embodiments may sense resulting signals using at least one wavelength of light.
According to another aspect there is provided a system for identifying a subject, the system comprising: at least one first force sensor configured to generate a force signal representing force; a displacement sensor configured to generate a displacement signal representing displacement, the force sensor and the displacement sensor arranged relative to each other to allow positioning at substantially the same location on a subject to allow generating the signals; and at least one processor coupled to the force sensor and the displacement sensor, the at least one processor configured to process the force signal and the displacement signal to determine identification of the subject.
Preferably, at least one processor may be coupled to a memory and further configured to determine the identification of the subject based on at least one standardised historical signal for the same subject stored in the memory.
Preferably, the system may also include a photoplethysmography sensor configured to generate a photoplethysmography signal, and a pair of electrocardiogram electrodes configured to generate an electrocardiogram signal, and the at least one processor is coupled to the photoplethysmography sensor and/or the pair of electrocardiogram electrodes configured to process at least one of the force and displacement signals and at least one of the photoplethysmography and electrocardiogram signals to determine the identification of the subject.
Preferably, the at least one processor may be further configured to determine the identification of the subject based on a combination of at least two standardised historical signals for the same subject stored in the memory.
Preferably, each operation of the system may generate one or more of the signals causes the one or more corresponding standardised historical signals to be updated.
Preferably, use of the system may involve arranging the system in contact a palmar side of a finger of the user to allow generating the force signal and the displacement signal. The system may be arranged to contact the tip of the index finger.
Preferably, responsive to the subject adjusting one or more of contact force and contact period exerted by the finger, the processor may be configured to communicate an alarm signal to one or more remotely located devices or systems.
Preferably, responsive to the subject adjusting one or more of contact force and contact period exerted by the finger, the processor is configured to communicate at least one of recorded signals and analysed signals to one or more remotely located devices or systems.
Embodiments of the disclosure are now described by way of example with reference to the accompanying drawings in which:
c show embodiments of a sensor assembly in various arrangements on a human subject;
Embodiments of the present disclosure relate to sensing systems and methods for monitoring physiological mechanics from local measurements of force and their propagation speed exerted by displacement of skin surfaces by organs, muscles, blood flow, and fluids shifts, i.e. digestion, deglutition, respiration, etc.
Some embodiments use force sensors, such as force sensitive resistors (FSRs), mechanically coupled with a subject on the thorax or upper abdomen, to measure recoil forces generated by the cardiac contraction and blood pumping action, so called “Forcecardiography (FCG)”. Embodiments can thus enable continuous and non-invasive monitoring of mechanical events of each cardiac cycle of a subject. Particularly by using multiple force sensors mechanically coupled with a subject, typically at the skin, information on physiological parameters can be obtained, such as identification and duration of each phase of a cardiac cycle, heart valves opening and closure timing, heart contractility level, stroke volume, cardiac output, pulse transit time, and central arterial pressure. Further, a morphic band may be combined for also determining chest volume changes in a subject. The morphic band is such that it can morph with the monitored body with negligible or without mechanical resistance. As heart failure is complex and multifaceted disease, it may affect multiple organ systems including the respiratory system. The additional information from the morphic band allows respiratory signals to be obtained. If the forces are calibrated against a known force, a quantified measurement of force and therefore pressure can be calculated. In turn, information can be obtained about heart diseases and/or malfunctions, such as but not limited to heart failures, mechanical dyssynchrony (e.g. as results of bundle branch blocks), valvular pathologies (e.g. aortic and mitral regurgitation, stenosis), etc.
When provided in proximity of peripheral pulse points or major vessels (i.e. neck pulse, radial pulse, etc.), force sensors can be used to measure force and their propagation time and hence speed of blood movements and flow. Such flow may include venous return as well as changes in hydrostatic pressure due to respiration. As such, embodiments make it possible to infer respiratory rate from force measurements of the peripheral limbs.
Some embodiments use one or more force sensors (such as FSRs) in combination with a displacement sensor (such as a piezoelectric sensor), both mechanically coupled with the subject, to simultaneously measure force displacement of the subject and speed or velocity of such displacement. The compression force (DC baseline of the force sensor signal) and the dynamic force (AC component of force sensor signal) exerted on the force sensor can be used to calibrate the displacement velocity signal generated by the displacement sensor, allowing accurate and continuous direct measurement of speed or velocity of displacement of the skin as well as force displacement itself. As such, accurate and continuous measurement blood impulse and therefore cardiac impulse can be obtained from movement of skin alone.
In some embodiments, the force sensor can be initially calibrated against a gold standard blood pressure measuring device such as a cuff or a finger device such as a Biopac. This step would allow an ongoing calibrated value for a measurement of the force to the sensor and therefore an ongoing measurement of blood pressure.
In another embodiment, the force sensors may have a force sensing surface and the displacement sensor may have a displacement sensing surface. Each of the sensing surfaces are surfaces that allows detection of signals of the target area or subject. While the surfaces each have a shape and size, it is advantageous to have the displacement sensing surface of the displacement or piezoelectric sensor having a profile shape and size congruent or smaller in size relative to the force sensing surface of the force sensitive resistor (FSR) so as to allow optimal coupling and contact between sensors. For example, a force sensitive resistor may have a circular force sensing surface and a displacement sensor may also have a circular force sensing surface. It may be appreciated that the surface, which may be a planar shape, is not limited to a circle but may be of any shape that allows the sensor to sense. For example, a possible size measurement of congruent shape sensing surfaces may be 10 mm2 for a force sensing surface and 9 mm2 for a displacement sensing surface as a means of describing of how a congruent sensing surfaces can have a larger or smaller size relative to each other. While the above measurements are mentioned by example, it is not limited to these values and it may be appreciated that the surface can be of different sizes.
Some embodiments use one or more force sensors (such as FSRs) in combination with one or more optical sensors (such as photoplethysmography (PPG) sensors), both in contact with the subject's skin to simultaneously measure force displacement of the subject's skin and change in blood volume or blood flow within an organ or vessel below the skin. Further embodiments also include a displacement sensor, such as a piezoelectric sensor, in combination with the one or more force sensors and optical sensors. Typically embodiments including an optical sensor also have an annulus arranged to allow the optical sensor(s) to be placed in contact with the subject's skin.
While the sensor assemblies described herein have been developed specifically for measuring physiological parameters, for example, cardiac activity and respiratory activity, directly from the skin of a living subject, those skilled in the art will appreciate that embodiments of the disclosed force sensor and displacement sensor assemblies may be used through a layer or layers of fabric arranged across the skin, such as clothing or bedding. In some such embodiments, the sensor assemblies may be held in place by being embedded in, or attached to, an upholstered or otherwise fabric-covered structure, such as a mattress of a bed, a seat of a chair, including a wheelchair and a vehicle seat, a steering wheel of a vehicle, or a seatbelt secured to a vehicle.
While the sensor assemblies described herein have been developed specifically for measuring physiological parameters, such as, for example, cardiac activity and respiratory activity, of a living subject, those skilled in the art will appreciate that the sensor assemblies which are the subject of the disclosure could be used with other objects where a force is applied by a part underlying the sensor assembly. Thus, sensor assemblies described herein could be used in industrial applications such as soft robotics or other inanimate objects where such force is applied.
The coupler 106 comprises a rigid material such as rigid plastic or rubber. In some embodiments, the coupler 106 may comprise an acrylic resin. In other embodiments, the coupler 106 may be partially or wholly conductive. For example, the coupler 106 may partially or wholly comprise a conductive material, such as silver or silver chloride. The front surface 108 of the coupler 106 configured to face and preferable be placed in contact with a surface of the subject may be dome shaped so as to depress into a compliant surface of the subject, such as skin. Providing a dome shaped front surface 108 assists in improving the coupling of mechanical displacement from the subject to the force sensor 102 and the displacement sensor 104. Other shapes for the front surfaces 108 providing a similar effect include cone shapes, mushroom shapes, etc.
The coupler 106 has a generally circular cross-section when viewed in a plane parallel to the subject facing plane of the sensor assembly 100. In addition to coupling movement (force and displacement), the coupler 106 may be configured as a biopotential electrode and may be electrically coupled to processing circuitry (not shown) for measuring biopotential (e.g. electrocardiogramalectromyography (EMG), electroencephalography (EEG), etc.
The force sensor 102 is mounted to a rear surface of the coupler 106 via a force sensor carrier 110 which comprises a flexible medium. The force sensor 102 is mounted to the carrier 110 by glue, lamination, or otherwise. Electrical connections to the force sensor 102 are made using two or more electrodes 112 which also act as anchoring points to anchor the force sensor 102 to the sensor carrier 110. The force sensor 102 is a force sensitive resistor (FSR) or a load cell. As will be described in more detail below, a characteristic of the force sensor 102 changes in response to a force signal being applied to the force sensor, the change representing a force displacement of an organ in contact with the front surface 108 of the coupler 106. Such a characteristic is, for example, the impedance of the force sensor 102 or an output current or voltage. Where the force sensor 102 is an FSR, changes in resistance of the force sensor 102 represent force displacement from which an output voltage can be generated, as will be described below in more detail.
In an embodiment, a front surface of the force sensor 102 facing toward the subject in use has a surface area of between about 5 mm2 and 25 mm2, for example, 7 mm2, 15 mm2 or 20 mm2.
The force sensor 102 and the displacement sensor 104 are mounted together via an optional a rigid interface layer 114. The rigid interface layer 114 is provided on a rear surface of the force sensor 102. The rigid interface layer 114 may comprise brass, rigid plastic, or similar rigid material. In some embodiments, the rigid interface layer 114 may be a double sided PCB, the force sensor 102 mounted on a first surface of the PCB (i.e. the surface facing the subject in use) and the displacement sensor 104 being mounted on an opposed, second surface of the PCB.
In any case, the displacement sensor 104 is mechanically coupled to the rear surface of the force sensor 102 as shown in
In an embodiment, a front, subject-facing surface of the displacement sensor 104 has a surface area of between about 5 mm2 and 25 mm2, for example, 7 mm2, 15 mm2 or 20 mm2.
Advantageously, the surface area of the force and displacements sensors 102, 104 are substantially matched to ensure uniform transfer of displacement from the force sensor 102 to the displacement sensor 104. The force and displacement sensors 102, 104 are therefore also preferably axially aligned along a central, operatively vertical axis of the assembly 100 for similar reasons.
An optional protective cover 116 may be provided around a rear surface of the displacement sensor 104. The protective cover 116 may be separated from the rear surface by a fluid gap filled with air or other gas, or a vacuum. In doing so, the protective cover 116 protects the displacement sensor 104 from impacts on the operatively rear, non-subject facing side of the assembly 100.
In addition to the force sensor 102 and the displacement sensor 104, the sensor assembly 100 may optionally comprise an accelerometer 120. The accelerometer 120 is configured to measure acceleration in one or more axes. For example, the accelerometer 120 may be configured to measure acceleration at least in an axis perpendicular to the surface of the subject to which the sensor assembly 100 is affixed in use. Preferably, additionally, the accelerometer 120 measures acceleration in one or more planes parallel to the surface of a subject to which the sensor assembly 100 is affixed in use, so as to measure movement of the sensor assembly in such a plane(s) or axes. The accelerometer 120 may be positioned at any location on the sensor assembly 100 provided mechanical coupling is provided (direct or indirect) to the coupler 106. For example, the accelerometer 120 may be coupled to the rear of the protective cover 116.
A housing 118 encapsulates the sensor assembly 100 to protect elements of the assembly 100 from detritus such as dust, grit, water, and/or any other matter that might affect operation of the assembly 100 and to inhibit the ingress of foreign bodies into the assembly 100. The operative, front surface 108 of the coupler 106 extends through an aperture of the housing 118. Instead, the housing 118 could include at least a flexible portion (not shown) which extends over and conforms to the front surface 108 of the coupler 106 thereby fully encapsulating the force sensor 102, the displacement sensor 104 and the coupler 106.
During operation, the front surface 108 of the coupler 106 of the sensor assembly 100 is placed in contact with a surface of a subject, such as the skin of the subject, the sensor assembly 100 fixed relative to the subject by one or more fixing devices, such as a belt, an adhesive patch, adhesive tape or the like (not shown). Such tape may be made from the material from which sports tape, also known as kinesiology tape, is made. With the force and displacement sensors 102, 104 mechanically coupled to the coupler 106 and the coupler 106 mechanically coupled to the surface of the subject, the sensor assembly 100 is configured to generate simultaneous force displacement and displacement velocity signals. These signals are, in turn, used to enable continuous and non-invasive monitoring of mechanical physiological events as will be described in more detail below.
In addition to the elements of the sensor assembly 100, the sensor assembly 200 of
This measured external force signal is able to be used to compensate for carrier pressure force (i.e. the force applied by fixing devices to the rear of the sensor assembly 200) and surface resilience of the subject (i.e. how resilient the surface of the subject being sensed is). For example, knowing the pressure applied from an external carrier or the operator of the assembly 200 will allow for artefact rejection. For example, a sudden knock or shearing of the sensor i.e. during movements may alter the application of pressure of the force sensor 102 which in turn may create artefacts in the signal from the force sensor 102. Additionally, rhythmic movements caused by activities such as running of the subject may impress a baseline wander and associated artefact to the signal from the force sensor 102. Such artefacts can be cancelled (either in real time or in post processing) using signals derived from each of the two force sensors 102, 202 and the displacement sensor 104, as will be described in more detail below.
Referring now to
In both embodiments, the coupler 106 includes a collar 109 which is received within the housing 118 with the dome-shaped surface 108 of the coupler 106 projecting through an opening (not shown) in the housing 118. The opening has a smaller diameter than that of the collar 109 so that the collar 109 assists in holding the coupler 106 captive relative to the housing 118 and inhibits separation of the coupler 106 from the housing 118.
Further, in both embodiments, the diameter of the coupler 106, at its base, i.e. that part of the coupler 106 in contact with the sensor carrier 110 (referred to as the “base diameter”), is less than that of the force sensor 102. However, it is desirable and preferable that the coupler 106 distributes its force over the entire surface area of the displacement sensor 104. As such, the base diameter of the coupler 106 approximates the diameter of the displacement sensor 104. Typically, the base diameter of the coupler 106 is approximately 70% to 90% and, for example, about 80% of the diameter of the force sensor 102.
In the embodiment shown in
While the coupler 111 has been shown as a plate—like structure, it will be appreciated that the coupler 111 could have any suitable shape including a dome shape similar to that of the coupler 106. Once again, the coupler 111 has a diameter less than that of the force sensor 202, typically approximately 70% to 90% and, for example, about 80% of the diameter of the force sensor 202.
As indicated above, a dome shaped coupler 106 aids in depressing into a compliant surface of the subject, such as skin. Providing a couple 106 with a dome shaped front surface 108 thus improves the coupling of mechanical displacement from the subject to the force sensor 102 and the displacement sensor 104.
The sensor assemblies 100, 200 described above comprise force and displacement sensors in a “sandwich” arrangement stacked relative to one another. However, embodiments of the present disclosure are not limited to such an arrangement. For example, in other embodiments, force and displacement sensors may be arranged in a planar configuration, for example, arranged next to each other or arranged concentrically (one within the other), and may be arranged either on a common substrate or on different, separate substrates. In each embodiment, each force sensor and displacement sensor is preferably mechanically coupled (either directly or indirectly) to a coupler, such as the coupler 106, 111, of
The sensor assembly 400 includes a coupler 406 arranged to transfer force to the force sensor 102, and, optionally, to the displacement sensor 104 (neither shown in
The PPG sensor 402 is arranged to be approximately aligned with an operatively top surface of the coupler 406 to allow the PPG sensor 402 to be placed against the subject's skin simultaneously with force being exerted on the coupler 406 by the skin. Typically, the coupler 406 is formed from an opaque material to inhibit light passing through the coupler 406 which could affect the PPG sensor 402 readings. The PPG sensor 402 is configured to sense blood volume biometrics, simultaneously with operation of the other sensors 102, 104, to derive further information relating to status of the subject's cardiovascular system.
The embodiment shown in
The sensor assemblies 100, 200 described above each comprise a displacement sensor 104. It is noted however, that embodiments of the present disclosure are not limited to using the combination of force and displacement sensors. For example, various novel techniques will be described below, for using multiple force sensors positioned at different locations on a subject for detecting various physiological parameters. Such techniques do not require simultaneous displacement sensing. Such techniques may use the sensor assemblies 100, 200 described above, or alternatively may use sensor assemblies comprising only a force sensor and a coupler. Such sensor assemblies may comprise any conceivable coupling arrangement, for example one of the arrangements shown in any one of
In
In
The displacement sensor 104, the second force sensor 202, and the accelerometer 120 are shown in
The signal processing chain 700 comprises a signal conditioning stage 702, an analogue-to-digital conversion stage 704 and filtering stage 706 to generate representations of one or more physiological parameters, including, but not limited to, respiration, blood ejection pulse, force parameters, velocity parameters, heart sounds, and blood pressure.
During the signal conditioning stage 702, a resistance FSR1 of the force sensor 102 is converted into an output voltage Vn either by hardware (processing circuitry) or by software in post processing.
Exemplary hardware for performing such a conversion is shown in
As described above, the second force sensor 202 may be used to calibrate for varying force applied to the rear (non-subject facing) side of the sensor assembly 200 by any fixing device or the subject itself. Referring again to
It will be appreciated that any of the above hardware solutions may alternatively be implemented in software, either in real time or after recording of signals from two or more of the sensors 102, 104, 202.
It will be also appreciated that, in addition to calibrating the first sensor 102, signals derived from the first sensor 102 can be used to determine flesh compliance, e.g. to distinguish between tissues (fat/muscle percentages etc.). Such measurements may be used to determine an amount of fat under the skin of a subject.
As described above, in some embodiments, the displacement sensor 104 comprises a piezoelectric sensor configured to generate a current in response to a change in displacement. In such cases, the DC offset and AC voltage swing of the signal output form the displacement sensor 104 may need to be adjusted or calibrated. To do so, the signal conditioning stage 702 conditions the signal output from the displacement sensor 104 by implementing process circuitry such as that shown in
Referring to
This improves the overall low-frequency response of the signal conditioning circuitry 1502 by reducing the high-pass cut-off frequency which is selected to reduce the possible phase-shift introduced by the high-pass response, even at the lowest frequencies of interest, being the lower limit of the respiratory signals band to assist in comparison with the signals from the force sensor 102. In some applications, the cut-off frequency is to be set to a range of about 0.01-0.05 Hz.
To be able to use different displacement sensors 104 without the need for bespoke circuitry, the signal conditioning circuitry 1502 may be tunable based on the particular capacitance of the selected displacement sensor 104. Using surface mounted device (SMD) resistors in a bootstrapping configuration, smaller resistance values can be employed reducing the cost of the circuitry 1502. As an example, a resistor R1 of 100 MΩ, a resistor R3 of 100Ω and a trimmer, R2, of 100 kΩ could be used in circuit 1502 so that an impedance RIN of 100 MΩ is “seen” by the displacement sensor 104 when R2 is set to 0 (to provide a cut-off frequency of 0.05 Hz for a displacement sensor 104 capacitance of 30 nF). RIN could be increased to 1011Ω by increasing the trimmer resistance by adjusting R2.
Referring again to
Digital signals F, V, A are then provided to a digital filter stage 706 configured to implement one or more filters 710, 712, 714, 716 to filter the force, velocity and (optional) accelerometer signals F, V, A to generate one or more outputs representative of physiological parameters of the subject. Such parameters are specific to the location on a living subject at which the assemblies 100, 200 are located during measurement. For example, when positioned at locations on the thorax of a subject as shown in
A respiration signal 720 from the subject is extracted by low pass filtering the force signal F using a low pass filter 710. The low pass filter 710 may, for example, have a low pass threshold of about 0.5 Hz.
A pulse signal is generated from the force signal by band pass filtering the force signal F with a band pass filter 712. The band pass filter may, for example, have a passband of between about 0.5 Hz and about 8 Hz.
Force and velocity parameters specific to the organ of the living subject being monitored are extracted from each of the force and velocity signals F. V, respectively, by band pass filtering the signals F. V with a further band pass filter 714. For force and velocity parameters of the heart, for example, the band pass filter 714 may have a passband of between about 8 Hz and about 40 Hz.
Body sounds are also able to be extracted from the force and velocity signals F. V using a band pass filter 716 having a lower threshold of about 20 Hz, about 30 Hz, about 40 Hz, or about 50 Hz in combination with an upper threshold that is usually about 150 Hz reaching about 5000 Hz in specific applications i.e. wheeze, crackling and snoring sounds. Acoustic analyses of wheezing are clinically important as it is sound produced by airflow through an abnormally narrowed or compressed airways. Timely identification and intervention of early onset asthma from wheezing might reduce the risk of long term morbidity. Early detection of these sounds and early treatment is expected to reduce the prevalence of symptoms and improve health-related quality of life. Acoustic analyses and timing of crackling sounds are also important as these sounds may allow a clinician to identify whether the patient or subject have severe airways obstruction (early inspiratory/expiratory crackles), restrictive lung disease such as pulmonary fibrosis and also in interstitial pulmonary edema (late inspiratory crackles), and left ventricular failure (inspiratory crackles). Acoustic analyses of these snoring sounds are clinically important in examining the subject's sleep characteristics, respiratory disorders and other abnormalities can be detected. Major application may include but not limited to prediction of the outcome of surgical treatment, assessment of snoring before and after therapeutic interventions and the important differentiation of primary snoring from Obstructive Sleep Apnea (OSA). These can be utilized to study adult patient snoring as well as paediatric patient snoring. Early identification of these sounds enable a clinician to identify abnormalities early as early diagnosis and treatment of will allow a patient to reduce the risk of cardiovascular disease. Further benefits of early treatment may save or avoid on more expensive treatments in the future such as, for example, using a ventricular assist device which may have to be implanted for severe heart failure which may be caused by OSA. In some embodiments, the band pass filter 716 may have a passband of between about 40 Hz, about 300 Hz and even 5000 Hz. Depending on the position of the sensor assembly 100, 200, the body sounds may comprise one or more of heart sounds (e.g. rushing blood, valve movement), gut sounds (e.g. gas displacement), respiration, snoring, swallowing and foetal sounds (including foetal movement, foetal heart sounds, foetal respiration, foetal gas displacement etc.), muscle contraction around airways, such as the trachea.
Size reduction in airways may also be monitored by monitoring changes in sounds emanating from the neck region. For example, wheezing or higher pitched sound or vibrations at the neck may be indicative of hypopneas (partial reduction in breathing), apnoeas, or asthma and other pulmonary and respiratory conditions. As discussed below with reference to
Extracted body sounds may be output to one or more speakers or headsets to be heard by a clinician. As such, the sensor assemblies 100, 200 may act as digital stethoscopes providing a high resolution digital representation of body sounds. Such extracted body sounds can be modulated and/or shifted in frequency to be more easily heard by the human ear. For example, extracted body sounds may be shifted in frequency into the centre of the human hearing range.
It is noted that the various filters 710, 712, 714, 716 of the digital filter stage 706 are provided only as examples of filters which may be implemented to extract information from the force and velocity signals F, V. One or more of the filters 710, 712, 714, 716, 718 may be omitted or other filters added depending on the physiological parameters to be extracted and the location(s) of the assembly(s) 100, 200 on the subject.
Where multiple sensor assemblies are provided at different locations on the subject, each of the force, velocity and accelerometer signals generated from such assemblies may be filtered in a similar manner to that described above with reference to
In addition to filtering individual force and velocity signals from one or more of the sensor assemblies 1602, 1604, the digital filter bank 1606 is also configured to combine force and/or velocity signals from two or more of the sensor assemblies 1602, 1604 either before or after filtering. For example, the filter bank 1606 may comprise a bandpass filter and combine module 1608 configured to combine force signals F1, FN from two of the sensor assemblies 1602, 1604 positioned at different locations on the subject to generate a blood pressure signal 1610. The signals F1, FN may be band pass filtered before being combined or the signals may be combined and the band pass filter applied to the combined signal to generate the blood pressure signal 1610.
The filter bank 1606 is configured to combine any combination of signals received before or after filtering in any manner without departing from the scope of the present disclosure.
Having regard to the above,
As mentioned above, the sensor assemblies 100, 200 may be provided with one or more accelerometers configured to measure acceleration of the sensor assemblies 100, 200.
Similar to
The optical signals represented by plot 2522 may be used to calculate blood oxygen saturation at the position of the PPG sensor 402, 614. Alternatively, the PPG sensor 402, 614 may be used in place of one or both of the force sensor 102 and the displacement sensor 104 to allow heart-rate tracing. The back FSR signal is not shown in this example, and only red light and infrared light signals are shown, as these signals have been found to enhance accurately calculating blood oxygen saturation.
The flexible carrier layer 2304 is preferably made from a material that, whilst being flexible, is not able to stretch substantially in a direction perpendicular to the surface of a subject to which the layer 2304 may conform. As such, flexing of the carrier layer 2304 and, therefore, the flexible sensor 2302 leads to a change in resistance of the flexible sensor 2302 (when an FSR) or otherwise leads to a change in characteristics of the flexible sensor 2302. The sensor assembly 2300 further comprises a fixation device 2306 for maintaining the sensor assembly 2300 in position relative to a subject. For example, the fixation device 2306 is an anchoring point for attaching the sensor assembly 2300 to a carrier, such as a garment worn by a subject. The garment may be a shirt, strap, belt, vest, or the like. Equally, the sensor assembly 2300 is able to be worn in the pocket of a garment in the absence of the fixation device 2306. Any of the conditioning or signal processing modules or circuitry described above in relation to the sensor assemblies 100, 200 is equally able to be used to condition or generate signals from the flexible sensor 2302.
In use, the sensor assembly 2300 is positioned at a fixed location on a surface of a subject 2500 having a varying radius of curvature over time. For example, as shown in
Operation of the sensor assemblies 2700, 2800 is similar to that of respective sensor assemblies 100, 200 and so will not be described in detail again here.
Sensor assemblies 100, 200 were placed on a healthy subject's chest wall and on the right common iliac artery of the subject. Trace 3202 represents the velocity of a pulse detected by the displacement sensor 104, after removal of respiration artefacts, at the iliac crest and trace 3204 represents the velocity of the pulse detected by the displacement sensor 104, after removal of respiration artefacts at the chest wall of the subject, in proximity to the apex of the subject's heart.
In
In this test, a sensor assembly 100, 200 was attached to the chest wall of the subject. The subject was then required to lift a weight at two different rates to achieve two different effort levels. In these figures, trace 3402 represents the low-frequency force cardiogram (FCG) as measured by the force sensor 102 of the sensor assembly 100, 200. Trace 3404 represents the high frequency FCG as measured by the force sensor 102 of the sensor assembly 100, 200. Trace 3406 represents respiratory effort as measured by the displacement sensor 104 of the sensor assembly 100, 200. Trace 3408 represents a standard ECG and is provided for comparative purposes.
The results clearly demonstrate a consistent increase in amplitude in both the low-frequency and a high-frequency FCGs which is proportional to the effort level of the subject's heart. In particular, with respect to the values of the FCGs measured prior to exercise, the amplitude of the low-frequency FCG doubled in response to weight lifting at the low rate and trebled in response to the weightlifting at the higher rate. Conversely, the high-frequency FCG, which is known to be highly correlated with a seismocardiogram as extracted by the displacement sensor 104, increased by approximately 1.5 times in response to weightlifting at the low rate and almost double in response to weightlifting at the higher rate. These results demonstrate that the two FCG components carry different information on cardiac mechanics with the low-frequency FCG being more correlated with stroke volume than the high-frequency FCG.
It will be appreciated that identification of a specific person may be achieved by identifying, with a processor, one or more unique physiological signals, or unique portion of a signal, such as generated in response to the person operating the sensor assembly 100, 200. An example of a relevant ECG-based approach is disclosed in “Individual identification via electrocardiogram analysis” by Antonio Fratini, Mario Sansone, Paolo Bifulco and Mario Cesarelli, published on 14 Aug. 2015 in Biomedical Engineering Online (Fratini et al. BioMed Eng OnLine (2015) 14:78, DOI 10.1186/s12938-015-0072-y).
Unique physiological signals, or aspects of signals, may be stored in a memory. The signals may be generated in response to a user contacting the sensor assembly 100, 200 of the system 3900, or obtained with an alternative system or device. Temporal, frequency and morphological features of a signal generated in response to a subject operating the assembly 100, 200 may be compared, by the processor, to the samples stored in the memory to allow subject identification. This may involve determining the identification based on at least one standardised historical signal for the same subject stored in the memory. In some embodiments the system 3900 includes at least one of a photoplethysmography sensor configured to generate a photoplethysmography signal, and a pair of electrocardiogram electrodes configured to generate an electrocardiogram signal. In such embodiments, determining the identification of the subject may be based on a combination of at least two standardised historical signals for the same subject stored in the memory. The morphic dot worn or attached with the user may be in communication with the morphic band and force sensors in the apparatus. While the morphic dot may require a user's finger to contact, for the user's vitals to be obtained, in case of sudden events, the morphic dot may also advantageously comprise an accelerometer for determining the position and/or movement of the user when in use. This positional information is important as in particular for elderly patients, the information may signify whether the subject may have a sudden fall or whether the subject is in a lying position for resting. In case of a detection of a sudden fall, the morphic dot can communicate or sound an alarm to a carer or a person responsible for the patient or subject. This alarm may sound without or without the user's finger in contact with the morphic dot in case the sudden fall rendered the user unconscious. This is advantageous as if the subject is alone or untended when this event happens, someone will be alerted and can immediately attend to the care of the subject as early as possible.
Operating the system 3900 may involve the person manually applying a coded pattern of touches or forces to the assembly 100, 200, such as varying pressure and/or duration of contact within a defined period, as described in greater detail below. The coded pattern may be stored in the memory as a specifically configured password, or other authentication code, to allow or cause a further action, such as access to a digital or physical environment. For example, the processor may be configured to identify the specific pattern to emit an emergency alarm beacon. In some embodiments, as shown in
The embodiment illustrated in
In some embodiments, the assembly 100, 200 may be embedded in a device or structure, such as a key of a keyboard, or screen of a smartphone, or region of furniture, and/or arranged on the subject. This may allow digitally authorising an action, such as securely turning an electrically powered device on or off, such as a vehicle, computer, or mobile phone, or allowing access to a building or area. This approach may also authorise access to digital systems that require levels of security beyond, or instead of, conventional manual or biometric authorisation, such as a password, text code, finger print, eye scan, or facial recognition method.
Operating the embodiment of the assembly 100, 200 shown in
Operating the embodiment of the assembly 100, 200 shown in
The difference between the calibrated DC component of the force measured by the front FSR 4804 and the DC component of the force measured by the back FSR 4805 gives an indication of the body district/tissue compliance.
One or more of the sensor assemblies described herein may be integrated in any combination into a medical device for in situ monitoring of a subject in various situations. For example, the sensor assemblies are able to be mounted in or on a mattress, a chair or a seat; a seatbelt or steering wheel of a car; a collar, strap, attached patch, harness or ear tag of an animal; and configured to monitor one of more physiological parameters of the subject (such as any of those described above). In addition the sensor assemblies may be configured to detect and monitor movement and position of the subject relative to the sensor assemblies on a seat, bed or mattress. Such monitoring may be advantageous in the prevention of bed sores (where the sensor assembly/assemblies is/are integrated into a mattress or the like.
It will be appreciated that embodiments of the present disclosure may be used in the diagnosis and monitoring of a multitude of human and animal diseases and conditions where such diseases and conditions can be diagnosed and monitored by measurements of force, displacement, and/or acceleration of the skin. Non-limiting examples of cardiac conditions and diseases include innocent murmur, sclerosis, hypertension, angina pectoris, myocardial infarction, ventricular aneurysm, mitral valve prolapse (MVP), isolated click and murmur, mitral regurgitation, mitral stenosis (MS), tricuspid regurgitation (TR), mitral regurgitation, aortic regurgitation, aortic stenosis, hypertrophic obstructive cardiomyopathy, cardiomyopathy, pericarditis, pulmonary hypertension, atrial septal defect, ventricular septal defect, patent ductus arteriosus, pulmonary stenosis, coarctation of the aorta, tetralogy of fallot, coronary disease, heart failure, cardiac dyssynchrony, systolic heart failure, diastolic heart failure, pulmonary embolism, cor pulmonale, arterial stiffness, or the like.
Pulmonary diseases and conditions of the lungs may also be diagnosed, including lung congestion. Embodiments of the present disclosure may also be used to diagnose and monitor sleep disorders such as sleep apnoea, for example by placing one or more sensor assemblies as described herein at or near the trachea or at other positions around the neck of a subject. The sensor assemblies may be configured to monitor snoring, swallowing, muscle contraction around an airway (e.g. trachea), size reduction in the airway, optionally in addition to respiration.
Arterial and/or venous conditions (calcification, collapse etc.) may be diagnosed and monitored by placing one or more sensor assemblies described herein on the subject at or near an artery or vein to be monitored. In some embodiments, for example, sensor assemblies may be positioned bilaterally at respective left and right arteries of either both the arms or legs, or one arm and one leg, and a comparison may be made between left and right arteries on the different limbs to determine a condition of one or the other of the arteries (or both).
In any of the embodiments described above, sensor assemblies may be integrated into wearable devices for short or long term use and force, velocity and/or acceleration measurements may be collected and stored so that conditions and disease can be monitored in real time via for example telehealth consultations or over time.
Sensor assemblies described herein may also be used to monitor uterine contractions during pregnancy. A pregnant subject may wear one or more sensor assemblies at location(s) on the skin proximate the uterus, the contraction causing force displacement of the skin and corresponding signals being derived from the force and displacement sensors and optional accelerometers of the sensor assemblies.
Sensor assemblies described herein may not only be used to measure, diagnose, and monitor human or animal subjects, but may also be used to monitor foetal activity in such subjects. For example, one or more sensor assemblies, such as sensor assemblies 100, 200, may be placed at locations about the stomach to monitor movement, respiration, and cardiac signals of a foetus in the womb of an animal or human subject in a manner similar to that described above with reference to the human or animal subject itself. By comparing the foetal signals (eg movement and/or heart rate) to other sensors positioned to measure maternal signals, the change in foetal signals can be correlated to changes in the maternal signals (eg. blood pressure for mothers at risk of preeclampsia)
In embodiments described herein, particularly with reference to
It should be understood, especially by those having ordinary skill in the art with the benefit of this disclosure, that the various operations described herein, particularly in connection with the figures, may be implemented by other circuitry or other hardware components. The order in which each operation of a given method is performed may be changed, and various elements of the systems illustrated herein may be added, reordered, combined, omitted, modified, etc. It is intended that this disclosure embrace all such modifications and changes and, accordingly, the above description should be regarded in an illustrative rather than a restrictive sense.
Similarly, although this disclosure makes reference to specific embodiments, certain modifications and changes can be made to those embodiments without departing from the scope and coverage of this disclosure. Moreover, any benefits, advantages, or solutions to problems that are described herein with regard to specific embodiments are not intended to be construed as a critical, required, or essential feature or element.
Further embodiments likewise, with the benefit of this disclosure, will be apparent to those having ordinary skill in the art, and such embodiments should be deemed as being encompassed herein.
For many applications embodiments may be implemented on a DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array). Thus the code may comprise conventional program code or microcode or, for example code for setting up or controlling an ASIC or FPGA. The code may also comprise code for dynamically configuring re-configurable apparatus such as re-programmable logic gate arrays. Similarly the code may comprise code for a hardware description language such as Verilog TM or VHDL (Very high speed integrated circuit Hardware Description Language). As the skilled person will appreciate, the code may be distributed between a plurality of coupled components in communication with one another. Where appropriate, the embodiments may also be implemented using code running on a field-(re)programmable analogue array or similar device in order to configure analogue hardware.
Note that as used herein the term module shall be used to refer to a functional unit or block which may be implemented at least partly by dedicated hardware components such as custom defined circuitry and/or at least partly be implemented by one or more software processors or appropriate code running on a suitable general purpose processor or the like. A module may itself comprise other modules or functional units. A module may be provided by multiple components or sub-modules which need not be co-located and could be provided on different integrated circuits and/or running on different processors.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021901125 | Apr 2021 | AU | national |
| 2021902991 | Sep 2021 | AU | national |
| 2022900760 | Mar 2022 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/AU2022/050320 | 4/11/2022 | WO |
