CONTROLLER AND METHOD FOR INDUCTION SENSING - Patent application

Abstract

The switching mechanism is for enabling the inductive sensing circuit to be used with a portable handheld device having electromagnetic transmission capabilities in a manner that avoids harmful interference of the portable device's electromagnetic transmissions with a subject when medical sensing is being performed. Specifically, embodiments provide a controller configured to control switching between two modes: a first mode in which at least a portion of the portable device's transmission capabilities are deactivated while the inductive sensing circuit is activated, and a second mode in which the electromagnetic portable device's transmission capabilities are fully activated and the inductive sensing circuit is deactivated. Thus, embodiments provide means for toggling between the two modes, the modes configured to avoid simultaneous inductive sensing and full-power electromagnetic transmission of the portable handheld device.

Description

[Technical Field]

[0001] The present invention relates to controllers and methods in the field of inductive sensing, and in particular to means for switching between sensing and non-sensing modes in the context of portable handheld devices associated with inductive sensing. [Background technology]

[0002] Basic patient triage must be performed at all levels of healthcare worldwide. Rapid initial triage is important to categorize patients in order of priority based on the urgency of their medical condition. For example, many parts of the world have overcrowded major medical facilities where patients are at risk of worsening while waiting in line for tests. In low-resource countries, patients must be triaged by less-skilled personnel for hospital referral. Even in high-resource countries or hospitals, basic patient triage must be performed, for example, in emergency rooms (ERs).

[0003] In developed countries, the trend to "push back" non-urgent care patients to save costs is also increasing the need for regular spot checks and triage in non-urgent care settings (e.g., skilled nursing facilities, patients' homes, remote GP visits).

[0004] Additionally, there is a need for a quick and simple means for detecting the presence of cardiac arrest, preferably one that can be used by both clinicians and non-specialist operators.

[0005] Two basic vital sign measurements that can indicate a wide range of different medical conditions are pulse rate and respiratory rate, which can also indicate abnormalities in the condition and the risk of deterioration. Summary of the Invention [Problem to be solved by the invention]

[0006] In a typical hospital, heart rate and respiratory rate measurements are performed with two separate devices, which are typically large units transported, for example, on a handcart. Therefore, the patient must be brought to a location, such as a triage bed, where both devices are located and plugged in. Furthermore, standard devices for measuring heart rate and respiratory rate require direct contact sensors, such as a PPG finger clip sensor for heart rate, which must be cleaned between patients to avoid cross-contamination, or the sensor contacts must be completely replaced.

[0007] In view of the above, it would be useful to have a simple, mobile, contactless, and easily accessible device to perform an assessment of a patient's vital signs, preferably including at least pulse rate and respiratory rate.

[0008] The inventors have recognized that the increasing ubiquity of smartphones makes the use of these devices an attractive approach. Typically, individuals already carry a smartphone for internet access, email, telephone communications, and various other purposes. Therefore, incorporating vital sign measurement functionality into these devices would also be highly efficient, as it avoids duplication. This also means that measurements can be performed by unskilled personnel and the measurement device is always at hand. Furthermore, smartphones already integrate functionality for transmitting or communicating collected data and, if necessary, for making emergency calls or triggering emergency alarms.

[0009] The integration of medical sensing technology into mobile phones has been proposed previously but has not been widely adopted for several reasons. Most specifically, a problem with smartphones is that they emit electromagnetic radiation at levels higher than those permitted by current regulations for medical devices. For example, implantable medical devices are not designed to operate near an active mobile phone. Pacemakers, for example, would cease functioning in such conditions. A second major problem is that current solutions require contact between the mobile phone and the patient. For example, pulse rate and respiratory rate can be measured using a mobile phone's camera in combination with an LED, which together form a contact photoplethysmography (PPG) sensor. Other solutions are complex or unreliable. For example, camera-based methods for measuring vital signs require high levels of illumination, which is not always available, and may require the subject to remain sufficiently still and the camera to be held very steady. In a hospital triage situation, these conditions are not always possible.

[0010] An improved approach for utilizing portable handheld devices with electromagnetic transmission capabilities to perform medical sensing of vital signs could overcome one or more of the above problems and would therefore be useful. [Means for solving the problem]

[0011] The invention is defined by the claims.

[0012] According to an example according to an aspect of the present invention, there is provided a controller, the controller comprises an input / output for receiving and transmitting data when communicatively coupled with the inductive sensing circuitry and the portable handheld device, the portable handheld device having electromagnetic radiation capabilities; a first mode in which the controller communicates with the portable handheld device to deactivate at least a portion of the device's electromagnetic emissions and simultaneously communicates with the inductive sensing circuit to activate the inductive sensing circuit; and The controller is operable to communicate with the portable handheld device to implement a switching function for switching between two modes, with a second mode activating at least a portion of the electromagnetic emissions of the device while deactivating the inductive sensing circuitry.

[0013] Preferably, the inductive sensing circuitry is arranged to draw power from the portable handheld device in the first mode. As such, the inductive sensing circuitry is supported by or supplied by the portable handheld device and is used in conjunction with the portable handheld device. Various suitable physical and functional arrangements of the two are possible, as discussed further below.

[0014] Preferably, the inductive sensing circuit is configured to be electrically and / or physically coupled to the portable handheld device in use.

[0015] An inductive sensing circuit, for example, refers to a circuit comprising a resonant circuit with an antenna and, preferably, a signal generator, configured to be driven at resonance to generate an electromagnetic excitation signal for application to the body. During inductive sensing, these excitation fields induce eddy currents in the body's tissues, which in turn generate secondary electromagnetic emissions that interact with the primary excitation signal to alter the electromagnetic vibrations encountered at the inductive circuit's antenna. This changes the electrical properties of the current in the resonant circuit, such as its resonant frequency or amplitude, and by measuring these changes over time, signals representative of tissue motion (e.g., cardiac or pulmonary motion) can be derived. These signals can be used to derive the magnitude of vital signs, such as heart rate and respiratory rate.

[0016] Inductive sensing uses electromagnetic radiation of much lower power than the typical emissions of a mobile phone or other mobile communication device, and is therefore within the permitted emission levels for medical devices.

[0017] Ideally, such inductive sensing circuits would be integrated within or connected to a portable handheld device, such as a mobile phone, which could, for example, power and, optionally, control and coordinate the sensing functions of the circuit, for example, via an app. Nevertheless, as noted above, the use of devices with electromagnetic (EM) emission levels as high as those of mobile portable devices is not appropriate in a medical context.

[0018] Embodiments of the present invention provide a solution to this problem by effectively proposing a switching mechanism that allows a portable handheld device with electromagnetic transmission capabilities and an apparatus comprising an inductive sensing circuit to be switched between a medical sensing mode (first mode) and a mobile communication mode (second mode). In the first mode, the proposed controller simultaneously controls the electromagnetic emissions of the handheld portable device to be stopped or at least limited or restricted in a defined manner (e.g., by stopping emissions within a specific frequency range or above a specific power, or by switching off a defined subset of the portable handheld device's wireless transmitter) and to activate power to the inductive sensing circuit or control the inductive sensing circuit to begin being driven with a drive signal to resonate it. In the second mode, these two actions are reversed, with the inductive sensing circuit deactivated and the electromagnetic transmission capabilities of the portable handheld device fully activated. These two modes can be toggled between to switch between the medical sensing function and the normal functionality of the portable handheld device.

[0019] Thus, embodiments of the present invention provide a means for automatically disabling potentially harmful electromagnetic emissions of a portable handheld device whenever a medical sensing function is performed by the inductive sensing circuitry. By controlling the device's inductive sensing circuitry and electromagnetic emissions in parallel, this relieves the user of the burden of manually disabling the mobile device's wireless transmissions whenever they need to perform inductive sensing, eliminating the possibility of forgetting to do so. This allows such devices to ensure, for example, that medical sensing is never performed without switching off harmful electromagnetic transmissions, thereby enabling such devices to comply with regulations for medical devices.

[0020] The controller is an electronic controller. The controller is, in different examples, a controller, a control arrangement, a control unit, a control module, or a processor arrangement. The controller comprises one or more processors or controllers.

[0021] The controller is arranged to receive a control command and to effect switching between the two modes in response to receiving a predefined control command. The controller is arranged to receive the control command, in use, for example from a portable handheld device or from an external device.

[0022] For example, control commands may be generated upon activation of a particular operating mode by a user on the user interface of a portable handheld device.

[0023] The controller is arranged to detect a change in state of the portable handheld device and to effect switching in response to detecting the change in state.

[0024] A controller can be, for example, a control unit or module, which is or comprises one or more processors or processing arrangements.

[0025] The controller may comprise a single controller or processing unit or may be distributed among different controllers and / or different devices. For example, the controller may be facilitated jointly by a processor in the portable device and a processor in the secondary unit. Deactivation / activation of EM emissions may be controlled by the portable device processor, and activation / deactivation of the sensing circuitry may be controlled by the secondary sensor unit processor. The two may cooperatively exchange signals to jointly implement switching between two different modes.

[0026] In one or more embodiments, the second mode includes deactivating one or more electromagnetic transmitters of the portable device.

[0027] The transmitter or transmitters to be deactivated are a defined subset of the full set of transmitters that the mobile device comprises, for example, transmitters that emit in frequencies or power ranges that exceed regulations for medical devices.

[0028] According to one or more embodiments, the second mode includes halting emissions in one or more electromagnetic frequency bands / ranges or includes halting all electromagnetic radiation above a defined threshold power.

[0029] According to one or more embodiments, the controller is further configured to receive the inductive sensing signal input from the inductive sensing circuit and derive one or more physiological parameters from the signal, such as, for example, heart rate and / or respiratory rate.

[0030] According to one or more embodiments, the controller is configured to switch between the two modes in response to receiving one or more predefined control commands, and preferably the controller is arranged to receive the control commands from a portable handheld device.

[0031] The control command may, in certain instances, be received (directly or indirectly) from a hardware switch on the portable device or from a software trigger command.

[0032] According to one or more embodiments, in a first mode, the controller is configured to cause the portable handheld device to activate a power supply from the portable device to the detection circuitry, and in a second mode, the controller is configured to cause the portable handheld device to deactivate a power supply from the portable handheld device to the detection circuitry.

[0033] Examples according to further aspects of the invention also include 1. An inductive sensing circuit for sensing an electromagnetic signal returned from a body in response to application of an electromagnetic excitation signal to the body, comprising: The inductive sensing circuit includes a resonant circuit including a loop antenna, the resonant circuit generating an excitation signal when driven with a drive signal. an inductive sensing circuit; a controller according to any example or embodiment outlined above or described below, or according to any claim of the present application, operably coupled to the inductive sensing circuit; A carrier on which the induction detection circuit and controller are mounted An inductive sensing assembly is provided, comprising:

[0034] The assembly is for example a chip.

[0035] Thus, in this aspect, an integrated chip or circuit assembly is provided that includes both a controller and an inductive sensing circuit for performing the inductive sensing function. In different embodiments, the assembly can be integrated directly into a portable handheld device, e.g., a mobile communication device, such as a mobile phone (smartphone) or tablet computer. Thus, the principles of the present invention can be implemented in a dedicated chip attached to the portable handheld device, or alternatively, in a separate unit, e.g., to which the portable handheld device is operatively coupled. The separate unit can, for example, comprise a sleeve configured to be removably wrapped around the portable handheld device, with the assembly (e.g., chip) integrated within the sleeve.

[0036] The carrier may be or comprise a substrate, for example the substrate may be or comprise a circuit board, for example a PCB.

[0037] The inductive sensing circuit includes a signal generator for generating a drive signal suitable for driving an antenna to generate an electromagnetic excitation signal.

[0038] For example, the signal generator can generate an AC drive signal, e.g., the signal generator is an oscillating component, and the signal generator drives the antenna to resonance, e.g., by driving the antenna with a signal having a frequency that matches the resonant frequency of the resonant circuit.

[0039] The inductive sensing circuit comprises a signal detection / pickup means for detecting signals returned from the body based on detecting variations in one or more electrical properties of the resonant circuit, including, for example, the resonant frequency and / or amplitude of the resonant circuit.

[0040] An example according to a further aspect of the present invention also provides an apparatus for inductive sensing, the apparatus comprising a portable handheld device having electromagnetic radiation capability and a controller according to any example or embodiment outlined above or described below, or according to any claim of the present application.

[0041] In different implementations, the controller is executed by an integrated (native or local) controller or processor of the portable handheld unit, or the device is provided with a dedicated controller, e.g., a dedicated controller or processor, for executing the controller. In the first case, the control functions of the controller are executed, e.g., by an app or other computer code means installed on the portable device (e.g., installed on the device's local / native controller or processor). In the second case, the dedicated controller or processor is configured to perform the control functions of the controller. For example, the dedicated controller or processor has computer code means installed or stored on the dedicated controller or processor and is configured to execute this code.

[0042] The device further includes an inductive sensing circuit operably coupled to the controller, the inductive sensing circuit detecting an electromagnetic signal returned from the body in response to application of the electromagnetic excitation signal to the body, the inductive sensing circuit including a resonant circuit, for example, a loop antenna, that generates the excitation signal when driven with the drive signal.

[0043] The inductive sensing circuit is adapted to draw power from the portable handheld device to power the circuit when in the first mode.

[0044] In the first mode, the controller is configured to activate a power supply from the portable device to the sensing circuitry in the portable handheld device.

[0045] In the second mode, the controller is configured to cause the portable handheld device to deactivate the power supply from the portable device to the sensing circuitry.

[0046] There are different options for the relative spatial configuration of the various components.

[0047] For example, in one or more embodiments, the inductive sensing circuitry is integrated into the portable handheld unit, for example as part of a dedicated chip or circuit assembly.

[0048] The chip or assembly may or may not include a controller, which may be separate or may be part of the assembly.

[0049] In an alternative example, the device includes a secondary unit, the inductive sensing circuitry is integrated within the secondary unit, and the portable handheld unit is operatively coupled to the secondary unit.

[0050] The secondary unit may be, for example, a peripheral or auxiliary sensor unit that houses an induction circuit arrangement. The secondary unit is separate from the portable handheld unit.

[0051] In some examples, for example, the secondary unit comprises a sleeve item configured to be removably wrapped around the portable handheld device, and the inductive sensing circuitry is integrated within the sleeve item.

[0052] According to one or more embodiments, the device comprises an inductive sensing assembly according to any example or embodiment outlined above or described below, or according to any claim of the present application, where the above-mentioned controller and inductive sensing circuitry are provided by the inductive sensing assembly, which in this example is provided in operative association with a portable handheld unit.

[0053] The inductive sensing assembly is operatively coupled to, for example, a controller or processor of the portable handheld unit, e.g., the sensing assembly takes the form of a chip, such that in this example, the portable handheld device is provided with a dedicated inductive sensing chip that includes both the controller and the inductive sensing circuitry.

[0054] The inductive sensing assembly is integrated into a portable handheld unit.

[0055] An alternative arrangement may be to provide the sensing circuitry on a dedicated chip, for example, and the controller is separate. The controller can be provided by its own dedicated chip, or facilitated or executed by a local / native controller or processor of the portable handheld device.

[0056] As described above, the device includes a secondary unit, and in some instances, the inductive sensing assembly is integrated within the secondary unit, and the portable handheld unit is operably coupled to the secondary unit, e.g., the sensing assembly of the secondary unit.

[0057] The secondary unit may be, for example, a peripheral or auxiliary sensor unit housing an inductive sensor arrangement.

[0058] It can thus be seen that there are a wide variety of different possible associated spatial arrangements of the controller, inductive sensing circuitry, and portable handheld device in different examples.

[0059] According to an advantageous embodiment, the device comprises means for processing the signals sensed by the signal sensing means and for deriving one or more physiological parameters based on the sensed signals.

[0060] Preferably, the portable handheld device is a mobile communications device, such as a mobile phone device.

[0061] The portable handheld device may be, for example, a smartphone. The device may alternatively be, for example, a tablet computer.

[0062] An example according to a further aspect of the present invention provides a method for controlling a portable handheld device having inductive sensing circuitry and electromagnetic radiation capabilities.

[0063] The method is: a first mode in which the controller communicates with the portable handheld device to deactivate at least a portion of the device's electromagnetic emissions and simultaneously communicates with the inductive sensing circuit to activate the inductive sensing circuit; a second mode in which the controller communicates with the portable device to activate at least a portion of the electromagnetic radiation of the device while simultaneously deactivating the inductive sensing circuitry; and and implementing a switching function to switch between the two modes.

[0064] As described above, switching between modes is performed in response to a control command, such as in response to opening a software application (app) on the portable handheld device, which may trigger the generation of a control command to trigger the mode switch.

[0065] An example according to a further aspect of the present invention also provides a computer program product comprising code means configured to, when executed on a processor, cause the processor to perform a method according to any example or embodiment outlined above or described below, or according to any claim of the present application.

[0066] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0067] For a better understanding of the present invention, and to show more clearly how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Brief explanation of the drawings]

[0068] [Figure 1] FIG. 1 is a diagram illustrating the basic principle of inductive sensing. [Figure 2] FIG. 1 illustrates components of an example apparatus in accordance with one or more embodiments of the present invention. [Figure 3] 2A-2C are diagrams illustrating two modes of operation implemented by the switching functionality of an embodiment of the present invention; [Figure 4] FIG. 1 is a diagram outlining components of an example inductive sensing circuit in accordance with one or more embodiments of the present invention. [Figure 5] 1A-1C are schematic diagrams illustrating example sensing assemblies and devices according to one or more embodiments. [Figure 6] FIG. 1 is a schematic diagram of an example apparatus according to one or more embodiments. [Figure 7] FIG. 10 is a schematic diagram of a further apparatus according to one or more embodiments. [Figure 8] FIG. 10 is a schematic diagram of a further apparatus according to one or more embodiments. [Figure 9] 1A-1C are diagrams that schematically illustrate use of an example apparatus in accordance with one or more embodiments. [Figure 10] FIG. 1 is a diagram illustrating the software and hardware architecture of an example device according to one or more embodiments. [Figure 11] FIG. 10 is a schematic diagram illustrating the software and hardware architecture of a further example device according to one or more embodiments. [Figure 12]FIG. 10 is a schematic diagram illustrating the software and hardware architecture of a further example device according to one or more embodiments. [Figure 13] FIG. 1 is a diagram illustrating components of an example inductive sensing circuit in accordance with one or more embodiments. [Figure 14] FIG. 10 shows the maximum allowable loop current as a function of the operating frequency for two antennas of different diameters to limit the operating current of the antennas. DETAILED DESCRIPTION OF THE INVENTION

[0069] The present invention will now be described with reference to the figures.

[0070] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems, and methods, are intended 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 better understood from the following description, the appended claims, and the accompanying drawings. It should be understood that the figures are schematic only and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the figures to indicate the same or similar parts.

[0071] The present invention provides a switching mechanism for enabling the use of an inductive sensing circuit with a portable handheld device having electromagnetic transmission capabilities in a manner that avoids harmful interference of the portable device's electromagnetic transmissions with a subject when medical sensing is being performed. Specifically, embodiments provide a controller arranged to control switching between two modes: a first mode in which at least a portion of the portable device's transmission capabilities are deactivated while the inductive sensing circuit is activated, and a second mode in which the electromagnetic portable device's transmission capabilities are fully activated and the inductive sensing circuit is deactivated. Thus, embodiments provide means for toggling between the two modes, the modes configured to avoid simultaneous inductive sensing and full-power electromagnetic transmission of the portable handheld device.

[0072] In the first mode, only some of the electrical and electromagnetic transmission functions of the portable device are deactivated, for example, only the radio transmitters that are consistent with electromagnetic compliance regulations.

[0073] As discussed above, a problem with using portable handheld units such as mobile phones for medical testing is that their standard electromagnetic (EM) emissions typically do not comply with EMC (electromagnetic compliance) regulations. These limit the allowable EM emissions of medical devices. Therefore, use of mobile phones for medical sensing applications is not possible without adaptation of some of the mobile phone's normal transmission functions. A controller according to an embodiment of the present invention automatically enables the suppression of some transmission functions when inductive sensing using inductive sensing circuitry is to be performed.

[0074] By way of background, current significant electromagnetic compliance (EMC) regulations will now be briefly discussed. This is simply for background and context, and the scope of what is discussed is not intended to limit the invention. Obviously, the specific characteristics of regulations may change over time, and therefore the invention is not intended to be bound by the specific numbers discussed below, nor is it intended to be described in terms of any current regulations.

[0075] At the time of writing, the generally accepted standard (by both European and American regulatory authorities) for electromagnetic radiation emissions by medical devices is IEC 60601-1-2. This describes both immunity to and emissions of electromagnetic radiation, with the goal of preventing electromagnetic interference from electrical or electronic equipment in a clinical environment. Annex C of IEC 60601-1-2 provides guidance for classification according to CISPR 11.

[0076] For medical devices in Class B (domestic environment such as home), electromagnetic emission limits are set in terms of permissible levels of electromagnetic energy measured at a distance of 10 meters from the device. Table 1 below outlines the emission limits for different frequency ranges.

[0077] [Table 1]

[0078] Radar systems have previously been investigated in academic settings with a view to measuring pulse and respiratory rates. Radar systems have also been proposed for building into future consumer electronics devices for gesture detection (e.g., Project Soli) to enable hands-free operation. Yet, such radar systems do not comply with current compliance regulations for electromagnetic emissions, such as those outlined in Table 1 above.

[0079] Radar systems are generally not EMC compliant. Radar systems are therefore not suitable for development or use as medical devices. Exemptions to EMC regulations have previously been granted for, for example, MRI or X-ray scanners, but only if there are no alternative means of performing the medical detection function. Still, when it comes to detecting pulse rate and respiratory rate, this does not mean that other modalities already exist for measuring these parameters. Therefore, it is unlikely that an exemption will be made in the near future.

[0080] Further regulations now exist regarding the maximum permissible exposure of the human body to electromagnetic fields (EMF).

[0081] Based on scientific evidence, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) provides guidelines for maximum human exposure to electromagnetic fields. Most regulatory authorities around the world have adopted these guidelines into their legislation, for example European Council Recommendation 1999 / 519 / EC.

[0082] There are basic regulations in place for different quantities and different frequency ranges. Table 2 below provides an overview.

[0083] [Table 2]

[0084] Further technical and regulatory limitations exist regarding the permissible exposure of the human body to electromagnetic radiation when an implantable medical device is implanted in the body.

[0085] The European Active Implantable Medical Devices (AIMD) Directive (90 / 385 / EEC) and associated standards (EN 45502-2-1:2003; EN 45502-2-2:2008; EN 50527-1:2016) ensure that AIMDs will operate unaffected as long as the general population reference levels of the European Council Recommendation (1999 / 519 / EC) are not exceeded (excluding static fields and without any time averaging (EN 50527-1:2020 5.1.2)). The 1999 / 519 / EC reference levels are described below in Table 3. These limits are stricter than the basic limits described above in Table 2.

[0086] [Table 3]

[0087] For example, for a sensor used as a stethoscope close to a patient's chest cavity, the above reference levels significantly limit the maximum electromagnetic field that can be imposed on the patient. The various wireless systems present in current smartphones do not comply with these levels. Additionally, currently known radar-based systems sometimes used to measure pulse and respiration are highly likely to exceed these reference levels when used in close proximity to a patient's chest cavity.

[0088] As noted above, embodiments of the present invention are based on controlling the operation of an inductive sensing circuit. Some embodiments include an inductive sensing circuit, preferably including an antenna and a resonant circuit having a signal generating means coupled to the antenna for driving the antenna to generate an alternating electromagnetic field or signal.

[0089] For a better understanding of the present invention, the basic principles of inductive sensing as referred to in this disclosure will now be briefly reviewed.

[0090] Inductive sensing operates on the principle of inductive coupling, whereby a coil or wire has a potential difference induced across it due to exposure to a time-varying magnetic field. Embodiments of the present invention use this principle to measure the strength of electromagnetic signals generated within a region of the body by sensing changes in the inductance of a coil or loop antenna placed near the body; these changes are detected based on the changing resonance characteristics of the antenna or resonant circuit.

[0091] Certain embodiments of the present invention use a resonant circuit comprising an antenna (which in a preferred embodiment may comprise a single turn loop) to stimulate or excite the body with electromagnetic signals (waves) and to sense signals emitted back from the body in response to these excitation signals.

[0092] The coil is driven with an alternating current to generate an excitation signal for application to the body. These can be propagating electromagnetic signals, which are sometimes propagated into the medium, or the signal can consist of a non-propagating electromagnetic field, which is applied to the medium, i.e., by bringing a loop antenna source close to the target medium. The alternating current creates a field of the alternating field strength.

[0093] When the body is brought close to the coil, the inductance L is increased by an additional reflected inductance component L caused by eddy currents induced in the stimulated body as a result of the application of the excitation signal. r to acquire.

[0094] This is shown schematically in Figure 1, which shows, by way of example, a loop antenna 32 near the subject's thoracic cavity 4, powered with an alternating current to apply an electromagnetic signal 22 to the thoracic cavity.

[0095] As a result, eddy currents 6 are induced within the thoracic cavity.

[0096] These eddy currents consequently substantially affect the inductance of the loop antenna 32 because they themselves generate a time-varying magnetic flux 24 at a frequency comparable to that generated by the primary antenna 32. These eddy current fluxes combine with the antenna's primary flux to produce a modified induced back EMF in the antenna and therefore a larger measurable effective inductance.

[0097] The additional component of inductance resulting from eddy currents is the "reflected inductance" L r The total inductance of the coil antenna 32 is called L t is expressed as follows: L t =L0+L r where L0 is the self-inductance of the coil antenna 32 in free space, and L r is the reflected inductance caused by the presence of a nearby body.

[0098] Generally, the reflected inductance L r is a complex number and can be expressed as

number

number

number

[0099] Reflected component of inductance L r When an additional inductance is added, the electrical characteristics of the resonant circuit are detuned. Specifically, both the natural radiation frequency of the resonant circuit and the damping coefficient of the resonant circuit change. By measuring this detuning of the electrical characteristics, the reflected inductance Lr The real and imaginary parts of can be found.

[0100] Specifically, the additional inductance component L r The real part of the inductance appears at the frequency of the resonant circuit or antenna. The imaginary part of the additional inductance component appears at the amplitude of the resonant circuit. Therefore, by measuring the changes in frequency and amplitude of the resonant circuit (current) and deriving the first and second input signals, respectively, signals indicative of hidden anatomical movements and phenomena are detected.

[0101] An example arrangement according to an embodiment of the present invention is shown schematically in FIG.

[0102] According to one aspect of the present invention, a controller is provided. An example controller 12 is shown in Figure 2. The controller may comprise, for example, one or more control components or processors.

[0103] The controller includes an inductive sensing circuit and an input / output for receiving and transmitting data when communicatively coupled to a portable handheld device, the portable handheld device having electromagnetic radiation capabilities. The portable handheld device may be, for example, a mobile communications device. The portable handheld device 14 includes a set of electromagnetic (EM) emitters or transmitters (e.g., antennas) 15a-15n, each of which is controllable between an active (transmitting) state and an inactive (non-transmitting) state. These, in certain examples, emit at different frequencies or powers.

[0104] The controller 12 is configured with a switching function, which controls the switching between the two modes.

[0105] In the first mode, controller 12 is configured to communicate with portable handheld device 14 to deactivate at least a portion of the portable device's electromagnetic emissions and simultaneously communicate with inductive sensing circuitry 16 to activate inductive sensing. For example, the controller may communicate with portable handheld device 14 to cause the portable handheld device to deactivate one or more sets of electromagnetic transmitters 15a-15n or to cause the portable handheld device to discontinue providing one or more transmission signals provided to the transmitters by the portable handheld device's controller.

[0106] The controller communicates with the inductive sensing circuit 16 to activate a signal generator in the circuit to trigger the application of a drive signal to an antenna in the inductive sensing circuit 16. Alternatively, the controller communicates with the portable device 14 to activate the portable device 14 to supply power (not shown) from the portable device 14 to the inductive sensing circuit 60.

[0107] In the second mode, the controller 12 communicates with the portable device 14 to activate at least a portion of the device's electromagnetic emissions while simultaneously deactivating the inductive sensing circuit 16 .

[0108] The controller 12 may be provided by itself and may be arranged to couple, in use, with the inductive sensing circuit 16 and the portable handheld device 14 (via inputs and outputs for receiving and transmitting data when coupled with the inductive sensing circuit and the portable handheld device) and to effect switching between the two modes. Alternatively, an apparatus may be provided, the apparatus including the controller 12 and one or both of the inductive sensing circuit and the portable handheld device. The controller may be integrated into one or other of the portable device and the inductive sensing circuit, and / or all three components may be integrated into a single device. These various options are outlined in more detail below.

[0109] Thus, embodiments of the present invention provide a control function configured such that, for example, whenever an inductive medical sensor 16 is activated for pulse and respiration measurements, certain portions of the on-board wireless transmitter (e.g., one that is consistent with EMC regulations for medical devices) are simultaneously and automatically disabled.

[0110] The control function may be implemented by a software-controlled switch or by a hardware switch, which in either case is configured to simultaneously coordinate two things: (1) enabling / disabling inductive medical sensors and (2) disabling / enabling certain wireless transmission functions, e.g., a subset of transmitters that do not comply with EMC regulations for medical devices.

[0111] Combining these two functions into a single variable or switch reduces the risk of both the sensor and a harmful wireless transmitter being enabled at the same time.

[0112] The portable handheld device, in an example, is a smartphone. Currently, the smartphone can be set to airplane mode. Airplane mode is a separate switch that can be toggled by the user, but this switch is not coupled to the activation of the sensor.

[0113] More generally, a portable handheld device is a mobile communication device such as a smartphone. A portable handheld device includes a display and a user interface. A portable handheld device includes, for example, a touchscreen display. A portable handheld device includes a local controller or processor for facilitating local or native operation of the device. A portable handheld device includes one or more sets of electromagnetic emitters or transmitters 15a-15n that facilitate mobile communication functionality. These sets include microwave emitters, such as GPRS transmitters, for facilitating cellular network communications. These sets include transmitters for enabling local area communications, such as Bluetooth communications. These sets include radio frequency transmitters, such as RFID transmitters, for enabling RFID functionality. These sets include transmitters for enabling Wi-Fi communications.

[0114] In certain embodiments of the present invention, a global software setting is added that simultaneously disables harmful wireless transmitters and enables specialized medical sensors, while leaving the functionality of the airplane mode setting unchanged. Thus, the two modes are implemented with completely separate switches, in this case independent of the airplane mode setting.

[0115] Figure 3 shows two switchable modes.

[0116] As shown, in Mode 1, the electromagnetic transmission functionality of the portable handheld device 14 is deactivated while simultaneously activating the inductive sensing circuit 16. Conversely, in Mode 2, the electromagnetic transmission functionality of the mobile portable handheld device 14 is activated while simultaneously deactivating the electromagnetic emissions of the inductive sensing circuit 16.

[0117] In certain embodiments, an apparatus is provided that includes both the controller 12 and the inductive sensing circuit 16 .

[0118] An example inductive sensing circuit 16 is shown schematically in FIG.

[0119] The inductive sensing circuit 16 includes a resonant circuit 30 comprising a loop antenna 32 and, preferably, an electrically coupled capacitor 33. The capacitance of the capacitor 33 at least partially defines the natural resonant frequency of the resonant circuit (in the absence of forcing or damping). When the antenna 32 is excited, the antenna 32 tends to naturally resonate at the defined resonant frequency and generate an electromagnetic signal at the same frequency. Thus, the capacitance of the capacitor can be selected to at least partially tune the frequency of the generated electromagnetic signal.

[0120] The inductive sensing circuit 16 preferably further comprises signal generating means 34 adapted to excite the loop antenna 32 to generate an electromagnetic excitation signal. The signal generating means may for example comprise driving means for driving the antenna at the radiation frequency ω, i.e. for driving the antenna with an alternating current of frequency ω. The driving means may for example be or comprise an oscillator.

[0121] A signal generating means 34 drives the antenna 32 of the resonant circuit 30 with an excitation signal at the radiation frequency ω, with a current at the desired radiation frequency ω.

[0122] By exciting the resonant circuit 30, a resonating current is induced to flow back and forth through the capacitor through the loop antenna. By driving an alternating current through the antenna, the generation of an oscillating electromagnetic signal (wave) is thereby stimulated.

[0123] Preferably, the same antenna 32 is used to generate the excitation signal as is used to detect the electromagnetic signal received from the body in response.

[0124] For the avoidance of doubt, "electromagnetic excitation signal" simply means an electromagnetic signal that is applied to a body to excite or stimulate the generation of eddy currents within the body, and thereby stimulate the emission of an electromagnetic signal back from the body that can be detected by a detection system.

[0125] Generally, by "electromagnetic signal" is meant an emission of electromagnetic radiation or an electromagnetic near-field oscillation, or an electromagnetic oscillation and / or an electromagnetic wave.

[0126] The inductive sensing circuit 16 advantageously further comprises signal detection (signal recognition) or signal pick-up means 40 adapted to detect secondary electromagnetic signals returned from the body due to eddy currents induced therein by the primary excitation signal. The detection of the signal is based on detecting variations in the electrical properties of the resonant circuit 30. The signal detection means includes signal processing or analysis means for detecting or monitoring the electrical properties of the current in the resonant circuit 30.

[0127] For example, the signal sensing means 40 is adapted to monitor at least the frequency of the resonant circuit current and the amplitude of the resonant circuit current, which characteristics of the current will vary depending on the strength of the reflected electromagnetic signal returned from the body and detected at the antenna.

[0128] The detection of these signal characteristics is preferably performed simultaneously with (i.e., in parallel with) the excitation of the antenna to generate the excitation signal, and thus signal transmission and detection are preferably performed in parallel.

[0129] The alternating electromagnetic fields generated by the inductive sensing circuit 16 are configured to be sufficiently weak to remain within EMC regulations for medical devices. Nevertheless, due to the operating principles of inductive sensing, these relatively weak signals are sufficient to detect the pulsation of objects within the body, such as the heart, or the inflation level of the lungs, thereby enabling the detection of vital signs such as heart rate or respiratory rate, when in use.

[0130] In certain examples, the inductive sensing circuit 16 further includes a controller or microprocessor module 42 (“MPU”). The microprocessor module is configured to control the operation of the inductive sensing circuit, for example, by controlling the signal generator 34 and / or the signal sensing means. The microprocessor module controls the activation and / or deactivation of the signal generator. The microprocessor module controls the frequency of the drive signal generated by the signal generator 34. In certain examples, the microprocessor module is configured with signal processing functionality and is configured to process the inductive signals detected or extracted by the signal sensing module 40 to derive one or more physiological parameters from the inductive signals. The microprocessor module derives one or more physiological signals representative of one or more physiological phenomena, such as cardiac or pulmonary movement. The microprocessor module derives values ​​or signals representative of one or more physiological parameters, such as vital signs.

[0131] By way of non-limiting example, physiological or anatomical parameters that the microprocessor is configured to derive may include, in different examples, pulse rate, respiratory rate, pulse waveform, respiratory waveform, detection of the presence or absence of a pulse, or other cardiac or respiratory parameters (e.g., cardiac output, stroke volume, vital capacity / volume), and any other parameters may also be derived in further examples.

[0132] The derivation of physiological parameters is based on the application of suitable algorithms, e.g., pre-installed or pre-stored in a microprocessor unit.

[0133] Various options are possible regarding the controller, inductive sensing circuitry, and associated physical configuration of the portable handheld device.

[0134] In some embodiments, an apparatus is provided that includes a controller and an inductive sensing circuit. In some embodiments, an apparatus is provided that includes a controller 12 and a portable handheld device. In a further example, an apparatus is provided that includes a controller, an inductive sensing circuit 16, and a portable handheld device 14.

[0135] According to one set of embodiments, an inductive sensing assembly 50 is provided that includes a carrier (e.g., substrate) 52 on which the controller 12 and the inductive sensing circuitry 16 are mounted. The substrate is or includes a circuit board, such as a PCB.

[0136] An example inductive sensing assembly 50 is shown schematically in FIG.

[0137] The assembly 50 may be in the form of, for example, a chip. The chip may be suitable for integration, for example, within the portable handheld device or within a secondary device to which the portable handheld device can be operatively coupled in use. The interaction between the sensing assembly 50 and the portable handheld device 14 in use is shown schematically in Figure 5. In Figure 5, the inductive sensing assembly is shown as external to the portable handheld device 14.

[0138] 6 schematically illustrates an example apparatus according to one or more embodiments comprising a portable handheld device 14 having an inductive sensing assembly 50, such as that shown in FIG. 5, integrated therein. For example, the assembly 50 may be a chip formed from a substrate 52 on which the inductive sensing circuitry 16 and the controller 12 are mounted, and the chip may be integrally installed within the portable handheld device 14. The chip may be arranged, for example, to communicate with a set of electromagnetic transmitters 15 of the portable device to control activation and / or deactivation of at least a subset of the transmitters in the second and first modes, respectively.

[0139] Other arrangements are possible, and FIG. 7 shows a further example apparatus according to one or more embodiments comprising a portable handheld device 14, in which the controller 12 is integrated within the portable device 14 and the inductive sensing assembly is also integrated within the device. In this example, the controller 12 and the inductive sensing assembly are integrated within the portable device as separate components, i.e., not part of a single integrated circuit assembly or chip. For example, the controller may be provided by one or more processors or controllers integrated within the portable handheld device. These may be dedicated controllers or processors, or the portable handheld device's native or local control or processor may be utilized to provide the control functions of the controller 12.

[0140] A further possible arrangement is shown diagrammatically in FIG. 8 . The apparatus, in this case, comprises a portable handheld device 14 with an integrated controller 12, but the inductive sensing circuit 16 is provided separately in the portable handheld device. For example, the inductive sensing circuit 16 is integrated into a secondary unit, such as a peripheral or auxiliary sensing unit, which is advantageously provided so as to be physically coupled to the portable handheld device during use. For example, in some cases, it can be integrated into a sleeve that is shaped and configured to be removably wrapped around the portable mobile device 14 during use. In this way, the inductive sensing circuit is provided in association with the portable handheld device, thereby enabling the two to be utilized together in unison. Nevertheless, the secondary unit may take any physical form and is preferably provided with coupling means for removably or releasably mechanically coupling the secondary unit to the portable handheld device.

[0141] According to any of the above-described arrangements, in use, the controller 12 is configured to control switching between the two modes in response to receiving one or more predetermined control commands. For example, these may be received from a controller or processor of the portable handheld device 14 and triggered by manual activation by, for example, a user, which may be by pressing a button within an associated app. Alternatively, this may be triggered automatically by software in the portable handheld device 14.

[0142] In use, the controller 12 first switches the apparatus into a first mode, thereby deactivating some of the transmission capabilities of the portable handheld device.

[0143] According to any of the above-described arrangements, the user then contactlessly holds the apparatus, including the portable handheld device 14, the inductive sensing circuit 16, and the controller 12, over a relevant area of ​​the patient's body, such as the thorax. This is shown, for example, in FIG. 9. In this example, the apparatus is shown as a portable handheld device integrating the controller 12 and the inductive sensing circuit 16. The user then activates the initiation of inductive sensing. For example, the portable handheld device controls the operation of the inductive sensing circuit to acquire sense signals. The sense signals are processed to derive one or more physiological signals therefrom, such as pulse rate and respiratory rate. The inductive sensing circuit includes signal processing means for processing the inductive sense signals to derive one or more physiological parameters. Alternatively, the inductive sense signals are communicated from the inductive sensing circuit to a controller or processor of the portable handheld device and processed by the portable handheld device to derive the physiological signals.

[0144] The switching function of the controller 12 may be implemented in numerous different ways. In a preferred embodiment, the switching function is implemented using software in the portable handheld device. Specifically, the switching function is preferably implemented using software variables in the software in the portable handheld device. This may be a global software variable or a software variable local to the particular application associated with the switching function or induction sensing.

[0145] For example, in an Android system, global settings are found in setting.Global. For illustrative purposes, a software variable associated with the two modes is named "MEDICAL_SENSOR". When the device is in mode 1, this variable is set to "MEDICAL_SENSOR_ON". When the device is in mode 2, this variable is set to "MEDICAL_SENSOR_OFF". The controller 12 is configured to switch between modes 1 and 2 in response to, or depending on the value of, this software variable.

[0146] The advantage of using a global variable or setting is that other applications cannot unilaterally change the mode, so this is the most secure approach.

[0147] This approach also means that applications installed on the portable handheld device to control the operation of medical sensing require system privileges to set global settings. Regular applications (i.e., those downloaded from public application directories such as Google Play) do not have the system privileges to set global settings in the Android operating system. Nevertheless, manufacturers of portable handheld devices can ship pre-configured applications with these privileges pre-assigned (as is possible starting with Android 5.0). Thus, for example, according to one or more embodiments, a device may be provided with a portable handheld device pre-installed with a medical application that has the system privileges to set the MEDICAL_SENSOR global setting. This leads to a highly secure approach.

[0148] 10 illustrates a schematic diagram of an example apparatus architecture according to one or more embodiments. The apparatus, in this case, is assumed to comprise a portable handheld device 14 with an integrated controller 12 and inductive sensing circuitry 16 ("medical sensor"). The portable handheld device 14 also comprises a set of internal electromagnetic transmitters ("radio") 15 controllable by the controller 12.

[0149] The controller, in this case, is assumed to be the native or local controller or processor of the portable handheld device, such as the device's mother processor. The portable device's operating software therefore implements the control functions of the controller 12 in this example, i.e., controls the switching between two modes, Mode 1 and Mode 2. The controller 12 of FIG. 10 is therefore shown in terms of the software components of the handheld portable device 14. These software elements include a dedicated application ("Medical Application") installed to control the functionality of the inductive sensing circuit 16, the operating system of the portable handheld device 14, and a set of global settings ("settings.global").

[0150] The device in Figure 10 is shown with a global variable or setting ("MEDICAL_SENSOR_ON") associated with the switching function. As shown, this is a separate global variable from airplane mode ("AIRPLANE_MODE_ON"), and airplane mode will operate independently of inductive sensor mode. This means that the electromagnetic transmitter 15 cannot be activated unless both AIR_PLANE_MODE_ON and MEDICAL_SENSOR_ON are set to false.

[0151] An alternative software-based implementation of the controller switching functionality is shown schematically in Figure 11. In this example, the apparatus is assumed to be the same as that of Figure 10, comprising a portable handheld device 14 with integrated inductive sensing circuitry 16, with the portable device's native or local controller or processor acting as the device's controller 12. Again, the software components of the portable device include a dedicated application (the "medical application") for controlling the inductive sensing circuitry, the device's operating system, and a set of global settings.

[0152] In this example, software variables associated with different inductive sensing modes (mode 1, mode 2) are placed in the memory space of a dedicated application for inductive sensing ("medical application").

[0153] An advantage of the embodiment of Figure 11 is that it is not necessary to add the settings.Global variable MEDICAL_SENSOR_ON to the collection of global settings. The embodiment further employs a global variable of the form AIRPLANE_MODE_ON, which is used to deactivate and reactivate the wireless transmitter of the mobile device 14. The use of a global variable for this purpose ensures that regular applications (i.e., applications that do not have the privileges to modify global settings) cannot override the actions of a medical application when deactivating the wireless transmitter of the portable handheld device 14.

[0154] A further alternative software-based implementation of the switching functionality of the controller 12 is shown schematically in Figure 12. In this example, the apparatus is again assumed to be the same as the apparatus of Figures 10 and 11, comprising a portable handheld device 14 with integrated inductive sensing circuitry 16, with the portable device's native or local controller or processor acting as the apparatus's controller 12.

[0155] In this example, a single software variable ("MEDICAL SENSOR_ON") resides in the memory space of a dedicated application ("Medical Application") for controlling inductive sensing. In this embodiment, there is no global variable for enabling or disabling the medical driver. Instead, enabling or disabling the medical sensor can be done by a normal application. While this is less secure than the implementations of FIGS. 10 and 11, it still provides a key advantage of the inventive concept in that a user cannot accidentally activate the medical sensing function while the portable mobile device's wireless transmitter is active.

[0156] According to one or more embodiments, means are provided for generating an automatic notification to alert the user if the user forgets to switch the device from inductive sensing mode (Mode 1) back to normal operating mode (Mode 2). The automatic notification is, in further examples, implemented by the controller 12 or by the portable handheld device software 14. The automatic notification is configured to trigger, for example, after a specific period of user inactivity (e.g., user interface inactivity or accelerometer inactivity) and / or after a specific period of the absence of any detectable physiological signal in the inductive sensing signal of the inductive sensing circuitry 16.

[0157] As described above, the inductive sensing circuit 16 preferably includes a resonant circuit, which includes an antenna 32. The resonant circuit may, in some instances, further include a capacitor, or the resonant circuit may be self-tuning and may not include a capacitor. Preferably, the inductive sensing circuit further includes a signal generator 34 configured to generate an AC drive signal for driving the antenna to oscillate at the resonant frequency of the resonant circuit. The antenna 32 is preferably a loop antenna having a single loop or winding.

[0158] The frequency range in which the resonant circuit is driven is preferably between 30 and 1000 MHz. Advantageous frequency ranges for inductive sensors have been discussed in detail, for example, in WO2018 / 127482.

[0159] In some examples, a multi-frequency drive scheme is implemented in which the resonant circuit is driven at multiple frequencies in parallel or sequentially. Different frequencies may allow penetration to different depths within the body or may be useful for inducing responses in different types of tissue.

[0160] Preferably, current limiting means is included for limiting the maximum drive current of the resonant circuit and thereby limiting the maximum electromagnetic output power of the inductive sensing circuit, thereby enabling compliance with EMC regulations. Optionally, the current limiting means allows adjustment of the maximum drive current of the resonant circuit, for example in the event of regulatory changes or to comply with regulations in different parts of the world.

[0161] Optionally, the loop antenna 32 is a multi-purpose antenna configured to perform multiple functions. For example, the loop antenna 32 can be an integrated loop antenna in the mobile portable device 14 provided for wireless charging functionality. In accordance with embodiments of the present invention, the same inductive loop is utilized to perform the function of the antenna in the inductive sensing circuit. This saves space in the mobile portable device 14, reducing the total number of components, and the overall form factor of the mobile portable device can be reduced, or space can be freed up for more components for additional functionality.

[0162] The architecture of an example inductive sensing circuit is shown schematically in Figure 13. The circuit comprises a resonant circuit 30 comprising an antenna 32 with a capacitor. A signal generator 34, e.g., an oscillator, is coupled to the antenna. The signal generator is configured to drive the antenna with an alternating current signal to cause the antenna to resonate, thereby generating an electromagnetic excitation signal for application to the body. A returned signal from the body is sensed in parallel by the antenna. Signal sensing means (not shown) are provided for detecting the returned signal at the antenna.

[0163] The detection is based on analyzing changes in one or more electrical characteristics of the resonant circuit 30, such as the resonant frequency of the resonant circuit or the intrinsic amplitude of the resonant circuit. Separate signals corresponding to these electrical characteristics can be extracted. This is shown schematically in FIG. 13, where, by way of example, two signals are extracted over time, corresponding to variations in the intrinsic frequency of the resonant circuit and variations in the intrinsic amplitude of the resonant circuit. These two signals correspond to the real and imaginary parts of the impedance of the resonant circuit. Therefore, by measuring the frequency and amplitude variations, one effectively measures the variations in the impedance of the loop.

[0164] These two signals are output to a signal processing unit 44, which processes the signals to derive a measure from the signals indicative of one or more physiological parameters. For example, the signal processing unit 44 derives a measure or signal from one or both of the signals indicative of the subject's heart rate and / or respiratory rate. Although not shown in FIG. 13 , the inductive sensing circuit 16 is further provided with a controller, such as a microprocessor unit 42, configured to control the operation of the inductive sensing circuit. For example, the microprocessor controls the operation of the signal generator 34 and / or the signal processing unit 44. The microprocessor controls the frequency at which the signal generator 34 generates a drive signal to drive the resonant circuit, thereby adjusting the operating frequency of the resonant circuit. Alternatively, the operation of the inductive sensing circuit 16 is controlled by the apparatus controller 12 or by a controller or processor of the portable handheld device 14.

[0165] The optimum frequency for the drive signal to drive the antenna depends on the diameter of the antenna being used.

[0166] We have found that it is optimal to use a loop antenna with a diameter of approximately 4-6 cm to detect heart rate and / or respiratory rate. The corresponding optimal frequency range for this diameter range is:

number

number

number

[0167] An operating frequency in the range of approximately 150 MHz to 300 MHz has been found to provide particularly effective performance, although frequencies outside this range may also be effective.

[0168] As mentioned above, the operating frequency of the resonant circuit can, in some examples, be continuously switched between different values. The different operating frequencies can be switched between relatively quickly, for example, to perform a sweep of frequency values. In this example, signals from multiple frequencies can effectively be captured in a time-division multiplexed manner. This has the advantage of increasing the dimensionality of the signal, which can be utilized to separate signal components arising from different physiological sources (e.g., respiration, pulse, body movement, other noise sources).

[0169] As mentioned above, the inductive sensing circuit may include means for limiting the maximum operating current of the resonant circuit so as to limit the maximum electromagnetic output power of the inductive sensing circuit, which allows compliance with EMC regulations.

[0170] The maximum allowable loop current for a given set maximum output power depends on the diameter of the loop antenna 32 and on the intended operating frequency for the resonant circuit.

[0171] The maximum loop current as a function of frequency for two different diameter antennas 32 is plotted in the graph of Figure 14. Line 62 corresponds to a 20 mm diameter loop antenna 32. Line 64 corresponds to a 50 mm diameter loop antenna. The regions of each of the lines that comply with AIMD regulations (see Table 3 above) and EMI regulations (see Tables 1 and 2 above), respectively, are indicated on the graph.

[0172] Limiting the current in a resonant circuit without unduly impacting the circuit's sensing performance is not simple, as current limiters typically induce additional noise and reduce the sensitivity of the inductive sensing circuit.

[0173] To limit the current in the resonant circuit 30, several different approaches are possible.

[0174] According to the first approach, the bias current of the signal generator 34 (oscillator) is limited. Limiting the bias current has the effect of reducing the voltage swing of the resonating LC circuit, and therefore reducing the open-loop gain of the oscillator electronics. This results in a more limited loop current.

[0175] The bias current can be (actively) limited through several means.

[0176] These include, for example, increasing the impedance at the source / emitter or drain / collector and / or reducing the supply voltage provided to oscillator 34 .

[0177] Specifically, a balanced oscillator circuit can contain at least two transistors. The bias current of a signal generator (oscillator) is the sum of the drain-source current (in the case of a field-effect transistor) or the collector-emitter current (in the case of a bipolar junction transistor). The bias current can be controlled by adding resistors in these current paths. For example, a fixed resistor can be added to the drain of an FET, or a fixed resistor can be added to the collector of a BJT. More generally, these resistors can be controlled or variable resistors, such as voltage-controlled resistors, which allow dynamic adjustment of the bias current according to the actual oscillation amplitude.

[0178] Therefore, oscillators can be configured to have an adjustable bias voltage rather than one fixed value. Control of the bias voltage is performed in both the analog and digital domains. Controlling the bias current is useful for maximizing signal quality while still meeting EMI requirements.

[0179] A second approach to limiting the current in the resonant circuit 30 is to increase the impedance of the loop antenna 12 and / or the resonant circuit 30. For the same supply voltage, the larger the loop impedance, the smaller the loop current. Two means of increasing the loop impedance include adding series inductance to the antenna loop and / or adding series resistance to the loop antenna.

[0180] Adding series inductance is preferable because the inductor does not add much noise to the signal (assuming a high Q inductor). One downside to these solutions is that the sensitivity to changes in inductance and resistance of the resonant circuit, i.e., changes in frequency and amplitude, is also reduced. If these electrical properties are used to detect physiological signals, this means that induced perception sensitivity is reduced.

[0181] A further possible means of increasing the impedance of the antenna 32 is to add a transformer between the antenna 32 and the electronics of the signal generator 34. The ratio between the antenna current and the signal generator current can now be tuned so that the antenna current is below a defined maximum (i.e., so that defined EMI regulations can be met) and so that the oscillator 34 has a stable operating point. For example, a low loop current and a high oscillator current can be achieved in parallel.

[0182] Specifically, a stable operating point means that the signal-generating circuit's current amplitude is high enough to generate a stable, i.e., low-noise, oscillating signal. Oscillators typically become unstable when the current amplitude becomes too small—that is, when the oscillator threatens to shut down or the oscillation amplitude becomes noisy. For low noise, it is beneficial for the oscillator current to be sufficiently high, which is called the ideal operating point. Because this current typically exceeds the maximum loop current, it is desirable to add a transformer between the signal-generating oscillator and the loop. In this way, the signal-generating oscillator's operating point (which adds an oscillating current) can be high enough, while the loop's operating point (oscillating current) is low enough to meet the loop's EMC requirements.

[0183] In different examples, the transformer may be, for example, an air-core transformer or a ferrite-core transformer.

[0184] One disadvantage of a transformer compared to using a series inductance or resistor is that the transformer cannot be controlled to actively change the value of the loop impedance, and therefore may cause the sensor to operate at a non-ideal operating point.

[0185] A further possible approach to limiting the current in the antenna 32 is to control the open-loop gain of the oscillator. This can reduce the voltage swing across the resonant LC circuit and therefore the current through the antenna loop 32.

[0186] One possible approach to controlling the open-loop gain is to change the DC operating point of the transistor used in oscillator 34. The operating point can be moved, for example, to a value that falls on a less steep or steeper portion of the transistor's transconductance curve, thereby controlling the oscillator's open-loop gain. The DC operating point can alternatively be actively controlled. A disadvantage of active control is that noise sources in the oscillator's circuitry are not as suppressed by the loop gain, thus degrading the signal quality of the measurement.

[0187] An example according to a further aspect of the present invention provides a method for controlling a portable handheld device having inductive sensing circuitry and electromagnetic radiation capabilities.

[0188] The method is: a first mode in which the portable handheld device is controlled to deactivate at least a portion of the device's electromagnetic emissions and simultaneously the inductive sensing circuitry is controlled to activate the inductive sensing circuitry; a second mode in which the portable device is controlled to activate at least a portion of the device's electromagnetic emissions and, simultaneously, the inductive sensing circuitry is controlled to deactivate the inductive sensing circuitry; and and performing a switching function to switch between the two modes.

[0189] The implementation options and details for each of the above steps are to be understood and interpreted in accordance with the explanations and descriptions provided above for the apparatus aspects (ie, controller aspects) of the present invention.

[0190] Any of the features or details of the examples, options or embodiments described above with respect to the apparatus aspect of the invention (with respect to the controller) may be applied, combined or incorporated mutatis mutandis in the method aspect of the invention.

[0191] An example according to a further aspect of the present invention also provides a computer program product comprising code means configured to, when executed on a processor, cause the processor to perform a method according to any example or embodiment outlined above or described below, or according to any claim of the present application.

[0192] Embodiments of the present invention offer numerous advantages over known medical sensing devices and systems, a summary of the main advantages will now be outlined.

[0193] One advantage is that embodiments enable medical sensing utilizing or associated with portable handheld devices, such as mobile phones, without violating EMC regulations (discussed above). Specifically, the switching mechanism provides a means by which harmful radio transmitters in the portable handheld device can be ensured to be automatically disabled whenever the inductive sensing circuitry is enabled. This ensures improved safety of the device and opens the possibility of regulatory approval for the device to be used as a medical device.

[0194] This automatic disabling of predefined portions of the mobile device's EM emissions also allows for avoidance of any interference between the mobile device's EM emissions and the inductive sensor, so that inductive sensing can be performed without interference from the mobile device, avoiding degradation or corruption of the inductive sensing signal.

[0195] Additionally, other functions of the portable medical device may be fully utilized in the second, non-sensing mode. For example, when measurements are performed using the inductive sensing circuitry, the communication capabilities of the portable handheld device may be utilized to communicate or transmit the recorded measurements via an on-board wireless transmitter.

[0196] In use, embodiments of the present invention can ensure that patients are not exposed to electromagnetic fields that exceed safe limits for electromagnetic radiation. As discussed above, this is particularly important for patients with implantable medical devices, such as pacemakers. Often, operators do not know whether a patient has an implantable device, such as a pacemaker, when performing measurements. Therefore, it would be advantageous to have the ability to automatically ensure that potentially dangerous EM emissions are deactivated whenever inductive sensing measurements are performed.

[0197] A further advantage is that the user is not burdened with the requirement to manually disable the wireless transmitter when using the inductive sensor (because the controller ensures that this happens automatically when the inductive sensor is enabled in mode 1).

[0198] Furthermore, inductive sensing is a relatively easy modality to operate (e.g., compared to other modalities such as ultrasound, MRI, or perhaps a traditional stethoscope). In particular, untrained or non-expert personnel can easily use inductive-based sensors to perform measurements. It can also be used in challenging situations, such as obese or overweight people, patient movement, poor lighting, or heavy clothing.

[0199] A further advantage of inductive sensing as a modality is that it is contactless, avoiding the risk of cross-contamination.

[0200] As described above, the embodiments use a controller. The controller can be implemented in numerous ways using software and / or hardware to perform the various functions required. A processor is one example of a controller that employs one or more microprocessors programmed using software (e.g., microcode) to perform the necessary functions. A controller may nevertheless be implemented with or without a processor, and may also be implemented 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.

[0201] Examples of controller components employed 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).

[0202] In various implementations, a processor or controller is associated with one or more storage media, such as volatile and non-volatile computer memory, including RAM, PROM, EPROM, and EEPROM. The storage media are 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 are fixed within the processor or controller and are transportable, such that the one or more programs stored on the storage media can be loaded into the processor or controller.

[0203] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study 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.

[0204] A single processor or other unit may fulfill the functions of several items recited in the claims.

[0205] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0206] The computer program may be stored and / or distributed on any suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

[0207] It is noted that when the term "adapted to" is used in the claims or description, it is intended that the term "adapted to" is equivalent to the term "configured to."

[0208] Any reference signs in the claims shall not be construed as limiting the scope.

Claims

1. A smartphone having a controller, an inductive sensing circuit, and a wireless transmitter for mobile communication functions, the controller is configured to switch the smartphone between two modes: a first mode in which at least a portion of the electromagnetic radiation of the wireless transmitter is deactivated and the inductive sensing circuit is activated; and a second mode in which at least a portion of the electromagnetic radiation of the wireless transmitter is activated and the inductive sensing circuit is deactivated; In the first mode, the controller activates a power supply to the inductive sensing circuit and / or causes the inductive sensing circuit to activate a signal generator in the inductive sensing circuit to trigger a drive signal to be supplied to an antenna in the inductive sensing circuit, and in the second mode, the controller deactivates the power supply to the inductive sensing circuit; The smartphone is operable in a user-toggled airplane mode, wherein switching to the first mode is performed independently of setting the airplane mode.

2. 10. The smartphone of claim 1, wherein the first mode includes terminating electromagnetic radiation in one or more electromagnetic frequency bands or ranges and / or terminating any electromagnetic radiation above a defined threshold power.

3. A smartphone as described in claim 1, wherein the controller receives an inductive sensing signal input from the inductive sensing circuit and derives one or more physiological parameters, such as heart rate and / or respiratory rate, from the inductive sensing signal.

4. The smartphone of claim 1 , wherein the controller switches between the two modes in response to receiving one or more predefined control commands.

5. A smartphone as described in any one of claims 1 to 4, wherein the inductive sensing circuit detects an electromagnetic signal returned from the body in response to application of an electromagnetic excitation signal to the body, and the inductive sensing circuit comprises a resonant circuit having a loop antenna, and the resonant circuit generates the electromagnetic excitation signal when driven by a drive signal.

6. 6. The smartphone of claim 5, wherein the inductive sensing circuit comprises a signal generator for generating a drive signal that drives the loop antenna to generate the electromagnetic excitation signal, and optionally the inductive sensing circuit comprises signal detection or pickup means for detecting signals returned from the body based on detecting variations in one or more electrical properties of the resonant circuit.

7. 1. A method for controlling a smartphone having an inductive sensing circuit and a wireless transmitter for mobile communication functions, comprising: a step of causing a controller of the smartphone to switch the smartphone between two modes: a first mode in which at least a portion of the electromagnetic radiation of the wireless transmitter is deactivated and the inductive sensing circuit is activated; and a second mode in which at least a portion of the electromagnetic radiation of the wireless transmitter is activated and the inductive sensing circuit is deactivated; In the first mode, the controller activates the power supply to the inductive sensing circuit and / or the inductive sensing circuit activates a signal generator in the inductive sensing circuit to trigger the supply of a drive signal to an antenna in the inductive sensing circuit, and in the second mode, the controller deactivates the power supply to the inductive sensing circuit; The method, wherein the smartphone is operable in a user-toggled airplane mode, and switching to the first mode is performed independently of setting the airplane mode.

8. A computer program comprising code means which, when executed on a processor, causes said processor to perform the method of claim 7.

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