Patent Description:
The increasing prevalence of patients with cardiovascular diseases and neurological disorders with the simultaneous medical progress has enforced the number as well as complexity of minimally invasive procedures over the past decades as shown by <NPL> Advanced diagnostic and therapeutic catheters have been developed for such interventions. The trend goes towards catheters that integrate multiple transducers, i.e. sensors and actuators, and maintain application-specific flexibility and steerability. However, design and manufacturing of high-density catheters is cumbersome due to typical soft material properties and small dimensions, respectively. The resulting manual manufacturing is labour intensive and prevents process automation and design extensions. To overcome these limitations, a novel catheter design and manufacturing process based on thin-film, flexible printed circuit boards (FPCB's) is proposed. Liquid crystal polymer (LCP) has been investigated as FPCB for lamination with thermoplastic tubular elastomers to build high-density catheters. LCP has recently gained much attention for various biomedical applications such as the encapsulation of micro-electrocorticographic arrays shown by <NPL>. The use of LCP in multichannel cochlear electrode arrays was introduced in <NPL>. The application of LCP in small and light-weight retinal prostheses was shown in <NPL>. Furthermore magnetic nerve cuff electrodes based on LCP were presented in <NPL>. Most of these applications share LCP as durable material with excellent mechanical and electrical properties such as mechanical stability, chemical inertness, and controllable stiffness vs. flexibility, low water absorption rate, and biocompatibility.

Current manufacturing technologies for attaching a FPCB on a catheter rely on bonding, ultrasonic welding or other mechanical means that are known from <CIT> as well as from <CIT> and <CIT>.

These processes usually result in catheters with a high stiffness because the edges have been glued or welded together in order to establish a tubular structure. Such catheters are limited to specific applications where no bendability and flexibility is required.

The majority of the bonding processes are promoting additives as key element to adhere the FPCB, which are generally sensitive to environmental conditions and additive dosage. Furthermore, the presence of adhesives is undesirable in a cleanroom setting during manufacturing.

<CIT> uses a laser etching onto the surface of the catheter to reach improved adhesion properties while bonding.

discloses the insertion of a FPCB in a single or multi lumen tube and it's expansion on the distal end of the catheter. The presented catheter is configured to be used as a diagnostic device for the detection of paroxysmal arrhythmias.

<CIT> discloses a catheter with an insertion tube, a flexible substrate and one or more electrical devices. The insertion tube is configured for insertion into a patient body. The flexible substrate is configured to wrap around a distal end of the insertion tube and includes electrical interconnections. The electrical devices are coupled to the flexible substrate and are connected to the electrical interconnections. The PCB sheet has a plurality of irrigation holes arranged in circumferential rows and lines in the longitudinal direction of the PCB sheet, wherein micro-electrodes are provided on places where no irrigation holes are provided, i.e. interrupting in the <FIG> of <CIT> two rows on one line for every micro-electrode.

<CIT> "Method for producing a catheter comprising a FPCB" discloses a manufacturing method for a catheter that is based on a FPCB made from LCP and a TPU base substrate. The adhesion strength of the LCP is increased by the introduction of adhesion promotion holes on the edge of the FPCB shown in Fig. 2C of <CIT>.

<CIT> "Catheter distal end made of plastic tube and flexible printed circuit boards" shows an ablation catheter tip made of a LCP based FPCB that is wrapped around the catheter tip in a semi-spherical shape.

<CIT> "Stretchable electrode conductor assembly and medical implant" discloses the concept of a catheter comprising the support of the electrode arrangement from an essentially non-stretchable material that exerts only small tensile forces on the interface to the conductor tracks when the arrangement is stretched. This can ensure a longer life during operation, even with frequent stretching by relatively large amounts. The required stretchability of the arrangement is realized as a whole by cutting the support in a zigzag or meandering pattern to adapt it to the contour of the conductor track(s). Thus, the stretchability of the support, like that of the conductor tracks, is realized by the special geometric configuration.

<CIT> uses an FPC, especially an enrolled FPC, for providing contacts at the opposite sides and discloses that it is necessary to bend it only; the FPCB is not extensible as such and needs a configuration like in Fig. 4C of said document to accommodate different lengths.

<CIT> discloses thin film devices and methods of manufacturing and implanting the same. This comprises a shaped insulator having an inner surface, an outer surface, and a profile shaped according to a selected dielectric use. A layer of conductive traces is fabricated on the inner surface of the shaped insulator using biocompatible metallization. An insulating layer is applied over the layer of conductive traces. An electrode array and a connection array are fabricated on the outer surface of the shaped insulator and/or the insulating layer, and the electrode array and the connection array are in electrical communication with the layer of conductive traces to form a flexible circuit.

<CIT> discloses various devices and methods for modulating targeted nerve fibers or other tissue as well as for cooling energy delivery members, wherein these systems may be configured to access tortuous anatomy of or adjacent hepatic vasculature.

<CIT> shows a stretchable electrode conductor arrangement, <CIT> discloses ablation systems and methods using a catheter including one or more image sensors. and <CIT> shows microelectrode array devices for electrical stimulation.

Based on this prior art, it is an object of the present invention to provide an improved catheter, comprising passive and/or active transducers with/without electronic components providing the desired catheter bendability, pushability, torquability and kinking compensation or prevention. One or multiple transducers can be sensors, actuators, or both.

Although it is mentioned in prior art documents that such medical devices as catheters comprise a FPCB or an FPC, it is to be noted that they comprise transducers, e.g. sensors, where the wording FPCB is correct, and connecting portions as well as between distant transducers positioned on a flexible printing circuit as well as connecting portions which should be qualified as FFC for flexible flat cable. But since connector portions can be seen as part of a printed circuit board, the entire segment with transducers and connections is mentioned as FPCB transducer segment.

This object is achieved with a catheter with a catheter according to claim <NUM> and a catheter according to claim <NUM>, wherein these features give the catheter a wide variety of different configuration possibilities to meet requirements on mechanical deformation, transducer efficiency and signal quality.

The feature that the FPCB covers essentially the catheter circumference for the length of the FPCB transducer segment with the exception of the FPCB free surface portion meaning that the FPCB in the FPCB transducer segment can be seen as having a sheet form with a distal and a proximal side and two lateral sides which are mainly directed in longitudinal direction of the catheter but these lateral sides never contact each other but maintain in-between a FPCB free surface portion, which is not necessarily following a straight line. The leftmost portion of the left side is positioned in a recess of the right side of the FPCB scaffold what is in line with a polygonal shape of the scaffold.

Such a catheter comprises a catheter tube, preferably a thermoplastic polymer tube and a FPCB, preferably made of LCP, wherein the FPCB partially covers the catheter circumference on predetermined segments along the longitudinal axis of the catheter tube. On the body-exposed distal segment of the catheter the FPCB is conceived as interlinked, regular scaffold structure with a plurality of FPCB free spaces providing the FPCB covered segment with the maximum stability, while using the minimal amount of material. The resulting functional scaffold structure ensures the desired bendability, pushability and torquability, prevention or compensation of catheter kinking and the selective placement of one or multiple transducer patches.

The basic FPCB form is a scaffold structure in longitudinal and/or transverse direction that has sufficient FPCB free spaces. FPCB free space means that a straight line in the longitudinal or transverse direction has portions which are not occupied by FPCB material compared to portions occupied by FPCB material. Such FPCB free spaces ensure to fulfill catheter requirements with respect to bendability. The FPCB covered catheter segments and transducers are decreasing the catheter bendability. FPCB free spaces can be provided in both, the longitudinal and the transverse direction to ensure the desired catheter bendability in said directions. The longitudinal and/or transverse symmetry further allows reducing the amount of freestanding FPCB segments and concurrently improves the catheter stability. The FPCB free space can have the shape of a polygon, whereby multiple FPCB corners, internal angles and edges constitute the specific shape of the cut-out. The FPCB edges and FPCB corners can be arranged in a specific shape according to the mechanical requirement of the catheter design. The FPCB free spaces can be shaped regular, which means axial-symmetric with FPCB edges of similar length or irregular which means non axial-symmetric with FPCB edges of different lengths.

It is an advantage for the flexprint when it is based on a hexagonal or diamond basic pattern which serves as the basis for all openings which was derived by structural-mechanical simulation. The openings are hexagonal or diamond in shape which allows an improved bendability and they are especially created based on a FEM simulation. Transducer patches are especially provided on the FPCB basis hexagonal or diamond shape pattern, but it is also possible that the extend beyond the hexagonal or diamond shape FPCB basic film into the inner hexagonal or diamond shaped openings, which does not hinder the bendability. It is possible to have a connecting FPCB web between the transducer patches on the FPCB basic film.

In one example the smallest element of the herein described scaffold structure is a hexagonal axial-symmetrical honeycomb FPCB free space that can be described by a defined set of parameters like the internal angles alpha, beta and the polygon height h. These honeycombs can form regular or irregular spaced clusters in order to create a scaffold structure on which transducer patches can be placed. The honeycomb shaped FPCB free space can be rotated in a desired direction according to the required bending behaviour of the complete scaffold structure. In the herein described document the honeycomb shaped FPCB free space was rotated by <NUM> degrees. In other words, the direction of a predetermined honeycomb defining line can be oriented not only along the longitudinal axis of the catheter but also in any angle between <NUM> and <NUM> degrees.

Another example is a modified version of the honeycomb, namely an ellipsoid shaped FPCB free space in the transverse direction, which allows for improved bending in the longitudinal direction. Through multiple cuts that result in FPCB free spaces the catheter gets bendable in a multitude of directions. The ellipsoid shaped FPCB free space can have any quantity or orientation and can gradually change dimensions along the catheter axis to accommodate for various bending requirements. The FPCB corners can be undercut or overcut to diminish the stress peaks during bending. An ellipsoid outline can be added to the FPCB edges of the FPCB (in order to disseminate stress on the FPCB and improve bendability of the catheter. The ellipsoid shaped FPCB free spaces has preferably a cut-out that is a larger than the dimensions of the natural kinking of the catheter that occurs when no LCP is present on the circumference. This kinking compensated cut-out is preventing stress peaks in the LCP material and ensures a bending angle from <NUM> to -<NUM> degree without LCP delamination.

Although the FPCB free portion between the opposite edges of the FPCB segment is direction in the longitudinal direction of the medical device, It is possible that the FPCB segment has an outer circumference of a parallelogram and therefore the FPCB free portion will be essentially helix-shaped, since also a parallelogram FPCB segment would follow an essential helix-shape around the lateral surface of the cylinder of the catheter. Electronic components can be placed on the upper or bottom side of the FPCB and the FPCB can subsequently be thermoformed on the interior or the exterior wall of the catheter tube. The four presented options to place electronic components allow for the seamless integration of electronic components of any size, without interfering with the outside of the catheter. The electronic components can comprise transducers, i.e. sensors and actuators, multiplexer, integrated circuits, amplifiers, coils or capacitors. To mitigate stresses on the FPCB during thermoforming of the flat electronic components, small FPCB openings are cut with a laser. Therefore, the electronic components, especially, if they have a certain height are preferably positioned on the side of the FPCB where such FPCB openings can be provided to accommodate the thickness of the associated electronic component, and to mitigate the rigidity of such an IC extending in the FPCB opening.

Further embodiments of the invention are laid down in the dependent claims.

Preferred embodiments of the invention are described in the following list with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings.

<FIG> shows a schematic drawing of a FPCB sheet for an embodiment similar to <FIG>. The FPCB <NUM>, i.e. the hexagonal shaped FPCB free spaces <NUM> are longer in the longitudinal direction <NUM> than in the transverse direction <NUM> , i.e. the width of the FPCB sheet. The length of the hexagonal shaped FPCB free space <NUM> is determined by the internal angle alpha <NUM>, beta <NUM> in longitudinal direction and the polygon height h <NUM> of the free space between the center of the FPCB free space <NUM> and the FPCB edge <NUM>. The internal angle alpha <NUM>, beta <NUM> and the polygon height <NUM> determine the form of the inner hexagonal FPCB free space <NUM>. In addition is the form of the transducer patch <NUM> defined by the transducer patch width EW <NUM> and the transducer diameter ED <NUM>. The distance from transducer to transducer patch <NUM> is defined by the transducer patch distance e1 <NUM>, whereby the distance of transducer patch <NUM> clusters is defined by e2 <NUM>. The transducer patch <NUM> distance to the edge of the FPCB is defined by wside <NUM>. The FPCB surrounded free spaces <NUM> can also be named FFC surrounded free spaces, and the FPCB free surface portion <NUM> is a FFC free surface portion.

<FIG> shows a schematic drawing similar to <FIG> with the main difference that the FPCB free spaces <NUM> are turned <NUM> degrees and the internal angle alpha <NUM> and beta <NUM> have been changed to a different value. The transducer patches <NUM> have a different shape than shown in <FIG> but can also be of circular design.

<FIG> shows a perspective view of a catheter <NUM> with a flexible printed circuit board, i.e. FPCB <NUM> according to a first embodiment of the invention and <FIG> shows the catheter tube <NUM> of <FIG> with the FPCB <NUM> separated from the tube <NUM>. The catheter <NUM> comprises at least the catheter tube <NUM> based on a polymer, preferably a thermoplastic polymer onto which the FPCB <NUM> was thermobonded on its circumference.

<FIG> shows that the FPCB <NUM> can be provided initially as a separate flat sheet and comprises a scaffold structure <NUM> and a plurality of transducer patches <NUM>. The scaffold structure <NUM> comprises straight scaffolds <NUM> forming a periodic structure of FPCB free spaces <NUM>. Transducer patches <NUM> are attached or integrated intermittently on every second corner of the hexagons, i.e. for every hexagon three corners where the straight scaffolds <NUM> are connected comprise such a round transducer patch <NUM>. The diameter of the transducer patches <NUM> is larger than the width of the straight scaffolds <NUM> and therefore can slightly protrude into the adjacent hexagon shaped FPCB free space <NUM>. Within the embodiment of <FIG> the straight scaffold <NUM> in the longitudinal direction <NUM> of the catheter <NUM> are longer than the connecting inclined straight scaffolds <NUM> so that the FPCB free spaces <NUM> are lengthened in the longitudinal direction <NUM>.

The straight scaffolds <NUM> comprise, where necessary, conductors, i.e. are in these portions flat flexible cables with one or more conductors, having a pitch which can e.g. be <NUM> millimeter, provided on the flat and flexible LCP base. These conductors are distributed inside different straight scaffolds <NUM> according to the wiring needs for the transducers to be used on the transducer patches <NUM>. Therefore, wiring conductors can bifurcate at inner FPCB free spaces <NUM> and come together (again) when the three straight scaffolds <NUM> meet again at the node points. The conductors are shown as the traces <NUM> in Fig. <NUM>, <FIG> or <FIG>. and are embedded inside the FPCB <NUM>. In other words, not all straight scaffolds <NUM> comprise a conducting connection <NUM> or wire and some comprise far more than one.

The scaffold structure <NUM> is cut out off a sheet having a predetermined length in the longitudinal direction <NUM> such that the transducers on the transducer patches <NUM> have the necessary transducer distribution. The width of the sheet, i.e. in the transverse sheet direction <NUM>, is predetermined so that in can be attached around the catheter tube <NUM> without portions of the left side of the FPCB <NUM> sheet overlapping portion of the right side of the sheet. In other words, as can be seen in <FIG>, a continuous FPCB free surface portion <NUM> remains in the longitudinal direction <NUM>. However, it is not necessary that the continuous FPCB free surface portion <NUM> comprises a straight line along the catheter <NUM>. Here, transducer patches <NUM> and <NUM> at the left and right sheet border, respectively "block" such a straight line. In other words, every longitudinal line <NUM> at the circumference comprises portions of FPCB free spaces <NUM> and/or free spaces from the FPCB free surface portion <NUM> as well as portions of the straight scaffold <NUM> and at some places transducer patch <NUM>.

This FPCB <NUM> sheet can be attached at the catheter tube <NUM> by the means of lamination or thermobonding. A segment of the FPCB <NUM> is cylindrically wrapped around the catheter tube <NUM> and adhered due to the temperature and pressure generated by the thermobonding process, whereby the melting temperature of the catheter tube <NUM> is exceeded.

The scaffold structure <NUM> is attached with the proximal end, which is during use of the catheter <NUM> the end portion of the catheter which is exterior of the patient via wires or attached FPCB traces <NUM> as known from the prior art. The FPCB connector segment <NUM> is usually provided at or near the distal end of the catheter and provides electrical connections via the traces <NUM> to the transducer patches <NUM>. The transducer patches <NUM> can be made of gold and coated with platinum-iridium alloy for increased signal quality and biocompatibility.

The transducer patches <NUM> are shown as having a greater height than the adjacent straight scaffold <NUM>. This existence of an adjacent height or the transducer patches <NUM> being flush with the scaffold structure <NUM> depend on the kind of transducer patches that are used. In any case, such thicker patches increase the rigidity of the structure, while the thinner straight scaffolds <NUM> and especially the FPCB free spaces <NUM> provides high flexibility in the longitudinal direction <NUM> which is necessary when the catheter <NUM> is bent at the upper and lower side of the curvature. The total FPCB free space is added up from the FPCB free spaces <NUM> inside the hexagons as well as the continuous FPCB free surface portion <NUM> between the non-contacting left and right sides from the originating printed flat FPCB <NUM>.

The embodiment of <FIG> shows a sequence of two-hexagon-wide scaffold structures <NUM>. The width can also be one, two or more polygons depending on the size of the scaffold structure <NUM> and the size of the catheter tube <NUM>. This will be shown within the embodiment of Fig. <NUM>. The embodiment of <FIG> shows transducer patch clusters <NUM>, wherein the rectangle showing these six transducers patches <NUM> forming a cluster is only a virtual line to show that <FIG> shows three such clusters with intermittent FPCB-only scaffold portions. It is possible to have regular distribution of transducer patches or such transducer patch clusters <NUM> with intermittent areas of higher bendability due to less transducer patch <NUM> portions.

<FIG> shows a perspective view of a catheter <NUM> with a FPCB <NUM> according to a second embodiment of the invention and <FIG> shows the catheter tube <NUM> of <FIG> with the FPCB <NUM> separated from the tube <NUM>. The catheter <NUM> comprises at least the catheter tube <NUM> based on a polymer, preferably a thermoplastic polymer onto which is affixed the FPCB <NUM>.

The FPCB <NUM> can be provided initially as a separate flat sheet as shown in <FIG> and comprises a scaffold structure <NUM> and a plurality of transducer patches <NUM>. The scaffold structure <NUM> comprises a straight scaffold <NUM> forming a periodic structure of hollow openings with an interior hollow space <NUM>.

Pairs of hexagonal transducer patches <NUM> are attached or integrated intermittently on a predetermined number of straight scaffolds <NUM> pairs but also can be of circular design. The diameter of the transducer patches <NUM> is not larger than the width of the straight scaffold <NUM>.

<FIG> shows a perspective view of a catheter <NUM> with a FPCB <NUM> according to a third embodiment of the invention and Fig. <NUM> shows the catheter tube <NUM> of <FIG> with the FPCB <NUM> separated from the tube <NUM>. The catheter <NUM> comprises at least the catheter tube <NUM> based on a polymer, preferably a thermoplastic polymer onto which is affixed the FPCB <NUM>. The FPCB <NUM> can be provided initially as a separate flat sheet as shown in Fig. <NUM> and comprises a scaffold structure <NUM> and a plurality of transducer patches <NUM>. The scaffold structure <NUM> comprises straight scaffolds <NUM> forming a periodic structure of hollow hexagons with an interior hollow space <NUM>. Transducer patches <NUM> are attached or integrated intermittently on every second corner of the hexagons, i.e. for every hexagon three corners where the straight scaffolds <NUM> are connected comprise such a round transducer patch <NUM>. The diameter of the transducer patches <NUM> is larger than the width of the straight scaffolds <NUM> and therefore slightly project into the adjacent hexagonal hollow space <NUM>. Within the embodiment of <FIG> the straight scaffolds <NUM> in the longitudinal direction <NUM> of the catheter <NUM> are longer than the connecting inclined straight scaffolds <NUM> so that the hexagonal hollow space <NUM> are lengthened in the longitudinal direction <NUM>. The embodiment of <FIG> is therefore similar to the embodiment of <FIG>.

Fig. <NUM> shows the traces <NUM> which are the electric conducting lines within the FPCB and shows that the scaffold structure effectively creates a scaffold of flexible flat cables being the straight elements <NUM> which may and which may not carry traces <NUM> depending on the use of the transducer patches <NUM> and the necessary connectivity. It is a preferred embodiment to provide different traces <NUM> and connections for different transducers in a distance one from another so that the traces are distributed over the width of the straight scaffolds <NUM>. If there are two groups of traces <NUM> on a scaffold <NUM>, they are positioned at the opposite edges of the scaffold. If there would be a third group, it would be positioned in the middle to maintain the greatest possible distance. The traces <NUM> are running through the transducer patches <NUM> (not shown in Fig. <NUM>) and connect the transducers provided there.

<FIG> shows a perspective view of a catheter <NUM> with a FPCB <NUM> according to an exemplary embodiment and <FIG> shows the catheter tube <NUM> of <FIG> with the FPCB <NUM> separated from the tube <NUM>. The catheter <NUM> comprises at least the catheter tube <NUM> based on a polymer, preferably a thermoplastic polymer onto which is affixed the FPCB <NUM>. The FPCB <NUM> can be provided initially as a separate flat sheet as shown in Fig. <NUM> and comprises a scaffold structure <NUM> and a plurality of transducer patches <NUM> that are integrated into the scaffold structure. The scaffold structure <NUM> comprises straight scaffolds <NUM> forming a periodic structure of hollow hexagons with an interior hollow space <NUM>. Within the embodiment of <FIG> the straight scaffold structure <NUM> in the longitudinal direction <NUM> of the catheter <NUM> are far shorter than the connecting inclined straight scaffolds <NUM> so that the internal hollow space <NUM> are lengthened in the transverse direction <NUM>.

<FIG> shows a perspective view of a catheter <NUM> with a FPCB <NUM> according to another embodiment of the invention and <FIG> shows the catheter tube <NUM> of <FIG> with the FPCB <NUM> separated from the tube <NUM>. The catheter <NUM> comprises at least the catheter tube <NUM> based on a polymer, preferably a thermoplastic polymer onto which is affixed the FPCB <NUM>. The FPCB <NUM> can be provided initially as a separate flat sheet as shown in <FIG> and comprises a scaffold structure <NUM> and a plurality of transducer patches <NUM>. The scaffold structure <NUM> comprises straight scaffolds <NUM> forming a periodic structure of hollow hexagons with an interior hollow space <NUM>.

Transducer patches <NUM> are attached or integrated intermittently on every straight scaffold <NUM> in the longitudinal direction of the hexagons, i.e. for every hexagon the two opposite scaffolds in longitudinal direction <NUM> comprise such an oval transducer patch <NUM>. The ovoid diameter of the transducer patches <NUM> is larger than the width of the straight scaffolds <NUM> and therefore slightly project into the adjacent FPCB free space <NUM>.

Within the embodiment of <FIG> the straight scaffolds <NUM> in the longitudinal direction <NUM> of the catheter <NUM> are longer than the connecting inclined straight scaffolds <NUM> so that the hollow spaced <NUM> are lengthened in the longitudinal direction <NUM>.

The scaffold structure <NUM> is cut out of a sheet having a predetermined length in the longitudinal direction <NUM> so that the transducers on the transducer patches <NUM> have the necessary transducer distribution. The width of the sheet, i.e. in the transverse sheet direction <NUM> , is predetermined so that in can be attached around the catheter tube <NUM> without portions of the left side of the sheet overlaps portion of the right side of the sheet. In other words, as can be seen in <FIG>, a continuous FPCB free surface portion <NUM> remains in the longitudinal direction <NUM>. However, it is not necessary that the continuous FPCB free surface portion <NUM> comprises a straight line along the catheter <NUM>. Here, patches <NUM> and <NUM> at the left and right sheet border, respectively "block" such a straight line. But it always exist - over the length of the structure - at least one, possibly meandering way of said FPCB free surface portion <NUM>. In other words, every longitudinal line <NUM> at the circumference comprises portions of the FPCB free spaces <NUM> and/or free spaces from the FPCB free spaces <NUM> as well as portions of the straight scaffolds <NUM> and at some places transducer patches <NUM> as well as said FPCB free surface portion <NUM>.

<FIG> shows a sequence of two-hexagon-wide FPCB free spaces <NUM>. The width can also be only one or more than two hexagonal FPCB free spaces <NUM> depending on the internal angle alpha <NUM> and internal angle beta <NUM> shown in <FIG> and the size of the catheter tube <NUM>.

<FIG> shows an electronic component <NUM> that is placed on the FPCB <NUM> and is thermobonded inside the catheter tube <NUM>. The catheter opening <NUM> provides space for the electronic component <NUM> and electronic traces <NUM> are connecting the electronic component <NUM> with the FPCB connector on the distal end of the FPCB <NUM>.

<FIG> shows an electronic component <NUM> that is placed on the FPCB <NUM> and is thermobonded outside of the catheter tube <NUM>. The catheter opening <NUM> provides space for the electronic component <NUM> and electronic traces <NUM> are connecting the electronic component <NUM> with the FPCB connector segment <NUM> on the proximal end of the FPCB <NUM>.

<FIG> shows the example of a complete catheter <NUM> similar to the one shown in <FIG>. Starting from the distal end there is a FPCB transducer segment <NUM> followed by a segment where electronic components <NUM> are placed. Extending from the FPCB transducer segment <NUM> there is a FPCB tail segment <NUM> that transitions in to the FPCB connector segment <NUM>. The FPCB tail segment <NUM> can be folded in a <NUM> angle to extend the length in the longitudinal direction of the FPCB <NUM>. This folding happens at the FPCB folding segment <NUM>.

<FIG> shows a schematic drawing of a FPCB sheet <NUM> for an embodiment similar to <FIG>. This FPCB sheet is used and shown in a perspective view of <FIG> wound around a catheter segment <NUM> creating a catheter <NUM>; and finally <FIG> shows a perspective view of the catheter <NUM> of <FIG> with the surrounding FPCB sheet <NUM> bent in an exaggerated angle shown by arrow <NUM>. In this context "exaggerated" means that introducing the catheter <NUM> in a vessel of a patient will not require such a bending angle, but it shows that even such bending angles are possible without damaging the FPCB print <NUM> and put transducers on the transducer patches <NUM> out of functioning.

<FIG> shows a FPCB sheet <NUM> with a sequence of hexagonal and diamond or ellipsoid shaped FPCB free spaces <NUM>, wherein transducer patches <NUM> are provided at corners of the hexagonal shaped FPCB free spaces <NUM> as well as near the transition segments between diamond or ellipsoid and hexagonal shapes extending into a hexagonal shaped FPCB free space <NUM>. It is possible, if two such transducer patches <NUM> are provided extending into the same hexagonal shaped FPCB free space <NUM> that they are connected with a FPCB web <NUM>. The embodiment of <FIG> shows in schematical way two not interconnected streams <NUM> of adjacent traces <NUM> extending on opposite straight scaffolds <NUM> of hexagonal and diamond shaped FPCB free spaces <NUM> extending in the longitudinal direction of the FPCB sheet <NUM>. In some parts only the most exterior and interior traces <NUM> are represented for the streams <NUM> of traces. <FIG> shows four or fives traces <NUM>. This number, however, depends on the applccation case and can go up beyond ten traces <NUM>.

Furthermore, only in the left part of <FIG> delamination preventing holes <NUM> are shown. These are a sequence of small holes in essentially constant distance one from another adjacent to any border of the FPCB sheet <NUM>. They are at least provided around the inner FPCB free spaces <NUM> but are preferably also provided along the outer edges of the FPCB sheet <NUM> (not shown in <FIG>). When the FPCB sheet <NUM> is laminated on a catheter tube, the material of the catheter tube is flowing into the delamination preventing holes <NUM> and fix additionally the edges of the FPCB sheet <NUM> with the underlying catheter tube material.

<FIG> shows the FPCB sheet <NUM> of <FIG> applied on a catheter tube <NUM> creating the catheter <NUM>, wherein the FPCB transducer segment starts in the direction of the arrow with the numeral <NUM>'. The FPCB free surface portion <NUM> is essentially behind the drawing plan and only the adjoining surfaces adjacent to the diamond shaped FPCB part are visible in <FIG>. Traces <NUM> are not shown in <FIG> but some delamination preventing holes <NUM> are there for illustrative purposes.

Said catheter <NUM> of the embodiment of <FIG> is shown bent in <FIG> in an about <NUM> degree angle. Every even slight bending angle creates in a side view or cross section view on the bending angle a concave bending depression <NUM> on the inside of the angle (<<NUM> degrees) which is of course far more pronounced at the sharp about <NUM> degree concave bending <NUM>, whereas on the opposite side of the bending a convex embossing <NUM> can be seen. Bending always happen either at the FPCB free surface portions <NUM> or at the internal FPCB free space <NUM>. Both FPCB free surface portions <NUM> or <NUM> allows bending while the remaining scaffold structure <NUM> and <NUM> remain essentially as in the non-bent conidition and allow the transition of the stream <NUM> of traces <NUM> on them which is here schematically shown at the corner.

Claim 1:
Catheter (<NUM>,... <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising a catheter tube (<NUM>), a Flexible Printed Circuit Board FPCB transducer segment (<NUM>) and a FPCB free surface portion (<NUM>), wherein the FPCB transducer segment (<NUM>) comprises a scaffold structure (<NUM>) with a plurality of FPCB surrounded free spaces (<NUM>) and predetermined placed transducer patches (<NUM>), wherein the FPCB transducer segment (<NUM>) covers essentially the catheter circumference for the length of the FPCB transducer segment (<NUM>) with the exception of said FPCB free surface portion (<NUM>), characterized in that a leftmost portion of a left side of the FPCB transducer segment (<NUM>) is positioned in a recess of a right side of the scaffold structure (<NUM>).