WO2025054721A1 - Method and system for determining positioning configuration of antennas used in scanning biological tissue - Google Patents

Abstract

Disclosed examples generally relate to a method and system for determining positioning configuration of antennas used in scanning biological tissue. In at least one example, there is provided a method for determining the position configuration of antennas used in scanning a biological tissue, the method comprising: generating at least one signal that propagates, along a corresponding signal path, between (i) a primary localization device in a multi-sensing unit, and (ii) at least one auxiliary localization device, wherein the multi-sensing unit includes at least one antenna used for scanning the tissue; determining the propagation delay of the signal along each signal path; determining a distance between the primary localization device and each of the at least one auxiliary localization device; and based on each distance, determining a spatial position of the at least one antenna, in the multi-sensing unit, relative to other antennas used for scanning the tissue.

Description

METHOD AND SYSTEM FOR DETERMINING POSITIONING CONFIGURATION

OF ANTENNAS USED IN SCANNING BIOLOGICAL TISSUE

FIELD OF THE INVENTION

[0001] The present application claims priority to, and the benefit of, United States Provisional Patent Application No. 63/582,191 titled “A System for Microwave Imaging of Biological Tissues and Methods of Use thereof’ filed on September 12, 2023, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] Disclosed examples generally relate to microwave imaging and sensing of biological tissue, and in particular, a method and system for determining positioning configuration of antennas used in scanning biological tissue.

BACKGROUND

[0003] Imaging and sensing of biological tissues with different technologies is desired to improve detection and diagnosis of medical condition and diseases. Using electromagnetic signals in the microwave range is one technology that is being actively developed.

[0004] In recent years, there have been numerous applications of imaging and sensing of biological tissues using electromagnetic signals at microwave frequencies. Applications in imaging, such as breast cancer and brain trauma, are being actively developed. In other applications, electromagnetic signals are used for monitoring water content to establish dehydration and water accumulation in the body in lungs and limbs.

[0005] In all applications, there are key challenges to overcome in implementing electromagnetic signal scanning. These challenges include coupling microwave signals into tissues, recording very low signal levels, developing algorithms able to efficiently use the data, and interpreting results.

[0006] More particularly, the challenge of properly coupling microwave signals into biological tissues is limited by the large mismatch between the electrical properties of the tissues and air. [0007] One approach to improving coupling is using a liquid or a solid between the emitter and the tissue to reduce the mismatch. An alternative solution is to bring the antenna in contact with the tissue, e.g., skin. When in contact, the antenna may be designed in such a way that all radiation is emitted into the biological tissues without necessitating a solid or liquid between the emitter and the tissue.

[0008] The foregoing background is provided solely to facilitate an understanding of the art to which the present disclosure pertains, and is not an admission that any art is relevant prior art.

SUMMARY

[0009] In at least one broad aspect, there is provided a method for determining the position configuration of antennas used in scanning a biological tissue, the method comprising: generating at least one signal that propagates, along a corresponding signal path, between (i) a primary localization device in a multi-sensing unit, and (ii) at least one auxiliary localization device, wherein the multi-sensing unit includes at least one antenna used for scanning the tissue; determining the propagation delay of the signal along each signal path; determining a distance between the primary localization device and each of the at least one auxiliary localization device, based on the corresponding propagation delay along the respective signal path; and based on each distance, determining a spatial position of the at least one antenna, in the multi-sensing unit, relative to other antennas used for scanning the tissue.

[0010] In some examples, the method comprises generating the at least one signal by one of the first localization device and the at least one second localization device.

[0011] In some examples, the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is in a second antenna array, the first and second array positioned on different sides of the biological tissue.

[0012] In some examples, the multi-sensing unit is in a flexible antenna array comprising a plurality of multi-sensing units.

[0013] In some examples, the antenna locations are used to analyze properties of signals transmitted between the antennas to determine electrical properties of the tissue. [0014] In some examples, the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is spaced away from the first array in a direction away from the tissue.

[0015] In some examples, the at least one signal is one of an ultrasound signal, an electromagnetic signal, a magnetic field and an optical signal.

[0016] In some examples, the primary and auxiliary localization devices are located along a common two-dimensional plane, and the at least one auxiliary localization device comprises a first and second auxiliary localization device, and the method further comprising: determining a first distance between the primary localization device and the first auxiliary localization distance, and a second distance between the primary localization device and the second auxiliary localization device; determining the position of the multi-sensing unit by triangulating between the first and second distance, and a known lateral distance separating the first and second auxiliary device.

[0017] In some examples, the other antennas are located in a rigid antenna array positioned at a known reference location from the second localization devices, and the method comprising determining a separation distance between the multi-sensing unit and each antenna in the rigid array based on triangulating the position coordinate of the multi-sensing unit, the reference location of the rigid antenna array and a position coordinate of the antenna in the rigid array in function to the said reference location.

[0018] In some examples, the primary and auxiliary localization devices are located along different two-dimensional planes, and the at least one auxiliary localization device comprises three auxiliary localization devices, and the method further comprising: determining the distance between the primary localization device and each of the three auxiliary localization devices; and determining the position of the multi-sensing unit by using a tetrahedron defined between the three distances, and a known fixed position of each of the three auxiliary localization devices.

[0019] In another broad aspect, there is provided a system for determining the position configuration of antenna arrays used in scanning a biological tissue, the system comprising: a multi-sensing unit comprising a primary localization device and at least one antenna used for scanning the tissue; at least one auxiliary localization device; and at least one processor configured for: generating at least one signal that propagates, along a corresponding signal path, between the primary localization device and the at least one auxiliary localization device; determining the propagation delay of the signal along each signal path; determining a distance between the primary localization device and each of the at least one auxiliary localization device, based on the corresponding propagation delay along the respective signal path; and based on each distance, determining a spatial position of the at least one antenna, in the multisensing unit, relative to other antennas used for scanning the tissue.

[0020] In some examples, the at least one processor is further configured for generating the at least one signal by one of the first localization device and the at least one second localization device.

[0021] In some examples, the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is in a second antenna array, the first and second array positioned on different sides of the biological tissue.

[0022] In some examples, the multi-sensing unit is in a flexible antenna array comprising a plurality of multi-sensing units.

[0023] In some examples, the at least one processor is further configured for using the antenna locations to analyze properties of signals transmitted between the antennas to determine electrical properties of the tissue.

[0024] In some examples, the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is spaced away from the first array in a direction away from the tissue.

[0025] In some examples, the at least one signal is one of an ultrasound signal, an electromagnetic signal, a magnetic field and an optical signal.

[0026] In some examples, the primary and auxiliary localization devices are located along a common two-dimensional plane, and the at least one auxiliary localization device comprises a first and second auxiliary localization device, and the at least one processor is further configured for: determining a first distance between the primary localization device and the first auxiliary localization distance, and a second distance between the primary localization device and the second auxiliary localization device; determining the position of the multisensing unit by triangulating between the first and second distance, and a known lateral distance separating the first and second auxiliary device.

[0027] In some examples, the other antennas are located in a rigid antenna array positioned at a known reference location from the second localization devices, and the at least one processor is further configured for: determining a separation distance between the multisensing unit and each antenna in the rigid array based on triangulating the position coordinate of the multi-sensing unit, the reference location of the rigid antenna array and a position coordinate of the antenna in the rigid array in function to the said reference location.

[0028] In some examples, the primary and auxiliary localization devices are located along different two-dimensional planes, and the at least one auxiliary localization device comprises three auxiliary localization devices, and the at least one processor is further configured for: determining the distance between the primary localization device and each of the three auxiliary localization devices; and determining the position of the multi-sensing unit by using a tetrahedron defined between the three distances, and a known fixed position of each of the three auxiliary localization devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] So that the manner in which the above recited features of the present invention can be understood in detail, some embodiments are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope.

[0030] FIG. 1 is a perspective view of an example device for microwave imaging, in accordance with disclosed examples.

[0031] FIG. 2A is an illustration of two antenna arrays, and a number of signal paths extending between the antenna arrays.

[0032] FIG. 2B is a two-dimensional (2D) view of two antenna arrays, and a plurality of signal paths extending between the antenna arrays.

[0033] FIG. 2C is an example 2D image reconstruction of electrical permittivity properties of an example breast tissue.

[0034] FIG. 2D is an example three-dimensional (3D) image reconstruction of an example breast tissue.

[0035] FIG. 3 is an example microwave imaging system, in accordance with disclosed examples.

[0036] FIG. 4A is an example microwave imaging system using two antennas.

[0037] FIG. 4B is an example microwave imaging system using flexible and rigid antenna arrays. [0038] FIG. 4C is another example microwave imaging system using two flexible antenna arrays.

[0039] FIG. 4D is another example microwave imaging system using a single flexible antenna array.

[0040] FIG. 5A is still another example microwave imaging system using two antennas.

[0041] FIG. 5B is still another example microwave imaging system using flexible and rigid antenna arrays.

[0042] FIG. 6A is an example microwave imaging system using two antennas, according to some examples.

[0043] FIG. 6B is an example microwave imaging system using flexible and rigid antenna arrays, according to some examples.

[0044] FIG. 7A is an example microwave imaging system using two antennas, according to some other examples.

[0045] FIG. 7B is an example microwave imaging system using flexible and rigid antenna arrays, according to some other examples.

[0046] FIG. 8A is another example microwave imaging system using two antennas.

[0047] FIG. 8B is another example microwave imaging system using flexible and rigid antenna arrays.

[0048] FIG. 9 is an example microwave imaging system using flexible and rigid antenna arrays.

[0049] FIGs. 10A and 10B illustrate how the location of all antennas on a plane is defined based on the measured distance between each of the antennas.

[0050] FIG. 10C illustrates distance measurement to fully define the location of antenna locations in a three-dimensional (3D) structure

[0051] FIG. 11 A is a 3D illustration of a flexible and rigid array.

[0052] FIG. 1 IB is a 3D illustration of two flexible arrays.

[0053] FIG. 12A is a process flow for an example method for determining positioning configuration of antennas used in scanning biological tissue.

[0054] FIG. 12B is a process flow for scanning of biological tissue. DESCRIPTION OF THE INVENTION

[0055] Any term or expression not expressly defined herein shall have its commonly accepted definition understood by a person skilled in the art.

[0056] "Microwave” refers to electromagnetic (EM) waves in the microwave region, generally considered to be in the range of about 300 MHz to about 300 GHz, corresponding to wavelengths in the range of between about 1 m and 1 mm.

[0057] “Biological tissue” refers to biological tissues are animal or human tissues. The biological tissues may be any limbs, head, neck or torso or breast.

I. GENERAL OVERVIEW

[0058] FIG. 1 illustrates an example device 100 for microwave imaging of biological tissue (e.g., breast tissue). Device 100 uses microwave signals to scan tissue, and to determine various properties of that tissue.

[0059] FIGs. 2C and 2D exemplify outputs generatable by the device 100. These include two-dimensional (2D) image outputs of biological tissue (FIG. 2C) and/or three- dimensional (3D) image outputs (FIG. 2D). In other examples, various other data outputs are generated, including numerical scores, etc.

[0060] As shown in FIG. 1, device 100 includes two antenna arrays 102a, 102b. Each antenna array 102a, 102b may be housed in a separate corresponding housing 104a, 104b. As referenced herein, each antenna array 102 may include one or more antenna devices 206, multisensing units 302 and/or auxiliary localization devices 304b (as defined below).

[0061] As used herein, the “spatial axial distance” (also referred to herein throughout interchangeably as “spatial distance” or “axial distance”) between the antenna arrays 102a, 102b, refers to the distance 152, defined along an orientation axis 150 (FIG. 2A), between the spaced antenna arrays 102a, 102b.

[0062] A gap (or void) 158 is defined by the separation distance 152 (FIG. 2A). In some examples, gap 158 is also referred to herein as the scanning region 158. This is because a biological tissue requiring scanning, is insertable within the region 158 and between the two antenna arrays 102. For example, this can be the biological tissue 212 in FIG. 3.

[0063] In an example application where the device 100 scans breast tissue, a patient may be in a sitting or standing position, and may position their breast tissue between the opposing antenna arrays 102a, 102b, and within the scanning region 158. In other examples, other types of tissue are positioned between the opposing arrays 102a, 102b.

[0064] Continuing with reference to FIG. 1, device 100 includes a mechanical system 108. Mechanical system 108 supports and positions the antenna housings 104a, 104b. A knob 110 allows adjusting the mechanical system 108, such as to adjust the spatial axial distance 152, between the arrays 102a, 102b.

[0065] Device 100 can also include a computer terminal 112. Computer terminal 112 can include a computer display screen 114 and an input interface 116 (e.g., keyboard and/or trackpad or mouse). The computer terminal 112 allows the operator to control the device.

[0066] As shown in FIG. 3, the device 100 can incorporate a microwave scanning system 300. Microwave scanning system 300 includes two antenna assemblies 202a, 202b. Each antenna assembly 202 is disposed within a respective antenna housing 104a, 104b.

[0067] Each antenna assembly 202 includes the corresponding antenna array 102a, 102b. Each antenna array 102a, 102b includes a plurality of antenna devices 206 (e.g., two or more antenna devices), coupled to a respective switching network 204a, 204b.

[0068] System 300 also includes a signal transceiver 216 and controller 218.

[0069] Signal transceiver 216 includes: (i) at least one signal source transmitter 216a; and (ii) at least one signal receiver 216b.

[0070] The signals generated and received by the source and receiver 216a, 216b can be various types of signals. For example, these can be micro wave signals in respect of antenna devices 206, or broadly electromagnetic signals. They can also be secondary signals generated by a localization device 304, as described herein. For example, this can be ultrasound, magnetic and/or optic signals. In some cases, the transceiver 216 may in fact include multiple transceivers for different types of signals generated and received, including a microwave transceiver, ultrasound transceiver, etc.

[0071] Controller 218 performs various functions including controlling the signal transceiver 216 (e.g., transmitter 216a and/or receiver 216b) and controlling the switching networks 204a, 204b. In some examples, controller 218 also provides signal processing and analysis functionality, as disclosed herein.

[0072] In operation, switching networks 204a, 204b couple any antenna device 206, in an antenna array 102a, 102b, to either the micro wave transmitter 216a or micro wave receiver 216b.

[0073] For example, in FIG. 2A, switching network 204a couples antenna device 206a - in transmitting array 102a - to the micro wave transmitter 216a. Further, switching network 204b individually couples each of a group 250 of antenna devices 206b - in the receiving array 102b - to the microwave receiver 216b.

[0074] In this manner, the antenna device 206a emits (e.g., transmits) a micro wave signal, while the group of antenna devices 250 receive the microwave signal. The received microwave signals are then analyzed to determine various signal properties that indicate response properties of the scanned tissue. The microwave switches, in switching networks 204a, 204b, can be solid-state microwave switches, which are integrated in the antenna array printed circuit board (PCB).

[0075] As best shown in FIG. 2B, a signal path 252 is defined between each pair of activated transmitting and receiving antennas (FIG. 2B).

[0076] As used here, an ‘activated’ antenna device 206, is an antenna device 206 coupled, e.g., by the switching network 204, to either the microwave transmitter 216a or receiver 216b, e.g., in the microwave transceiver 216.

[0077] Each signal path 252, in FIG. 2B, is associated between a pair of transmitting and receiving antenna devices 206a, 206b. Accordingly, a plurality of signal paths 252 are generated for each antenna set 254 (FIG. 2A).

[0078] As further used herein, an “antenna set” 254 refers to a single transmitting antenna device 206a, and one or more receiving antenna devices 206b associated (e.g., assigned to) the transmitting antenna element 206a, e.g., the group of receiving antennas 250.

[0079] In use, the system alternates between different activated antenna sets 254. Each activated set 254 corresponds to a single “signal” of the biological tissue. For example, FIG. 2B shows a single “scan” of the tissue made out of multiple signals measured using multiple activated antenna set 254. By alternating between different antenna sets 254, a plurality of signals are generated such that signal paths 252 intersect each portion of the imaged tissue (see e g., FIG. 2B).

[0080] Once a scan is completed, all microwave signals received at transceiver 216 are analyzed. The signals are analyzed to determine tissue response properties (e.g., tissue electrical response properties). For each analyzed microwave signal, the analysis requires knowledge of the antenna locations to define the signal path length 256 (FIG. 2B) between the pair of transmi tting/receiving antennas associated with that microwave signal. This analysis allows for imaging the entire tissue in 2D or 3D, as shown in FIGs. 2C and 2D.

[0081] To this end, there are a number of drawbacks to using rigid or planar antenna arrays 102a, 102b as exemplified in FIGs. 2A and 2B. [0082] First, it is often difficult to properly couple the microwave signal to the biological tissue using a fixed antenna array 102. If the antenna does not directly contact the tissue, a large mismatch results between the electrical properties of the tissue and the air disposed between the antenna and tissue. For this reason, it is important that the antenna directly contacts the issue to remove the intermediate air barrier.

[0083] Directly contacting the antenna array with the tissue is, however, challenging when the antenna arrays are flat or rigid. This is because many types of tissue, including breast tissue, are curved and do not interface well with a flat array. This prevents the flat antenna array from perfectly contacting the tissue, thereby resulting in a coupling problem.

[0084] One approach to mitigating the coupling problem is to tightly “sandwich” the tissue 212 between the opposing antenna arrays 102a, 102b, thereby ensuring direct contact. However, this is uncomfortable to the patient.

[0085] Another approach is to add more than one degree of freedom to the mechanical actuation 108 such as to properly conform the array to the shape of the biological tissues. However, this not only complicates the mechanical actuation, but also complicates measurement of the antenna position and separation distance 152, which is necessary for determining signal path lengths 256 (FIG. 2A), and in turn, analyzing electrical tissue response properties.

[0086] In view of the foregoing, disclosed examples provide for use of flexible antenna arrays 102a, 102b. Flexible antenna arrays, as opposed to rigid antenna arrays (FIGs. 2A and 2B), are able to deform to take the shape of any irregular shaped tissue 212.

[0087] By using flexible antenna arrays, each antenna device 206 directly contacts the scanned tissue, thereby mitigating coupling problems. Further, unlike rigid antenna arrays, a flexible antenna array allows for direct coupling without (i) forcibly sandwiching the tissue between rigid antenna arrays, and/or (ii) using complex mechanical actuation systems.

[0088] One significant challenge in realizing flexible antenna arrays, however, is determining the relative positioning between the transmitting and receiving antennas. As noted previously, the separation distance is important to determining the signal path length 256 (FIG. 2A) between transmitting/receiving antennas to analyze microwave signals for electrical tissue response properties. Further, in the case of antennas not maintaining isotropic radiation in the direction of interest, it is also useful to determine the path azimuths 255, and path elevations 257 (FIG. 2A) with respect to both the transmitting and receiving antenna 206a, 206b. [0089] In the case of rigid or planar arrays (FIG. 2A), the signal path length 256 is easily determined based on the separation distance 152 between the flat arrays. This separation distance 152 is typically monitored using an auxiliary measurement device. For example, this includes integrating a distance sensor within the mechanical system 108 to monitor the separation between the antenna housings 104a, 104b. In addition, as the antennas are at a fixed and known locations withing the rigid array 102a, 102b, both the path azimuth and elevation can be determined. This simple approach is possible because only the separation distance 152 can be modified between the rigid antenna arrays 102a, 102b, and because all antennas, in the rigid array, are at known location within the array. As such, only a single distance sensor is necessary to measure the path length, along with the path azimuth and path elevation with respect to each transmitting and receiving antennas if necessary.

[0090] However, when using flexible antenna arrays, the same method is not applicable. For instance, FIGs. 4 - 9 exemplify different configurations for a flexible antenna arrays 102a, 102b, which are described in greater detail herein. As exemplified, when the antenna array 102a, 102b is deformable, each antenna device 206 is now uniquely separated from antennas in the opposing array. As such, a single distance sensor does not account for the varying antenna separation distances between opposing transmitting and receiving antennas.

[0091] To mitigate this issue, disclosed examples more generally provide for methods and systems for determining the positioning configuration of antenna array(s) used for scanning biological tissue. In some examples, the disclosed methods and systems are used with flexible antenna arrays, however they are not limited to use with only flexible arrays.

II. EXAMPLE SYSTEMS FOR USING MULTI-SENSING UNITS TO DETERMINE POSITION CONFIGURATION OF ANTENNA ARRAYS

[0092] FIGs. 4 to 9 exemplify systems for scanning of biological tissue 212 using one or more multi-sensing units 302 (or simply, “sensing units” 302). Broadly, the multi-sensing units 302 are used for determining the position configuration of antennas during tissue scanning, including for use in flexible antenna arrays.

[0093] As best exemplified in FIGs. 4A, 5A, 6A, 7A, and 8A, each sensing unit 302 includes at least one: (i) antenna device 206; and (ii) position localization device 304. [0094] The antenna device 206 generates or receives electromagnetic (EM) waves, e.g., microwaves, used to scan the biological tissue 212. This is similar to the antenna devices 206 previously described in relation to FIGs. 1 - 2, and operate in a similar manner.

[0095] The localization device 304 generates or receives a secondary wave used to determine the relative positioning of the antenna device(s) 206 relative to other antenna devices 206 in the scanning system. By determining antenna relative positioning, the localization device 304 determines the signal path length between any set of transmitting and receiving antennas 206. The signal path length is used when processing the EM signals passing through the tissue to determine tissue response properties.

[0096] In some examples, each sensing unit 302 includes only a single antenna 206 and associated localization device 302 (e.g., FIGs. 4 - 9). In other examples, a sensing unit 302 can include multiple localization devices 304 and associated antennas 206 (FIG. 11 A). As explained herein, the inclusion of more than one localization device 304 can allow not only determining the position of a sensing unit 302 (and associated antennas 206), but also its 3D orientation in space. The antenna orientation can also be useful in determining tissue response properties, such as by enabling calculating the signal path azimuth 255 and elevation 257 (FIG. 2A) between transmitting and receiving antennas, as described further below.

[0097] As explained herein, the use of the multi-sensing unit 306 also facilitates use of flexible antenna arrays 102.

[0098] In at least one example, within each sensing unit 302, the one or more localization devices 304 are positioned directly adjacent (e.g., laterally adjacent) the one or more antennas 206. This allows each localization device 304 to more correctly localize the position of its associated antenna(s).

[0099] In some examples, all localization devices 304 and antennas 206 in the same unit 302 are fixedly coupled together. This ensures that the localization devices 304 are not displaced relative to the antennas 206, thereby ensuring that the localization devices 304 correctly localize the position of their associated antennas 206.

[00100] Various types of localization devices 304 can be used. These include ultrasound transducers (FIGs. 4 - 6), secondary antennas (FIG. 7), magnetic field devices (FIG. 8) or optical-based devices (FIG. 9). In each case, the localization device 302 is configured to generate or receive some form of secondary wave, which is secondary to the EM wave generated by the primary antenna 206. [00101] The localization device 304 is oriented to emit signals in the same or at a different direction than the primary antenna 206. For example, in FIGs. 4 - 5, the localization device 304 is oriented to transmit secondary wave signals in the same direction as the antenna 206, and through the biological tissue 212. In these cases, the localization device 304 may be in direct contact with the tissue 212. In other examples, shown in FIGs. 6 - 9, the localization device 304 is oriented away from the tissue to transmit secondary wave signals in a different direction.

[00102] In some examples, best shown in FIGs. 4B - 4D, 5B, 6B, 7B and 8B - two or more of the sensing units 302 are coupled together to form a flexible antenna array. The scanning system can include a single flexible array 102a (FIGs. 4B, 4D, 5B, 6B, 7B, 8B, 9 and 11 A). In other cases, the system uses two flexible antenna arrays 102a, 102b (FIGs. 4C and 11B).

[00103] As shown in these figures, to form the flexible antenna array 102, the units 302 are coupled side-by-side (e.g., laterally) using one or more flexible coupling links 390. The flexible coupling link 390 therefore couple between laterally adjacent sensing units 302.

[00104] Flexible coupling links 390 include any mechanism known in the art enabling the sensing units 302 to move relative to one another. For instance, the flexible coupling links 390 can include rotatable joints, elastic bands or the like.

[00105] By using flexible coupling, the antenna array is able to deform to substantially complement the outer profile shape of various scanned tissue. This ensures that the antennas 206, in each sensing unit 302, directly contact the scanned tissue.

[00106] FIGs. 4 - 9 show a 2D cross-sectional view, where each sensing unit 302 in the flexible array 102a is coupled to two adjacent units 304, other than at the terminal ends.

[00107] FIGs. 11A and 11B exemplify a three-dimensional (3D) representation, where each sensing units 302 in the flexible array 102a is coupled to a plurality of adjacent units 304, other than at the terminal ends and edges. The flexible links therefore allow for a 2D array, having a thickness of one sensing unit 302 to be deformed into various 3D profile configurations.

[00108] In the exemplified cases, the flexible antenna array can be a stand-alone array, or may be integrated into a corresponding housing 104, e.g., of a device 100 (FIG. 1). For example, in FIG. 4D, the flexible array is a stand-alone array that functions to flexibly wrap around tissue 212, e.g., a head, an arm, a lower leg or a wrist. In FIGs. 4B, 4C and 5B, the flexible array is attached at its terminal ends to moving members 392 (e.g., arms). The members 392 can move, for example, vertically upwardly and downwardly to bring the flexible array proximally and distally to the tissue 212. FIGs. 6B, 7B, 8B and 9 exemplify a case where the flexible antenna array 102a is secured inside of an antenna housing 104a. In these examples, the antenna housing 104a may also displace along a vertical axis to move closer and farther away from an opposing housing 104b, which houses a rigid array 102b.

[00109] The various types and configurations of multi-sensing units 302 are now described in greater detail.

(i.) Single Multi-Sensing Units for Antenna Position Localization.

[00110] FIGs. 4A, 5 A, 6A, 7A, and 8A exemplify cases where the antenna arrays 102 include a single multi-sensing unit 302.

[00111] (i.a) Multi-Sensing Unit with Ultrasound Transducer

[00112] FIGs. 4A, 5 A and 6A exemplify cases where the multi-sensing unit 302 includes a localization device 304 comprising an ultrasound transducer.

[00113] At a general level, an advantage of using ultrasound for antenna localization is that ultrasound passes through biological tissues. Ultrasound speeds, in biological tissues, do not vary significantly between different tissue types. For example, the minimum speed of ultrasound in fat tissue is at approximately 1450 meters per second, compared to a maximum speed in muscle tissue of 1580 meters per second. This represents only a± 4 % variation from the mean. In view of this, disclosed examples use the transmission and/or reflection time of ultrasound as an accurate estimate of the separation distance between transmitting and receiving antennas 206.

[00114] FIG. 4A shows an example tissue scanning system 400a where the antenna array 102a includes a single sensing unit 302a having an ultrasound transducer 304a. The opposing antenna array 102b includes an antenna device 206b and can also include an auxiliary localization device 304b. Auxiliary localization device 304b may be coupled to the antenna 206b to form a multi-sensing unit 302, or it may be separated therefrom. Where the auxiliary device 304b is separated from the antenna 206b, it may not be necessarily adjacent to the antenna 206b as exemplified. [00115] In operation, the antenna device 206a, in the first sensing unit 302a, transmits a first microwave signal 306. This signal is received by the antenna 206b on the opposite side of the tissue 212.

[00116] Concurrently, or at any other time before or thereafter, the ultrasound transducer 304a, in sensing unit 302, transmits a separate ultrasound signal 308 through the tissue 212, which is received by the auxiliary ultrasound transducer 304b. The antenna separation distance 310 between the antenna devices 206a, 206b is then determined by the propagation delay for the ultrasound signal 308 to travel from the first transducer 304a, through the tissue 212, and to the second transducer 304b.

[00117] In some examples, the antenna separation distance 310 is determined according to Equation (1), which determines the distance (/)) between transducers 304:

D = AT * V_tissue (1) wherein D is the distance between the transducers 304a, 304b, AT is the time delay, or travel time, from when the ultrasound signal 308 is sent and received, and V_tissue is the average speed of sound in the type of tissue being measured. The time delay between the emitted and reflected ultrasound signal is measured with techniques well known in the art (see e.g., Morten Willatzen et al, Arrival -Time Detection and Ultrasonic Flow-Meter Applications, Journal of Physics: Conference Series, 2006, Ser. 52 58, which is incorporated herein in its entirety by reference).

[00118] The average speed of sound (V_tissue) in Equation (1) is adapted in function of the type of tissues being measured, and from known values. For example, if brain tissue is measured, the average travel speed may be different compared to if breast or muscle tissues are measured.

[00119] In Equation (1), it is assumed that the transducers are located proximal the antennas 206. Accordingly, the distance (/)) between transducers is equal to the antenna separation distance 310. However, in other cases, it is possible that transducer 304b is not positioned directly adjacent the antenna 206b. In these cases, the antenna separation distance 310 is determined by triangulating between: (i) the distance (Z>) between the transducers; and a (ii) a known lateral offset distance separating the transducer 304b from antenna 206b.

[00120] The antenna separation distance 310 is then used, in conjunction with the signal properties (e.g., from EM signal 306), to determine the electrical response properties of tissue 212. In particular, the antenna separation distance 310 indicates the signal path length for the EM wave 306.

[00121] In other examples, the transmitting and receiving transducers 304a, 304b are reversed, such that the transducer 304b transmits the signal, and the transducer 304a receives the signal.

[00122] FIG. 5 A exemplifies a similar concept, however the tissue scanning system 500a now includes a sensing unit 302 provided in only one of the antenna arrays 102a.

[00123] In this example, the system monitors the propagation delay from the total time taken for the ultrasound signal 308 to travel and reflect back from the opposite antenna 206b to the ultrasound transducer 304. The antenna separation distance 310 is then determined according to Equation (2):

[00124] As such, system 500a provides a simple use of the multi-sensing unit 302 in a single antenna array for position localization of the transmitting and receiving antennas.

[00125] FIG. 6A exemplifies still a further use of a sensing unit 302 for position localization such as to determine the antenna separation distance 310.

[00126] In this case, only one of the antenna arrays 102 includes a multi-sensing unit 302. The ultrasound transducer 304a, in sensing unit 302, is directed to face away from the scanned tissue 212. An auxiliary or external localization device 304b, also comprising an ultrasound transducer 304b, is positioned at a distance 312a from the first transducer 304a. Any medium can occupy the space 312a between the two transducers, e.g., air or liquid. The auxiliary transducer 304b is also positioned at a determinable or known distance 312b from the second antenna 206b.

[00127] In this example, one of the ultrasound transducers 304a, 304b generates the ultrasound signal 308 while the other transducer receives the signal. Based on Equation (1), the separation distance 312a between the transducers is determined based on the propagation delay. The transducer separation distance 312a is then subtracted from the known distance 312b to resolve the antenna separation distance 310. [00128] (i.b) Multi-Sensing Unit with Antenna

[00129] FIG. 7A exemplifies a case where the localization device 304, in the sensing unit 302, comprises a second antenna device.

[00130] For example, as shown, the sensing unit 302 includes a localization antenna 304a. Localization antenna 304a may be identical in function and configuration as the primary antenna 206a.

[00131] In this case, the microwave imaging system 700a can operate analogous to the system 600a, in FIG. 6A. That is, an auxiliary localization antenna 304b is positioned at a separation distance 312a from the localization antenna 304a in sensing unit 302. The secondary EM signal 308 can be generated and received by any one of the antennas 304a, 304b. The propagation delay of the secondary EM signal 308 between the two antennas is measured to determine the separation distance 312a, e.g., using Equation (1). This is then subtracted from the known distance 312b to resolve the antenna separation distance 310.

[00132] (i.c) Multi-Sensing Unit with Magnetic Field Device

[00133] FIG. 8A exemplifies a case where the localization device 304, in the multisensing unit 302, comprises a magnetic field device.

[00134] In this case, a sensing units 302a, 302b are provided in each antenna array 102a, 102b. Each sensing unit 302a, 302b includes a magnetic field generator or receiver.

[00135] In this example, the magnetic field generator 304a (e.g., a permanent magnet or a coil antenna) generates a secondary magnetic field wave 308 which propagates through the tissue 212. The field wave is then detected by the magnetic field receiver 304b (e.g., a hall sensor or coil antenna).

[00136] In some cases, the field is mentioned over multiple dimensions (e.g., 3 axis). The distance between the two antennas is determined based on the known magnetic field properties. Accordingly, based on the strength of the received field at the receiver 304b, the system can determine the antenna separation distance 310.

(ii.) Flexible Arrays Using Multi-Sensing Units for Antenna Position Localization.

[00137] FIGs. 4B - 4D, 5B, 6B, 7B and 8B exemplify use of the multi-sensing units 302 for flexible antenna arrays. [00138] In some examples, the flexible antenna arrays 102 can comprise sensing units 302 comprising localization device(s) 304 directed: (a) towards the scanned tissue 212 (FIGs. 4B - 4D, 5B); or (b) away from the scanned tissue (FIGs. 6B, 7B and 8B).

[00139] (ii.a) Tissue Directed Localization Device

[00140] FIGs. 4B - 4D and 5B exemplify flexible antenna arrays 102 using sensing units 302 comprising tissue directed localization devices 304.

[00141] In these examples, the localization device 304 is typically an ultrasound transducer. This is because, as explained previously, the propagation delay of an ultrasound signal is largely unaffected by the type of tissue the ultrasound wave passes through.

[00142] FIG. 4B provides an example for how localization of antennas is performed using flexible arrays with sensing units 302 having tissued directed localization devices 304.

[00143] As shown, in the tissue scanning system 400b, the flexible antenna array 102a includes a plurality of sensing units 302. Each sensing unit 302 includes a localization device 304a (e.g., the ultrasound transducer) directed towards and in contact with the scanned tissue 212.

[00144] The opposing antenna array 102b is rigid and includes a plurality of antennas 206b having predefined locations along a common flat 2D plane. For example, each antenna 206b may have a known position coordinate along an x-axis, with reference to an origin point (O). The system may be configured such that the origin point (O) is defined at the location of the rigid array 102b, such that each antenna 206b has a 2D coordinate position (x, y) along the plane (x, 0).

[00145] The opposing antenna array 102b also includes one or more auxiliary localization devices 304b, also comprising ultrasound transducers. The position coordinates of these ultrasound transducers 304b may also be known relative to the reference point. In this sense, scanning system 400b represents an extension of scanning system 400a (FIG. 4A).

[00146] In some examples, the origin reference point is referenced along an axis (e.g., a horizontal y-axis) that extends to intersect the location of the auxiliary localization devices 304b. More generally, the reference point can be defined with respect to the position of the auxiliary localization devices 304b.

[00147] In use, the auxiliary localization devices 304b are used to localize the position of each sensing unit 302. For example, for multi-sensing unit 302’, the associated ultrasound transducer 304a is activated to generate the ultrasound signal 308. The ultrasound signal 308 travels along the signal paths 402a, 402b and is received by the two auxiliary transducers 304b.

[00148] The system can then determine the propagation delay, according to Equation (1), for each of the signal paths 402a, 402b. Using known triangulation and trigonometric equations, the system can determine the 2D position coordinates (xy) of the multi-sensing unit 302’ relative to the reference origin point (<9).

[00149] For example, as shown in FIG. 4B, a triangle 452 is formed between: (i) the determined path lengths 402a, 402b as determined individually from Equation (1), and (ii) the known lateral separation distance 450 between the two auxiliary ultrasound transducers 304b extending along the horizontal x-axis. The triangulation of triangle 452 then resolves the (x,y) 2D position coordinate of the sensing unit 302’ relative to the known position coordinates (x,0) of the two auxiliary transducers 304b. In turn, this allows the system to estimate the position coordinates of the antenna 206a in the sensing unit 302’.

[00150] The system can then repeat the same process for each of the remaining sensing units 302 in the flexible array 102a. In doing so, the system iteratively (e.g., one by one, using switching network 204) activates the ultrasound transducer 304a for a given sensing unit 302. The propagation delay is then determined for two signal paths to each of the two auxiliary transducers 304b. This allows the system to resolve the position coordinates for each sensing unit 302. In turn, the system can determine the position coordinates for each antenna 206a, in the flexible antenna array 102a, while the position coordinates of antennas 206b are known.

[00151] Additionally, because the position coordinates of antennas 206b, in the rigid array 102b are known - the determined position coordinates (x O of antennas 206a in the flexible array 102a, are further used according to Equation (3) to determine the antenna separation distance 310 between any two antennas in the flexible and rigid arrays 102a, 102b.

) wherein L_path is the antenna separation distance 310, x_206a, y_206a , ^%206Z» T206Z> > ^are the (x,y) coordinate of the antennas 206a and 206b respectively. In some examples, it is assumed that all antennas 206b in the rigid array are positioned along a common axis.

[00152] In this manner, the localization devices 304 are used to determine the signal path length between any two antennas in system 400b. [00153] In other examples, the same concept is applied in reverse, whereby the auxiliary localization devices 304b generate, rather than receive, the ultrasound signals. Further, the transducer 304a in the sensing unit 302 is activated to receive the signal. In these cases, for each sensing unit 302, the two transducers 304a, 304b are activated one at a time. The propagation delay between each transducer and the sensing unit 302 is then determined in a similar manner to resolve the position coordinates of the sensing unit 302.

[00154] In other examples, any number of auxiliary transducers 304b are provided in the rigid array 102b.

[00155] In the example of FIG. 4B, it is assumed that all antennas exist in a common 2D plane. In that case, it is required that at least two external transducers 304b be provided in the rigid array. This allows using triangulation to localize the 2D coordinate position of each antenna 206a in the flexible array in the common plane.

[00156] In a 3D system (FIG. 10C and 11 A and 1 IB), the system may use at least three auxiliary transducers 304b to localize the 3D position of each antenna in the flexible array. Three separate measurements are required to identify a unique 3D position coordinate for each antenna using a triangular prism and trigonometric techniques.

[00157] For example, as shown in FIG. 10C, a tetrahedron 1150 is formed to triangulate in 3D the 3D position coordinate (x,y,z) of a transducer 304a, in a sensing unit 302. In this case, Equation (1) is used to resolve the signal path lengths 402a - 402c between the ultrasound transducer 304a, and each of the three auxiliary transducers 304b. Further, the system may have predefined knowledge of the 3D position coordinates of each of the three auxiliary transducers, which allows determining the lateral spacing distances 1102a- 1102c between the auxiliary transducers. The combination of the lengths 402a - 402c and lateral distances 1102a - 1102c localizes the 3D position of the ultrasound transducer 304a, and therefore, the antenna 206 located in the same multi-sensing unit 302. Equation (3) can then be expanded to determine the 3D antenna separation distances between antennas in the fixed and rigid arrays.

[00158] FIG. 4C exemplifies a tissue scanning system 400c using two flexible antenna arrays 102a, 102b. In this case, each antenna array 102a, 120b includes a plurality of sensing units 302.

[00159] In this example, a similar process as FIG. 4B is used to localize the relative position of each sensing unit 302 relative to other sensing units, and thereby localizing the antennas 206 in each sensing unit 302. [00160] To localize the position of a sensing unit 302’ in a first array 102a, in function of all other sensing unit in the system, the distance between multiple sensing units is measured in order to fully define the sensing unit locations relative to each other’s.

[00161] As best shown in FIG. 10A, if three locations need to be defined, a total of three distances need to be measured (e.g., solid line in FIG. 10A) and for each additional point two more distances need to be measured. In essence, each location should have a known distance with at least two other locations while forming a triangle that is dependent to other triangles. The number of distances needed is driven by Equation (4):

^Distance ^sensing unit * 2 3 (4) whereas N_{D istance} is the number of distance that need to be measured and N_{sensing unit} is the number of sensing units forming the flexible array.

[00162] As shown in FIG. 10A, known triangulation and trigonometric techniques can be used to determine the relative 2D coordinates of each sensing unit 302 in the system. This assumes, however, that all sensing units 302 exist in a common plane.

[00163] As shown in FIG. 10B, the same concept is extended when the sensing units 302 are in different planes (e.g., 3D). In this case, the signal path distance is determined between a given ultrasound transducer 304 and three unique paths for transducers in the opposing array 102b.

[00164] FIG. 4D exemplifies a micro wave imaging system 400c that uses the same concept as system 400c, however the two arrays 102a, 102b are simply combined into a single flexible array 102. In practice, the array 102 (FIG. 4D) can be similar to an elastic wrist band that wraps around the tissue 212, such as a human head, lower leg, wrist or arm.

[00165] FIG. 5B exemplifies a case where multi-sensing units 302 are provided on the flexible array, and no transducers are provided on the rigid array while the surface of the rigid array 102b is not completely flat.

[00166] In this situation the localization devices 304 transmits a wave through the tissue, towards the rigid array which surface reflects the pressure waves such that the distance between the surface and the sensing unit 302 is measured using Equation (2).

[00167] With knowledge of the shape of the rigid array 102a, those distances can be evaluated in such a way that the sensing unit 302 can be localized in function of the shape features of the rigid array 102b. In other words, using all ultrasound transducers an image of the surface of the rigid array 102b can be defined provided that the locations of the transducer 304 is known.

[00168] Since the transducer 304 locations is unknown, but the rigid array surface profile is known, it is then possible to define the location of the transducer 304, hence the sensing unit 302, by adapting their position such that the image of the rigid surface fits exactly the known surface profile. As the antenna 206b are at known locations with respect to the surface profile the position of the sensing units can be defined relative to the antenna 206b.

[00169] (ii.b) Non-Tissue Directed Localization Device

[00170] FIGs. 6B, 7B and 8B exemplify further microwave imaging systems using multi-sensing units 302. In these cases, the units 302 include localization devices 304a which are directed away from the tissue.

[00171] An advantage of this configuration is that it is not necessary to transmit signals through the tissue. This allows using various other types of localization devices 304 which generate waves that are not optimal for propagation in tissue. In these examples, the localization device 304 can be an ultrasound transducer (FIG. 6B), a secondary antenna (FIG. 7B) or a magnetic field device (FIG. 8B).

[00172] With respect to FIGs. 6B and 7B, the tissue scanning systems 600b, 700b exemplified therein operate generally similarly to system 400b (FIG. 4B), with the exception that the auxiliary localization device 304b is not positioned on the opposite side of the tissue. Rather, as shown in the figures, the auxiliary localization devices 304b are now positioned around the sensing units 302 in the flexible array 102a. In this manner, the signal 308 between localization devices 304a, 304b does not travel through the tissue 212.

[00173] In at least one example, as shown, the auxiliary localization devices 304b are coupled to a rigid structure at a known location. This rigid structure can be the first antenna housing 104a, e.g., an inside surface thereof.

[00174] Similar to system 400b, the distance for signal paths 402a, 402b is determined between the auxiliary transducers 304b and each transducer 304a in a given sensing unit 302. This allows using triangulation techniques, as discussed previously, to determine the 2D position coordinates (x,y) of each sensing unit 302 - and therefore, each antenna 206a in each sensing unit 302 - with respect to a reference origin point on the antenna housing 104a. The triangulation here is also based on the lateral spacing distance 450 between the auxiliary localization devices 304b. [00175] In this case, the position coordinates (x,y) of the sensing units 302 are determined relative to the reference point (< ). which is again defined with respect to the auxiliary localization devices 304b. As contrasted to FIG. 4A, the reference point (O) is now shifted to accommodate the fact that auxiliary localization devices 304a, 304b are in a different position relative to the flexible array 102a. In these cases, each of the auxiliary devices may again have some coordinate along the vertical y-axis defined as (x,0).

[00176] The position coordinates (x,y) for each antenna 206a in the flexible array 102a is then used to determine the distance between each antenna 206a in the flexible array 102a and each antenna in the rigid array 102b. This may assume that: (i) the coordinate position of each antenna in the rigid array 102b is known (e.g., along the x-axis), and further, (ii) that separation distance 604a between the auxiliary devices 304b and the rigid antenna array 102b is known (i.e., thereby defining the y-coordinate of each of the rigid antennas 102b).

[00177] In some examples, the antenna array housing 104a can be moved to adapt the flexible array 102a to the size of the biological tissue 212. In these cases, a position sensor 602 monitors the separation distance 604b between the two antenna housings 104b. The separation distance 604b is then monitored and used to correct the value of the separation distance 604a.

[00178] In some embodiments the volume 650 between the back of the flexible array and the rigid structure may be filled with a deformable volume such as liquid or gel.

[00179] FIG. 11 A expands the example to a 3D case. In this case, at least three auxiliary devices 304b are provided to allow for measuring three signal paths (FIG. 10C). FIG. 11A includes additional auxiliary devices 304b to ensure that there is line of sight between each localization device 304a and at least three auxiliary devices 304b. In turn, this allows for 3D position localization of each sensing unit 302. FIG. 11A also describes an implementation where multiple antennas are integrated in the sensing unit 302 along with three localization devices 304b. With three localization devices 304 on the sensing unit 302, it is then possible to measure not only its location but also orientation, as three points defines a plane. As such the azimuth 255 and elevation 257 (FIG. 2A) of the path can be defined in function of the antenna structure.

[00180] FIG. 11B exemplifies the same principle, however both antenna arrays 102a, 102b are now flexible. Further each antenna array includes corresponding auxiliary localization devices 304b. [00181] More generally, FIGs. 11A and FIG. 11B depict an implementation where the localization device 304a and auxiliary device 304b are secondary antenna. Using secondary antennas to measure antenna locations has the advantage to use the same microwave transceiver 216 that is used to generate the microwave signal 214, hence reducing complexity and cost.

[00182] FIG. 8B shows an example tissue scanning system 800b, whereby the localization device 304a, in each sensing unit 302 is a magnetic sensor (e.g., a hall sensor or coil antenna). Further the auxiliary localization device 304b is a magnetic field generator (e.g., a permanent magnet or a coil antenna).

[00183] In use, the magnetic field generator 304b generates a magnetic field having a known intensity profile through space. The magnetic field sensor 304a, in each unit 302, measures the strength of the magnetic field. Based on the measured strength, the system can quantify the position coordinate of each multi-sensing unit 302. The antenna separation distances are determined, from these position coordinates, as discussed in relation to FIGs. 6B and 7B. In some embodiments the field measuring device measures the field in more than one dimensions by using multiple field measuring devices 304a in each unit.

[00184] FIG. 9 exemplifies a tissue scanning system 900 using optical-based localization devices 304.

[00185] In this example, each sensing unit 302 includes a localization device 304a that includes an optical markers. The auxiliary localization devices 304b include an optical light source 304bi for generating an optical signal 904, and optical receivers 304b2 (e.g., camera). The optical light source can use high frequency electromagnetic waves 904, such as infrared or visible light.

[00186] The two cameras 304b2 are placed above the flexible array 102a at known locations from the rigid array and recording optical markers 304a on the flexible array either by means of flashing light 304bi onto the array or providing the array with light emitting capability. The exact location of the sensing units within flexible array are measured by means of photogrammetry which uses triangulation principles to measure the location of the optical markers. These locations are measured with respect to the array housing 104a as the cameras 304b2 are connected to it. [00187] With knowledge of the position of the array housing 104a holding the flexible array, with respect with the rigid array, it is possible to know exactly the location of the antennas relative to each others.

III. EXAMPLE METHOD

[00188] FIG. 12A shows a process flow for a method 1200a for determining antenna position configuration in antenna arrays used for scanning biological tissue. In some examples, the method 1200a is performed by controller 218.

[00189] At 1202a, at least one signal is generated to propagate between: (a) a primary localization device 304a in a multi-sensing unit 302, e.g., in a flexible array, and (b) each of one or more auxiliary localization devices 304b.

[00190] In FIGs. 4A and 6A, this involves generating an ultrasound signal between the ultrasound transducer 304a in the sensing unit 302, and the auxiliary ultrasound transducer 304b that is either: (i) positioned across tissue 212 (FIG. 4A), or (ii) positioned externally from the tissue 212 (FIG. 6A).

[00191] In FIGs. 4B - 4D, 5B, 6B, 7B, 8B and 9, this involves generating a signal (e.g., ultrasound, electromagnetic, magnetic or optical) between the localization device 304a in the sensing unit 302, and the auxiliary localization device(s) 304b that are either: (i) positioned across tissue 212 (FIGs. 4B - 4D), or (ii) positioned externally from the tissue 212 (FIGs. 6B, 7B, 8B and 9).

[00192] The number of auxiliary localization devices 304b may depend on the space dimension. For example, if all antennas he in the same 2D plane, then at a minimum only two auxiliary localization devices 304b are required to resolve 2D (x,y) coordinate positions (FIG. 4B). If the antennas he in 3D space, then a minimum of three auxiliary localization devices 304b are required to solve the 3D (x,y,z) coordinate positions (FIG. 10C).

[00193] In some examples, if more than the necessary auxiliary localization devices 304b are provided in the system, the system may use all or any subset of such devices.

[00194] At 1204a, the propagation delay for each of the at least one signal generated at 1202a is determined. The propagation delay can be a time or phase delay.

[00195] For example, in FIGs. 4A and 6A, the propagation delay is determined for the signal 308. In FIGs. 4B - 4D, 5B, 6B and 7B, the propagation delay is determined along each of the signal paths 402a, 402b. In 3D space (FIG. 10C), the propagation delay is determined for at least three signal paths 402a - 402c.

[00196] At 1206a, based on the propagation delay, the distance between the first localization device 304a and each of the one or more auxiliary localization devices 304b is determined. For example, this can be determined using Equation (1) for each signal path.

[00197] At 1208a, based on the distances determined at 1206a, the system can determine a 2D or 3D coordinate position - relative to some origin reference point - for that multi-sensor unit 302. This can be determined using triangulation and trigonometric techniques as previously explained in relation to each of the systems. For 3D space, this can involve trigonometric techniques based on defining a tetrahedron (FIG. 10C).

[00198] At 1210a, based on the position coordinates determined at 1208a, the system can determine the antenna separation distance between the antenna in that multi-sensor unit, and relative to each antenna in the opposing array. This can be determined in various manners, as explained previously, depending on the system configuration. In various cases, the antennas in the opposing array have predefined or known coordinate positions (e.g., stored in the controller 218 memory), relative to the reference location (< ).

[00199] In other examples, act 1210a is not necessary. For example, it is possible that only providing the system with the position coordinates of all antennas in the systems is sufficient to analyze microwave signals for tissue response properties.

[00200] In some examples, the method 1200a is iterated for each multi-sensing unit 302 in a flexible antenna array such that the system can localize each sensing unit 302 and, in turn, each corresponding antenna 206a. In these examples, the system can activate one localization device 304, in each sensing unit 302 at a time. For example, this can occur using a switching network 204 coupled to each device in each sensing unit 302 (FIG. 3). The switching network can also couple to the various auxiliary localization devices 304b. This can be the same, or a different switching network, than the networks used for the antennas 206.

[00201] As used herein, “activating” a localization device can involve controller 218 operating a switching network to couple that device to the appropriate signal transmitter 216a or signal receiver 216b, based on the type of localization device.

[00202] FIG. 12B shows a process flow for a method 1200b is a process flow for scanning of biological tissue. [00203] At 1202b, the microwave transmission response is measured for each antenna set 254 (FIG. 2A).

[00204] At 1204b, the electrical properties of tissue are determined based on transmission response and location of the antennas relative to each other, as determined using method 1200a (FIG. 12 A).

[00205] At 1206b, one or more outputs are generated based on the tissue response, including the scanning images shown in FIGs. 2A and 2B. In some examples, the tissue response data (including images) are output on a display interface 1310 (FIG. 13).

IV. DETERMINING ELECTRICAL PROPERTIES OF TISSUE

[00206] The microwave transmission coefficient in biological tissues is measured in term of magnitude and phase shift experienced by the microwaves. It can be deducted from the scattering coefficient parameters (S parameters) measured between the two antenna ports. S parameters of a two ports network (two antennas) comprises of 4 parameters S_i S₂₁ , S₁₂, S₂₂ which relates the signals transmitted and reflected from each port. Those parameters can be measured using a vector network analyser (VNA). Calibrations well known in the art can be included to improve the accuracy of those measurements.

[00207] From the S-parameters a conversion method is necessary to obtain the transmission and reflection coefficient of the biological tissues themselves, T and T respectively. Multiple techniques exist to achieve this, some that are more adapted than others. One example is the Nicholson-Ross-Weir (NRW) technique that relates those coefficients ant the S parameters with these relationships in Equation (5): c r(i-r²) , „ r(i-r²) (5)

^{11 —} (i-r²T²) ^{an 21 —} (i-r²T²)

[00208] In some embodiment the full S-parameter matrix may not be measured to estimate those parameters as the above formula uses only the S-parameters related to signal sent to port 1. However, including the entire matrix may increase the accuracy of those parameters.

[00209] In some embodiment only the reflection T may be set to a fixed system specific value. Hence, only microwave transmission measurement is necessary to obtain S₂₁. [00210] The electrical properties can then be calculated based on the reflection and transmission coefficient, T and T respectively along with the knowledge of the separation distance. Specifically, the electrical permittivity E and magnetic permeability /z of the tissues can be calculated. Unless a contrast agent is used the relative magnetic permeability of the biologic material is one. Hence the rest of the description will focus on the permittivity, however same principle could be used to extract the permeability.

[00211] The electrical permittivity is usually measured relative to the value measured in a vacuum environment E₀ and is denoted as relative permittivity s_r. It is common practice in the field to avoid referring to the ‘relative permittivity’ as simply the ‘permittivity’. This will be the case in this description as well.

[00212] The formula used to calculate the permittivity is as shown in Equation (6):

wherein /z_r is the relative permeability, equal to 1 for biological tissues as they are not magnetic, A_o is free space wavelength, A_c is the cutoff wavelength (in case of the use of a waveguide), D is the separation distance. The permittivity value that is obtained is a complex number, where the real part corresponds to the ability for the tissue to store energy while the imaginary part relates to the dielectric loss which can be interpreted as electrical conductivity.

[00213] Another simpler method uses the time delay measurement of the microwave signals, as shown in Equation (7). This time delay can be measured simply by transforming the transmission coefficient in the time domain and measure the time of flight of the microwave signals. A calibration signal is required in the form of known time of flight in a known material. The permittivity is found with the simple formula shown below. However, this technique can only provide the real part of the permittivity as it influences the most the time of flight.

wherein s_c is the permittivity of the known material for the same separation distance, At is delta time of arrival between the tissue measurement and the calibration measurement. [00214] Extracting electrical properties is not limited to those two methods presented here and many other techniques can be implemented (see e.g., Lisen R, Brink W, van den Berg C, Webb A, Remis R. Electrical Properties Tomography: A Methodological Review. Diagnostics (Basel). 2021 Jan 26;11(2):176. doi: 10.3390/diagnosticsl 1020176. PMID: 33530587; PMCID: PMC7910937, which is incorporated herein in its entirety by reference). Some of them uses complex algorithm to reconstruct the electrical properties over a 2D slice or 3D volume. However, any technique will require knowledge of the relative position of all the antennas used to collect the microwave data in order to define electrical properties. In the methods shown above the distance over which the microwave transmission is measured, is specifically required but may not be specifically required for other techniques cited above.

V. EXAMPLE HARDWARE CONFIGURATION FOR CONTROLLER

[00215] FIG. 13 shows an example electrical hardware configuration for the controller 218.

[00216] As shown, the controller 218 can include the processor 1302 coupled to a memory 1304, as well as one or more of an input interface 1308, an output or display interface 1310, a communication interface 1306 and an input/output (I/O) interface 1312.

[00217] Processor 1302 refers to one or more electronic devices that is/are capable of reading and executing instructions stored on a memory to perform operations on data, which may be stored on a memory or provided in a data signal. The term "processor" includes a plurality of physically discrete, operatively connected devices despite use of the term in the singular. Non-limiting examples of processors include devices referred to as microprocessors, microcontrollers, central processing units (CPU), and digital signal processors. In some embodiments, the processing unit comprises a stand-alone embedded processor system, optionally connected to a standard computer. In some embodiments, the embedded processor system may comprise a microcontroller and a Field Programmable Gate Array (FPGA). The processor is linked to a memory which includes instructions to implement the scanning and imaging steps described herein.

[00218] Memory 1304 refers to a non-transitory tangible computer-readable medium for storing information in a format readable by a processor, and/or instructions readable by a processor to implement an algorithm. The term "memory" includes a plurality of physically discrete, operatively connected devices despite use of the term in the singular. Non-limiting types of memory include solid-state, optical, and magnetic computer readable media. Memory may be non-volatile or volatile. Instructions stored by a memory may be based on a plurality of programming languages known in the art, with non-limiting examples including the C, C++, Python ™, MATLAB ™, and Java ™ programming languages.

[00219] In some examples, memory 1304 can store various computer-executable instructions for performing the methods 1200a - 1200b or any portion thereof. To that end, it will be understood by those of skill in the art that references herein to controller 218 as carrying out a function or acting in a particular way imply that processor 1302 is executing instructions (e.g., a software program) stored in memory 1304 and possibly transmitting or receiving inputs and outputs via one or more interfaces.

[00220] Input interface 1308 can include various devices for inputting data into the controller 218, e.g., keyboards, mouse, trackage, a virtual reality headset, gesture recognition, voice command recognition, or an augmented reality display. Input interface 1308 can be analogous to input interface 116 (FIG. 1).

[00221] Display interface 1310 can be an output interface for displaying data (e.g., an LCD screen). In some examples, the display interface 1310 comprises the display screen 114 (FIG. 1). In some examples, the display interface 1310 display a user interface that allows an operator to interact with the system.

[00222] In some examples, the input and display interfaces may be one of the same (e.g., touch display screen).

[00223] Communication interface 1306 may comprise a cellular modem and antenna for wireless transmission of data to the communications network. In some examples, where the above described methods are preformed using external computing devices (e.g., external servers), these external computing devices may communicate to receive and transmit data to controller 218, via the communication interface 1306.

[00224] I/O interface 1312 can be used to connect the controller 218 to other external devices, including the signal transceiver 216 and the switching networks 204a, 204b. VI. INTERPRETATION

[00225] Any term or expression not expressly defined herein shall have its commonly accepted definition understood by a person skilled in the art.

[00226] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

[00227] References in the specification to "one embodiment", "an embodiment", etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

[00228] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely," "only," and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms "preferably," "preferred," "prefer," "optionally," "may," and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[00229] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and/or" means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase "one or more" is readily understood by one of skill in the art, particularly when read in context of its usage.

[00230] The term "about" can refer to a variation of ± 5%, ± 10%, ± 20%, or ± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and/or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[00231] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges recited herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof, as well as the individual values making up the range, particularly integer values. A recited range includes each specific value, integer, decimal, or identity within the range. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc.

[00232] As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into subranges as discussed above. In the same manner, all ratios recited herein also include all subratios falling within the broader ratio.

Claims

CLAIMS:

1. A method for determining the position configuration of antennas used in scanning a biological tissue, the method comprising:

- generating at least one signal that propagates, along a corresponding signal path, between (i) a primary localization device in a multi-sensing unit, and (ii) at least one auxiliary localization device, wherein the multi-sensing unit includes at least one antenna used for scanning the tissue; determining the propagation delay of the signal along each signal path; determining a distance between the primary localization device and each of the at least one auxiliary localization device, based on the corresponding propagation delay along the respective signal path; and

- based on each distance, determining a spatial position of the at least one antenna, in the multi-sensing unit, relative to other antennas used for scanning the tissue.

2. The method of claim 1, comprising generating the at least one signal by one of the first localization device and the at least one second localization device.

3. The method of claim 1, wherein the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is in a second antenna array, the first and second array positioned on different sides of the biological tissue.

4. The method of claim 3, wherein the multi-sensing unit is in a flexible antenna array comprising a plurality of multi-sensing units.

5. The method of claim 1, wherein the antenna locations are used to analyze properties of signals transmitted between the antennas to determine electrical properties of the tissue.

6. The method of claim 1, wherein the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is spaced away from the first array in a direction away from the tissue.

7. The method of claim 1, wherein the at least one signal is one of an ultrasound signal, an electromagnetic signal, a magnetic field and an optical signal.

8. The method of claim 1, wherein the primary and auxiliary localization devices are located along a common two-dimensional plane, and the at least one auxiliary localization device comprises a first and second auxiliary localization device, and the method further comprising: determining a first distance between the primary localization device and the first auxiliary localization distance, and a second distance between the primary localization device and the second auxiliary localization device; determining the position of the multi-sensing unit by triangulating between the first and second distance, and a known lateral distance separating the first and second auxiliary device.

9. The method of claim 8, wherein the other antennas are located in a rigid antenna array positioned at a known reference location from the second localization devices, and the method comprising determining a separation distance between the multisensing unit and each antenna in the rigid array based on triangulating the position coordinate of the multi-sensing unit, the reference location of the rigid antenna array and a position coordinate of the antenna in the rigid array in function to the said reference location.

10. The method of claim 1, wherein the primary and auxiliary localization devices are located along different two-dimensional planes, and the at least one auxiliary localization device comprises three auxiliary localization devices, and the method further comprising: determining the distance between the primary localization device and each of the three auxiliary localization devices; and determining the position of the multi-sensing unit by using a tetrahedron defined between the three distances, and a known fixed position of each of the three auxiliary localization devices.

11. A system for determining the position configuration of antenna arrays used in scanning a biological tissue, the system comprising: a multi-sensing unit comprising a primary localization device and at least one antenna used for scanning the tissue; at least one auxiliary localization device; and at least one processor configured for: generating at least one signal that propagates, along a corresponding signal path, between the primary localization device and the at least one auxiliary localization device; determining the propagation delay of the signal along each signal path; determining a distance between the primary localization device and each of the at least one auxiliary localization device, based on the corresponding propagation delay along the respective signal path; and

- based on each distance, determining a spatial position of the at least one antenna, in the multi-sensing unit, relative to other antennas used for scanning the tissue.

12. The system of claim 11, wherein the at least one processor is further configured for generating the at least one signal by one of the first localization device and the at least one second localization device.

13. The system of claim 11, wherein the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is in a second antenna array, the first and second array positioned on different sides of the biological tissue.

14. The system of claim 13, wherein the multi-sensing unit is in a flexible antenna array comprising a plurality of multi-sensing units.

15. The system of claim 11, wherein the at least one processor is further configured for using the antenna locations to analyze properties of signals transmitted between the antennas to determine electrical properties of the tissue.

16. The system of claim 11, wherein the multi-sensing unit is in a first antenna array, and the at least one auxiliary localization device is spaced away from the first array in a direction away from the tissue.

17. The system of claim 11, wherein the at least one signal is one of an ultrasound signal, an electromagnetic signal, a magnetic field and an optical signal.

18. The system of claim 11, wherein the primary and auxiliary localization devices are located along a common two-dimensional plane, and the at least one auxiliary localization device comprises a first and second auxiliary localization device, and the at least one processor is further configured for: determining a first distance between the primary localization device and the first auxiliary localization distance, and a second distance between the primary localization device and the second auxiliary localization device; determining the position of the multi-sensing unit by triangulating between the first and second distance, and a known lateral distance separating the first and second auxiliary device.

19. The system of claim 18, wherein the other antennas are located in a rigid antenna array positioned at a known reference location from the second localization devices, and the at least one processor is further configured for: determining a separation distance between the multi-sensing unit and each antenna in the rigid array based on triangulating the position coordinate of the multisensing unit, the reference location of the rigid antenna array and a position coordinate of the antenna in the rigid array in function to the said reference location.

20. The system of claim 11, wherein the primary and auxiliary localization devices are located along different two-dimensional planes, and the at least one auxiliary localization device comprises three auxiliary localization devices, and the at least one processor is further configured for: determining the distance between the primary localization device and each of the three auxiliary localization devices; and determining the position of the multi-sensing unit by using a tetrahedron defined between the three distances, and a known fixed position of each of the three auxiliary localization devices.