Inductive sensing system and method

Abstract

The inductive sensing system 8 is for detecting bleeding (e.g., blood pools) in one or more regions of the body. The system includes a resonator circuit 10 with at least one antenna 12 driven with an oscillating drive signal to generate an electromagnetic signal for delivery to the body. The signal induces eddy currents within the body, which generate secondary EM signals that are returned from the body. These interact with the resonator circuit by adding an additional component of inductance to the circuit. This inductance component varies depending on the conductivity of the fluid in which the eddy currents are induced. Blood has a different conductivity than other bodily fluids. The system is configured to detect the presence of an abnormal accumulation of blood based on the additional inductance component. The system generates a data output representative of the determination.

Description

[Technical field]

[0001] The present invention relates to an inductive sensing system and method, particularly for sensing the presence of a blood pool in one or more regions of the body. [Background technology]

[0002] Internal bleeding is the primary acute symptom and requires prompt treatment to prevent rapid deterioration. Two common types of internal bleeding include intracerebral bleeding and abdominal bleeding.

[0003] Intracerebral hemorrhage (ICH) requires very rapid treatment and time is a critical factor for patient outcome. The main problem is that ICH is often not immediately recognized in the prehospital environment (e.g., in the community, at the patient's home or in the ambulance). It is often diagnosed much later, in the hospital or only after the patient has started to decompensate. An early and proper diagnosis in the prehospital environment would facilitate transport to the appropriate facility and, if the patient did not suffer from ICH, would allow timely treatment to be administered, preventing serious deterioration, and also improve the preparation and planning of correct treatment when the patient arrives at the hospital. Furthermore, currently the only known method for ICH diagnosis is expensive in-hospital scans (CT scans or MRI scans), the results of which are evaluated by neuroradiologists. Although accurate, these scans are expensive and time-consuming, and are not suitable for the prehospital environment.

[0004] Thus, there remains a need for a rapid, relatively compact means for reliably diagnosing intracerebral hemorrhage in a pre-hospital setting.

[0005] Abdominal pain is one of the most common clinical symptoms in the emergency department. Diagnosis of blunt abdominal injury is important for a good patient outcome. Undiagnosed abdominal bleeding can have serious consequences for the patient, even fatal. In current practice, testing for intraperitoneal bleeding is done via manual palpation or via the use of ultrasound as part of the Fast Ultrasound Assessment for Trauma (FAST) approach. These methods are fast but not accurate. Manual palpation requires the expertise of a medical professional to probe the abdominal tenderness. Furthermore, even with the input of a medical professional, only the liver and kidneys are palpable, while other organs may be more difficult to diagnose. Furthermore, the patient needs to be conscious to demonstrate tenderness, which is not always the case in a triage situation.

[0006] FAST technology has made great advances in recent years and is used to detect abdominal bleeding. However, this method is not completely accurate. Acquiring diagnostic quality ultrasound images is not always reliable as it depends on the operator's training. Due to the low sensitivity of ultrasound to intraperitoneal bleeding, some diagnostic errors occur frequently. Visceral bleeding in particular is difficult or even impossible to detect using ultrasound, which means a large false negative rate in ultrasound scans. Furthermore, human interpretation of the ultrasound output poses the risk of medical errors.

[0007] As with ICH, the most accurate method remains the use of CT or MRI scans. However, unnecessary tomography scans are not beneficial to the patient (exposing the patient to unnecessary radiation and prolonging their stay in the hospital) and consume valuable resources for the hospital. Accurate and timely assessment and triage of trauma patients for possible internal bleeding is therefore required to meet the needs of both the patient and the emergency department. Summary of the Invention [Problem to be solved by the invention]

[0008] Thus, there remains a need for an accurate and rapid method for detecting abdominal bleeding in patients presenting to an emergency department.

[0009] Therefore, an improved means for detecting internal bleeding that could overcome one or more of the above-mentioned drawbacks would be advantageous. [Means for solving the problem]

[0010] The invention is defined by the claims.

[0011] According to an example according to one aspect of the invention, there is provided an inductive sensing system configured to sense electromagnetic signals returned from a body in response to application of an electromagnetic excitation signal to the body and configured to detect the presence of bleeding in one or more regions of the body, the system comprising: a resonator circuit comprising at least one loop antenna and an electronic signal generator coupled to the antenna, the resonator circuit driving the antenna with a drive signal to generate the electromagnetic excitation signal in the antenna; and signal sensing means for sensing the return signal based on detecting a measure indicative of an additional inductance component added to the antenna of the resonator circuit by the return signal from the body contemporaneously with generation of the signal; The system comprises: determining whether blood has accumulated based on the detected measure of the additional inductance component; and generating a data output indicative of a result of said determining; It is configured as follows: the resonator circuit includes at least two single loop antennas; The system detects an additional inductance component added to each of the antennas by the return signal from the body. It is configured as follows.

[0012] The system is for detecting (abnormal) blood pools, ie the accumulation or accumulation of blood.

[0013] The system may include a controller or processor configured to perform the determining and generating steps.

[0014] Thus, embodiments of the present invention are based on the use of inductive sensing to detect bleeding.

[0015] According to one group of embodiments, the determination of the presence or absence of blood accumulation is based on a predefined threshold, which is related to the presence of bleeding or blood accumulation in at least one of the one or more regions of the body. However, the use of a threshold is only one example. Alternative approaches include, for example, the use of an algorithmic model configured to determine the presence or absence of blood in one or more specific regions based on the detected additional inductance component. Other alternative approaches may include, for example, the use of an artificial intelligence or machine learning algorithm trained to differentiate between, for example, a normal level of blood in an area and an abnormal pooling or accumulation of blood in an area. For example, a machine learning algorithm may be trained with training data having different additional inductance component signals for different regions, each labeled as corresponding to a normal presence of blood or an abnormal accumulation or pooling of blood.

[0016] Inductive sensing is based on the generation of a primary alternating magnetic field via a primary antenna loop, which leads to the induction of eddy currents in conductive materials or tissue within the primary magnetic field and the resulting induction of a secondary magnetic field, the interaction of which with the primary loop or magnetic field can be used to detect characteristics of the object being probed, especially those containing conductive tissue or materials such as water or other liquid inclusions.

[0017] In particular, this magnetic field interaction leads to a change in a detectable electrical characteristic of the current flowing through the antenna coil: for example, the current frequency may be changed and / or the current amplitude may be attenuated.

[0018] In inductive sensing, a signal generator (such as an oscillator) is connected to a loop antenna. The oscillator is usually an amplifier made of one or more transistors, which induces a resonance condition in a coupled circuit in combination with an inductive and capacitive source. The inductance is provided by the loop antenna, while the capacitance is provided by an optional capacitor component placed in parallel with the loop, the parasitic capacitance of the loop itself and its environment, and the parasitic capacitance of the oscillator. The entire system is called a resonator.

[0019] The secondary magnetic field generated by the body has the effect of adding an additional complex inductance to the resonator circuit in the antenna loop, which causes a detectable change in the circuit current. The real part of the additional inductance can be detected, for example, as a change in the frequency of the oscillating circuit current. The imaginary part of the additional inductance can be detected, for example, as a change in the amplitude of the oscillating circuit current (or voltage).

[0020] Inductive sensing can also be used to distinguish different fluids within a substance. The electromagnetic signal response from different fluids varies depending on their conductivity, which varies depending on their physical properties. This provides a means to detect the presence of pools of blood in locations within the body where normally no blood or only small amounts of blood should be present. For example, in the brain region of a healthy patient, there should be a layer of only cerebrospinal fluid (CSF) in addition to the normal blood flow. In the case of intracerebral hemorrhage, there is additionally or instead a pool or accumulation of blood due to abnormal bleeding. Similarly, in the abdominal region of a healthy patient, there should be only abdominal or visceral fluid in addition to the normal blood flow through the arteries, veins and capillaries in the region. Abdominal or visceral fluid has a different conductivity than blood. A pool or accumulation of blood will produce a return inductive signal that is different from the normal blood flow and normal abdominal and visceral fluid. Thus, by measuring the inductive signal response in the relevant anatomical region, it can be determined whether there is an abnormal accumulation of blood or only normal body fluid.

[0021] For example, according to one or more embodiments, the system may be configured to detect the presence of blood accumulation in an intracerebral region of the body, in which case the system may be configured to detect the occurrence of intracerebral hemorrhage based on the detection of said blood.

[0022] For example, a signal threshold can be defined that is known to be associated with the presence of hemorrhage in intracerebral or abdominal regions, as appropriate.

[0023] According to one or more embodiments, the system may be configured to detect the presence of blood accumulation in an abdominal region of the body, where the system may be configured to detect the presence of abdominal bleeding based on the detection of blood.

[0024] For example, a signal threshold can be defined, which may be a threshold known to be associated with the presence of hemorrhage in intracerebral or abdominal regions, as appropriate.

[0025] According to one or more embodiments, the system has at least two detection modes: - a first detection mode, in which the system is adapted to detect the presence of blood accumulation in a cranial region of the body; and - a second detection mode, in which the system is adapted to detect the presence of blood accumulation in an abdominal region of the body; It may be switchable between

[0026] There may be different possible configurations for the resonator circuit and the antennas. In particular, the resonator may be provided with only a single antenna or with multiple antennas. In each case, preferably, each antenna has only a single loop (single turn or winding).

[0027] It has been found that when the resonator circuit comprises only a single antenna, the maximum difference in inductive response between blood and non-blood body fluids is exhibited by the real component of the additional inductance component added to the resonator circuit.

[0028] Thus, where a single antenna is provided, the signal sensing means may be arranged to detect the real component of the additional inductance component added to the resonator circuit, however this is not essential and the method also works if the imaginary component of the additional inductance is detected instead.

[0029] In certain embodiments, detecting the presence or absence of blood accumulation may comprise comparing the detected real component of the additional inductance to a real inductance threshold associated with the presence of blood accumulation.

[0030] The use of two or more antennas may improve the accuracy or reliability of blood detection. In particular, measurements with two or more loop antennas are less sensitive to small changes in the tissue layer between the loop and the fluid. For example, if the fat layer of the abdominal wall differs from patient to patient, the additional inductance measured with a single loop may change due to the increase or decrease in the distance of the loop from the (accumulated) blood layer. With a multi-loop configuration, the measurements of both loops will change, but the ratio between the two measurements will remain approximately stable. Thus, the accuracy of determining the presence of blood is improved.

[0031] In a multi-loop configuration, according to a particular example, the system may be further configured to determine a ratio between additional inductance components added to each of the two antennas and determine the presence or absence of blood accumulation based on this ratio.

[0032] Ratio in this context may refer to the quotient of the reflected inductance components of the two loops.

[0033] In certain instances, the system can be configured to compare the ratio to a predefined threshold to determine the presence or absence of blood accumulation.

[0034] Therefore, in this example, a threshold is predefined, which is a threshold on the ratio of values ​​between the two loops.

[0035] In another example, the detection of blood accumulation may be based on the difference between an additional inductance component added to each of the two antennas, for example, the difference may be compared to a predefined threshold to determine the presence or absence of blood accumulation.

[0036] Thus, more generally, detection of blood accumulation may be based on the comparative values ​​of the inductance components added to each of the two antennas.

[0037] It has been found that in the case of a multi-loop configuration, where the ratio between the inductances added to each loop is used, the maximum difference in the inductance signal between blood and other fluids is exhibited in terms of the imaginary component of the inductance. Therefore, in an advantageous example, the signal sensing means may be configured in these cases to extract the imaginary part of the additional inductance components added to each of the antennas and to determine the ratio between said imaginary components. This configuration may provide more accurate or reliable detection results.

[0038] However, the use of imaginary components is not essential, for example the method would also work using real components for the additional inductance components added to each antenna.

[0039] Although an example with two antennas has been described, the resonator circuit may also have more than two antennas.

[0040] When more than one loop is provided, there are different options for their configuration.

[0041] The two loop antennas may be arranged concentrically with respect to each other.

[0042] Additionally or alternatively, the two loop antennas may be mounted axially offset with respect to each other, where axially offset in this context means offset in a direction perpendicular to the plane defined by at least one of the antenna loops (the plane in which the antenna lies).

[0043] Additionally or alternatively, the signal generator may be configured to drive each of the two antennas with a drive signal at a different AC frequency.

[0044] In accordance with one or more embodiments, the system may include a support structure, with the at least one loop antenna mounted to the support structure.

[0045] The support structure is for example for holding the one or more antennas in a fixed position. If two antennas are present, the support structure can hold them in a fixed position relative to each other. The support structure can be or include a frame structure. The support structure can be or include a housing structure. If a housing is provided, the housing can be configured to house a resonator circuit including the antennas.

[0046] According to one or more embodiments, the sensing system may comprise a handheld probe unit, which may comprise (e.g. include or house) at least the resonator circuit.

[0047] The handheld probe configuration allows the system to be used for blood detection in a range of different regions of the body, including the head or abdomen, as desired. The system may be switchable between different detection modes, e.g., as described above, for use in different regions of the body.

[0048] According to one or more embodiments, the system may include a head-wearable cap with at least one antenna attached to the cap such that when the cap is worn, the at least one antenna is held in a fixed relationship relative to a surface of the head.

[0049] In a preferred example, the system may have multiple antennas, preferably attached at different positions to the cap, such that when the cap is worn the multiple antennas are held at different positions around the head.

[0050] Such a cap provides an efficient arrangement for detecting bleeding in the head region, for example to detect intracerebral bleeding. Providing multiple antennas at different positions around the cap means that bleeding over the whole area of ​​the head can be monitored, e.g. a map of detected signals around the head can be produced.

[0051] In some instances, the cap may be made from a flexible material such that it will be retained around the head when worn, although this is not required.

[0052] According to one or more embodiments, the system may include a garment or sheet (e.g., of fabric) for covering at least one of the one or more regions of the body, and the at least one loop antenna is attached to the garment or sheet.

[0053] In a preferred embodiment, the system may have multiple antennas attached at different locations on the garment or seat.

[0054] According to a particular example, said garment or sheet may comprise a blanket or a vest.

[0055] The garment or sheet may be particularly advantageous for detecting bleeding in the abdominal region: for example, a blanket may be draped over the patient's abdomen, simultaneously providing an insulating function and allowing inductive detection of any pools of blood in the abdomen.

[0056] According to one or more advantageous embodiments, the garment or seat may comprise a visual indicator means, the system being configured to control the visual indicator means to provide a visual indication of the determination of the presence or absence of blood. The visual indicator may comprise, for example, one or more light sources, e.g. red and green lights, indicating the presence and absence of bleeding, respectively. This feature may additionally or alternatively be applied to the head wearable cap described above to provide a visual indication of the presence of bleeding.

[0057] An example according to a further aspect of the invention provides an inductive sensing method for detecting the presence of bleeding in one or more regions of a patient's body, the method being based on sensing an electromagnetic signal returned from the body in response to application of an electromagnetic excitation signal to the body, the method comprising: driving at least two loop antennas of the resonator circuit with a drive signal to generate said electromagnetic excitation signal in each loop antenna; sensing the return signal based on detecting a measure indicative of an additional inductance component added to each of the antennas of the resonator circuit by the return signal from the body contemporaneously with generation of the signal; determining whether blood has accumulated based on the detected measure of the additional inductance component; and generating a data output indicative of the result of said determining; has.

[0058] In certain embodiments, the step of determining whether or not there is accumulation or pooling of blood may be based on a predefined threshold value, which is related to the presence of (abnormal) accumulation of blood in at least one of the one or more regions of the body.

[0059] The method may be for detecting the presence of blood accumulation in an intracerebral region.The method may be for detecting the presence of blood accumulation in an abdominal region.The method may further include determining the occurrence of either an intracerebral hemorrhage or an abdominal hemorrhage based on the detection of blood.

[0060] For example, the method may include positioning at least one antenna of the resonator circuit to apply an electromagnetic excitation signal to the head region or the abdomen region, and receiving a return electromagnetic signal from the head region or the abdomen region.

[0061] Where a threshold is used to make the detection, the threshold may be a threshold known to be associated with the presence of bleeding in the cranial or abdominal region, as appropriate.

[0062] An example according to a further aspect of the present invention may provide a computer program product, the computer program product comprising: - a resonator circuit comprising at least one loop antenna and an electronic signal generator coupled to the antenna for driving the antenna with a drive signal to generate an electromagnetic excitation signal in the antenna; and - signal sensing means configured to sense the return signal based on detecting a measure indicative of an additional inductance component added to the antenna of the resonator circuit by the return signal from the body simultaneously with generation of the signal; The device further comprises code means configured, when executed on a processor operatively coupled to the device, to cause the processor to perform an inductive sensing method according to any preceding or following embodiment or according to any claim of the present application.

[0063] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0064] For a better understanding of the invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Brief description of the drawings]

[0065] [Figure 1] FIG. 1 shows a schematic representation of eddy current induction in a body to which the system is applied. [Diagram 2] FIG. 2 illustrates a schematic block diagram of components of an example system in accordance with one or more embodiments. [Diagram 3] FIG. 3 shows an example configuration with two antennas. [Figure 4] FIG. 4 shows a graph illustrating the comparative inductance response of blood and CSF using a single antenna, plotted in terms of the imaginary component of inductance. [Diagram 5] FIG. 5 shows a graph illustrating the comparative inductance response of blood and CSF using a single antenna, plotted in terms of the real component of inductance. [Figure 6] FIG. 6 shows a graph illustrating the comparative inductance response of blood and CSF using two antennas, plotted in terms of the imaginary component of inductance. [Figure 7] FIG. 7 shows a graph illustrating the comparative inductance response of blood and CSF using two antennas, plotted in terms of the real component of inductance. [Figure 8] FIG. 8 shows a schematic of a head mounted cap unit having multiple antennas attached thereto. [Figure 9] FIG. 9 shows a schematic of a head mounted cap unit having multiple antennas attached thereto. [Figure 10a] FIG. 10a shows a close-up view of the attachment means of the antenna to the head cap. [Figure 10b] FIG. 10b shows a close-up view of the attachment means of the antenna to the head cap. [Figure 11] FIG. 11 shows a schematic of an exemplary sheet or garment having multiple antennas attached thereto. [Figure 12] FIG. 12 illustrates, in flow chart form, an example method according to one or more embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] The present invention will now be described with reference to the drawings.

[0067] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the devices, systems and methods of the present invention will become more clearly understood from the following description, appended claims and accompanying drawings. It should be understood that the figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the figures to denote the same or similar parts.

[0068] The present invention provides an inductive sensing system for detecting bleeding (e.g., blood pools) in one or more regions of the body. The system includes a resonator circuit with at least one antenna driven with an oscillatory drive signal to generate an electromagnetic signal for delivery to the body. The signal induces eddy currents in the body, which generate a secondary EM signal that is returned from the body. These interact with the resonator circuit by adding an additional component of inductance to the circuit. This inductance component varies depending on the conductivity of the fluid in which the eddy currents are induced. Blood has a different conductivity than other body fluids. The system is configured to detect (determine) the presence of blood based on the additional inductance component. The system generates a data output representative of the determination.

[0069] As mentioned above, the present invention is based on inductive sensing technology.

[0070] Inductive sensing can be used as a means to non-invasively probe properties of the body.

[0071] Inductive sensing is based on the generation of a primary alternating magnetic field via a primary antenna loop, which leads to the induction of eddy currents in conductive materials or tissues within the primary field and a resulting secondary magnetic field, whose interaction with the primary loop or magnetic field can be used to detect patterns of movement within the body being probed, particularly those involving water.

[0072] In particular, this magnetic field interaction leads to a change in a detectable electrical characteristic of the current flowing through the antenna coil: for example, the current frequency may be changed and / or the current amplitude may be attenuated.

[0073] In inductive sensing, a signal generator (such as an oscillator) is connected to a loop antenna. The oscillator is typically an amplifier, consisting of one or more transistors, which in combination with inductive and capacitive sources induces a resonance condition in the coupled circuit. The inductance is provided by the loop antenna, while the capacitance is provided by an optional capacitor component placed in parallel with the loop, the parasitic capacitance of the loop itself and its surroundings, and the parasitic capacitance of the oscillator. The entire system is called a resonator.

[0074] The secondary magnetic field generated by the body has the effect of adding an additional complex inductance to the resonator circuit in the antenna loop, which leads to a detectable change in the circuit current. The real part of the additional inductance can be detected, for example, as a change in the frequency of the oscillating circuit current. The imaginary part of the additional inductance can be detected, for example, as a change in the amplitude of the oscillating circuit current (or voltage).

[0075] Inductive sensing is based on the generation of a primary alternating magnetic field through a primary antenna loop, which induces eddy currents and a resultant secondary magnetic field in any conductive material or tissue within the primary field. This is shown diagrammatically in Figure 1. A loop antenna 12 of a resonator circuit is driven by an alternating current (drive signal). This induces a current oscillation in the antenna.

[0076] In use, the antenna 12 is brought close to a body 16 to be probed. Driving the antenna generates a primary electromagnetic (EM) signal 22, which couples with the body to generate eddy currents 18 in the body. These eddy currents depend on the electrical conductivity of the body. The eddy currents generate a secondary magnetic field 24, which interacts with the primary magnetic field 22 to change the vibration characteristics of the resonator circuit.

[0077] In particular, generally, when the loop antenna is brought close to the body, the inductance L acquires an additional reflected inductance component Lr caused by eddy currents 18 induced in the stimulated body as a result of application of the excitation signal 22.

[0078] These eddy currents 18 effectively contribute to the inductance of the loop antenna 12 by creating a secondary, time-varying magnetic flux. These eddy current fluxes combine with the antenna's primary magnetic flux, producing a larger induced back-EMF in the antenna and therefore a larger measurable effective inductance.

[0079] This additional component of inductance resulting from eddy currents may be synonymously referred to as "reflected inductance" in this disclosure.

[0080] In general, the reflected inductance Lr is a complex number,

number

[0081] The addition of the reflected inductive component Lr causes a detuning of the characteristics of the antenna (or resonator circuit): in particular, both the natural radiation frequency of the coil antenna circuit and the damping coefficient of the coil antenna circuit change.

[0082] In particular, the real part of the additional inductance component Lr appears at the natural frequency of the resonator circuit or antenna, and the imaginary part of said additional inductance component appears at the (natural) amplitude of oscillation of the resonator circuit.

[0083] For completeness, it is noted that the circuit inductance is electrically related to the circuit impedance, and thus measurements of the real and imaginary parts of the impedance may, in some instances, provide the necessary measures of imaginary and real inductance. In particular, the impedance Z consists of real and imaginary parts, i.e., Z=R+iX, where R is the resistance and X is the reactance. This can also be written as Z=R+iω*L, where ω is the radiation frequency and L is the inductance.

[0084] The reflected inductance Lr mentioned above can be defined as Lr = Z / (iω) = L-iR / ω (=L' + iL"). In this case, L is called the real part of the reflected inductance (also called L'), and -R / ω is called the imaginary part of the reflected inductance (also called L").

[0085] Inductive sensing can also be used to distinguish between different fluids within a material. The electromagnetic signal response from different fluids varies depending on their electrical conductivity, which in turn varies depending on their physical properties. This provides a means to detect the presence of blood pools in locations within the body where normally no blood should be present or where only normal blood flow should be present.

[0086] For example, in a healthy patient's skull or intracerebral region, there should be a layer of only cerebrospinal fluid (CSF) with normal blood flow through the blood vessels in that region. In the case of intracerebral hemorrhage, there is also an accumulation or pool of blood. Blood and CSF have different electrical conductivities. Thus, if there is a pool or accumulation of blood, the average electrical conductance of the region being explored will change due to the presence of a higher than normal blood concentration in that region. Thus, by measuring the induced EM response in (for example) an intracerebral region, it can be determined whether there is blood accumulation or only normal blood and CSF are present.

[0087] Similarly, in the case of the abdomen for a healthy patient, in addition to the normal blood flow through the blood vessels, there should only be abdominal or visceral fluid present. Abdominal or visceral fluid has a different conductivity than blood. Thus, the inductive response of the application of the inductive sensor to the abdominal area allows the presence of blood accumulation to be detected compared to the presence of only normal levels of blood in addition to abdominal or visceral fluid. As previously mentioned, if there is abnormal bleeding and thus a pool of blood, the average conductivity of the area being explored will change, resulting in a change in the inductive response. This allows the accumulation of unusual blood to be distinguished from normal blood flow combined with other normal body fluids.

[0088] Thus, embodiments of the present invention use inductive sensing to detect blood accumulation based on these principles.

[0089] FIG. 2 illustrates, in block diagram form, a sensing system in accordance with one or more embodiments of the present invention.

[0090] The system 8 includes a resonator circuit 10 comprising a loop antenna 12 and an electronic signal generator 14 coupled to the antenna for driving the antenna with a drive signal to generate an electromagnetic (EM) excitation signal. The signal generator in this example is in the form of an oscillator 14 that generates the drive signal at a drive frequency.

[0091] In this example, the resonator circuit 10 further includes a capacitor 13 for setting or adjusting the natural free-space resonant frequency of the resonator circuit (i.e., the natural frequency in the absence of any applied field), which in some examples may be a variable capacitor to allow the natural free-space resonant frequency to be adjusted.

[0092] The system 8 further comprises a signal sensing means 30 configured to sense the signal returning from the body simultaneously with signal generation based on detecting a measure indicative of the additional (complex) inductance component added by the returning signal to the antenna 12 of the resonator circuit 10.

[0093] As mentioned above, secondary EM signals from the body add an additional (complex) inductance component to the circuit. This can be detected based on detecting a change in one or more electrical properties of the resonator circuit, for example by detecting a change in the inherent damping coefficient of the resonator circuit and / or in the inherent frequency of the resonator circuit. These can be detected based on detecting a change in the amplitude of the oscillation of the current in the resonator circuit or based on detecting a change in the oscillation frequency of the resonator circuit, respectively. The additional inductance component varies depending on the properties of the medium being probed (as mentioned above).

[0094] The system is further configured to determine the presence or absence of blood accumulation based on the detected measure of the additional inductance component.

[0095] The system is further configured to generate a data output indicative of the result of said determining.

[0096] In some instances, for example, the determination of the presence or absence of blood may be based on one or more predefined thresholds related to the presence of bleeding in at least one of the one or more regions of the body. In this manner, bleeding may be detected.

[0097] However, the use of a threshold is not required. Alternative approaches include, for example, the use of an algorithmic model configured to determine the presence or absence of blood in one or more particular regions based on the detected additional inductance component. Other alternative approaches may also include, for example, the use of an artificial intelligence or machine learning algorithm trained to distinguish between, for example, normal blood levels in a region and abnormal pooling or accumulation of blood in a region. For example, a machine learning algorithm may be trained with training data that includes different additional inductance component signals for different regions, with each signal component labeled as corresponding to either the presence of normal blood or the accumulation or pooling of abnormal blood.

[0098] The above represent exemplary approaches only, and embodiments of the present invention are not limited thereto.

[0099] The system may, in some examples, include a controller or processor configured to perform the determining and generating steps.

[0100] 2, the system 8 further comprises a microprocessor 32 configured to be operatively coupled to the signal sensing means 30 and the resonator circuit 10. For example, the microprocessor may be configured to control the drive frequency of the drive signal generator 14 and / or to perform signal processing, e.g., for the determination of the presence or absence of bleeding. The processor may also in some examples perform other signal processing, e.g., for deriving one or more physiological or anatomical parameters from the sensed or measured signal detected by the signal sensing means 30.

[0101] The signal sensing means 30 may take different forms and operate in different manners to derive a measure indicative of the additional inductance component added to the antenna of the resonator circuit by the return signal.

[0102] The inductive sensing system can be configured in either a single antenna configuration or a multi-antenna configuration.

[0103] In a single antenna configuration, the resonator circuit preferably comprises only a single antenna with a single loop.

[0104] In a multi-antenna configuration, the resonator circuit has two or more antennas each driven with a drive signal to generate an excitation signal, and an additional inductance component added to each antenna is sensed by the signal sensing means.

[0105] 3 shows a schematic of an exemplary multi-antenna configuration. In this example, two antennas are provided: a first, larger diameter antenna 12a and a second, smaller diameter antenna 12b. In the example shown, the two antennas are concentrically arranged with the smaller antenna 12b fitted inside (e.g., coaxially) the periphery of the larger antenna 12a. A support structure, such as a frame or housing, may be provided to hold the two (or more) antennas in fixed relationship to each other.

[0106] In this example, the two antennas are in a coplanar arrangement, i.e., lie in the same plane, however, in other examples, two or more antennas may be mounted axially offset from one another (i.e., offset in a direction perpendicular to a plane defined by at least one of the antennas).

[0107] Furthermore, a concentric arrangement is not required. In other examples, the second antenna 12b may be disposed outside the circumference of the first antenna 12a, or the inner loop surface area of ​​the second antenna may overlap that of the first antenna.

[0108] Moreover, according to one or more examples, the two or more antennas may each be driven with a drive signal at a different frequency, as described further below.

[0109] The above single and multi-antenna configurations are described in further detail below.

[0110] A single antenna 12 can be used to measure reflected inductance at a specific location, for example, on the skull or abdominal region. For example, a single loop placed on the skull can be used to detect intracerebral hemorrhage. A single loop placed on the abdomen can be used to detect abdominal hemorrhage, for example, caused by abdominal trauma. An example of use for detection of intracerebral hemorrhage is discussed below.

[0111] The value of the reflected inductance varies based on the tissue in the vicinity of the loop antenna 12, the geometry of the loop, and the position of the loop relative to the body (e.g., distance to the body). The term "reflected inductance" was introduced above and refers to the additional component of inductance added to the resonator circuit by secondary electromagnetic (EM) signals returning from the body in response to application of an EM excitation signal.

[0112] Because blood is more conductive compared to cerebrospinal fluid (CSF) or abdominal and visceral fluids, the presence of blood creates a greater reflected inductance. By measuring the exact value of the reflected inductance, it can be determined whether there is more blood than would normally be expected, or whether blood is present in places where it should not be. In this manner, inductive sensing can be used to detect internal bleeding in the abdominal area or the brain.

[0113] For example, according to one set of possible embodiments, a pre-determined detection threshold can be defined for the reflected inductance component, which is known to be associated with the presence of hemorrhage, i.e., abnormal accumulation or pooling of blood in the anatomical region being explored. The system can be configured to compare the detected reflected inductance component acquired in a single loop to the threshold to determine whether hemorrhage is present or not (abnormal blood pool, or normal amount of blood). The value of the threshold can vary depending on the region of the body being examined. For example, a different threshold can be defined for detecting intracerebral hemorrhage compared to detecting abdominal hemorrhage. The threshold can be pre-determined, for example, based on empirical measurements or based on the use of models or simulations.

[0114] It should be noted that in some cases, a threshold may not be necessary and a model or simulation may be applied directly to determine the presence or absence of blood accumulation, for example, by providing a measured additional inductance component as an input to the model or simulation.

[0115] To illustrate the principle of blood detection with a single loop configuration, an exemplary simulation for intracerebral hemorrhage detection was performed by the inventors.

[0116] Figures 4 and 5 show the difference in the imaginary (y-axis in Figure 4) and real (y-axis in Figure 5) parts of the reflected inductance as a function of (normalized) frequency (x-axis in Figures 4 and 5) when there is a thin layer of blood or CSF behind the skull. Each graph shows the results for both blood and CSF. In Figure 4, solid line 42 shows the results for CSF while solid line 44 shows the results for blood. In Figure 5, solid line 52 shows the results for CSF while solid line 54 shows the results for blood.

[0117] In each graph, the frequency is normalized to the loop diameter, this normalization approach being described in detail in International Patent Application Publication No. WO2018 / 127482.

[0118] From the graphs of Figures 4 and 5, it is clear that the presence of blood behind the skull results in a larger observable real component of the reflected inductance 54 (Figure 5) compared to the CSF result 52. Although differences between the blood 44 and CSF 42 results can also be observed in the imaginary component of the reflected inductance (Figure 4), the difference in the results is small. Thus, for a single antenna configuration, detecting the real component of the reflected inductance may provide a more reliable and robust blood accumulation detection result.

[0119] For example, in an advantageous embodiment, system 8 may be configured to detect an additional real inductance component added to the resonator circuit and determine whether it exceeds a predetermined threshold, where the predetermined threshold may be based on a known value (or value as a function of frequency) detected for a normal body fluid such as CSF, or for a known normal level of blood flow in a given area in addition to CSF.

[0120] As another example, since the real component of inductance is related to the imaginary component of impedance, in some advantageous embodiments the system 8 is configured to detect an additional imaginary impedance component added to the resonator circuit and determine whether it exceeds a predetermined threshold, where the predetermined threshold may be based on a known value (or value as a function of frequency) detected for normal body fluids such as CSF, or for known normal levels of blood flow in a given area added with CSF.

[0121] The layer model used for the simulation in this example consists of the following layers and corresponding thicknesses (mm):

[0122] [Table 1]

[0123] The loop is assumed to be placed at a distance of 3 mm from the first layer of cortical bone, which corresponds to a realistic value for e.g. the outer wall of the probe housing that would be located between the loop and the skull.

[0124] Next, a multi-antenna configuration will be described.

[0125] In accordance with one or more embodiments, a multi-loop configuration may be provided with two or more antennas, preferably each consisting of a single loop or winding, each with a different geometry (e.g., diameter, shape), position relative to the body (e.g., distance), and / or driven at a different drive frequency.

[0126] The multi-loop configuration can be used to detect bleeding in any area of ​​the body, including, for example, for the detection of intracerebral and abdominal bleeding.

[0127] Combining the measurements of two or more antennas makes the measurements less sensitive to small changes in the tissue layer near the loop. For example, if the fat layer of the abdominal wall is different for each patient, the reflected inductance measured by a single antenna will change due to the increase or decrease in the distance of the blood layer to the loop. However, with a multi-loop configuration, although the measurements of both antennas will change, the ratio between the two measurements will remain approximately stable. Thus, the accuracy of blood presence detection is improved.

[0128] Advantageously, this also means that calibration of the system between different patients is not required, since although the absolute measurement of the additional inductance (at a single antenna) may vary from patient to patient, the ratio between the values ​​of the two loops remains relatively stable across the majority of patients. Thus, accuracy is improved without the need for patient-specific calibration.

[0129] Similarly, when a multi-loop configuration is used to detect intracerebral hemorrhage, changes in skull thickness have minimal effect on the ratio of reflected inductances, whereas results with a single loop may vary.

[0130] Thus, in a multi-loop configuration, the system may be configured to detect the return signal from the body with an additional inductance component added to each of the multiple antennas.

[0131] In some embodiments, the system may be further configured to determine a ratio between the additional inductance components added to each of the two antennas and compare said ratio to a predetermined threshold (for said ratio) to determine the presence or absence of blood. In another example, the difference between the inductance components added to each of the two antennas may be determined and compared to a predetermined threshold for said difference. More generally, the comparison value of the additional inductance components of the two antennas may be used for the determination.

[0132] A predefined (predetermined) threshold can be defined for the ratio of the reflected inductance component values ​​between two (or more) loops. This ratio can be specific to the loop configuration. For example, the ratio can correspond to the ratio of the smaller loop 12b to the larger loop 12a. Ratio in this context means the quotient of the reflected inductance component values ​​for the two loops. The ratio threshold can be a ratio known to be associated with the presence of (abnormal) blood accumulation or pooling.

[0133] The ratio threshold may be predetermined based on empirical measurements, or may be based on a model or simulation, for example.

[0134] Further simulations were performed by the inventors to characterize the multi-antenna configuration, the results of which are shown in the graphs of Figures 6 and 7. The simulations were performed on the same tissue layers (i.e., as shown in Table 1 above) as used in the simulation of the single loop configuration. The configuration consisted of two concentric loops (e.g., as shown in Figure 3) with diameters of 10 mm and 20 mm, respectively, arranged in a coplanar arrangement such that the distance from the antenna to the skull was the same for both antennas. These diameter sizes are merely examples, and in further examples, any other antenna diameter value could be used instead.

[0135] The ratio of the measured reflected inductances of these two loops is plotted as a function of frequency (x-axis in Figures 6 and 7) for the imaginary (y-axis in Figure 6) and real (y-axis in Figure 7) parts of the inductance. The ratio in each case corresponds to the inductance value of the smaller loop (loop 1) divided by the inductance value of the larger loop (loop 2), i.e., the quotient of the smaller loop over the larger loop.

[0136] Each graph shows ratio results for both CSF and blood. In Figure 6, solid line 62 shows the results for CSF while solid line 64 shows the results for blood. In Figure 7, solid line 72 shows the results for CSF while solid line 74 shows the results for blood.

[0137] In this case, the largest difference between the blood and CSF results is seen in the ratio for the imaginary component of the reflected inductance (Figure 6). In this case, the ratio between the imaginary reflected inductance components of the two loops (Loop 1 / Loop 2) is observably smaller for blood than for CSF.

[0138] Thus, in some embodiments, the system 8 may be configured to extract the imaginary components of the reflected inductance components added to each antenna and determine only the ratio or quotient between these imaginary components. Using the imaginary components for the ratio may result in more reliable or accurate detection results.

[0139] Also, because the imaginary component of the inductance is related to the real component of the impedance, in some advantageous embodiments, system 8 may alternatively be configured to extract the real part of the additional component of the impedance added to each antenna and determine the quotient or ratio between these real components of the impedance.

[0140] However, differences are also seen in the results for the ratio of the real components of the reflected inductance (Figure 7). Therefore, in other embodiments, the ratio of the real components of the reflected inductance can be used instead or in addition in multi-loop configurations.

[0141] Although a configuration having only two antennas (two loops) has been described, in further embodiments, three or more antennas (loops) may be provided. In some embodiments, the detection of blood accumulation may be based on the relative value of an additional inductance component added to each of the three or more antennas. For example, the difference between the inductance components of different pairs of the three or more loops may be calculated, the average difference between the loops may be calculated, or the quotient between the inductance components of the three or more loops may be calculated. In some examples, the difference between the inductance components of various pairs of three or more antennas may be calculated and a common baseline or offset known to exist in each (e.g., representing the thickness of the skull) may be subtracted. This allows the comparison values ​​to more reliably indicate differences in blood volume in different regions.

[0142] Additionally, although the configurations described above have concentric, coplanar antennas, in other embodiments the antennas may be provided axially offset from one another and / or non-concentrically positioned.

[0143] According to one or more embodiments, the two or more loops may each be driven with a drive signal at a different drive frequency. This may further improve the robustness of the measurement, since different frequencies change to different degrees as a function of the varying layer thickness. Thus, the ratio of the reflected inductance of two loops driven at different frequencies will be more consistent across different patients than a two-loop configuration in which both loops are driven at the same frequency.

[0144] According to one or more embodiments, one or both loops may be driven at a time-varying frequency. For example, the frequency may be changed continuously (i.e., a frequency sweep is performed) and / or the frequency may be changed in discrete steps. The strength of the signal response (at the desired measurement depth) may vary depending on the driving frequency. Thus, by performing a frequency sweep, an optimal frequency (which provides the strongest signal response) may be identified.

[0145] As previously explained, for either single or multi-antenna configurations, according to one group of embodiments, a threshold can be used for blood detection. The value of the threshold can vary depending on the part of the body being examined. For example, there can be a different threshold for intracerebral regions compared to abdominal regions. As also previously mentioned, the use of a threshold is not mandatory, and other algorithms or models, or machine learning based detection approaches are possible, for example.

[0146] According to one or more embodiments, the system has at least two detection modes: - a first detection mode, in which the system is configured to detect the presence of blood accumulation in an intracerebral region of the body; and - a second detection mode, in which the system is configured to detect the presence of blood accumulation in an abdominal region of the body; It may be switchable between

[0147] Both the single and multi-loop configurations can be implemented in different ways.

[0148] In either case, a support structure may be provided to hold one or more antennas of the resonator circuit in a fixed position, e.g., in a fixed relationship to each other. Various exemplary support structures are outlined below.

[0149] According to one or more embodiments, the sensing system may comprise a handheld probe unit, the handheld probe unit comprising at least the resonator circuit, the handheld probe unit in this case may comprise a housing or frame providing a support structure.

[0150] A universal handheld device in a single or multi-loop configuration can be used to explore both the skull and torso (and other body regions as required). Means may be provided for inputting into the device the anatomical region in which the device is being used, e.g. skull or torso or other region. If thresholds are used to perform blood pool detection, threshold settings can be set based on this input. The device may be provided with means for automatically detecting the region in which it is sensing, e.g. a position sensor. As another example, there may be a user input means for providing this information to the probe. This may be, for example, a simple switch to switch between different modes for different regions, e.g. skull mode or torso mode. In some examples, this may be a "software switch" implemented by the control unit or processor of the device or system.

[0151] In some examples, the system may be configured to automatically select a mode based on an inductance signal value detected in the region where the probe is placed. For example, an initialization phase may be triggered to automatically set the correct mode. The handheld unit is placed in the anatomical region to be searched and an initialization phase is initiated. The system may start generating an inductive sensing signal and determine which anatomical region is being searched based on, for example, the value of the additional inductance component measured at the antenna. For example, a look-up table may be stored that records typical ranges of inductive signal (e.g., additional inductance component) values ​​for different anatomical regions. Based on consulting such a table, the location of the anatomical region of the device may be estimated and therefore the correct mode for that region may be automatically selected.

[0152] According to another group of embodiments, the system 8 may comprise a head-wearable cap, the at least one antenna being mounted on the cap. Preferably, there is provided a plurality of antennas 12 mounted on the cap.

[0153] An example is shown diagrammatically in Figure 8. Figure 8 shows an exemplary head cap 82 having multiple antennas 12 attached or coupled to an outer surface (i.e., the surface that is furthest from the head when worn). The hat or cap can be placed on the patient's head in use, with single or multiple antenna loops measuring reflected inductance at multiple locations on the skull. This configuration offers the advantage that the device does not need to be held by clinical staff, which may be beneficial in, for example, an ambulance. The cap can ensure that the antennas are held in a stable position relative to the head, and also at a fixed, constant distance from each other, for example. This may be beneficial for reliable and comparable measurement results between test cases and between patients.

[0154] The cap can be configured such that the position of the antenna is fixed relative to the head and the separation or spacing of each inductive sensor relative to the skull is uniform across the skull.

[0155] This can be done, for example, by using a flexible cap to ensure that contact with the skull is maintained (the cap is held around and by the head when worn). Optionally, the cap may be sectioned by a number of holes so that it takes the form of a net or mesh.

[0156] In a preferred embodiment, each of the single or multiple antennas may be connected to the flexible cap or flexible net at a single point, thus allowing the loops to be rigid while the cap itself is fully flexible.

[0157] This is shown in Figure 9 and Figures 10a and 10b. Figure 9 shows an exemplary cap 82 and an arrangement of multiple single antennas 12, each attached to the cap via a single connection point 102. Each antenna is attached to the outer surface of the cap or netting via a spacer member 102 that holds each antenna upright or elevated above the outer surface of the cap, hat or netting (i.e., the surface facing away from the head). Each spacer member is in the form of a stem or rod that holds each antenna elevated above the outer surface of the cap.

[0158] The spacer 102 or stem ensures that the circumferential centre of the antenna loop 12 is maintained at a constant distance from the outer surface of the cap. In another example, the spacer may be provided in the form of a cladding surrounding the wire of the antenna.

[0159] An array of inductive sensor antennas, as shown in Figure 9, allows the generation of a map of the electrical conductivity of the skull, for example in the top 5-10 cm of the skull, where intracerebral hemorrhage at the surface of the skull can be detected, for example, as a local increase in electrical conductivity.

[0160] In one advantageous group of examples, the cap 82 may include a visual indicator means, in which case the system is configured to control the visual indicator means to provide a visual indication regarding the determination of the presence or absence of bleeding in a brain (e.g., intracerebral) region.

[0161] This indicator may, for example, comprise a red / green light or indicator attached to the cap 82, where red indicates bleeding and green indicates no bleeding.

[0162] In use, the cap may be operatively connected to a readout device or patient monitor via a wired or wireless connection.

[0163] Figure 10 shows an exemplary antenna 12 and a coupled spacer 102 or stem (single point connector). Figure 10b shows a view of the spacer 102 or stem by itself.

[0164] According to another group of embodiments, the system may include a garment or sheet (e.g., of fabric) for covering one or more areas of the body to be inductively sensed, with the at least one antenna 12 attached to the garment or sheet.

[0165] Preferably, the system includes a plurality of antennas attached at different positions on the garment or seat.

[0166] Such a configuration is particularly advantageous for performing inductive sensing of the torso, for example the abdomen.

[0167] According to one or more examples, for example, a blanket or vest may be provided that may be placed over a patient, with multiple antennas 12 attached to the blanket or vest.

[0168] An example is shown diagrammatically in Figure 11, which shows an exemplary blanket product 92 having an array of antennas 12 attached across its entire area. The antennas can be attached to the exterior surface of the blanket or can be incorporated within the body of the blanket, e.g., sewn or stitched to the inside.

[0169] The blanket 92 can, for example, be draped over the patient while measurements are being taken, allowing medical staff to concentrate on other tasks.

[0170] In one advantageous set of examples, the blanket may include a visual indicator means, in which case the system is configured to control the visual indicator means to provide a visual indication of the determination of the presence or absence of bleeding in the abdominal region.

[0171] This indicator may, for example, comprise a red / green light or indicator attached to the blanket, where red indicates bleeding and green indicates no bleeding.

[0172] In one set of embodiments, the visual indicator means may be configured to detect blood accumulation over multiple areas of the patient's body that may be covered by a garment or sheet (e.g. a blanket). The visual indicator means may have multiple visual indicator portions arranged to provide visual indicators at different locations on the garment or sheet to indicate the corresponding body location of the detected blood pool. For example, the visual indicator means may have multiple light sources arranged at different locations across the sheet or garment, in which case the system is configured to illuminate light sources at locations aligned with (e.g. located above) all locations on the body where the multiple antennas of the sheet or vest detect blood accumulation.

[0173] For example, the position of the garment or vest on the patient can be marked, e.g., the center of the top edge of the blanket product is aligned with the suprasternal fossa or the xiphoid process. When placing the garment or vest on the patient, the clinician can verify that the reference points on the garment or vest are correctly aligned with predefined reference alignment locations on the patient's body. In this manner, the product is positionally calibrated.

[0174] Similar features are applicable to the head-mountable cap 82 described above, i.e. the head-mountable cap may have visual indicator means arranged to provide visual indicators at different positions on the cap to indicate the corresponding brain locations of detected blood pools.

[0175] The blanket may be operatively connectable, in use, to a readout device or patient monitor via a wired or wireless connection.

[0176] Multiple antenna loops 12 can be used distributed over the area of ​​the blanket to measure multiple locations at once without the need to hold any equipment. For such an embodiment, the same single point attachment described and illustrated above for flexible cap 82 can be used.

[0177] Thus, embodiments of the present invention provide an inductive sensor that can be used in almost any environment to detect the presence of bleeding. Advantages of the provided system include that it can be provided in a compact form factor, e.g. embodied as a handheld device, blanket or small cap as described above. This means that it can be easily used in pre-hospital or emergency triage environments. Furthermore, the results are instantaneous and easy to interpret. In particular, the data output signal of the inductive sensor system will immediately indicate any bleeding due to differences in reflected inductance. Thus, early triage (e.g., for ICH or abdominal bleeding) can be performed in a timely manner wherever there is a low level of operator expertise.

[0178] An example according to another aspect of the invention provides an inductive sensing method for detecting the presence of bleeding in one or more regions of a patient's body, the method being based on sensing an electromagnetic signal returned from the body in response to application of an electromagnetic excitation signal to the body.

[0179] FIG. 11 illustrates a block diagram of steps of an exemplary method 100 according to one or more embodiments.

[0180] The method further comprises the step 102 of driving at least one loop antenna of the resonator circuit with a drive signal to generate an electromagnetic excitation signal in the antenna.

[0181] Concurrently with the signal generation, the method includes sensing 104 the return signal based on detecting a measure indicative of the additional inductance added to the antenna of the resonator circuit by the return signal from the body.

[0182] The method further includes determining 106 the presence or absence of blood based on the detected measure of the additional inductance component.

[0183] The method further comprises the step of generating 108 a data output indicative of the result of said determining.

[0184] The method may be for detecting the presence of blood in a cranial region.The method may be for detecting the presence of blood in an abdominal region.The method may further comprise determining the occurrence of either intracerebral or abdominal hemorrhage based on the detection of blood.

[0185] For example, the method may include positioning at least one antenna of the resonator circuit to apply an electromagnetic excitation signal to the head region or the abdomen region, and receiving an electromagnetic signal returned from the head region or the abdomen region.

[0186] As described above in connection with aspects of the system of the present invention, the determination of the presence or absence of blood accumulation can be based on a predefined threshold value, which is related to the presence of blood in at least one of the one or more regions of the body.

[0187] The threshold may be one known to be associated with the presence of bleeding in the cranial or abdominal regions, as appropriate.

[0188] The implementation options and details regarding each of the above steps can be understood and interpreted according to the explanations and descriptions provided above with respect to the apparatus aspects (ie, system aspects) of the present invention.

[0189] Any of the features or details of the examples, options or embodiments described above with respect to the apparatus aspects of the invention (with respect to the inductive sensing system) may be applied to, combined with or incorporated in the method aspects of the invention.

[0190] An example according to a further aspect of the present invention may provide a computer program product, the program product comprising: - a resonator circuit 10 comprising at least one loop antenna 12 and an electronic signal generator 14 coupled to said antenna, for driving said antenna with a drive signal to generate an electromagnetic excitation signal in said antenna; and - signal sensing means 30 configured to sense a return signal based on detecting a measure indicative of an additional inductance component added to the antenna of the resonator circuit by a return signal from the body simultaneously with said signal generation; The method comprises code means configured, when executed on a processor operably coupled to the device, to cause the processor to perform an inductive sensing method according to any embodiment described above or below or according to any claim of the present application.

[0191] As mentioned above, some embodiments utilize a control means, microcontroller and / or microprocessor.

[0192] Any or each of these components may be implemented in various ways using software and / or hardware to perform the various functions required. For example, a processor may be used using one or more microprocessors that may be programmed using software (e.g., microcode) to perform the required functions. However, the control means may be implemented with or without a processor, or as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions.

[0193] Examples of controller components that may be used in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

[0194] In various implementations, a processor or controller may be associated with one or more storage media, such as volatile and non-volatile computer memory, such as RAM, PROM, EPROM, and EEPROM. The storage media may be encoded with one or more programs that, when executed on the one or more processors and / or controllers, perform the necessary functions. The various storage media may be fixed within the processor or controller, or may be portable such that the stored one or more programs can be loaded into the processor or controller.

[0195] Variations of the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from an examination of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the singular does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. Where a computer program is described above, the program may not only be stored / distributed by an appropriate medium, such as an optical storage medium or a solid-state medium, provided together with or as part of other hardware, but also distributed in other forms, such as via the Internet or other wired or wireless communication systems. It should be noted that when the term "adapted" is used in the claims or description, the term "adapted" is intended to be equivalent to the term "configured". Any reference signs in the claims should not be interpreted as limiting the scope.

Claims

1. 1. An inductive sensing system for detecting the presence of bleeding in one or more regions of a body by sensing an electromagnetic signal, the return signal being a signal returned from a body in response to application of an electromagnetic excitation signal to the body, the inductive sensing system comprising: a resonator circuit comprising at least two single loop antennas and an electronic signal generator coupled to the at least two antennas, the resonator circuit driving the antennas with a drive signal to cause the antennas to generate the electromagnetic excitation signal; and signal sensing means for sensing said return signal based on detecting a measure indicative of a respective additional inductance component added to each of said antennas of said resonator circuit by said return signal from said body contemporaneously with the generation of said electromagnetic excitation signal. the inductive sensing system comprising: determining a ratio between the detected measures of the additional inductance components added to each of the at least two antennas; determining whether blood has accumulated based on the determined ratio of the additional inductance components; generating a data output indicative of the result of said determining; Inductive sensing system.

2. 2. The inductive sensing system of claim 1, wherein the determination of the presence or absence of blood accumulation is based on a predefined threshold, the threshold being related to the presence of bleeding or blood accumulation in at least one of the one or more regions of the body.

3. 3. The inductive sensing system of claim 1 or 2, wherein the inductive sensing system detects the presence of blood accumulation in an intracranial region of the body.

4. The inductive sensing system of claim 1 , wherein the inductive sensing system detects the presence of blood accumulation in an abdominal region of the body.

5. The inductive sensing system has at least two detection modes: a first detection mode in which the inductive sensing system detects the presence of blood accumulation in an intracerebral region of the body; a second detection mode in which the inductive sensing system detects the presence of blood accumulation in an abdominal region of the body.

5. An inductive sensing system according to claim 3 or 4, wherein the inductive sensing system is switchable between:

6. The inductive sensing system of claim 1 , further comprising: a first inductive sensing unit configured to compare the ratio to a predefined threshold to determine the presence or absence of blood accumulation.

7. the at least two loop antennas are arranged concentrically with respect to each other; the at least two loop antennas are mounted axially offset relative to each other; and / or the electronic signal generator drives the at least two loop antennas with drive signals of different AC frequencies; An inductive sensing system according to any one of claims 1 to 6.

8. 8. An inductive sensing system according to claim 1, wherein the inductive sensing system comprises a support structure, and the at least two single loop antennas are mounted in fixed relationship to the support structure.

9. 9. An inductive sensing system according to any one of claims 1 to 8, wherein the inductive sensing system comprises a hand-held probe unit, the hand-held probe unit comprising at least the resonator circuit.

10. 10. The inductive sensing system of claim 1, wherein the inductive sensing system has a head-wearable cap, and the at least two antennas are attached to the cap such that when the cap is worn, the at least two single loop antennas are held in a fixed relationship relative to a surface of the head.

11. 10. The inductive sensing system of claim 1 , wherein the inductive sensing system comprises a garment or sheet for covering at least one of the one or more regions of the body, and the at least two loop antennas are attached to the garment or sheet.

12. 1. An inductive sensing method for detecting the presence of bleeding in one or more regions of a patient's body, the inductive sensing method being based on sensing an electromagnetic signal that is a return signal returned from the body in response to application of an electromagnetic excitation signal to the body, the inductive sensing method comprising: driving at least two loop antennas of a resonator circuit with a drive signal to generate said electromagnetic excitation signal in each loop antenna; sensing the return signal based on detecting a measure indicative of an additional inductance component added to each of the antennas of the resonator circuit by the return signal from the body contemporaneously with generation of the electromagnetic excitation signal; determining a ratio between the detected measures of the additional inductance components added to each of the at least two antennas; determining whether or not blood has accumulated based on the determined ratio of the additional inductance components; and generating a data output indicative of the result of said determining. The inductive sensing method comprises:

13. 13. The inductive sensing method of claim 12, wherein the inductive sensing method is for detecting the presence of blood in a brain region or in an abdominal region, the inductive sensing method further comprising the step of determining the occurrence of either a brain hemorrhage or an abdominal hemorrhage based on the detection of blood.

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