Device for detecting magnetic signal generated by beating heart

Abstract

The invention relates to a device (2) for detecting magnetic signals generated by a beating heart (M), comprising a base body (1) with a bearing surface (1a) and a system (3) of at least two nitrogen vacancy-center, NV, magnetometer units (4), the system being embedded in the base body (1), wherein the base pad body (1) is designed to receive a user on the support surface (1a) in a sitting or lying manner.

Description

[0001] The present invention relates to a device for detecting magnetic signals generated by a beating heart. Background Art

[0002] In order to measure very low magnetic field strengths, optically pumped quantum sensors or those based on NV centers in diamond are particularly suitable as sensors. DE 10 2022 204 526.2 describes a magnetometer that utilizes optically pumped and optically detected magnetic resonance (ODMR). This utilizes the energy level splitting of specific spin states of unpaired electrons under the influence of an external magnetic field, the so-called Zeeman effect. This splitting of the energy levels produces variable transitions during relaxation from the excited state, which can then be measured, for example, by optical excitation and frequency-dependent detection of the generated fluorescence radiation or by observing optical properties such as light absorption. The magnetic field strength can then be inferred from the measured optical parameters. Summary of the Invention

[0003] According to the invention, a device for detecting magnetic signals generated by a beating heart is provided, having the features of claim 1. Advantageous embodiments are the subject matter of the dependent claims and the following description.

[0004] Magnetocardiography (MKG) is the recording and visualization of the magnetic field of the heart, generated by the electrophysiological activity of the cardiomyocytes. Within the scope of the present invention, a contactless, passive approach for long-term monitoring of the human heart with high resolution is presented. This is achieved using nitrogen-vacancy magnetometers (so-called NV magnetometers) in a geometric configuration.

[0005] Specifically, a device for detecting magnetic signals generated by a beating heart is described. The device comprises a base mat body with a support surface and a system of at least two NV magnetometer units, wherein the system is embedded in the base mat body. The base mat body is configured to accommodate a user sitting up or lying flat on the support surface. Such a device can also be referred to as a magnetocardiograph.

[0006] A particular advantage of NV sensor systems is their size, particularly the size of the sensor medium. For these applications, the active measurement volume should be small relative to the object to be measured (the heart), because otherwise the signal would be integrated over a large portion of the surface area, potentially fading because the integral is zero. The smaller the active measurement volume relative to the heart, the better the signal detection. NV sensor systems have a very small active sensor volume. Furthermore, this miniaturization allows for the use of sensors in various geometric configurations. In particular, very high-resolution configurations are possible that pass through a very small active sensor volume.

[0007] This also allows for easy integration into textiles or other everyday items, with numerous options conceivable. In one embodiment, the base cushion is a cushion, a mattress, a couch, a mat, a bed, a seat (such as a car seat), or a stool; it can also be integrated into, for example, a topper, a cushion, a sheet, a slatted mat, a bed frame, a bedspread, a pillow, a side sleeper pillow, etc.

[0008] Diamond NV magnetometers are based on the readout of the magnetic resonance of specific vacancy centers in diamond, in particular nitrogen vacancies (NV), which occur as impurities in the carbon lattice of diamond and can also be introduced in a targeted manner. If the NV center in the ground state is optically excited, for example by irradiating a pump laser beam with a suitable wavelength (in this case in the green wavelength range, for example at 532 nm for off-resonance excitation), the electrons are lifted from the triplet ground state into the excited triplet state and relax at 650-800 nm (637 nm = zero phonon line) while emitting fluorescence in the red wavelength range. Since the NV center with m s = ±1 spin quantum number, the possibility of non-spin-maintaining transition is greater, so the continuous excitation pump makes the NV- center mostly in the spin state m s =0 is hyperpolarized.

[0009] In the basic state m s =0 and m s = ±1 spin states, which in this case is approximately 2.87 GHz. Therefore, if microwave radiation is irradiated into the diamond in addition to the optical excitation, then at this resonance frequency of 2.87 GHz, red fluorescence is generated, since the spin-polarized electrons are driven from the m by the microwave field. s =0 basic status increased to m s = ±1 basis state, and from there it is pumped to ms = ±1 excited. However, from there, non-radiative transitions and weak infrared fluorescence transitions first occur via the singlet state, while the fluorescence in the red range is canceled.

[0010] If an external magnetic field is present, the so-called Zeeman effect occurs: the energy m s = ±1 triplet levels are split into energetically equidistant Zeeman levels. When fluorescence is plotted close to the spectrum of microwave excitation, two dips (dips) appear in the fluorescence spectrum, whose frequency spacing is proportional to the strength of the external magnetic field. Magnetic field sensitivity is primarily defined by the smallest resolvable frequency shift and can reach 1 pT / √Hz or less. Because NV centers in single-crystal diamond have four possible arrangements in the crystal lattice, in the presence of an oriented magnetic field, the NV centers present in the crystal react to the external magnetic field to varying degrees depending on their position in the crystal. Ideally, this would result in four pairs of fluorescence minima in the spectrum, whose shape and relative position allow unambiguous determination of both the numerical strength and the direction of the external magnetic field.

[0011] In order to be able to perform vectorial magnetic field measurements, the device, in one embodiment, has a mechanism for generating a substantially uniform bias magnetic field in the region of the magnetometer unit or its sensor medium. The mechanism can also be integrated into the base body. This can involve a Helmholtz coil arrangement, wherein at least the sensor media of the at least two NV magnetometer units are arranged inside the Helmholtz coil arrangement. Other mechanisms can also be involved, such as simple coils, elongated coils, permanent magnet solutions such as in a Halbach array, and the like.

[0012] The heart signal has a magnetic signature with an amplitude of (still only) 1 to 2 picotesla (pT) at a distance of a few centimeters, compared to the Earth's magnetic field in Central Europe, for example, which is about 50 μT (microtesla), thus 10 times stronger. 6 However, even such low field strengths can be resolved with high precision over long periods of time using the proposed technology. For example, magnetic shielding or gradiometer wiring can be used for this purpose.

[0013] By detecting precise cardiac signals with high resolution, a large number of diseases such as persistent atrial fibrillation and paroxysmal ("burst") atrial fibrillation can be detected. This makes it possible to prevent myocardial infarction and, therefore, stroke (especially after an unrecognized myocardial infarction). In addition, the present invention is suitable for the early identification of ST-elevation myocardial infarction, other types of ST-elevation myocardial infarction, pulmonary embolism, AV-node reentry tachycardia, ventricular extrasystoles, but also for the early identification of very rare etiologies such as right ventricular tachyarrhythmias, which otherwise can only be identified by genetic sequencing.

[0014] Only precise resolution of the cardiac signal enables this detection of symptoms. This means that if the signal is heavily contaminated by noise or poorly resolved, offsets of the various PQRST complexes of the heart relative to one another or over time, fluctuations in their amplitude, deformations, or small disturbances cannot be detected. However, this resolution of these standards is crucial, as the aforementioned problems can lead to confusion of complexities (e.g., elevated and offset T waves being interpreted as R waves, which often occur in "healthy" hearts) and false alarms.

[0015] If the gradiometer wiring of the at least two NV-magnetometer units is used, one magnetometer unit always has a larger distance relative to the heart (as a relatively weak magnetic field source) than the other magnetometer unit. By means of the gradiometer wiring, that is, the basic (vectorial) subtraction of the measured parameters, the magnetic field gradient almost corresponds to the field emitted by the weak source, while the much stronger background field (which is basically the same in the two magnetometer units) is eliminated. Thus, the necessity of magnetic shielding is canceled, making it possible to measure magnetic fields in everyday environments. Accordingly, the present invention is particularly suitable for measuring weak magnetic fields without shielding. The technical details of the gradiometer solution that can also be used within the scope of the present invention are disclosed in DE 102022201690.4 and should be included here together.

[0016] The NV sensor system is advantageously integrated so that it cannot be sensed or interfered with. In one embodiment, the underlay body comprises an elastic material between the system and the support surface. By selecting a specific material with regard to thermal conductivity, elasticity, hardness, etc., it is also possible to achieve a certain temperature or pressure control so that the NV unit is not damaged and personnel are not injured.

[0017] In one embodiment, at least one structure made of a material with a high magnetic permeability of ≥1, for example greater than 10, 100 or 1000, in particular a ferromagnetic material such as iron, cobalt or nickel, is provided on the side of the system facing away from the support surface and / or on an (additional) support body. This can be used for field guidance or shielding (for example for other magnetic fields or microwaves). In particular, the structure can comprise a layer, such as a plate or film, a grid structure, such as a mesh, etc. If the structure is provided on the side of the system facing away from the support surface, it can be arranged below the base body or embedded in the base body. The support body can be a so-called upper cover or a blanket.

[0018] In one embodiment, the device is configured to detect the magnetic field strength and field direction with the aid of each of the at least two NV magnetometer units. Another advantage of the NV sensor system is the direction or vector information. Compared to other technologies, this technology is inherently generated for the NV sensor system. Therefore, it is not necessary to introduce interference through modulation technology or to use more unfavorable projections, nor is it necessary to use multiple separate sensors. As a result, one has vector and gradient measurement information (diamond size, i.e., single-digit mm) at exactly the same position. ∧ 3 and below) and without the separation of a few centimeters or more as with other technologies. Using NV magnetometer units that can determine not only the field strength but also the direction of the magnetic field, it is possible to achieve improved suppression of the background field and thus better detection of signals that are strongly superimposed by interfering signals.

[0019] In one embodiment, the device includes a signal processing unit to which the at least two NV magnetometer units are connected, wherein the device is configured to determine an effective magnetic field strength and / or an effective magnetic field direction using the signal processing unit as a difference in magnetic field strengths or field directions detected by the at least two NV magnetometer units. Both a wireless and a wired connection are provided between the sensor device and the signal processing unit.

[0020] For this application, a sampling rate higher than that of the heart signal, in particular greater than 50 Hz, is required to resolve the heart signal. A range of 200 Hz to 400 Hz is considered particularly advantageous. Higher ranges are always better for resolution, but increase the sensitivity requirements.

[0021] Further advantages and configurations of the invention are apparent from the description and the drawings.

[0022] The invention is schematically illustrated in the drawings on the basis of exemplary embodiments and is described below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The main components of an NV center magnetometer as can be used within the scope of the present invention are shown in a schematic block diagram.

[0024] Figure 2 In the various figures a) to c), a possible arrangement of an NV magnetometer unit of a device for detecting magnetic signals according to one embodiment is shown in each case as a schematic block diagram.

[0025] Figure 3 The side view schematically shows a user lying on a base cushion body according to one embodiment of the present invention.

[0026] Figure 4 Possible configurations of a cushion body according to an embodiment of the invention are schematically shown in three side views a) to c).

[0027] Figure 5 A possible embodiment of a cushion body according to an embodiment of the present invention is schematically shown in a side view.

[0028] Figure 6 Possible configurations of a cushion body according to an embodiment of the invention are schematically shown in four side views a) to d).

[0029] Figure 7 Possible configurations of a system having one or more NV magnetometer units according to embodiments of the present invention are schematically shown in six top views a) to f).

[0030] Figure 8 Possible configurations of a device according to an embodiment of the invention are schematically shown in four side views a) to d), which have different base bodies with one or more systems with NV magnetometer units.

[0031] Figure 9 Two side views a) and b) schematically illustrate possible configurations of a device according to an embodiment of the present invention, which has a plurality of systems with NV magnetometer units and a signal processing unit.

[0032] Figure 10 A configuration of a device according to one embodiment of the present invention is shown schematically in a side view, which comprises a plurality of systems with NV magnetometer units, a signal processing unit, and auxiliary devices. DETAILED DESCRIPTION

[0033] Figure 1 The main components of an NV center magnetometer are schematically shown. Diamond 110 containing nitrogen vacancy (NV) sites is first present as the sensor medium. Optical excitation of the NV centers can be achieved via a suitable light source 120, such as a pump laser. Suitable off-resonance excitation methods include frequency-doubled Nd:YAG lasers or semiconductor lasers in the green range, such as 510-532 nm, for example, at 532 nm. Alternatively, LEDs within a suitable wavelength range can also be used. Depending on the design, light from light source 120 can be injected into diamond 110 via suitable optical elements 122, such as mirrors, beam splitters, focusing optics, such as lenses, and, if necessary, fiber-optic elements. Furthermore, the excitation light can be injected continuously or pulsed by a laser, thereby preserving a time window for interference-free fluorescence measurement.

[0034] The magnetometer can also include a microwave source 150 that generates an electromagnetic field in the sensor medium, i.e., in the region of the NV centers of the diamond 110, within a bandwidth covering the desired resonance frequency. A microwave resonator structure can be used to uniformly distribute the generated microwaves over the spatial distribution of the measurement range in the diamond. The resonator structure or microwave source 150 is preferably matched to the frequency of the electron spin resonance. To enable vector magnetometry, an additional static bias magnetic field 140 is generated. This makes the measurement intrinsically vectorial. For this purpose, different spatial directions in the crystal structure are used. For example, Helmholtz coils are suitable for generating such a magnetic field 140, which can generate a substantially uniform magnetic field within a limited range using a coil pair.

[0035] The generated fluorescence 112 from the diamond 110 can, in turn, be directed via suitable optical elements 134, such as optical filters, beam splitters, lenses, and / or fiber optic elements, to a first photodetector 130, which is sensitive at least within the fluorescence wavelength range. The first photodetector 130 can also be positioned directly on the diamond 110. The second photodetector 132 is positioned so as to detect at least a portion of the excitation light from the light source 120, which can be coupled out, for example, via a beam splitter, filter, or partially transparent element. This detector signal 132 of the excitation light can be used as a reference signal to eliminate background signals and highlight the resonance signal of interest, for example, by modulating the excitation light using a lock-in amplifier. Additionally or alternatively, this reference signal can be used to account for fluctuations in the excitation light. Appropriate circuitry 160, such as a preamplifier, logarithmic amplifier, lock-in amplifier, signal filter, or other circuitry, is thus provided to acquire the signals from the first and second photodetectors and to pre-process them in a suitable manner for further evaluation. Finally, the preprocessed fluorescence signal can be evaluated by a signal processing unit 170 , for example using a suitable microcontroller or processor, in order to derive from it desired parameters of the detected magnetic field, in particular its magnetic field strength and direction.

[0036] It goes without saying that such a device can also have further units (not shown), such as a communication unit or an interface for outputting measurement results. Such a device can also be advantageously integrated into an ASIC or FPGA.

[0037] In order to be able to use in everyday environments, magnetic fields that do not originate from the desired weak sources, especially those at 10 -5 The Earth's magnetic field in the range of a few microteslas is eliminated from the measurement as much as possible. In contrast, the heart's magnetic field is in the range of 10-100 times 10 -12 Fluctuates within the range of Tesla (picotesla).

[0038] Elimination of the background magnetic field can be achieved during magnetic field measurement according to exemplary embodiments by shielding or by a gradiometer system. In principle, a gradiometer is a sensor unit that can detect not only the field strength but also the gradient of the field.

[0039] For this purpose, at least two individual magnetometer units can be used, which are arranged at different locations in space. Figure 2 A sensor unit is described that uses two or more NV center magnetometers in a gradiometer system.

[0040] Figure 2 Different illustrations a) to c) show possible geometric arrangements of NV magnetometer units for a device for detecting magnetic signals according to one design. FIG. a) shows a side view of at least two NV magnetometer units S1, S2, ..., Sn arranged in an arbitrary arrangement relative to one another in a single layer (this layer is perpendicular to the illustrated layer, i.e., only the first row is visible). FIG. b) shows a side view of two NV magnetometer units S1 and S2, whose sensor medium is a segment of the same diamond crystal 110. FIG. c) shows a side view of a certain number (n times m) of NV magnetometer units S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm in an arbitrary three-dimensional arrangement. Here, additional layers are connected behind the illustrated layer, thereby forming a cubic grid overall. Here, at least one NV magnetometer unit (not shown), for example located in one of the later layers, is not arranged in the following level (illustrated level): in which other NV magnetometer units S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm are arranged.

[0041] Furthermore, M denotes a signal source, here the heart, and O denotes an optional surface, in particular the body skin, which limits the accessibility or reachability of the magnetic field source M.

[0042] In the embodiment of the present invention, two NV-magnetometer units can always form a gradiometer, wherein a plurality of gradiometers can then be formed overall according to the number of NV-magnetometer units and detect the signal of interest. A valid measurement signal can then be generated from this, in particular by a signal processing unit, for example by averaging, summing, etc.

[0043] The distance d between two NV magnetometer units S1, S2, ... or more precisely their sensor media corresponds to the distance between the following positions: at which magnetic field measurements are performed simultaneously. If the distance between the measurement positions is relatively small, it can be assumed that the additional background magnetic field B env The intensity of the magnetic field B is roughly the same at both locations. In contrast, the weak magnetic field B of interest decreases significantly as the distance from the magnetic field source M increases.

[0044] Therefore, by arranging two NV-magnetometer units at different distances from the source or the heart, the background field can be eliminated by forming the difference between the detected sensor values, and the small magnetic field of interest or its gradient can be extracted: because the magnetic field decreases with the square of the distance, the largest magnetic field changes are detected by the NV-magnetometer unit located near the source. For this purpose, for example, two NV-magnetometer units can be arranged one above the other in an axial gradiometer configuration, so that an NV-magnetometer unit on the first layer forms a gradiometer with an NV-magnetometer unit on the second layer located below it. The background field can also be determined by another magnetometer unit at a larger distance from the two NV-magnetometer units, for example at least 1 meter.

[0045] exist Figures 3 to 10 A possible embodiment of the present invention is schematically shown in FIG and is generally described below. Identical elements are provided with the same reference numerals and are not described multiple times.

[0046] Here, each device 2 for detecting magnetic signals is shown. The device comprises a base mat body 1 with a support surface 1a and at least one system 3 consisting of at least two nitrogen-vacancy center (NV) magnetometer units 4, wherein the at least one system 3 is embedded in the base mat body 1. The base mat body is designed to accommodate a user 20 in a sitting position or lying position on the support surface. The device 2 is used to detect magnetic signals generated by a beating heart (M), but is generally capable of detecting all magnetic signals, in particular biosignals, i.e., biological signals emitted by a living being. For illustration purposes, the figures each have a coordinate system in the upper left portion, wherein the illustrated plane represents the xz plane and the y-axis extends into the illustrated plane.

[0047] exist Figure 3 The mattress as the base mattress body 1 is shown in FIG. Figure 4 a) shows a mattress on a bed, Figure 4 In b) a sofa is shown, and Figure 4 In c) a car seat is shown.

[0048] Figure 5 The schematic side view shows an expanded device 2 as it can be used, in particular for long-term monitoring of cardiac magnetic signals, in a mattress of a bed with a user. Figure 5 Neutralization Figure 6The right side of the figure shows different variants 2.a to 2.d of how one or more systems 3 consisting of NV-magnetometer units 4 can be arranged in the device 2. The device can have one system (variant 2.a) or more than one system (variants 2.b to 2.d). The systems can also be arranged in a specific geometric arrangement, such as in a line (1-dimensional), in a plane (2-dimensional), or distributed in space (3-dimensional). Figure 5 The lower right part of FIG shows a schematic diagram of a system 3 with a plurality of NV-magnetometer units 4 in a top view, which are themselves also arranged in a geometric arrangement, here as lines. The NV-magnetometer units 4 of the system 3 can also be arranged in a specific geometric arrangement, such as in a line (1D), in a plane (2D) or distributed in space (3D), as has also been described in connection with FIG. Figure 2 As explained. Here, two NV-magnetometer units can always form a gradiometer, wherein a plurality of gradiometers are then formed overall depending on the number of NV-magnetometer units, and these gradiometers detect the signal of interest. A useful measurement signal can then be formed from this, in particular by a signal processing unit, for example by averaging, summing, etc.

[0049] Figure 7 In the various views a) to f), variants 3.a to 3.f of the system 3 are shown in schematic top views, each having one or more NV-magnetometer units 4, each having no further sensor 5, or having one or more further sensors 5. The sensor 5 can be, in particular, a pressure sensor, a pulse and blood oxygen content meter, a temperature sensor, etc. The NV-magnetometer units 4 and / or the sensors 5 of the system 3 can be arranged in a specific geometrical arrangement, such as in a line (1-dimensional), in a plane (2-dimensional), or distributed in space (3-dimensional), as already described in connection with the present invention. Figure 2 Or as explained in 5.

[0050] exist Figure 8Four side views (a) through d) illustrate different variants 2.d of a device 2, each comprising two systems 3 in the area of ​​the upper side of the base and one system 3 in the area of ​​the lower side. In variant a), three systems 3 are embedded in the mattress 1.a, which serves as the base. In variant b), two systems 3 are embedded in the pillow 1.b, which serves as the base. Furthermore, one system is positioned beneath the mattress, for example, within the base pad 9. In variant c), two systems 3 are embedded in the upper cover 1.c, which serves as the base. Furthermore, one system is positioned beneath the mattress, for example, within the slatted padding 10. In variant d), three systems 3 are embedded in the mattress cover 1.d, which serves as the base. Various comfort-enhancing mechanisms, such as layers, foam materials, covers, or various covering materials, such as those used to protect electronic devices but also to shield and enhance comfort, can be used.

[0051] exist Figure 9 In the figure, two side views a) and b) show different variants 2.d and 2.d' of the device 2, which have two systems 3 in the area of ​​the bottom mattress body 1, in particular the upper side of the mattress, and one system 3 in the area of ​​the bottom mattress body 1, in particular the lower side of the mattress. In addition, the device has a signal processing unit 11, to which the NV-magnetometer unit of the system 3 is connected in order to determine the effective magnetic field strength and / or field direction. In addition, a communication unit 12 can be provided to connect the device 2 to other devices, such as a PC, tablet PC, or smartphone, for input and output and operation. The communication unit 12 can, for example, have a wired and / or wireless interface. In this case, in variant 2.d, the signal processing unit 11 and the communication unit 12 are also integrated into the bottom mattress body, and in variant 2.d', they are arranged outside the bottom mattress body.

[0052] exist Figure 10 In the figure, a design scheme of a device 2.d according to an embodiment of the present invention is schematically shown in a side view, which has two variants of a system 3 with multiple NV-magnetometer units, a signal processing unit 11, a communication unit 12 and auxiliary devices 13.1, 13.2.

[0053] The auxiliary structures 13.1, 13.2 can perform at least one function selected from the group consisting of waste heat removal, heat insulation, heat conduction, magnetic field compensation (e.g., active via coils), (electro)magnetic shielding, moisture protection, and comfort improvement (using specific packaging materials and composite materials to make sleeping more pleasant and comfortable). The auxiliary structures 13.1, 13.2 can have a structure, such as a mesh, made of a ferromagnetic material with a high magnetic permeability, such as greater than 100.

[0054] The auxiliary mechanism 13.1 can also be embedded in the base mattress body. It can also be embedded below the base mattress body, such as in a bed frame or a slatted mattress, or embedded in a supporting body 13.2 on the user 20, such as in the form of a quilt.

Claims

1. A device (2) for detecting magnetic signals generated by a beating heart (M), comprising: A base pad body (1) with a support surface (1a), and A system (3) consisting of at least two nitrogen-vacancy-center-, NV, magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4), wherein the system is embedded in the base pad body (1), The base cushion body (1) is configured to accommodate a user (20) in a sitting position or lying position on the support surface (1a).

2. The device according to claim 1, wherein the base body (1) has an elastic material between the system (3) and the support surface (1a).

3. The device according to claim 1 or 2, wherein the base cushion body (1) is a cushion, a mattress, a couch, a mat, a bed, a chair or a stool.

4. The device according to any of the preceding claims has a structure consisting of a material having a magnetic permeability greater than 1 and / or a supporting body (13.2) containing the structure on the side of the system (3) facing away from the supporting surface (1a).

5. A device according to any of the preceding claims, which is configured to detect the magnetic field strength and field direction with the aid of each of the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4).

6. The device according to any of the preceding claims, comprising a signal processing unit (170, 11), to which the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) are connected, The device is configured to determine the effective magnetic field strength and / or field direction by means of a signal processing unit (170, 11) as a difference in magnetic field strengths or field directions detected by means of at least two NV magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4).

7. An apparatus according to any of the preceding claims, wherein the system (3) is a two-dimensional system (3), wherein the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) are arranged in a plane.

8. An apparatus according to any one of the preceding claims, wherein the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) include at least four NV-magnetometer units (4), and wherein the system (3) is a three-dimensional system (3), wherein at least one of the at least four NV-magnetometer units (4) is not arranged in the following layer: at least three other NV-magnetometer units of the at least four NV-magnetometer units (4) are arranged in the layer.

9. A device according to any of the preceding claims, wherein each of the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) has a diamond crystal or a segment of a diamond crystal with nitrogen-vacancy centers as a sensor medium (110), wherein the device is configured to detect the magnetic field strength and / or field direction by reading out a spin resonance in the sensor medium (110) that depends on the magnetic field strength.

10. The device according to claim 9 also has at least one excitation light source (120) for radiating light (124) into the sensor medium (110), at least one microwave source (150) for generating a resonance field in the sensor medium and at least one photodetector (130) for detecting resonance-dependent fluorescence (112) from the sensor medium (110).

11. The device according to claim 10, wherein the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) are assigned the same excitation light source (120) and / or the same microwave source (150).

12. A device according to any one of claims 9 to 11, wherein the sensor medium of the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) respectively has a segment of the same diamond crystal (110).

13. A device according to any one of claims 9 to 12, wherein the spacing (d) between the sensor media (110) of the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4) is between 1 and 30 mm, preferably between 5 and 20 mm.

14. The device according to any of the preceding claims further comprises another NV-magnetometer unit (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4), wherein the other NV-magnetometer unit is at least 1 m away from the at least two NV-magnetometer units (S1, S2, ..., Sn; S11, S21, ..., Sn1, S12, S22, ..., Sn2, S1m, ..., Snm; 4).

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