阅读说明：本技术 在感应式感测中使用的布置 (Arrangement for use in inductive sensing ) 是由 M·P·P·克雷吉嫩 R·拜泽梅尔 W·H·佩特斯 G·J·N·都德曼 T·P·斯图内布林克 于 2020-03-17 设计创作，主要内容包括：一种在感应式感测中使用的装置(20)包括：环形天线(26)和用于驱动所述天线的信号生成器(24),这些形成谐振器电路(22)。所述谐振器电路可在驱动状态中驱动,在所述驱动状态中,所述天线在谐振下被驱动,从而生成电磁信号。布置还包括用于可切换地禁用所述天线的所述驱动状态的切换模块(28)。这允许在使用中可控地切换所述天线进出驱动状态,从而控制将信号生成开启和关闭。(An apparatus (20) for use in inductive sensing comprising: a loop antenna (26) and a signal generator (24) for driving the antenna, these forming a resonator circuit (22). The resonator circuit may be driven in a drive state in which the antenna is driven at resonance, thereby generating an electromagnetic signal. The arrangement further comprises a switching module (28) for switchably disabling the driving state of the antenna. This allows the antenna to be controllably switched in and out of the drive state in use, thereby controlling the generation of signals on and off.)

1. An apparatus (20) for use in inductive sensing, comprising:

a resonator circuit (22) comprising a loop antenna (26) and an electronic signal generator (24) coupled to the antenna for driving the antenna with a drive signal such that the antenna generates an electromagnetic signal, the resonator circuit having a resonant frequency,

wherein the resonator circuit is configurable in a driven state in which the antenna is driven at resonance, thereby generating an electromagnetic signal; and

a switching module (28) operable to switchably disable the drive state based on interrupting or adjusting the drive signal or an electrical characteristic of the resonator circuit to allow switching of electromagnetic signal generation.

2. The apparatus (20) of claim 1, further comprising a controller (50) configured to control the switching module (28).

3. The apparatus (20) according to claim 2, wherein the controller (50) is configured to control the switching module (28) according to a defined control schedule or control program.

4. The apparatus (20) according to claim 2 or 3, wherein the controller (50) is configured to: communicating, in use, with an external device; receiving a signal from the external device indicating a timing of an active state of the external device; and controlling the switching such that the driving state of the resonator circuit (22) is disabled during occurrence of the active state of the external device.

5. The apparatus (20) according to any one of claims 2-4, wherein the controller (50) is adapted to implement a periodic switching of the switching module (28) to impose a duty cycle on the drive signal.

6. The apparatus (20) of claim 5, wherein the frequency of the periodic switching is adjustable to adjust the time-averaged electromagnetic output power of the apparatus, and

preferably wherein the frequency of the periodic switching is controllable based on a user input command, the user input command being receivable at the controller (50), for example via a user interface operatively coupled to the controller.

7. The apparatus (20) according to any one of claims 1-6, wherein the switching module (28) comprises a controllable switching element connected in series between the signal generator (24) and the antenna (26), thereby allowing switchable decoupling of the antenna and the signal generator.

8. The device (20) according to any one of claims 1-7, wherein the switching module (28) comprises a switching element electrically connected in parallel with the antenna (26), for switchably short-circuiting the antenna.

9. The apparatus (20) of any one of claims 1-8, wherein the switching module (28) is configured to disable the driven state based on changing the resonant frequency of the resonator circuit (22).

10. The apparatus (20) of claim 9, wherein:

the resonator circuit (22) comprises a capacitor (32) connected in parallel with the antenna (26) and comprises a switching element in series with the capacitor for switchably decoupling the capacitor from the resonator circuit (22) and/or

The resonator circuit (22) comprises a variable capacitor (34) and means for controlling switching of a capacitance of the variable capacitor between a first value and a second value to provide switchable adjustment of the resonant frequency.

11. The apparatus (20) of any preceding claim, wherein the resonator circuit (22) comprises a plurality of antennas (26) operatively coupled to the signal generator (24), the signal generator being operable to supply a drive signal to each of the antennas, and wherein the switching module allows selective disabling of the drive state in a selected one or more of the antennas.

12. The apparatus (20) of any preceding claim, comprising a plurality of the resonator circuits (22), each resonator circuit comprising an antenna (26), and a separate switching module (28) being provided for each resonator circuit, and further comprising a controller (50) for controlling the plurality of switching modules.

13. The apparatus (20) of claim 11 or 12, wherein switching is controlled such that no two of the antennas (26) are in a driven state at any one time.

14. An inductive sensing system, comprising:

the device (20) according to any one of claims 1-13; and

a signal processing unit configured to receive and process electromagnetic signals sensed at the antenna (16) of the apparatus to derive one or more sensing measurements.

15. An inductive sensing system, comprising:

the device (20) according to any one of claims 1-13; and

a signal processing unit configured to detect at the antenna an electromagnetic signal returned from a body in response to the generated electromagnetic signal based on detecting a change in an electrical characteristic of the resonator circuit over time, and optionally wherein

The signal processing unit is further configured to receive and process the electromagnetic signal sensed at the antenna (16) of the apparatus to derive one or more sensed measurements.

16. The inductive sensing system of claim 15, wherein said signal detection is performed simultaneously with said signal generation.

17. A method of configuring an apparatus for use in inductive sensing, the apparatus comprising:

a resonator circuit comprising a loop antenna and an electronic signal generator coupled to the antenna, the electronic signal generator for driving the antenna with a driving signal such that the antenna generates an electromagnetic signal, the resonator circuit having a resonant frequency,

wherein the resonator circuit is configurable in a drive state in which the antenna is driven at resonance to generate an electromagnetic signal, and

the method comprises controlling a switchable disabling of the driving state, thereby controlling a start or stop of an electromagnetic signal, the disabling being based on an interruption or an adjustment of the driving signal or an electrical characteristic of the resonator circuit.

18. A method, comprising:

driving a resonator circuit with a drive signal such that the resonator circuit generates an electromagnetic signal, the resonator circuit comprising a loop antenna and an electronic signal generator coupled to the antenna, and the resonator circuit having a resonant frequency, and wherein the resonator circuit is configurable in a drive state in which the antenna is driven at resonance thereby generating the electromagnetic signal, and

controlling a switchable disabling of the drive state, thereby controlling a start or stop of an electromagnetic signal, the disabling being based on an interruption or an adjustment of the drive signal or an electrical characteristic of the resonator circuit.

19. The method of claim 18, wherein the method is a medical sensing method and comprises positioning at least the loop antenna of the resonator circuit in proximity to a body of a subject and driving the resonator circuit with the drive signal, thereby generating an electromagnetic signal for penetrating a surface of the body, and preferably wherein the method further comprises detecting the electromagnetic signal returning from the body at the resonator circuit.

Technical Field

The present invention relates to an induction-based sensing arrangement and in particular comprises a switching module for control signal generation.

Background

Inductive sensing is based on the generation of a primary alternating magnetic field via a primary loop, which results in the induction of eddy currents in conductive materials or tissue within the primary magnetic field and a consequent secondary magnetic field. The interaction of the secondary magnetic field with the primary loop or primary magnetic field can be used to detect movement patterns within the body under investigation, particularly those that include water content.

It is particularly advantageous to use inductive sensing for detecting physiological signals such as heartbeat and breathing patterns (otherwise also referred to as beat (kymographic) signals).

In inductive sensing, a signal generator (such as an oscillator) is connected to a loop antenna. An oscillator is an amplifier, typically composed of one or more transistors, that in combination with an inductive source and a capacitive source induces a resonant state in a coupled circuit. Inductance is provided by the loop antenna, while capacitance is provided by optional capacitor components placed in parallel with the loop, as well as the loop's own and its environment parasitic capacitances, and the oscillator parasitic capacitance. The entire system is called a resonator.

When a single loop antenna is used in this manner for generating the primary magnetic field and sensing the secondary magnetic field, the current through the circuit can often be relatively high. Due to this, several problems may arise.

First, the current through the loop may often be too high to be specified by electromagnetic compatibility (EMC) or Specific Absorption Rate (SAR). The current is provided at a certain amplitude to achieve a clear signal sensing. However, this can result in regulatory requirements that exceed the limit power.

Second, the system may be incompatible for use within a Magnetic Resonance Imaging (MRI) system, as the RF field generated by the scanner will likely be disturbed by the inductive sensor. In addition, the high power of the RF field of the MRI scanner may damage or even destroy the signal generator of the inductive sensing system. The use of inductive sensing within MRI is a key application area for this technology. In particular, the current respiration measurement method used in known MRI devices is purely mechanical measurement. Inductive sensing offers potential for improvement. Thus, the prevention from this application field is restrictive.

Additional problems may also arise in systems comprising multiple antenna loops.

First, the magnetic fields of multiple antennas may interact with each other, which may result in a so-called "lock-in". Here, due to the strong magnetic coupling, two or more of the inductive sensors lock to the same frequency and are therefore no longer able to measure independently.

Second, multiple inductive sensors can interfere with each other's signals due to magnetic interactions. For example, it may happen that one inductive sensor measures both its own signal and the signals of its neighboring inductive sensors. This can occur even when the sensors are at different frequencies and have not locked to the same frequency.

It would be advantageous to provide an improved sensing arrangement capable of overcoming one or more of the above problems.

Disclosure of Invention

The invention is defined by the claims.

According to an example in accordance with an aspect of the present invention, there is provided an apparatus for use in inductive sensing, comprising:

a resonator circuit comprising an antenna and an electronic signal generator coupled to the antenna, the electronic signal generator for driving the antenna with a driving signal such that the antenna generates an electromagnetic signal, the resonator circuit having a resonant frequency,

wherein the resonator circuit is configurable in a driven state in which the antenna is driven at resonance, thereby generating an electromagnetic signal; and

a switching module operable to switchably disable (inhibit) the drive state based on the drive signal or an interruption or electrical change of the resonator circuit, thereby allowing switching of electromagnetic signal generation.

The invention is based on the provision of a controllable switching module that allows to enable or disable signal generation with an antenna. This allows the start or stop control of the generation of the electromagnetic signal. In an example, a number of different specific handover methods or schemes may be applied to achieve different advantageous effects.

The switching module typically performs some adjustment of the electrical properties of the resonator circuit, which results in the disabling of the drive state. When in operation, the switching module is operable to switch the resonator circuit from a driven state to a non-driven state.

The switching module may adjust one or more electrical characteristics of the resonator circuit. The electrical characteristic may comprise, for example, a capacitance of the resonator circuit or a part thereof, an inductance of the resonator circuit or a part thereof, a resistance of the circuit or a part thereof.

The apparatus is for use in inductive sensing, i.e. for use in a system or arrangement for generating an electromagnetic signal for application to a body to be investigated and for sensing an electromagnetic signal returned from the body in response to the applied electromagnetic signal. Accordingly, the apparatus may be otherwise referred to in this disclosure as a sensing arrangement, and reference to a sensing arrangement or "arrangement" may be understood to refer to an apparatus in accordance with one or more embodiments of the invention.

The resonance frequency of a resonator circuit refers to the natural frequency of the electronic oscillation of the resonator circuit. Which is the product of the natural capacitance and inductance within the circuit and optionally additional capacitor components included in the circuit. The resonant frequency is the current frequency at which the resonator circuit will be in a resonant state.

Driving the antenna at resonance means driving the antenna to oscillate at its resonance frequency or driving the resonator circuit to oscillate at its resonance frequency. This means that the antenna is driven, for example, with a driving signal that is matched to the resonance frequency.

The switching module may comprise electrical components comprised in the resonator circuit. Which is preferably located electrically or signally downstream of the signal generator. This allows the disabling of the driving state without adjusting the control of the signal generator.

The signal generator generates an oscillating or periodic electrical signal. The signal generator may comprise an electronic oscillator.

The antenna is a (magnetically) inductive loop antenna. Preferably, the antenna comprises a single loop (to reduce parasitic capacitance between multiple loops).

Preferably, the apparatus further comprises a controller further configured to control the switching module.

Preferably, the controller is configured to control the switching module according to a defined control schedule or control program.

In this embodiment, the controller controls the switching module with a specific timing program or based on specific triggers or references, for example, to the function or status of other components in a broader system. The control program or schedule may be programmed in the controller. Which may be adjustable, for example, based on user input commands. Which may be stored in local memory or in the processor.

The controller may be adapted to receive a signal indicative of an active state of the external device and to control the switching to disable the driving state of the resonator circuit in response to the signal.

In particular, the controller may be adapted to receive, in use, a signal from an external device indicative of the timing of an active state of the external device, and to control the switching such that the drive state of the resonator circuit is disabled during the occurrence of the active state of the external device.

For example, the controller may be configured to control switching to be consistent with enablement of one or more other components of a broader system or associated system. For example, the antenna arrangement may be used within a magnetic resonance system, and switching the circuit out of the drive state may be timed to coincide with the enablement of one or more electromagnetic signal sources (e.g., primary RF coils) of the MR system. The strong fields of these coils can damage the signal generator. In this case, the switching module may be configured to decouple the signal generator from the resonator circuit.

According to an advantageous set of embodiments, the controller may be adapted to implement a periodic switching of the switching module, thereby imposing a duty cycle on the drive signal.

This embodiment generates a drive signal that follows the duty cycle. As a result, the time-averaged output power of the electromagnetic signal generated by the system may be reduced. Thus, by controllably reducing the time-averaged output power without reducing the instantaneous output power during the signal transmission period, this achieves regulatory compliance in a simple and adjustable manner.

Furthermore, this method of adjusting the power output does not degrade the inductive sensing capability in applications for sensing physiological parameters. In particular, the oscillation parameters, such as heart movements or respiratory activity, which are usually measured in the body, usually have a much lower frequency (in the order of Hz) than the oscillation frequency of the resonator circuit (in the order of MHz, for example). Thus, there is no need to have a continuous signal acquisition in order to capture physiological signals. Thus, the reduced duty cycle applied according to the above example does not affect the acquisition of physiological measurements.

The frequency of the periodic switching or duty cycle may be adjustable to adjust the electromagnetic output power of the device.

Electromagnetic output power means time-averaged output power, i.e. over a number of cycles of the duty cycle.

A controller configured to control the frequency of the duty cycle/periodic switching to control the electromagnetic output power may be included in the apparatus.

The duty cycle or the frequency of the periodic switching may be controllable based on user input commands, e.g. receivable at the controller via a user interface operatively coupled to the controller

The switching module may comprise a controllable switching element connected in series between the signal generator and the antenna, thereby allowing switchable decoupling of the antenna from the signal generator (or from (the rest of) the resonator circuit).

The switching element is a circuit breaking element which can switchably introduce a break in a circuit line between the antenna and the signal generator, thereby achieving decoupling.

The switching module may comprise a switching element electrically connected in parallel with the antenna for switchably short-circuiting the resonator circuit.

When the switch is closed, the drive signal current will flow through the parallel switch rather than through the antenna, and thus the antenna will not oscillate to generate an electromagnetic signal.

The switching module may be configured to disable the drive state based on changing a resonant frequency of the resonator circuit.

By adjusting the circuit resonant frequency, the resonator circuit is detuned, which means that the oscillating drive signal generated by the signal generator (whose frequency previously resonated the circuit) no longer achieves a resonant state in the resonator circuit. The switching module introduces a mismatch between, for example, the frequency of the drive signal and the resonant frequency of the resonator circuit, thereby disabling oscillation of the circuit at resonance. Thus, the circuit is kept out of the driving state defined above.

The adjustment of the resonant frequency may be based on adjusting the capacitance of the resonator circuit. In this example, the resonator circuit may include a capacitor component that partially defines a resonant frequency of the resonator circuit.

In one set of examples, the resonator circuit may include a capacitor connected in parallel with the antenna, and further include a switchable circuit breaking element in series with the capacitor for switchably decoupling the capacitor from the resonator circuit

In this embodiment, the switching module switchably opens the circuit along the parallel branch or track containing the capacitor. This causes the capacitor to decouple from the antenna, thereby changing the capacitance of the resonator circuit, resulting in a change in the resonant frequency. This means that the drive signal no longer causes the resonator circuit to oscillate at resonance, thereby deactivating the drive state.

Additionally or alternatively, in another set of examples, the resonator circuit may include a variable capacitor and means for controlling switching of a capacitance of the variable capacitor between at least first and second values to provide switchable adjustment of the resonant frequency. This thereby provides switchable detuning of the resonator circuit and thus switchable disabling of the drive state.

Here, the switching module comprises an adjustable capacitor and/or a module for controlling the switching of its capacitance.

The means for controlling the capacitance adjustment may for example be a control circuit comprised in the variable capacitor or a separate controller.

The signal generator may comprise an amplifying device and wherein the switching module is comprised by the signal generator and adapted to change an amplification level of the amplifying module.

For example, by reducing the amplification, the amplitude of the drive signal is reduced to a sufficient level that the resonator circuit is no longer driven at resonance and thus the drive state is deactivated.

The resonator circuit may comprise a plurality of antennas operatively coupled to the signal generator, the signal generator being operable to supply a drive signal to each of the antennas, and wherein the switching module allows selective disabling of drive states in a selected one or more of the antennas.

Here, multiple antennas are connected to a single signal generator, and the switching module is operable to selectively disable the drive state in any one or more of the antennas. It may comprise a plurality of separate switch sections, for example separate switches in series or parallel with each antenna. It may comprise a control module for controlling the selective switching and for example for controlling the selective switching with a plurality of switch sections.

For example, the switching module may comprise a controllable capacitor having a controllable capacitance.

The apparatus may comprise a plurality of resonator circuits as described above, each resonator circuit comprising an antenna and a separate switching module being provided for each resonator circuit, and the apparatus further comprises a controller for controlling the plurality of switching modules.

This represents another option for providing multiple steerable antennas. Here, separate signal generators are provided for each antenna in addition to separate switching modules, enabling both independent switching and optionally independent control of the drive frequency. It also enables a signal generator to be provided close to each antenna, which is particularly advantageous for higher operating frequencies, where long connecting traces can impede signal transfer.

In accordance with one or more embodiments, the switching may be controlled such that no two of the antennas are in a driven state at any one time, i.e. only one antenna is active at any one time.

According to one or more embodiments, the switching may be controlled such that the driving state is disabled in at least one of the antennas at all times during use. In other words, the switching is controlled so as to prevent all antennas from being active (in a driven state) at any given time at the same time.

Examples according to another aspect of the invention provide an inductive sensing system comprising:

an apparatus according to any of the examples or embodiments summarized above or described below or according to any claim of the present application; and

a signal processing unit configured to receive and process electromagnetic signals sensed at the antenna of the apparatus to derive one or more sensing measurements.

Examples according to another aspect of the invention provide an inductive sensing system comprising:

an apparatus according to any of the examples or embodiments summarized above or described below or according to any claim of the present application; and

a signal processing unit configured to detect, at the antenna, an electromagnetic signal returned from a body in response to the generated electromagnetic signal based on detecting a change in the electrical characteristic of the resonator circuit over time.

Optionally, the signal processing unit may be further configured to receive and process the electromagnetic signal sensed at the antenna of the apparatus to derive one or more sensing measurements.

Preferably, the signal detection is performed simultaneously with the signal generation.

An example according to another aspect of the invention provides a method of configuring an apparatus, the apparatus comprising:

a resonator circuit comprising a loop antenna and an electronic signal generator coupled to the antenna, the electronic signal generator for driving the antenna with a driving signal such that the antenna generates an electromagnetic signal, the resonator circuit having a resonant frequency,

wherein the resonator circuit is configurable in a drive state in which the antenna is driven at resonance to generate an electromagnetic signal, and

the method comprises controlling a switchable disabling of the driving state, thereby controlling a start or stop of an electromagnetic signal, the disabling being based on an interruption or an electrical change of the driving signal or the resonator circuit.

An example according to another aspect of the invention provides a method comprising:

driving a resonator circuit with a drive signal such that the resonator circuit generates an electromagnetic signal, the resonator circuit comprising a loop antenna and an electronic signal generator coupled to the antenna, and the resonator circuit having a resonant frequency, and wherein the resonator circuit is configurable in a drive state in which the antenna is driven at resonance thereby generating the electromagnetic signal, and

controlling a switchable disabling of the drive state, thereby controlling a start or stop of an electromagnetic signal, the disabling being based on an interruption or an adjustment of the drive signal or an electrical characteristic of the resonator circuit.

According to one or more embodiments, the method may be a medical sensing method. It may comprise positioning at least the loop antenna of the resonator circuit in the vicinity of a body of a subject and driving the resonator circuit with the drive signal so as to generate an electromagnetic signal for penetrating a surface of the body.

Preferably, the method may further comprise detecting at the resonator circuit an electromagnetic signal returning from the body.

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

Drawings

For a better understanding of the present 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:

FIG. 1 shows a block diagram of an example sensing arrangement in accordance with one or more embodiments;

FIG. 2 shows an example sensing arrangement with switching elements connected in series;

FIG. 3 shows an example sensing arrangement with a switching element connected in parallel with an antenna;

fig. 4 shows an example sensing arrangement with an internal series switch included in the antenna loop, the internal series switch being operable to connect and disconnect the capacitor component;

FIG. 5 shows an example sensing arrangement with a variable capacitor;

FIG. 6 illustrates sensing an oscillating physiological signal using a duty cycle sensing signal;

figures 7 and 8 show two example sensing arrangements, each having multiple antennas, each antenna having a dedicated signal generator; and is

Fig. 9-12 show various example sensing arrangements that include multiple antennas, and in which a single signal generator is provided for the entire set of antennas.

Detailed Description

The present invention will be described with reference to the accompanying drawings.

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 apparatus, systems, and methods of the present invention will become better understood with regard to 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 indicate the same or similar parts.

The present invention provides an apparatus for use in inductive sensing, the apparatus comprising an inductive (magnetic) loop antenna (herein: antenna) and a signal generator for driving the antenna, these forming a resonator circuit. The resonator circuit may be driven in a driven state, wherein the antenna is driven at resonance, thereby generating an electromagnetic signal. The apparatus also includes a switching module to switchably disable a driving state of the antenna. This allows controllably switching the antenna into and out of the drive state in use, thereby controlling the switching on and off of the signal generation.

The device may be further referred to herein as a "sensing arrangement" because the device is used in inductive sensing.

The apparatus is particularly beneficial for use as a medical sensing arrangement, for example for acquiring physiological measurements such as heart rate or respiratory activity.

In use, an antenna driven at resonance generates a primary alternating electromagnetic field. When the antenna is brought close to the body to be probed, the alternating field penetrates the body surface, where it induces circulating eddy currents in the body. These in turn cause the generation of a secondary magnetic field that interacts with the primary field and changes the characteristics of the overall resultant field at the location of the loop antenna. In particular, the reflected secondary field is sensed at the antenna and effectively adds an additional component of inductance to the antenna (sometimes referred to as the reflected inductance component). As a result, certain electrical characteristics of the resonator circuit (in particular the natural resonant frequency and the damping factor of the resonator circuit) undergo a slight shift.

The displacement of these electrical characteristics may be sensed by a signal processing component electrically coupled to the resonator circuit. By monitoring the change in these characteristics over time, information relating to the movement of the element or object within the body being probed can be derived. These may be used, for example, to sense specific physiological parameters or measurements, such as heart rate, heart movement pattern, breathing rate, or lung movement pattern during breathing. These are merely examples, and other physiological measurements may also be derived in other examples.

Physiological signals that exhibit oscillatory or periodic characteristics such as these are sometimes referred to as oscillometric signals.

More details regarding the theory and application of inductive sensing using arrangements, such as the arrangement of the present invention, are described in the document WO2018/127482 (see e.g. page 14, line 3 to page 18, line 25), in particular for the purpose of sensing physiological signals.

A block diagram of the basic components of a device (or sensing arrangement) for use in inductive sensing according to an embodiment of the present invention is shown in fig. 1.

The device or sensing arrangement 20 is used in inductive sensing. The arrangement 20 comprises a resonator circuit 22, the resonator circuit 22 comprising an inductive antenna 26 and an electrically coupled electronic signal generator 24 coupled to the antenna. The resonator circuit has a resonant frequency. The signal generator is operable to generate a preferably oscillating (AC) electrical drive signal to cause the antenna to generate an electromagnetic signal.

The antenna is a loop antenna and preferably a single loop antenna, i.e. consisting of only a single winding. However, this is not essential to the invention.

The resonator circuit may be configured in a driven state in which the antenna is driven at resonance, thereby generating an electromagnetic signal. Driving at resonance means, for example, driving the resonator circuit such that it oscillates at its resonant frequency (electrical). This may be achieved, for example, by driving the circuit with a drive signal having a frequency that matches or substantially matches the resonant frequency of the circuit.

In an example, the signal generator may be an electronic oscillator, or may be any element capable of generating a drive signal for causing oscillation of the resonator circuit.

The arrangement further comprises a switching module 28, the switching module 28 providing switchable disabling of the driving state. The disabling of the drive state is based on switchably interrupting or adjusting the electrical characteristics of the drive signal or resonator circuit, thereby allowing switching on and off of the generation of the electromagnetic signal.

Various methods for implementing the switching of the driving states of the resonator circuit are possible. Moreover, and in combination with these, different particular embodiments implement a control method for controlling multiple antennas using one or more switching modules.

The various options for implementing the switching module will first be outlined below.

According to a first set of one or more embodiments, the switching module comprises a switching element comprised in the resonator circuit, operable to implement a break in the circuit at a point electrically downstream or downstream of the signal generator.

The switching elements may be arranged in different configurations within the resonator circuit to provide the required switchable disabling of the drive states.

According to one set of examples, the switching module comprises a switching element connected in series with the antenna, operable to switchably decouple the antenna from the signal generator. An example of such an arrangement is shown in figure 2.

As shown, the switching module 28 takes the form of a switching element in this example and is included in the resonator circuit electrically downstream of the signal generator 24 and between the signal generator 24 and the antenna 26. The switching element provides a circuit breaking function. Therefore, it may be otherwise referred to as a circuit-breaking switching element. By opening and closing the switch, an open circuit in the circuit at the point of the component can be introduced and removed.

The switching element may be controlled to switchably decouple the antenna 26 from the signal generator, thereby interrupting the resonator circuit and the drive signal, preventing the drive signal from reaching the antenna. This stops any electromagnetic signal generation and thus brings the resonator circuit out of the drive state.

By way of non-limiting example, the switching element may be implemented using a PIN diode or a (solid state) relay. Other kinds of controllable switching elements (for introducing a circuit break) will be immediately apparent to the skilled person and any one may be used.

Although in the example illustrated in fig. 2, the switching element 28 is provided electrically downstream of the signal generator 24 along a circuit trace extending between the signal generator and the antenna 26, in other examples, the switch may be included internally of the signal generator. Which may be provided integrally with the signal generator.

By way of example, such internal switching elements may be adapted to provide an adjustable or switchable supply voltage to the signal generator, or to facilitate an adjustable or switchable inductance, capacitance or resistance within the signal generator internal circuitry (e.g. oscillator circuitry). Such adjustment or switching of the electrical parameter may enable deactivation of the signal generator, or reduction of the output voltage of the signal generator by a sufficient amount such that the resulting drive signal cannot cause the antenna to oscillate at resonance. Changing the capacitance, inductance or resistance of the signal generator circuit can change the electrical characteristics of the drive signal sufficiently so that the drive signal no longer produces resonant oscillations in the antenna. In either case, the driving state of the resonator circuit is thereby switchably disabled by the switching module.

In a second set of examples, a switching element similar to that of the example of fig. 1 may alternatively be provided electrically connected in parallel with the antenna 26. This example is illustrated in fig. 3.

In this example, the switching module 28 takes the form of a switching element that is controllable to introduce and remove breaks in the circuit by opening and closing a switch. The switches are provided along a circuit track or track connected in parallel with the antenna 26.

When the switch 28 is closed, current will not flow through the antenna 26, but instead through the switch. Thus, the antenna is short-circuited. Thus, the total inductance in the resonator circuit is too low for the circuit to oscillate. Thus, the drive state (in which the resonator circuit is driven at resonance) is disabled by closing the switch. Then, when the switch is turned off, the driving state is released from being disabled.

The switching element 28 components may take the same form as the series switching example of fig. 2 above, for example.

According to another set of embodiments, the switching module 28 may be configured to disable the drive state based on changing a resonant frequency of the resonator circuit. Which may provide switching or toggling of the resonant frequency between at least two values.

By changing the resonant frequency of the resonator circuit 22, the resonator circuit is detuned, which means that the drive signal generated by the signal generator 24 (whose frequency previously caused the circuit to resonate) no longer produces a resonant state in the resonator circuit. The switching module introduces a mismatch between, for example, the frequency of the drive signal and the resonant frequency of the resonator circuit, thereby disabling oscillation of the circuit at resonance. Thus, the driving state is disabled.

The adjustment of the resonant frequency may be based on adjusting the capacitance of the resonator circuit. In this example, the resonator circuit may include a capacitor component that partially defines a resonant frequency of the resonator circuit.

This can be implemented in different ways. Fig. 4 illustrates a sensing arrangement 20 according to one set of examples. Here, the resonator circuit 22 comprises a capacitor component 32 connected in parallel with the antenna 26 and further comprises a switching module in the form of a switchable circuit breaking element 28 connected in series with the capacitor. The switchable circuit breaking element enables switchable decoupling of the capacitor from the resonator circuit. The capacitor is for example provided along a sub-branch connected in parallel with the antenna.

The switchable circuit breaking element 28 may take the same form as the switching element of the example of fig. 2 and 3, for example, discussed above.

In this embodiment, the switching module 28 switchably opens the circuit along the parallel branch or track containing the capacitor 32. By disconnecting the parallel capacitor, the resonant frequency of the resonator circuit 22 is shifted to a higher frequency. If the frequency is high enough, the amplifier of the signal generator 24 will not produce enough amplification to start oscillating in the resonator circuit 22. Thus, the driving state in which the resonator circuit oscillates at resonance is disabled.

This set of examples provides the same benefits as the examples of fig. 2 and 3 above, and additionally provides additional benefits. In particular, during the disabled (or "off state), in addition to ceasing generation of the outgoing electromagnetic signal, the sensing arrangement 20 is also made insensitive to any incoming electromagnetic signal of the same frequency as the normal operating frequency of the resonator circuit 22.

This is useful, for example, if there are other signal generating components in the vicinity that generate electromagnetic signals at the same frequency as the sensing arrangement 20, for example, when the sensing arrangement is part of a broader sensing system, such as a magnetic resonance system. In the off state, the resonant frequency of the circuit 22 is detuned, which means that the antenna and the resonator circuit are also insensitive to any incoming signal at the original resonant frequency.

Coordinated control may be implemented between the various signal sources of the wider system and the present sensing arrangement 20 such that the resonator circuit 22 of the present sensing arrangement is turned off whenever the other sources are on and generating electromagnetic signals.

Additionally or alternatively, in another set of examples, the resonator circuit 22 may comprise a variable capacitor and means for controlling switching of the capacitance of the capacitor between at least a first value and a second value to provide switchable adjustment of the resonant frequency. This thereby provides switchable detuning of the resonator circuit and thus switchable disabling of the drive state.

An example is shown in fig. 5. Here, a variable capacitor 34 is provided in parallel with the antenna loop 26. However, it is possible to provide a capacitor also in series with the antenna.

By varying the capacitance, the resonant frequency of the resonator circuit 22 is varied such that there is a mismatch between the circuit resonant frequency and the drive signal frequency generated by the signal generator 24. Thus, the signal generator may not be able to provide sufficient gain to cause the resonator circuit to resonate with the drive signal it is generating. Thus, the variable capacitor 34 may serve as a switching module for switchably disabling the driving state.

As described above, a potential benefit of embodiments of the present invention is to enable interference with signal generating components of any adjacent system (e.g. an MRI system) to be avoided. This will be discussed in more detail below.

Note that for this purpose, the embodiment of fig. 2 may be preferred in some circumstances, because no current can flow in the loop antenna 26 when the switching element 28 of the arrangement is open (putting the resonator circuit in an inactive state), regardless of the frequency of potential external electromagnetic fields received from adjacent components or systems.

In the closed (short-circuited) state of the embodiment of fig. 3, currents within a wide frequency range (starting from 0 Hz) can still flow in the loop antenna, which may result in some signal pickup by the arrangement and/or cause interruption or interference of potentially adjacent systems. In the off state of the embodiment of fig. 4, there is still a (narrow, high) frequency range at which current can flow in the loop, which again may lead to some signal pickup and/or potential interference within the adjacent system from which such a signal has been received.

The various embodiments described above utilize a circuit-breaking type switching element 28. In any such example, by way of example, the switch may be implemented by using a simple PIN diode. In forward bias, the PIN diode is a good Radio Frequency (RF) conductor, and the switch is "closed" (i.e., there is no open circuit in the circuit) in this state. When zero or reverse bias is applied, the PIN diode is a poor RF conductor and the switch is "open," i.e., a circuit break is applied.

Various possible switches are available in the art, which may or may not use PIN diodes internally. Any type of switch may be used.

Various implementation options for the switching module 28 have been outlined above. However, these are not exhaustive and the skilled person will appreciate that there are other possible methods for disabling the drive mode of the resonator circuit. Any suitable method may be used.

Other options include providing an adjustable or switchable resistor in series with the antenna, for example between the signal generator and the antenna in the resonator circuit. Alternatively, switchable or adjustable inductances may be provided in the resonator circuit. The resistance or inductance may be switchable between at least a first value and a second value to switch between the drive mode and the disabling of the drive mode. By changing the resistance or inductance of the circuit, the circuit is effectively detuned (i.e. the natural resonance frequency is shifted) with the result that the drive signal generated by the signal generator no longer causes resonance of the resonator circuit. This therefore disables the drive state. In particular, changing such electrical characteristics may have the following effects: the gain required to generate an oscillation with the antenna using the same drive signal is too high to be provided by the amplifier of the signal generator. Alternatively, a phase shift may be introduced due to the change, thereby disturbing the oscillation condition.

In another example, switching may include adjusting an electrical setting of a signal generator (e.g., an oscillator) to reduce a maximum achievable gain of the oscillator. Thus, the gain is not sufficient to produce oscillation of the resonator circuit at resonance, and the drive state is disabled.

In another example, the switching module may be operable to switchably disable and enable the power supply of the signal generator. This has the following advantages: during the non-driving state mode, the power consumption is reduced to zero. However, a potential disadvantage is that this approach may be slower than operating a switch disposed within the circuit. Thus, for some potential applications, such as for capturing certain faster physiological or wave recording signals, this switching method may not be fast enough to effectively capture the wave recording signal.

According to a set of advantageous embodiments, the sensing arrangement may comprise a controller, and wherein the controller is adapted to implement the periodic switching of the switching module, thereby applying a duty cycle to the drive signal. By duty cycle controlling the drive signal, the time averaged electromagnetic output power of the sensing arrangement during use may be reduced. Furthermore, this is reduced without having to reduce the maximum electromagnetic output power during the on or high order segments of the duty cycle.

This enables easier compliance with electromagnetic capability (EMC) and Specific Absorption Rate (SAR) regulations, which impose limits on the time-averaged output power of the inductive sensing arrangement.

Furthermore, this method of reducing the time-averaged power output does not reduce the sensing capability for the purpose of sensing oscillating (wave recording) physiological signals, such as heart rate or respiratory activity. This is because the wave recording signal of the human body, which may be captured by the sensing arrangement in certain applications, typically exhibits slower oscillations (in the order of magnitude: Hz) than the typical oscillation frequency (typically in the order of magnitude: MHz) of the resonator circuit and the antenna. Thus, there is no need to have continuous measurements in order to capture the recording signal. For example, it is sufficient to capture a representative measurement by measuring the frequency and damping of the resonator circuit only part of the time.

This is schematically illustrated in fig. 6, which fig. 6 shows an example resonator circuit oscillation 44 after an applied duty cycle and an example physiological (beat) signal adjacent thereto. As can be seen in this illustrative example, the duty cycle of the generated Electromagnetic (EM) signal 44 may be configured to follow the natural oscillation frequency of the physiological signal. In this way, the generated EM signal is still able to fully capture the physiological signal.

By thus rapidly switching on and off the driving state (i.e., duty cycle control), the total irradiation power within a certain time span can be greatly reduced.

This not only enables easier compliance with regulations, but also reduces power consumption, thereby saving energy and potentially reducing heat generation. The continuous oscillation consumes a constant power which may be particularly high, in particular at the typical oscillation frequency of the resonator circuit, i.e. in the order of MHz. Duty cycle control enables a reduction in average power consumption without reducing sensing capability.

The frequency of the periodic switching (i.e. the frequency of the duty cycle) is preferably adjustable, thereby adjusting the electromagnetic output power of the sensing arrangement. For example, the frequency of the periodic switching may be controllable based on a user input command, which may be received at a controller of the sensing arrangement, e.g. via a user interface operatively coupled to the controller.

As briefly discussed above, in certain advantageous embodiments, signal generation and/or sensing may be controlled to be disabled during an active (signal generating) state of another (proximal) signal generating component. For example, a beneficial application of embodiments of the sensing arrangement is for use within or in conjunction with a Magnetic Resonance (MR) sensing system (e.g., MRI).

About 3% of the time, an MRI scanner typically transmits a high power RF field at 64MHz (for a 1.5 Tesla scanner) or 128MHz (for a 3 Tesla scanner). If the loop antenna 26 of the present sensing arrangement 20 is in an active mode and located proximal or within the MRI scanner, it will pick up these fields. These external field sources not only interfere with the signal sensing performed by the arrangement, but the high power RF field may damage or even destroy the oscillator.

In such applications, it is therefore proposed to switch off the resonator circuit while the MR system RF pulses are being generated. The series switch embodiment of fig. 2 may be a preferred embodiment because the MRI RF signal will not be able to induce a current in the resonator circuit 22 because the antenna 26 is electrically decoupled from the signal generator 24, interrupting the circuit current.

To achieve such synchronous deactivation of the resonator circuit 22, according to at least one set of embodiments, a controller for the sensing arrangement may be provided, and wherein the controller is adapted to receive, in use, a signal from the external device indicative of the timing of an active state of the external device, and to control the switching such that a driving state of the resonator circuit is disabled during occurrence of said active state of the external device.

For example, the controller may receive a signal indicative of timing of enablement of one or more RF signal generators of the MR system, and control the switching such that the drive state is disabled during that time. After the period of RF loop activity ceases, it may switch back to the non-disabled mode.

Various options for implementing a switching module for switchably disabling the drive state of the sensing arrangement have been described above.

In combination with any of these options, there are various options for implementing selective switching of drive states among a plurality of antennas provided as part of the sensing arrangement. Multiple antennas may be connected to a single signal generator, or each provided with its own signal generator, and various configurations for placing switches within the circuit are also possible.

A benefit of using multiple antennas (e.g., an array of antennas) is that such a configuration may allow for determination of richer spatial information about the origin of the sensed physiological signal.

For example, in some examples, a set of multiple antennas may be sequentially enabled in some spatial pattern (e.g., in a round robin fashion). The sequential movement from one antenna to the next may be controlled at a sufficient rate that physiological signals (e.g., cardiorespiratory waveforms) may be sensed and interpreted from each antenna. The spatial pattern of the measurements enables, for example, the depth of the measured signal to be more easily determined (e.g., deep within the body, or shallower). Alternatively, in one contemplated embodiment, the array of antennas may be embedded within the mattress. Here, information relating to the position of the patient on the mattress can be deduced.

Another potential benefit of using multiple antennas is enabling selection of antennas for utilization in generating or sensing signals. Some antennas in an array or arrangement may provide stronger signal pickup. In some examples, the controller of the sensing arrangement may selectively enable a single one of the antennas that is detected to produce the strongest signal. For example, where multiple antennas are embedded in a mattress, the loop closest to the patient's chest will typically provide the best cardiopulmonary signal.

Various example sensing arrangement embodiments including multiple antennas will now be summarized.

Fig. 7 and 8 illustrate the sensing arrangement 20 according to the first and second set of examples, respectively. In both arrangements, a plurality of antennas 26a, 26b, 26c are provided, each with its own dedicated signal generator 24a, 24b, 24c, e.g. an oscillator. Thus, in these cases, a plurality of resonator circuits each including a signal generator, an antenna, and a switching module are effectively provided.

In both example arrangements, a separate switching module in the form of a circuit breaking switching element 28 is provided for each antenna, which is connected in series with the respective antenna along the branch. The switch may take the same form as discussed above with respect to the embodiments of fig. 2, 3 or 4. The signal generator 24 in each example arrangement is preferably positioned as close as possible to the respective antenna 26 terminal to which it is connected.

Each switching module 28 is connected to a controller 50, the controller 50 enabling central control of the switching of the plurality of antenna/resonator circuits 22.

The series switch enables independent disabling or non-disabling of the drive state of each respective antenna. This operates each antenna in a similar manner to the series switching mechanism of figure 4 above. In particular, each switching element is provided in series with the antenna and with the capacitor element, such that opening of the switch causes a shift of the resonance frequency of the local resonator circuit.

The internal series switch configuration in each of fig. 7 and 8 is particularly beneficial in a multi-loop embodiment because this switching method ensures that the antenna switched in the "off" state has a strong detuned resonant frequency (due to the opening of the capacitor element 32), thereby making the local resonator circuit for the antenna insensitive to electromagnetic fields generated by any other active antenna.

The arrangement of fig. 8 is the same as that of fig. 7, except that an additional circuit-breaking switching element 29 is provided for each of the local resonator circuits between the power supply 54 and the signal generator 24 of each of the resonator circuits. These additional switching elements 29 enable the power to each respective resonator circuit to be switched on and off. This therefore provides the additional benefit of enabling the power consumption of the antenna 26 to be reduced to zero by turning off power to the respective signal generator for the antenna when the antenna 26 is in an inactive state.

The controller 50 may manage the entire set of switches 28, 29 in such a way that only one of the resonator circuits is active at any one time. This ensures that there is no interference between the signals generated and sensed at the two different antennas. Preferably, for a single active resonator circuit, the two respective switching elements 29, 28 for that circuit are set to "closed". For the remaining resonator circuits, both the power switch 29 and the loop resonator internal switch 28 are set to "off". This means that for the remaining inactive resonator circuits, the power consumption is cut to zero and the circuits in each are made insensitive to the EM field generated by the active antenna (due to the above-mentioned detuning of the resonance frequency).

Although the exemplary switching module 28 of fig. 7 and 8 is shown as providing a series switch (in series with the loop circuit line of the antenna) inside the antenna 26, this represents only one possible implementation. In other examples, for example, a respective switching element may be provided that is electrically connected in parallel with each antenna 26. In such an arrangement, the switching module for each respective antenna would take a form similar to the example switching module of fig. 3 described above. In this example, closing the switch causes a short circuit of the respective antenna 26, which means that the antenna no longer oscillates and no longer generates an electromagnetic signal.

However, the internal series switch arrangement illustrated in fig. 7 and 8 may be preferred over the parallel switch arrangement in some cases due to the fact that: in the parallel switch embodiment, the antenna 26 is not truly decoupled from the rest of the resonator circuit, which means that there is still the potential for electromagnetic signals from neighboring antennas to be sensed by the deactivated antenna. However, in most practical implementations, this is not expected to occur due to the fact that the self-resonant frequency of the shorted antenna loop is typically much higher than the self-resonant frequency of the wider resonator circuit (and thus the possible operating frequency of the adjacent antenna). As a result, the incoming EM signal will be less likely to cause resonant pickup at the shorted antenna.

Fig. 9-12 show various exemplary embodiments of antenna arrangements 20, each including a plurality of antennas 26, and each including only a single signal generator 24 for driving the set of antennas. The different embodiments show different possible implementations of the switching module 28 for implementing the disabled or non-disabled selective switching of the driving state in each antenna.

The advantage of using a single signal generator 24 for multiple antennas 26 rather than a single signal generator for each antenna is due to the reduced cost of fewer required components. It also reduces general manufacturing complexity and potentially power consumption.

The circuit path between the signal generator 24 and each antenna 26 is preferably as short as possible because the connecting line path contributes inductance to the circuit. Thus, a long line path will contribute a large inductance, which may be problematic for certain high operating frequencies, since high frequency drive signals do not typically travel well along long line traces. However, providing a stub trace between each antenna and the central signal generator can be challenging for some applications, particularly where a spatial arrangement of antennas is desired having different antennas spaced fairly widely apart from one another. An example may be an arrangement in which the antenna is provided embedded at different places within the mattress.

Thus, for such cases, the arrangement has a separate signal generator for each antenna (as may be preferred in the examples of fig. 7 and 8).

Various examples of fig. 9-12 will now be described.

In the example of fig. 9, a single signal generator 24 (e.g., an oscillator) is electrically coupled to each of the three antennas 26a, 26b, 26 c. A separate respective switching element 28 is provided connected in series between the signal generator and each respective antenna 26. The switches are operable to introduce an open circuit in the circuit path to the respective antenna 26 when "off, while leaving the circuit path to the other antenna unaffected.

In fig. 10, the example sensing arrangement 20 is shown as including two antennas and a single signal generator. Here, the switching module includes an N-port switch 28 provided in series along one outgoing track of the signal generator 24. One end of the switch is connected to the outgoing terminal. The other end of the switch may be alternately connected to the first terminal of the first antenna 26a and the first terminal of the second antenna 26 b. A second terminal of each antenna is connected to a second outgoing terminal of the signal generator 24.

A greater number of antennas 26 may be provided in other arrangements, with an N-port switch alternately connected to each of them at the other end.

The N-port switch has the following effects: the drive signal generated by the signal generator 24 can only be provided to a single antenna 26 at a time, resulting in unique selective enablement of the antennas.

Fig. 11 shows a further example sensing arrangement comprising a plurality of antennas 26 connected to a single signal generator 24. In this example, the switching module is provided in the form of a separate switching element 28 connected in parallel with each of the antennas. The switching elements of each antenna are provided in the same configuration as the parallel switches in the example arrangement 20 of fig. 3 described above.

The switching elements 28 may be opened or closed to connect or disconnect branches running in parallel with the respective antennas 26. By closing the switch, the antenna is short-circuited, which means that no current flows through the respective antenna and thus electromagnetic signal generation is disabled in the respective antenna.

A controller (not shown) may be provided which is arranged to control the two switching elements 28 to facilitate central control of the switching of the plurality of antennas.

Fig. 12 shows a further example sensing arrangement 20 comprising a plurality of antennas 26a, 26b, 26 c. In this example, the switching module is provided in the form of a separate internal series switching element 28 connected in series with each antenna via a respective tuning capacitor 32. The switches for each respective antenna in this arrangement have the same configuration as the switches in the example of fig. 4 (and fig. 7 and 8). When each respective switching element 28 is opened, the capacitor 32 is disconnected from the respective antenna 26, causing a shift in the resonant frequency at the respective antenna, which means that oscillation at resonance no longer occurs (assuming the drive signal remains at the same frequency, i.e. substantially matches the original resonant frequency of the resonator circuit before detuning). Thus, generation of the electromagnetic signal is disabled.

Although a particular number of antennas are shown in this arrangement in the various multi-antenna embodiments described above and shown in fig. 7-12, this is not limiting and any number of antennas may generally be provided.

Another aspect of the present invention may provide an inductive sensing system comprising:

a sensing arrangement according to any of the examples or embodiments outlined above or described below or according to any claim of the present application; and

a signal processing unit for receiving and processing the electromagnetic signals sensed at the arranged antennas to derive one or more sensed measurements.

The sensing measurement is preferably a physiological signal, e.g. a wave recording physiological signal, such as a heart movement or heart rate signal or a respiration (respiration) or respiration (respiration) signal.

As described above, when the primary magnetic field generated by the antenna penetrates the body to be sensed, eddy currents are induced in the body, which in turn generate a secondary "reflected" magnetic field that is sensed at the antenna. These effectively result in the addition of secondary inductive components to the resonator circuit (reflection induction), which results in a change (or detuning) of certain electrical characteristics of the resonator circuit, in particular the natural resonant frequency and the damping factor. By measuring this detuning of the electrical properties, information about the movement of the object inside the body to be probed can be deduced.

There is therefore provided, in accordance with an embodiment of the above aspect of the present invention, a sensing system having a signal processing component in electrical communication with a resonator circuit, configured to sense a change in an electrical characteristic of the resonator circuit over time. From these, the signal processing unit or different operatively coupled components may determine one or more sensing measurements. In an advantageous embodiment, these may be physiological parameters or signals, for example, wave recording signals as mentioned above.

The signal processing unit may comprise a pre-stored algorithm or have pre-stored programming for deriving measurements of one or more physiological parameters from the detected changes in said electrical property.

More details on the option of implementing a process of electrical properties of the resonator circuit to derive a physiological parameter measurement are provided in document WO 2018/127482. Suitable signal processing means are described, for example, between page 27, line 32 and page 31, line 29.

In the preferred embodiment, an antenna 26 having a single loop (single winding) is provided, but this is not essential. A single loop winding provides benefits in signal strength due to reduced parasitic capacitive coupling between the windings. The same single loop antenna is used for both generating the excitation signal and sensing the returned signal. The returned signal may be sensed simultaneously with the signal generation by detecting a change in the electrical characteristic of the resonator circuit as the signal is generated (and the returned signal is received at the antenna). The combined sensing and generating antenna allows for providing a high quality sensing signal as well as providing the benefits of low cost, low complexity, and low power.

As discussed above, certain embodiments may utilize a controller. The controller can be implemented in a number of 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 that are programmed using software (e.g., microcode) to perform the required functions. However, the controller may 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.

Examples of controller components that may be 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).

In various embodiments, 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 medium may be encoded with one or more programs that, when executed on one or more processors and/or controllers, perform the required functions. Various storage media may be fixed within a processor or controller or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller.

Examples according to further aspects of the present invention provide a method of configuring a sensing arrangement, the sensing arrangement comprising:

a resonator circuit comprising an antenna and an electronic signal generator coupled to the antenna for driving the antenna with a drive signal such that it generates an electromagnetic signal, the resonator circuit having a resonant frequency,

wherein the resonator circuit is configurable in a drive state in which the antenna is driven at resonance to generate an electromagnetic signal, and

the method comprises the following steps: controlling a switchable disabling of the drive state, the disabling based on an interruption or change in the drive signal or the resonator circuit, thereby controlling a start or stop of an electromagnetic signal.

Implementation options and details of each of the above steps may be understood and interpreted in light of the explanations and descriptions provided above for the apparatus aspects (i.e., the sensing arrangement aspects) of the present invention.

Any of the example, option or embodiment features or details described above in relation to the apparatus aspect of the invention (in relation to the sensing arrangement) may be applied or combined or incorporated into the method aspect of the invention, mutatis mutandis.

A wide variety of potential applications exist for embodiments of the present invention. By way of non-limiting example, applications include: patient monitoring; remote measuring; carrying out spot check monitoring; an embodiment in a wearable device (e.g., a chest patch or wrist-worn device); monitoring the newborn; monitoring sleep; obstetrical monitoring; for use of mattress-based sensors.

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 word "a" or "an" 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 measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. If a computer program is discussed above, it may be stored/distributed on a 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 telecommunication systems. If the term "adapted" is used in the claims or specification, it is noted that the term "adapted" is intended to be equivalent to the term "configured to". Any reference signs in the claims shall not be construed as limiting the scope.