Patent Description:
One of the methods for sensing magnetic fields is to position a coil so that it is traversed by the field. A potential induced in the coil provides a measure of the field traversing the coil.

<CIT> describes a current sensing system for wireless energy transfer that may include a printed circuit board, wherein the printed circuit board may include at least a first layer, a second layer, and a third layer.

<CIT>, describes a substrate comprising an aperture for receiving a sample of a substance to be tested. The substrate has an electrically conductive coil printed thereon, which surrounds the aperture.

<CIT> describes a supporting member of a tachogenerator. The supporting member is executed as a printed circuit board (PCB), whereby contacts are provided on one side of the PCB.

<CIT> describes a portable locator for detecting a buried object characterized by an electromagnetic (EM) field emission employing three-dimensional sensor arrays each having three substantially-identical EM field sensors disposed on a flexible annular wall having a radial centroid defining a sensing axis.

<CIT> discloses a micro-antenna comprising a first substrate layer having a first antenna winding trace thereon: a second substrate layer having a second antenna winding trace thereon; and at least two couplers to couple the first and second antenna winding traces.

<CIT> discloses a device including a flexible substrate, N coiled conductors, and a plurality of folding regions. The N coiled conductors are deposited on the flexible substrate and connected in series by conductive interconnects. The flexible substrate is folded such that the N coiled conductors form a stack of N coiled conductors.

<CIT> discloses a flexible circuit assembly including a base layer, a plurality of circuit traces and an insulative layer. The plurality of circuit traces can each be coupled to a pair of circuit pads, and the circuit traces can be formed on an upper side of the base layer. The flexible circuit sheet is configured to conform to a non-planar surface of the medical device.

There is provided, according to an embodiment of the present invention apparatus, including:.

At least one of the first and the second conducting lines may include a rectilinear element. Alternatively or additionally, at least one of the first and the second conducting lines may include a curvilinear element.

In a disclosed embodiment the flexible insulating substrate includes a first flexible insulating substrate, and the apparatus further includes:.

The apparatus may include a magnetic tracking system, and, when the substrate is rolled about the axis and the via interconnects the first final termination and the second initial termination the first and second conducting lines may operate as a sensing coil in the magnetic tracking system.

The present disclosure will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings, in which:.

Embodiments of the present invention provide a system for forming coils, the coils typically comprising three coils that are mutually orthogonal to each other, on flexible printed circuit board (PCB). The PCB comprises an insulating substrate having a first and a second side, and conducting elements of the coils are formed on only one of the sides, so that the PCB is also termed a single-sided PCB. In order to form the coils the flexible single-sided PCB is rolled up, in a Swiss roll configuration, so that conducting elements formed on the one side align. The elements are then connected by vias penetrating the substrate, the connected elements forming the coils.

In one embodiment a flexible insulating substrate, having a first side and a second side, is rolled about an axis parallel to the substrate. Prior to the rolling, a first planar conducting spiral that is right-handed relative to a normal to the substrate, and a second planar conducting spiral that is left-handed relative to the normal, is formed on the first side of the substrate.

The first conducting spiral has a first initial termination and a first final termination, and the second conducting spiral has a second initial termination and a second final termination. There is a displacement with a preset magnitude between the spirals, so that when the substrate is rolled about the axis the first initial termination aligns with the second initial termination.

A conductive via penetrates the substrate from the first side to the second side so as to interconnect the first initial termination and the second initial termination of the two spirals.

Forming a set of three mutually orthogonal coils from a single-sided PCB significantly reduces the cost of preparing such coils, compared to prior art systems for producing the coils.

In the following description, like elements in the drawings are identified by like numerals, and the like elements are differentiated as necessary by appending a letter to the identifying numeral.

<FIG> is a schematic illustration of an invasive medical procedure using apparatus <NUM>. The procedure is performed by a medical professional <NUM>, and, by way of example, the procedure in the description hereinbelow is assumed to comprise an electropotential investigation of a portion of a myocardium <NUM> of the heart of a human patient <NUM>. However, it will be understood that embodiments of the present invention are not just applicable to this specific procedure, and may include substantially any procedure on biological tissue or on non-biological material.

In order to perform the investigation, professional <NUM> inserts a probe <NUM> into a sheath <NUM> that has been pre-positioned in a lumen of the patient. Sheath <NUM> is positioned so that a distal end <NUM> of the probe enters the heart of the patient. Distal end <NUM> comprises a position sensor <NUM>, described in more detail below, that enables the location and orientation of the distal end to be tracked. Distal end <NUM> also comprises an electrode <NUM> which is used to acquire electropotentials of myocardium <NUM>.

Sensor <NUM> comprises a plurality of coils. While the description herein describes using the coils for sensing magnetic fields, it will be understood that the coils may also be used to produce magnetic fields.

Apparatus <NUM> is controlled by a system processor <NUM>, which is located in an operating console <NUM> of the apparatus. Console <NUM> comprises controls <NUM> which are used by professional <NUM> to communicate with the processor. The software for processor <NUM> may be downloaded to the processor in electronic form, over a network, for example. Alternatively or additionally, the software may be provided on non-transitory tangible media, such as optical, magnetic, or electronic storage media. The track of distal end <NUM> is typically displayed on a three-dimensional representation <NUM> of the heart of patient <NUM> that is displayed on a screen <NUM>.

In order to operate apparatus <NUM>, processor <NUM> communicates with a memory <NUM>, which has a number of modules used by the processor to operate the apparatus. Thus, memory <NUM> comprises an electrocardiograph (ECG) module <NUM> which acquires and analyzes signals from electrode <NUM>. Memory <NUM> also comprises a tracking module <NUM>, which receives signals from sensor <NUM>, and which analyzes the signals in order to generate the location and orientation of distal end <NUM>. Modules <NUM> and <NUM> may comprise hardware and/or software components. Memory <NUM> typically comprises other modules, such as a force module for measuring the force on end <NUM>, and an irrigation module allowing the processor to control irrigation provided for distal end <NUM>. For simplicity, such other modules are not illustrated in <FIG>.

In addition to receiving and analyzing signals from sensor <NUM>, tracking module <NUM> also controls radiators <NUM><NUM>, and <NUM>. The radiators are positioned in proximity to myocardium <NUM>, and are configured to radiate alternating magnetic fields into a region in proximity to the myocardium. As is explained below, sensor <NUM> comprises three orthogonal coils, and each of the coils generate signals in response to the radiated magnetic fields traversing the coils; it is these signals that are received and analyzed by module <NUM>, so enabling processor <NUM> to track distal end <NUM>. The Carto® system produced by Biosense Webster, of Diamond Bar, CA, uses such a magnetic tracking system.

<FIG>, <FIG> and <FIG> are schematic diagrams illustrating a flexible sheet <NUM> used to produce sensor <NUM>, and <FIG>, <FIG> are schematic diagrams illustrating how the sheet is rolled up to form the sensor, according to an embodiment of the present invention. <FIG> illustrates a top portion of sheet <NUM>, which is not explicitly claimed, and <FIG> illustrates a bottom portion of the sheet according to the claimed invention, both figures being viewed from above the sheet. <FIG> is a side view of sheet <NUM> according to the claimed invention. <FIG> is a schematic perspective view of the formed sensor, <FIG> is a schematic cross-section of the sensor as viewed along an axis of the sensor, and <FIG> is a schematic cross-section of a portion of the sensor as viewed orthogonal to the sensor axis.

Referring to <FIG>, <FIG>, and <FIG>, sheet <NUM> comprises a flexible insulating, substantially two-dimensional (2D), substrate <NUM>, having a first side <NUM> and a second side <NUM>. In one embodiment substrate <NUM> is formed from a polyimide material, but other embodiments may comprise any convenient flexible insulating material. In producing sensor <NUM>, sheet <NUM> is typically initially clad with conducting material, typically copper, on first side <NUM>, while second side <NUM> does not have any conducting cladding. Thus, in the following description side <NUM> is also referred to as conducting side <NUM>, and side <NUM> is also referred to as non-conducting side <NUM>.

For clarity in the description of sheet <NUM>, the sheet is assumed to be referenced to a set of xyz orthogonal axes, wherein the sheet lies in an xy plane, and there is a z axis normal to the sheet. In <FIG> and <FIG> the z axis is assumed to be directed out of the plane of the paper.

On the conducting side three sets of conducting elements are formed. The conducting elements are rectilinear, i.e., all parts of the element are straight lines which are in one of two orthogonal directions. The directions are herein assumed to be parallel to the x axis or the y axis. A first set <NUM>, which is not explicitly claimed, of conducting elements comprises a first plurality of spiral conductors <NUM>. By way of example, <FIG> illustrates four spiral conductors, identified as spiral conductors 92A, 92B, 92C, 92D. A second set <NUM> comprises a second plurality of spiral conductors <NUM>, illustrated by way of example as spiral conductors 96A, 96B, 96C, 96D. A third set <NUM>, illustrated in <FIG>, comprises a third set of conductive lines <NUM>, and in <FIG> there are by way example four lines 102A, 102B, 102C, and 102D.

The spirals of first set <NUM> are positioned along a line segment parallel to the x-axis, and except as described below the spirals are generally similar. Each spiral of set <NUM> has an initial termination <NUM> and a final termination <NUM>, so that the four example spirals in the figure have initial terminations 110A, 110B, 110C, 110D and final terminations 112A, 112B, 112C, 112D. Adjacent spirals are typically mirror images, in a yz mirror plane centered between the spirals, so that the spirals alternate between rotating in a right handed direction around a normal to sheet <NUM> and in a left handed direction about the normal. Thus, as illustrated by the arrows around the spirals in <FIG>, spiral conductors 92A, 92C rotate in a right handed direction, and spiral conductors 92B, 92D rotate in a left handed direction.

As stated above the spirals of set <NUM> are positioned along a line segment parallel to the x-axis. Furthermore, the spirals are separated from each other along the line segment, and the separations are such that when sheet <NUM> is rolled about itself, around an axis <NUM> parallel to the y-axis that is herein also termed the sensor axis, the spirals of set <NUM> align with themselves, as is illustrated schematically in <FIG>. In addition, initial terminations 110A, 110B, 110C, 110D align with themselves, and final terminations 112A, 112B, 112C, 112D also align with themselves. Typically the separation of adjacent spirals on conducting side <NUM> is approximately constant, but differs because as sheet <NUM> rolls about itself, the distance of the sheet from the sheet axis increases.

In forming sensor <NUM> by rolling sheet <NUM> about itself, the sheet may be rolled about a former <NUM> as illustrated in <FIG>. In an alternative embodiment, the sheet is rolled about itself, so there is no former present in sensor <NUM>. For simplicity, in other diagrams of the present disclosure, former <NUM> is not shown. In one embodiment, sensor <NUM> is approximately cylindrical, having a diameter of approximately <NUM> - <NUM> and a length of approximately <NUM> - <NUM>.

In the rolled up configuration described above sheet <NUM> is in a configuration termed a Swiss roll configuration. In the Swiss roll configuration, for any given spiral in set <NUM> except the "end" spirals, a first conductive via <NUM> penetrates through the first side of sheet <NUM> to the second side of the sheet to interconnect the initial termination of the given spiral with the initial termination of a spiral immediately above the given spiral. In addition a second conductive via <NUM> penetrates through the first side of sheet <NUM> to the second side of the sheet to interconnect the final termination of the given spiral with the final termination of a spiral immediately below the given spiral. In <FIG> vias <NUM>, <NUM> are shown as broken lines.

<FIG> is a schematic cross-section of sensor <NUM>, taken in a plane orthogonal to sensor axis <NUM>, and <FIG> is a schematic cross-section of set <NUM> of the sensor, taken in a plane parallel to axis <NUM>. <FIG> illustrate the positioning of vias <NUM> and <NUM> as they interconnect spirals 92A, 92B, 92C, and 92D. In <FIG> spirals 92A and 92D are the end spirals of set <NUM>. Thus, a first via <NUM> connects initial terminations 110B and 110C of spirals 92B, 92C, a second via <NUM> connects final terminations 112C and 112D, and a second via <NUM> connects final terminations 112A and 112B. As is shown in <FIG>, the end spirals are only connected to one other spiral by one termination of the end spiral and a via, and the other termination of the end spiral is not connected to any spiral.

Except for the following differences, the spirals of second set <NUM>, which are not explicitly claimed, are generally similar in layout and configuration to the spirals of first set <NUM>. Thus, each spiral of set <NUM> has an initial termination <NUM> and a final termination <NUM>, so that the four example spirals in the figure have initial terminations 120A, 120B, 120C, 120D and final terminations 122A, 122B, 122C, 122D. As for set <NUM>, in set <NUM> adjacent spirals are typically mirror images, in a yz mirror plane centered between the spirals, so that the spirals alternate between rotating in a right handed direction around a normal to sheet <NUM> and in a left handed direction about the normal.

The spirals of set <NUM> are also positioned along a line segment parallel to the x-axis, and the spirals have substantially the same separations on the line segment as the spirals of set <NUM>. In the rolled up configuration described above, the spirals of set <NUM> are also connected, by vias <NUM> and <NUM>, substantially as described above for set <NUM>. However the line segment for set <NUM> is displaced relative to the line segment of set <NUM>. The displacement is in both the x and the y directions. A y displacement <NUM> causes set <NUM> to be displaced, with respect to set <NUM>, parallel to the sheet axis. y displacement <NUM> is illustrated in <FIG> and <FIG>, and in <FIG>. An x displacement <NUM> is selected so that in sensor <NUM>, an angle θ subtended by sets <NUM> and <NUM> to axis <NUM> is <NUM>°. x displacement <NUM> is illustrated in <FIG>, and the corresponding angle θ is illustrated in <FIG>.

As illustrated in <FIG>, and as stated above, third set <NUM> of conducting elements comprises a plurality of conducting lines <NUM>, and except for their terminations, the lines are typically parallel to the x axis and typically have equal lengths. The lines are displaced along the y axis relative to each other. Each line has an initial termination and a final termination, both of which are offset in the y direction from their respective line. Thus, the four example lines 102A, 102B, 102C, and 102D in the figure have initial terminations 104A, 104B, 104C, 104D and final terminations 106A, 106B, 106C, 106D respectively.

Each conducting line <NUM> defines a ray on first side <NUM> of the substrate extending from its initial termination to its final termination, and the lines are laid out on surface <NUM> so that the rays of each line have a common direction. <FIG> illustrates two rays having the common direction, a first ray 108A from initial termination 104A to final termination 106A for line 102A, and a second ray 108D from initial termination 104D to final termination 106D for line 102D.

In addition, the conducting lines of set <NUM> are displaced relative to each other, parallel to the y axis, so that in the rolled up configuration described above the initial termination of a given line <NUM> aligns with the final termination of a neighboring line <NUM>. This alignment applies except for the initial termination of a "first" line of set <NUM> and for the final termination of a "last" line of the set, which are not aligned with any terminations.

In the rolled up configuration, each pair of aligned terminations in set <NUM> is connected by a respective conductive via <NUM> which penetrates through the first side of sheet <NUM> to the second side of the sheet to interconnect the initial termination of a given line with the final termination of a neighboring line. Vias <NUM> are illustrated in <FIG> as broken lines.

Once sensor <NUM> has been formed, by sheet <NUM> being rolled up and the separate sets of spirals and lines connected by vias as described above, it will be understood that there are three orthogonal coils formed in the sensor, as is illustrated in <FIG>. Each set <NUM>, <NUM>, and <NUM> forms a respective coil, and each of the coils has two "free" terminations, i.e., terminations that are not connected to any other termination of the set. Thus the coil of set <NUM> has free terminations 110A and 110D, the coil of set <NUM> has free terminations 120A and 120D, and the coil of set <NUM> has free terminations 104A and 106D.

If current is input to one of the free terminations of a coil it exits from the other free termination, as is illustrated by the arrows at terminations 110A and 110D, 120A and 120D, and 104A and 106D (<FIG>, <FIG>). For each set (spirals or lines) the current traverses all the elements of the set in a common direction. Each coil of sensor <NUM> thus operates, in response to an alternating magnetic field traversing the coil, in the same way as a coil of wire in the field, generating an alternating potential between the two free terminations of the coil. Thus, via connected sets <NUM>. <NUM>, and <NUM> behave as respective coils of wire, so that in the via connected state the sets are also referred to herein as coils.

<FIG> is a schematic alternative depiction of sensor <NUM>. The depiction shows an end view of the sensor viewed along sensor axis <NUM>, and a side view of the sensor viewed orthogonal to the sensor axis. In the end view rolled up sheet <NUM> is shown as a circle, and sets <NUM>, <NUM> are shown as arcs on the circle. In the side view sheet <NUM> is shown as a rectangle, sets <NUM> and <NUM> are lines on or in the rectangle, and set <NUM> is also shown as a rectangle.

<FIG> is a schematic depiction of an exemplary sensor <NUM>. The depiction of sensor <NUM> is similar to that of sensor <NUM> in <FIG>. Apart from the differences described below, the operation of sensor <NUM> is generally similar to that of sensor <NUM> (<FIG>), and elements indicated by the same reference numerals in both sensors <NUM> and <NUM> are generally similar in construction and in operation.

In sensor <NUM> a set of conducting elements 100A is generally similar in construction to set <NUM>, as described above with respect to <FIG> and <FIG>. However, in sensor <NUM>, while sets 94A and 90A correspond respectively in operation to sets <NUM> and <NUM> of sensor <NUM>, the construction of sets 94A and 90A is different from that of sets <NUM> and <NUM>.

As is illustrated in the side view, sets 94A and 90A lie in a common plane that is orthogonal to sensor axis <NUM>, whereas sets <NUM> and <NUM> lie in different disjoint planes orthogonal to the sensor axis. Thus, in constructing sensor <NUM>, rather than sets 94A and 90A lying on different line segments parallel to the x-axis (<FIG>) on sheet <NUM> in its unrolled up state, the two sets of spirals lie on a common straight line segment. On the common line segment, the different spirals of the two sets are interleaved, and are located on the line segment so that when sheet <NUM> is rolled up, the spirals of set 94A overlap and alternate in rotation direction. Similarly, the spirals of set 90A overlap and alternate in rotation direction. Both sets of spirals are connected by vias as described above with respect to <FIG>.

<FIG> is a schematic depiction of an exemplary sensor <NUM>. The depiction of sensor <NUM> is similar to that of sensor <NUM> in <FIG>. Apart from the differences described below, the operation of sensor <NUM> is generally similar to that of sensor <NUM> (<FIG>, <FIG>), and elements indicated by the same reference numerals in both sensors <NUM> and <NUM> are generally similar in construction and in operation.

In contrast to sensor <NUM> which has three coils that are orthogonal to each other, sensor <NUM> comprises three pairs of similar coils, the coils in a given pair having a common axis of symmetry and being separated along the axis. The three axes of the three pairs are orthogonal to each other. Thus, in sensor <NUM> each of a pair of conducting coils 100B1, 100B2 is generally similar to set 100A (<FIG>), the pair having a common axis of symmetry coincident with sensor axis <NUM>, each of the coils in the pair defining a respective plane orthogonal to the axis, the planes being separated along the axis. In sensor <NUM> each of a pair of conducting coils 94B1, 94B2 is generally similar to set 94A, the pair having a common axis of symmetry orthogonal to, and intersecting, sensor axis <NUM>, and being separated along the axis. Also in sensor <NUM>, each of a pair of conducting coils 90B1, 90B2 is generally similar to set 90A (<FIG>), the pair having a common axis of symmetry orthogonal to sensor axis <NUM> and to the axis of coils 94B1, 94B2, and being separated along the axis.

When used as a magnetic field generator rather than as a sensor, each pair in sensor <NUM> may be configured to act as a Helmholtz pair of coils, so that at the intersection of the three axes of symmetry there is a region of nearly uniform magnetic field.

<FIG> is a schematic depiction of a plurality of exemplary sensors <NUM>. The depiction of sensors <NUM> is similar to that of sensor <NUM> in <FIG>. Apart from the differences described below, the operation of sensors <NUM> is generally similar to that of sensor <NUM> (<FIG>), and elements indicated by the same reference numerals in both sensors <NUM> and <NUM> are generally similar in construction and in operation.

In contrast to sensor <NUM>, which comprises one set of orthogonal coils, sensors <NUM> comprise two or more sets of orthogonal coils. Each set is substantially similar to sensor <NUM>. However, sensors <NUM> are constructed on a single sheet 80A, which has substantially the same properties as sheet <NUM> (described above). However, a length of sheet 80A, measured along a line parallel to the y axis, which is parallel, as explained above, to sensor axis <NUM>, is typically larger than that of sheet <NUM>, and the length is selected so as to accommodate the plurality of orthogonal sensors on sheet 80A.

<FIG>, <FIG>, and <FIG> are schematic diagrams illustrating a flexible sheet 80C used to produce an exemplary sensor <NUM>, and <FIG> is a schematic diagram illustrating how the sheet is rolled up to form the sensor. <FIG> illustrates a top portion of sheet 80C, which is not explicitly claimed, and <FIG> illustrates a bottom portion of the sheet according to the claimed invention, both figures being viewed from above the sheet. <FIG> is a side view of sheet 80C according to the claimed invention. <FIG> is a schematic perspective view of the formed sensor.

Apart from the differences described below, the operation of sensor <NUM> is generally similar to that of sensor <NUM> (<FIG>), and elements indicated by the same reference numerals in both sensors <NUM> and <NUM> are generally similar in construction and in operation. As for sensor <NUM>, sensor <NUM> comprises three coils oriented orthogonally to each other.

Sensor <NUM> is formed from single sheet <NUM>, which has single layers of conducting elements on conducting side <NUM> of the sheet for each of its coils, and there are no conducting elements within substrate <NUM> of the sheet. Sensor <NUM> is also formed from a single sheet 80C, which also has single layers of conducting elements on conducting side <NUM> of the sheet. However, in addition, in sheet 80C there are one or more conducting elements, similar to and aligned with those on the conducting side, embedded in respective layers within substrate <NUM> of the sheet. As is described below, the multiple sets of aligned conducting elements are connected in parallel by vias.

By way of example, in sheet 80C of sensor <NUM> there are two layers of conducting elements embedded in substrate <NUM>, but embodiments of the present invention comprise any number of layers of conducting elements embedded in the substrate.

A set 90C, which is not explicitly claimed, of conducting elements comprises a plurality of spiral conductors <NUM>, the same plurality of spiral conductors A92, and the same plurality of spiral conductors B92 (<FIG>). Spiral conductors <NUM> have been described above with reference to <FIG>. Spiral conductors A92 and B92 are congruent to spiral conductors <NUM>, but are displaced from conductors <NUM> in the z direction. The initial terminations of the three sets of spiral conductors are connected by conducting vias <NUM>, and the final terminations of the three sets are also connected by conducting vias <NUM>. It will be understood that in set 90C there are four groups of spirals, each group comprising three spirals connected, by vias <NUM>, in parallel.

A set 94C of conducting elements comprises a plurality of spiral conductors <NUM>, the same plurality of spiral conductors A96, and the same plurality of spiral conductors B96. Spiral conductors <NUM> have been described above with reference to <FIG>. Spiral conductors A96 and B96 are congruent to spiral conductors <NUM>, but are displaced from conductors <NUM> in the z direction. The initial terminations of the three sets of spiral conductors are connected by conducting vias <NUM>, and the final terminations of the three sets are also connected by conducting vias <NUM>. As for set 90C, in set 94C there are four groups of spirals, each group comprising three spirals connected, by vias <NUM>, in parallel.

A set 100C of conducting elements comprises a plurality of conductive lines <NUM>, the same plurality of lines A102, and the same plurality of lines B102. Lines <NUM> have been described above with reference to <FIG>. Lines A102 and B102 are congruent to lines <NUM>, but are displaced from lines <NUM> in the z direction. The initial terminations of the three sets of conductive lines are connected by conducting vias <NUM>, and the final terminations of the three sets are also connected by conducting vias <NUM>. In set 100C there are four groups of lines, each group comprising three lines connected, by vias <NUM>, in parallel.

When sheet 80C is rolled up to form sensor <NUM>, the different groups of spirals and lines are connected by vias <NUM>, <NUM>, and <NUM>, as illustrated in <FIG> and <FIG>. The connections are as described above with reference to sensor <NUM>, with the difference being that in sensor <NUM> vias <NUM> and <NUM> connect single spirals, whereas in sensor <NUM> vias <NUM> and <NUM> connect sets of spirals, each set comprising three spirals already connected in parallel. Similarly, in sensor <NUM> vias <NUM> connect sets of conductive lines, each set comprising three lines already connected in parallel.

<FIG>, <FIG>, and <FIG> are schematic diagrams illustrating flexible sheets <NUM>, 80D, and 80E used to produce an exemplary sensor <NUM>, and <FIG> is a schematic diagram illustrating how the sheets are rolled up to form the sensor. <FIG> illustrates a top portion of upper sheet <NUM>, which is not explicitly claimed, and <FIG> illustrates a bottom portion of the upper sheet according to the claimed invention, both figures being viewed from above the sheet. <FIG> is a side view of the three sheets <NUM>, 80D, and 80E according to the claimed invention. <FIG> is a schematic perspective view of the formed sensor.

In contrast to sensor <NUM>, sensor <NUM> is formed from a plurality of substantially similar single sheets. By way of example, sensor <NUM> is assumed to be formed from three sheets <NUM>, 80D, and 80E. However, embodiments of the present invention may form sensors from any number of substantially identical sheets. Sheets 80D and 80E are substantially identical to each other and to sheet <NUM>, described above with reference to sensor <NUM>.

Thus, sheets 80D and 80E have respective conducting sides 84D, 84E and non-conducting sides 86D, 86E (<FIG>). On conducting side 84D there are a plurality of spiral conductors D92 and D96, and a set of conductive lines D102, which are respectively congruent to spiral conductors <NUM>, <NUM> and lines <NUM>. Also, on conducting side 84E there are a plurality of spiral conductors E92 and E96, and a set of conductive lines E102, which are respectively congruent to spiral conductors <NUM>, <NUM> and lines <NUM>.

Prior to rolling up, sheets <NUM>, 80D, and 80E are stacked on each other so that the conducting side of one sheet contacts the non-conducting side of an abutting sheet, and so that congruent elements in each sheet align. Thus, as shown in <FIG>, sheet <NUM> overlays sheet 80D, which in turn overlays sheet 80E.

Once aligned, initial and final terminations of congruent conducting elements in each of the sheets are connected together, by vias, to form parallel configurations. Thus, the initial and final terminations of spiral conductors <NUM>, D92, and E92 are connected together by vias <NUM>, as is illustrated in <FIG>, to form a set 90D of spiral conducting elements. It will be understood that set 90D comprises four groups of spirals, each group comprising three spirals connected in parallel by vias <NUM>.

Similarly, the initial and final terminations of spiral conductors <NUM>, D96, and E96 are connected together by vias <NUM> to form a set 94D of spiral conducting elements. Set 94D comprises four groups of spirals, each group comprising three spirals connected in parallel by vias <NUM>.

In addition, the initial and final terminations of conductive lines <NUM>, D102, and E102 are connected together by vias <NUM> to form a set 102D of conducting line elements. Set 102D comprises four groups of conductive line elements, each group comprising three conductive line elements connected in parallel by vias <NUM>.

Sensor <NUM> is formed on single sheet <NUM>, which has single layers of conducting elements on conducting side <NUM> of the sheet for each of its coils, and there are no conducting elements within substrate <NUM> of the sheet. Sensor <NUM> is formed on a single sheet 80C, which also has single layers of conducting elements on conducting side <NUM> of the sheet. However, in addition, in sheet 80C there are one or more conducting elements, similar to and aligned with those on the conducting side, embedded in respective layers within substrate <NUM> of the sheet. As is described below, the multiple sets of aligned conducting elements are connected in parallel by vias.

When sheets <NUM>, 80D, and 80E are rolled up to form sensor <NUM>, the different groups of spirals and lines are connected by vias <NUM>, <NUM>, and <NUM>, as illustrated in <FIG> and <FIG>. The connections are as described above with reference to sensor <NUM>, with the difference being that in sensor <NUM> vias <NUM> and <NUM> connect single spirals, whereas in sensor <NUM> vias <NUM> and <NUM> connect sets of spirals, each set comprising three spirals already connected in parallel. Similarly, in sensor <NUM> vias <NUM> connect sets of conductive lines, each set comprising three lines already connected in parallel.

<FIG> is a schematic diagram illustrating a flexible sheet <NUM>, which is not explicitly claimed, used to produce an exemplary sensor <NUM>, and <FIG> is a schematic diagram illustrating how the sheet is rolled up to form the sensor. Apart from the differences described below, the operation of sensor <NUM> is generally similar to that of sensor <NUM> (<FIG>), and elements indicated by the same reference numerals in both sensors <NUM> and <NUM> are generally similar in construction and in operation.

In contrast to sensor <NUM>, wherein the elements of the sensor are formed from rectilinear conducting elements having sections which are orthogonal to each other, the elements of two sets 90E, 94E of spiral conducting elements of sensor <NUM> are formed from curvilinear elements. Also in contrast to sensor <NUM>, the conducting lines of a third set 100E of conducting lines of the sensor do not have initial terminations and final terminations which are offset from the lines; rather each conducting line of the third coil of sensor <NUM> is a line, typically a straight line, from its initial to its final termination.

Set 90E, which is not explicitly claimed, comprises four curvilinear spirals 192A, 192B, 192C, and 192D which have respective initial terminations 210A, 210B, 210C, 210D and final terminations 212A, 212B, 212C, 212D, and as for set <NUM> of sensor <NUM>, the spirals of set 90E are positioned on a straight line segment and adjacent spirals are mirror images of each other. Thus, as illustrated by the arrows around the spirals in <FIG>, spiral conductors 192A, 192C rotate in a right handed direction, and spiral conductors 192B, 192D rotate in a left handed direction.

As for sensor <NUM>, in the rolled up configuration of sensor <NUM>, the spirals of set 90E align with themselves, so that initial terminations 210A, 210B, 210C, 210D align with themselves, and final terminations 212A, 212B, 212C, 212D also align with themselves.

As for the rolled up configuration of sensor <NUM>, in the rolled up configuration of sensor <NUM>, except for end spirals, an initial termination is connected by a via to an initial termination of an adjacent spiral, and a final termination is connected by a via to a final termination. In the example illustrated, vias <NUM> connect initial terminations 210A and 210B, 210C and 210D, and a via <NUM> connects final terminations 212B and 212C. End spirals 192A, 192D each have a respective final termination not connected to another spiral.

Except for the following differences, the spirals of set 94E are generally similar in layout and configuration to the spirals of set 90E. Thus, the four example spirals in the figure have initial terminations 220A, 220B, 220C, 220D and final terminations 222A, 222B, 222C, 222D. As for set 90E, in set 94E adjacent spirals are typically mirror images, in a mirror plane centered between the spirals, so that the spirals alternate between rotating in a right handed direction around a normal to sheet <NUM> and in a left handed direction about the normal.

The spirals of set 94E are also positioned along a straight line segment parallel to the 90E line segment, and the spirals have substantially the same separations on their line segment as the spirals of set 90E. In the rolled up configuration of sensor <NUM> the spirals of set 94E align with themselves, as do the initial and final terminations of the set. The terminations are also connected, by vias <NUM> and <NUM>, as is illustrated in <FIG>.

As for sensor <NUM>, the line segment for set 94E is displaced relative to the line segment of set 90E. The displacement is substantially as described above for sensor <NUM> and is such that in the rolled up configuration of sensor <NUM> an angle subtended by sets 90E and 94E to sensor axis <NUM> is <NUM>°.

As stated above, third set 100E of conducting lines of sensor <NUM> do not have initial terminations and final terminations which are offset from the lines; rather each conducting line of the third set, that forms a third coil of sensor <NUM>, is a line, herein assumed to be a straight line, from its initial to its final termination. Thus conducting lines 202A, 202B, 202C, and 202D are lines between respective initial terminations 204A, 204B, 204C, and 204D and respective final terminations 206A, 206B, 206C, and 206D.

In sensor <NUM> rays from the initial termination to the final termination of a given conducting line of set 100E have a common direction.

As for sensor <NUM>, in sensor <NUM> the conducting lines of set 100E are displaced relative to each other, parallel to sensor axis <NUM>, so that in the rolled up configuration of the sensor the initial termination of a given line in set 100E aligns with the final termination of a neighboring line on the set. This alignment applies except for the initial termination of a "first" line of set 100E and for the final termination of a "last" line of the set, which are not aligned with any terminations. In addition, the aligned terminations are connected by vias.

Thus, as illustrated in <FIG>, in the rolled up configuration of sensor <NUM>, initial termination 204B aligns with, and is connected by a via <NUM> to, final termination 206A; initial termination 204C aligns with, and is connected by a via <NUM> to, final termination 206B; and initial termination 204D aligns with, and is connected by a via <NUM> to, final termination 206C. As for sensor <NUM>, in sensor <NUM> vias <NUM> penetrate through the first side of sheet <NUM> to the second side of the sheet to interconnect the initial termination of a given line with the final termination of a neighboring line.

As is apparent from the description above and from <FIG>, each of sets 90E, 94E, and 100E have two "free" terminations. If current is input to one of the free terminations of a coil it exits from the other free termination, as is illustrated by the arrows at terminations 212A and 212D, 222A and 222D, and 204A and 206D, and the current traverses all the elements of a given set in a common direction. Thus, as for sensor <NUM>, the via connected sets of sensor <NUM> behave as respective coils of wire.

The embodiments described above comprise rectilinear and curvilinear conducting lines, which are connected by vias to form coils. However, it will be understood that embodiments of the present invention are not limited to one type of conducting line, but may comprise mixtures of such lines. Furthermore, rectilinear conducting lines do not necessarily comprise sections which are orthogonal to each other, but rather may comprise sections making any convenient angles with each other, such as being sections of a hexagon or an octagon. In addition, in the case of the conducting lines comprising sets such as set <NUM>, it will be understood that at least a part of such lines may be curvilinear.

Claim 1:
A flexible insulating substrate (<NUM>), having a first side (<NUM>) and a second side (<NUM>), and suitable to be rolled about a sensor axis (<NUM>) parallel to a y-axis of the substrate;
a first conducting line (102A) and a second conducting line (102B) formed on the first side of the substrate, the first conducting line having a first initial termination (104A) and a first final termination (106A), wherein the first initial termination (104A) and the first final termination (106A) are offset from the first conducting line (102A) on opposite sides respectively of the first conducting line (102A), the second conducting line (102B) having a second initial termination (104B) and a second final termination (106B), wherein the second initial termination (104B) and the second final termination (106B) are offset from the second conducting line (102B) on opposite sides respectively of the second conducting line (102B), the first line defining a first ray (108A) along the substrate from the first initial termination to the first final termination, the second line defining a second ray along the substrate from the second initial termination to the second final termination, the first and second rays having a common direction, the lines, except for their terminations, being parallel to the x-axis, having equal lengths and having a displacement therebetween parallel to the y-axis, with a preset magnitude so that when the substrate is rolled about the sensor axis the first final termination aligns with the second initial termination; and
a via (<NUM>) penetrating the substrate from the first side to the second side so as to interconnect the first final termination with the second initial termination.