Medical device having a sensor stack and a method for manufacturing such a medical device - Patents.com

Abstract

The present invention relates to a medical device having a distal end provided for insertion into a patient's body and a sensor unit arranged at said distal end and configured for capturing a measured physical variable and converting said physical variable into an electrical measurement signal, said sensor unit being in the form of a sensor stack constructed in layers and having a first part and a second part, said first part and said second part each comprising a number of functional layers arranged one above the other, said functional layers being applied to one another in layers, in particular printed, so as to at least partially cover each other. The first part comprises at least the following functional layers: a first insulating layer at least partially covering and electrically insulating the distal end of the medical device, a first conductive electrode layer at least partially applied to the first insulating layer, in particular printed, a piezoelectric layer with piezoelectric activity at least partially applied to the first electrode layer, in particular printed, a second conductive electrode layer at least partially applied to the piezo layer, in particular printed, a second electrically insulating insulating layer at least partially applied to the second electrode layer, in particular printed, and a shielding layer at least partially applied to the second insulating layer, in particular printed. The second part comprises at least the following functional layers: an insulating layer at least partially covering and electrically insulating the distal end of the medical device, a first conductive conductor track at least partially applied to the insulating layer, in particular printed, and a second conductive conductor track at least partially applied to the insulating layer, in particular printed. The invention also relates to a sensor unit and to a method for manufacturing a medical device.

Description

[Technical field]

[0001] The present invention relates to medical devices having sensor stacks and methods of manufacturing such medical devices. [Background technology]

[0002] A medical instrument in the form of a catheter with a sensor unit for capturing and converting measured physical variables is known, for example, from WO 2017 / 013224 A1. The sensor unit is embodied in the form of an ultrasonic transducer and serves to position the tip of the catheter in the patient's body on the basis of ultrasound, which is also called tracking. The sensor unit is embodied from a number of film-like functional layers laminated on top of one another, and is therefore also called a sensor stack. In this context, the sensor stack is produced by adhesively bonding the individual functional layers to one another layer by layer, which is also called laminating. For application purposes, the laminated sensor stack is provided with an adhesive layer, wrapped around the catheter tip and glued to the catheter tip by the adhesive layer.

[0003] Furthermore, DE 10 2018 220 606 A1 discloses a medical instrument, which can be designed, for example, as a cannula, which at its distal end comprises a sensor unit configured to capture a measured physical variable and to convert the physical variable into an electrical measurement signal.

[0004] A common drawback of modern medical instruments with sensor units is the poor capture of the measured variables and, as a result, low signal strength, which makes it more difficult, for example, to navigate the medical instrument to the target area inside the patient's body. Moreover, as a rule, the production of correspondingly designed medical instruments is very time-consuming and cost-intensive. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide a medical device and a method for producing a medical device, in particular to partially or completely avoid the disadvantages mentioned at the beginning. [Means for solving the problem]

[0006] This object is achieved by a medical device having the features of independent claim 1 and a method according to claim 16. Preferred configurations of the invention are the subject matter of the dependent claims. The wording of all claims is incorporated into the content of this description by express reference.

[0007] According to a first aspect, the present invention relates to a medical instrument having a distal end provided for insertion into a patient's body. In particular, the medical instrument may be a catheter, a cannula or any other medical instrument provided for at least partial insertion into a patient's body. The distal end may therefore in particular be a catheter tip or a cannula tip.

[0008] The medical instrument comprises a sensor unit arranged at the distal end. The sensor unit is configured to capture a measured physical variable and convert the physical variable into an electrical measurement signal, said sensor unit being in the form of a layered sensor stack. For example, the sensor stack may be configured to capture temperature, hydrostatic pressure or other measured physical variables of therapeutic and / or diagnostic interest. Preferably, the sensor stack, in particular the piezo layer of the first part, is configured to capture and convert ultrasonic pulses, thus preferably forming an ultrasonic transducer.

[0009] The sensor stack comprises a first part and a second part, the first part may also be referred to as a sensor part in the sense of the present invention, the second part may also be referred to as a contact part in the sense of the present invention, where an electrical signal occurring in the first part of the sensor stack can be tapped or conducted.

[0010] Preferably, the first portion is a distal portion of the sensor stack and the second portion is a proximal portion of the sensor stack, in other words, the sensor stack may be positioned on the medical instrument such that the first portion is distally disposed at a distal end of the medical instrument and the second portion is proximally disposed at the distal end of the medical instrument.

[0011] Furthermore, the first and second parts are preferably arranged successively, in particular directly successively. The first and second parts are particularly preferably embodied as one piece and successively. Alternatively, the first and second parts can be embodied separately from one another and can be connected to one another, in particular glued together.

[0012] In particular, the sensor stack may consist of a first portion and a second portion.

[0013] Preferably, the sensor stack is manufactured by a printing method, in particular offset printing, inkjet printing, screen printing, aerosol jet printing, spray coating or dip coating.

[0014] The first and second parts of the sensor stack each consist of a number of functional layers arranged one on top of the other, in particular arranged directly or not directly on top of the other, which are applied to one another in layers, in particular printed, so as to cover each other at least partially, in particular only partially or entirely.

[0015] The first part comprises at least the following functional layers: a first insulating layer at least partially, in particular only partially, or entirely, i.e. entirely or continuously, covering and electrically insulating the distal end of the medical device; a conductive first electrode layer applied at least partially, in particular only partially, or entirely, i.e. entirely or continuously, to the first insulating layer, in particular printed, a piezo layer having piezoelectric activity, which is applied at least partially, in particular only partially, or entirely, i.e. entirely or continuously, to the first electrode layer, in particular printed, a conductive second electrode layer, which is applied at least partially, in particular only partially, or entirely, i.e. entirely or continuously, to the piezo layer, in particular printed, a second insulating layer which is electrically insulating and which is applied at least partially, in particular only partially, or entirely, i.e. entirely or continuously, to the second electrode layer, in particular printed, a shielding layer applied at least partially, in particular only partially, or entirely, ie entirely or continuously, to the second insulating layer, in particular a printed shielding layer.

[0016] In this case, the first insulating layer may or may not directly cover the distal end of the medical device.

[0017] Furthermore, the first electrode layer can be applied directly or not directly to the first insulating layer, in particular it can be printed, and / or the piezo layer can be applied directly or not directly to the first electrode layer, in particular it can be printed, and / or the second electrode layer can be applied directly or not directly to the piezo layer, in particular it can be printed, and / or the second insulating layer can be applied directly or not directly to the second electrode layer, in particular it can be printed, and / or the shielding layer can be applied directly or not directly to the second insulating layer, in particular it can be printed.

[0018] The second part comprises at least the following functional layers: an insulating layer which at least partially, in particular only partially or entirely, i.e. entirely or continuously covers and electrically insulates the distal end of the medical device; an electrically conductive first conductor track, which is applied at least partially, in particular only partially, or entirely, i.e. entirely or continuously, to the insulating layer, in particular printed, and a conductive second conductor track which is applied at least partially, in particular only partially, or entirely, ie entirely or continuously, to the insulating layer, in particular a printed second conductor track.

[0019] In this case, the insulating layer may directly or indirectly cover the distal end of the medical device.

[0020] Furthermore, the first conductor track can be applied, in particular printed, directly or not directly onto the insulating layer and / or the second conductor track can be applied, in particular printed, directly or not directly onto the electrically insulating insulating layer. Preferably, the first conductor track and the second conductor track are applied, in particular printed, onto different parts of the insulating layer.

[0021] In the sense of the present invention, the term "distal" should be understood to mean located further away from the center of the body of the person, in particular the physician, who is using the medical instrument as intended.

[0022] In the context of the present invention, the term "proximal" should be understood to mean a location closer to the center of the body of the person, particularly the physician, who is using the medical instrument as intended.

[0023] In the sense of the present invention, the term "sensor stack" is to be understood to mean a sensor unit constructed layer by layer of a number of functional layers and embodied in particular as a film or foil.

[0024] In the sense of the present invention, the term "piezolayer (having) piezoelectric activity" is to be understood to mean a layer in which a voltage is generated under the action of a mechanical pressure (piezoelectric effect).

[0025] The shielding layer preferably serves to shield the remaining functional layers of the sensor stack, in particular the first part, preferably the piezo layer, from electric and / or magnetic fields which may lead to errors when capturing the measured variable and / or when transforming the measured variable and / or when conducting the measured variable. The shielding layer enables as error-free functioning of the sensor stack as possible.

[0026] The first and second conductor tracks of the second part serve to conduct the electrical measurement signal from the first part, in particular from the piezo layer of the first part, in the direction of the proximal end of the medical device, from which the first and second conductor tracks are electrically communicable or contactable with an evaluation unit for the purpose of evaluating the electrical measurement signal from the first part, in particular from the piezo layer of the first part.

[0027] More preferably, the first insulating layer of the first part and the insulating layer of the second part have the same embodiment. In particular, the first insulating layer of the first part and the insulating layer of the second part are embodied continuously and integrally. Alternatively, the first insulating layer of the first part and the insulating layer of the second part can be embodied separately from each other and can be connected to each other, in particular glued together.

[0028] The second part of the sensor stack is preferably free of any further insulating layer, in particular a further insulating layer applied, in particular a printed, to the first conductor track and / or the second conductor track, and is free of any electrically shielding shielding layer. In other words, the first conductor track and the second conductor track of the second part are each preferably exposed conductor tracks. Advantageously, this allows for example to bring into contact with an amplification unit configured to amplify the measurement signal from the sensor stack and / or with an evaluation unit arranged in particular downstream of the amplification unit and configured to evaluate the electrical measurement signal.

[0029] More preferably, the first electrode layer of the first part and the first conductor track of the second part are embodied in one continuous piece. The one-piece embodiment of the first electrode layer and the first conductor track is in principle advantageous in that it allows for a quicker tapping of the electrical signal occurring in the first part of the sensor stack.

[0030] Alternatively, the first electrode layer can be applied, in particular printed, separately from the first conductor track and be in electrical contact with the latter.

[0031] Furthermore, the second electrode layer of the first part and the second conductor track of the second part are preferably embodied in one piece and in succession. The one-piece embodiment of the second electrode layer and the second conductor track is (also) advantageous in principle in that the electrical signal occurring in the first part of the sensor stack can be tapped more quickly.

[0032] Alternatively, the second electrode layer can be applied, in particular printed, separately from the second conductor track and be in electrical contact with the latter.

[0033] The mutually independent functional layers of the first and / or second part can have a layer thickness of 1 μm to 30 μm, in particular 0.5 μm to 20 μm, preferably 1 μm to 10 μm.

[0034] In an embodiment of the invention, the first and second electrode layers are in particular embodied at least partially, for example only partially or entirely, differently.

[0035] Alternatively, the first electrode layer and the second electrode layer may in particular be at least partially embodied in the same way, for example only partially or entirely.

[0036] Furthermore, the first electrode layer, in particular only the first electrode layer, can be embodied in the form of a plurality of layer parts embodied in one piece or separate from one another, and the second electrode layer, in particular only the second electrode layer, can be embodied in the form of a plurality of layer parts embodied in one piece or separate from one another.

[0037] Furthermore, the first electrode layer can be embodied in one continuous piece and the second electrode layer can be embodied in the form of multiple layer portions embodied separately from each other. Alternatively, the first electrode layer can be embodied in the form of multiple layer portions embodied separately from each other and the second electrode layer can be embodied in one continuous piece. Alternatively, the first electrode layer and the second electrode layer can each be embodied in one continuous piece or in the form of multiple layer portions embodied separately from each other.

[0038] The first electrode layer may have a thickness of 0.1 μm to 30 μm, particularly 0.5 μm to 10 μm, and preferably 1 μm to 2 μm. The second electrode layer may have a thickness of 0.1 μm to 30 μm, particularly 0.5 μm to 10 μm, and preferably 1 μm to 2 μm.

[0039] In principle, any electrically conductive material is suitable for the first and second electrode layers.

[0040] Preferably, the first and second electrode layers each comprise or preferably each consist of a printable conductive material. In particular, at least one of the two electrode layers comprises or consists of a material that can be structured very finely, in particular in the micrometer range, for example with line widths of 100 μm.

[0041] More preferably, the first and second electrode layers, independently of one another, comprise or consist of a conductive material, the conductive material being selected from the group consisting of a conductive polymer, a conductive metal, and a combination thereof. For suitable conductive polymers and conductive metals, see the description below. When the first and / or second electrode layer are embodied in the form of a plurality of layer portions embodied separately from one another, each layer portion of the first and / or second electrode layer may, independently of one another, comprise or consist of a conductive material selected from the aforementioned group.

[0042] In a further configuration of the invention, the first and second electrode layers independently of one another comprise or consist of a conductive material selected from the group consisting of polypyrrole, doped polyethylene, polyaniline, polythiophene, preferably poly(3,4-ethylenedioxythiophene), gold, platinum, indium, tin, copper, silver, preferably nanoscale silver and / or microscale silver, and combinations of at least two of the aforementioned conductive materials.

[0043] In a further configuration of the invention, the first electrode layer comprises a conductive metal, in particular a conductive nanoscale metal and / or a conductive microscale metal, or carbon, and the second electrode layer comprises a conductive polymer, or vice versa. Alternatively, the first and second electrode layers can consist of the respective aforementioned conductive materials. In particular, the conductive metal can be selected from the group consisting of silver, preferably nanoscale silver and / or microscale silver, gold, platinum, indium, tin, copper, and a combination of at least two of the aforementioned conductive metals. In particular, the conductive polymer can be selected from the group consisting of polythiophenes, preferably poly(3,4-ethylenedioxythiophene), polypyrrole, doped polyethylene, polyaniline, and a combination of at least two of the aforementioned conductive polymers.

[0044] In the sense of the present invention, the term "nanoscale metals" should be understood to mean metals with particle diameters, in particular with an average particle diameter, of 1 nm to 1000 nm, in particular 10 nm to 500 nm, particularly preferably 50 nm to 250 nm.

[0045] In the sense of the present invention, the term "microscale metal" should be understood to mean metals with particle diameters, in particular with an average particle diameter, of 1 μm to 100 μm, in particular 3 μm to 50 μm, in particular 5 μm to 30 μm.

[0046] In particular, the first electrode layer and / or the second electrode layer may be fabricated from a paste containing a nanoscale metal and / or a microscale metal.

[0047] In a further configuration of the invention, the conductive metal, in particular the conductive nanoscale metal and / or the conductive microscale metal, is silver and the conductive polymer is poly(3,4-ethylenedioxythiophene).

[0048] That is, in a further configuration of the invention, the first electrode layer comprises silver, in particular nanoscale silver and / or microscale silver, and the second electrode layer comprises poly(3,4-ethylenedioxythiophene), or vice versa. In particular, the electrode layers may consist of each of the aforementioned materials. The use of silver, in particular nanoscale silver, is advantageous in that it can be applied, in particular printed, in a particularly fine structure, for example by screen printing. For example, the silver can have a diameter, in particular an average diameter, of 0.5 μm to 30 μm, in particular 1 μm to 20 μm, in particular 5 μm to 15 μm. The use of poly(3,4-ethylenedioxythiophene) makes it possible, in particular, to advantageously avoid ruptures during high-voltage polarization in the piezo layer located between the first and second electrode layers.

[0049] Furthermore, electrode layers with or made of poly(3,4-ethylenedioxythiophene) advantageously have a self-healing effect in the event of an electrical rupture, due to the resulting heat generation, by which the layer reseals itself at the affected location. Furthermore, the smooth surface of poly(3,4-ethylenedioxythiophene) also has a positive effect in terms of preventing electrical failures. Overall, this can result in the elimination of the risk of permanent short circuits between the electrode layers.

[0050] The piezo layer can be embodied either in one continuous piece or in the form of a number of layer portions embodied separately from one another.

[0051] Furthermore, the piezoelectric layer may have a layer thickness of 0.5 μm to 30 μm, in particular 1 μm to 20 μm, and preferably 1 μm to 10 μm.

[0052] Furthermore, in principle all piezoresistive materials come into consideration for the piezo layer, in particular piezoresistive polymers, piezoresistive ceramics and combinations thereof. The piezoresistive polymers can be homopolymers or copolymers, in particular bipolymers and / or terpolymers, in particular as described below.

[0053] In a further configuration of the invention, the piezo layer comprises or consists of a material selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), lead zirconate titanate (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AlN), and combinations of at least two of the aforementioned materials. If the piezo layer is embodied in the form of a plurality of layer parts embodied separately from one another, the layer parts may comprise or consist, independently of one another, of a material selected from the aforementioned group.

[0054] Preferably, the piezo layer comprises or consists of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)).

[0055] Furthermore, the piezo layer can be applied, in particular printed, continuously in the circumferential direction of the distal end of the medical device. In contrast, the remaining functional layer can be applied, in particular printed, only partially on the distal end of the medical device. Advantageously, this allows uniform capture of the measurement variable in the circumferential direction. As a result, the capture of the measurement variable does not depend on the angular alignment of the distal end of the medical device, for example, with respect to the ultrasound source. As a result, a further improved capture of the measurement variable can be obtained, in particular an improved localization, for example an ultrasound-based localization, of the medical device can be obtained.

[0056] Furthermore, the first conductor track, in particular only the first conductor track, can be embodied in the form of a plurality of layer parts embodied separately from one another, and the second conductor track, in particular only the second conductor track, can be embodied in the form of a plurality of layer parts embodied separately from one another, and the second conductor track, in particular only the second conductor track, can be embodied in the form of a plurality of layer parts embodied separately from one another.

[0057] Furthermore, the first conductor track can be embodied in one continuous piece and the second conductor track can be embodied in the form of multiple layer portions embodied separately from one another. Alternatively, the first conductor track can be embodied in the form of multiple layer portions embodied separately from one another and the second conductor track can be embodied in one continuous piece. Alternatively, the first conductor track and the second conductor track can each be embodied in one continuous piece or each can be embodied in the form of multiple layer portions embodied separately from one another.

[0058] Furthermore, the first conductor track may have a layer thickness of 0.1 μm to 30 μm, in particular 0.5 μm to 10 μm, preferably 1 μm to 2 μm, and the second conductor track may have a layer thickness of 0.1 μm to 30 μm, in particular 0.5 μm to 10 μm, preferably 1 μm to 2 μm.

[0059] Furthermore, the first conductor track and the second conductor track may in particular be embodied at least partially differently, for example only partially or entirely.

[0060] Alternatively, the first conductor track and the second conductor track may in particular be at least partially embodied in the same way, for example only partially or entirely.

[0061] In principle, any conductive material is suitable for the first and second conductor tracks, but conductive materials that have as low an electrical resistivity as possible, a certain degree of flexibility and, in particular, good adhesion to the insulating layer of the second part are preferred.

[0062] In a further configuration of the invention, the first and second conductor tracks each comprise a conductive metal, in particular a conductive nanoscale metal and / or a conductive microscale metal, and in particular the first and second conductor tracks each may consist of such a metal.

[0063] Preferably, the first and second conductor tracks, independently of one another, comprise a conductive metal, in particular silver, preferably nanoscale and / or microscale silver, gold, platinum, indium, tin, copper or a combination of at least two of the aforementioned metals. If the first and / or the second conductor track are embodied in the form of a plurality of layer parts embodied separately from one another, each independent layer part of the first and / or second conductor track may comprise or consist of a material selected from the aforementioned group.

[0064] Preferably, the first and / or second conductor track comprises silver, in particular nanoscale silver. In particular, the first and / or second conductor track may consist of silver, in particular nanoscale silver. Preferably, the silver has a diameter, in particular an average diameter, of 1 nm to 1000 nm, in particular 10 nm to 500 nm, more preferably 50 nm to 250 nm. Conductor tracks embodied correspondingly are advantageously less brittle and more flexible or pliable. A further advantage lies in the fact that in the case of silver, the first and second conductor tracks adhere better to functional layers, in particular insulating layers, which are located below the conductor tracks with respect to the layer thickness direction D of the sensor stack.

[0065] In a further configuration of the invention, the sensor stack, in particular the first part and / or the second part of the sensor stack, further comprises an adhesive layer. The adhesive layer preferably serves to bond the sensor stack integrally to the medical device, in particular by adhesive bonding. Preferably, the adhesive layer is arranged, in particular directly or not, between the first insulating layer of the first part and the surface of the medical device and / or, in particular directly or not, between the insulating layer of the second part and the surface of the medical device.

[0066] In particular, the first portion of the sensor stack may comprise an adhesive layer, in particular disposed directly or not, between the first insulating layer and the surface of the medical device.

[0067] Preferably, the adhesion layer is arranged directly or not directly underneath the first insulating layer of the first part, in particular with respect to the layer thickness direction D of the sensor stack.

[0068] More preferably, the adhesive layer of the first part is applied, in particular printed, directly onto the medical device.

[0069] Furthermore, in particular the second part of the sensor stack may (also) comprise an adhesive layer, in particular arranged directly or not between the insulating layer and the surface of the medical device.

[0070] Preferably, the adhesive layer is arranged, in particular directly or not, underneath the insulating layer of the second part with respect to the layer thickness direction D of the sensor stack.

[0071] More preferably, the adhesive layer of the second part is (also) applied directly to the medical device, in particular printed.

[0072] Furthermore, the adhesive layer described in the previous paragraph may be embodied in one continuous piece or in the form of multiple layer portions embodied separately from one another.

[0073] Furthermore, the adhesive layer of the first part, in particular the adhesive layer of only the first part, can be embodied in the form of a plurality of layer parts embodied separately from one another.Furthermore, the adhesive layer, in particular the adhesive layer of only the second part, can be embodied in the form of a plurality of layer parts embodied separately from one another.

[0074] Furthermore, the adhesive layer of the first part can be embodied in one continuous piece, and the adhesive layer of the second part can be embodied in the form of multiple layer portions embodied separately from each other. Alternatively, the adhesive layer of the first part can be embodied in the form of multiple layer portions embodied separately from each other, and the adhesive layer of the second part can be embodied in one continuous piece. Alternatively, the adhesive layer of the first part and the adhesive layer of the second part can each be embodied in one continuous piece, or each can be embodied in the form of multiple layer portions embodied separately from each other.

[0075] Furthermore, the adhesive layer of the first portion and the adhesive layer of the second portion may be embodied as one continuous piece.

[0076] Alternatively, the adhesive layer of the first part may be applied, in particular printed, separately from the adhesive layer of the second part and may be integrally adhered to the adhesive layer of the second part.

[0077] Furthermore, the adhesive layer, in particular of the first part and / or the second part, can have a layer thickness of 1 μm to 50 μm, in particular 2 μm to 30 μm, particularly preferably 5 μm to 15 μm.

[0078] In a further configuration of the invention, the adhesive layer, in particular the adhesive layer of the first and / or second part of the sensor stack, comprises an electrically conductive metal, in particular an electrically conductive and microscale metal. Preferably, the metal is selected from the group consisting of silver, gold, platinum, indium, tin, copper and a combination of at least two of the aforementioned metals. If the adhesive layer is embodied in the form of a plurality of layer parts embodied separately from one another, the layer parts independent of one another may comprise a metal or consist of a metal selected from the aforementioned group.

[0079] In a further configuration of the invention, the metal of the adhesive layer, in particular of the first and / or second part, is silver, in particular microscale silver. Preferably, the silver has a diameter, in particular an average diameter, of 0.5 μm to 30 μm, in particular 1 μm to 20 μm, more preferably 5 μm to 15 μm. Correspondingly configured adhesive layers are advantageously distinguished by reduced brittleness and increased softness or flexibility.

[0080] In a further configuration of the invention, the sensor stack, in particular the first and / or second part of the sensor stack, preferably the second part, further comprises a corrosion protection layer, which advantageously ensures protection of the conductor tracks against corrosion during signal transmission, in particular in the contact areas with other materials, and thus ensures a constant electrical transmission resistance and a low contact resistance in the long term.

[0081] Preferably, the anticorrosion layer is applied, in particular directly or indirectly, in particular printed, above the first and second conductor tracks with respect to the layer thickness direction D of the sensor stack.

[0082] The sacrificial layer can be embodied as one continuous piece, or it can be embodied in the form of a number of layer portions embodied separately from one another.

[0083] Furthermore, the anticorrosion layer may have a layer thickness of 0.5 μm to 30 μm, particularly 1 μm to 20 μm, and preferably 2 μm to 10 μm.

[0084] In principle, all non-corroding, electrically conductive materials are suitable for the corrosion protection layer.

[0085] In a further embodiment of the invention, the anticorrosion layer comprises or consists of a material selected from the group consisting of carbon, precious metals, in particular gold and / or platinum, and a combination of at least two of the aforementioned materials. If the anticorrosion layer is embodied in the form of a plurality of layer parts embodied separately from one another, the layer parts may comprise or consist, independently of one another, of a material selected from the aforementioned group.

[0086] Preferably, the anticorrosion layer comprises conductive carbon. In particular, the anticorrosion layer may consist of conductive carbon. Carbon has been found to be particularly advantageous in terms of avoiding corrosion and thus ensuring a constant electrical transmission resistance over time. Furthermore, carbon is softer than, for example, the aforementioned noble metals and therefore can adhere better to the contacts.

[0087] In a further configuration of the invention, the sensor stack, in particular the first and / or second part of the sensor stack, in particular only the first part, comprises a biocompatible capping layer. Preferably, the capping layer is arranged on the outside with respect to the layer thickness direction D of the sensor stack. Preferably, the capping layer is applied, in particular printed, in particular directly or not, on the shielding layer with respect to the layer thickness direction D of the sensor stack. Thus, the biocompatible capping layer can preferably form a (terminal) outer layer of the sensor stack, in particular a (terminal) outer layer of the first part of the sensor stack.

[0088] Direct contact of the remaining functional layers with the patient's body is advantageously prevented by the biocompatible capping layer, thereby limiting possible undesirable chemical and / or biological interactions and thus potentially adverse effects on the patient's health.

[0089] The biocompatible capping layer can be embodied as one continuous piece, or it can be embodied in the form of multiple layer portions that are embodied separately from one another.

[0090] Furthermore, the biocompatible capping layer may have a layer thickness of 1 μm to 30 μm, in particular 2 μm to 20 μm, particularly preferably 5 μm to 15 μm.

[0091] In principle, all biocompatible materials, especially electrically insulating materials, are suitable for the biocompatible capping layer.Preferably, the biocompatible capping layer comprises or consists of a material selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polytetrafluoroethylene (PTFE), Teflon (PTFE) polyester, parylene, polyester, and a combination of at least two of the aforementioned materials.When the capping layer is embodied in the form of a plurality of layer parts embodied separately from each other, the layer parts may comprise or consist of a material selected from the aforementioned group, independently of each other.

[0092] The first insulating layer of the first portion of the sensor stack can be embodied in one continuous piece or in the form of a number of layer portions embodied separately from one another.

[0093] Furthermore, the first insulating layer of the first part and / or the insulating layer of the second part of the sensor stack can have a layer thickness of 1 μm to 50 μm, in particular 2 μm to 30 μm, particularly preferably 4 μm to 20 μm.

[0094] Furthermore, the second insulating layer of the first portion of the sensor stack may be embodied in one continuous piece or in the form of a plurality of layer portions embodied separately from one another.

[0095] Furthermore, the second insulating layer of the first portion may have a layer thickness of 1 μm to 50 μm, in particular 5 μm to 40 μm, and particularly preferably 10 μm to 30 μm.

[0096] Furthermore, the insulating layer of the second portion of the sensor stack can be embodied either in one continuous piece or in the form of multiple layer portions embodied separately from one another.

[0097] Furthermore, the insulating layer of the second portion may have a layer thickness of 1 μm to 50 μm, in particular 5 μm to 40 μm, particularly preferably 10 μm to 30 μm.

[0098] Furthermore, the first and second insulating layers of the first part and the insulating layer of the second part can in particular be embodied at least partially differently, for example only partially or entirely.

[0099] Alternatively, the first and second insulating layers of the first part and the insulating layer of the second part can in particular be embodied at least partially, for example only partially or entirely, identically.

[0100] In principle, all non-conductive materials are suitable for the first and second insulating layers of the first part and for the insulating layer of the second part, in particular the non-conductive materials in this case can be UV-curable and / or heat-curable materials.

[0101] These materials have the advantage that they cure quickly, thereby reducing the time required to manufacture sensor stacks, especially medical devices.

[0102] In a further configuration of the invention, the first and second insulating layers of the first part and the insulating layer of the second part comprise, independently of one another, an electrically insulating material selected from the group consisting of UV-curable materials, in particular polyester resins, thermosetting materials, in particular those mentioned above, i.e. resins or polyesters, plastics, in particular polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC) or polyetherimide (PEI), and combinations of at least two of the aforementioned electrically insulating materials. If the first insulating layer and / or the second insulating layer of the first part and / or the insulating layer of the second part are embodied in the form of a plurality of layer parts embodied separately from one another, the respective layer parts of the first insulating layer and / or the second insulating layer of the first part and / or the insulating layer of the second part may comprise or consist, independently of one another, of a material selected from the aforementioned group.

[0103] Preferably, the first insulating layer of the first part and the insulating layer of the second part at least partially, in particular only partially or entirely, comprise or consist of the same material. Preferably, the material is polyethylene naphthalate (PEN). As a result, high heat resistance and particularly good adhesion are advantageously obtained during the printing process. Regarding possible alternative materials, please refer to the explanations given above for the insulating layer.

[0104] Furthermore, the second insulating layer of the first part and / or the insulating layer of the second part preferably comprises or consists of a UV-curable material, preferably a polyester resin.

[0105] The use of UV-curable materials, in particular polyester resins, for the embodiment of the second insulating layer of the first part and / or the insulating layer of the second part has been found to be particularly advantageous with regard to reducing capacitive effects and protecting the functional layers, in particular the electrode layers and the conductor tracks, from damage. This advantageously allows the sensor unit to be bent without losing the integrity of the functional layers, in particular the electrode layers and / or the conductor tracks, in particular during application to the curved surface of the medical device. A further advantage is the improved adhesion effect to directly adjacent functional layers, in particular the shielding layer of the first part. Moreover, UV-curable materials, in particular polyester resins, do not cause any interaction with the underlying functional layers directly after application, in particular printing, and therefore do not adversely affect the properties of the sensor.

[0106] Furthermore, the second insulating layer of the first part serves as an electrical insulating layer between the shielding layer and the electrode layer of the first part, in particular the second electrode layer. Particularly advantageously, the distance between the shielding layer and the electrode layer, the possible capacitance and the size of the sensor unit can be deliberately influenced by the thickness of the second insulating layer of the first part.

[0107] For example, the second insulating layer of the first portion may have a layer thickness of 1 μm to 50 μm, particularly 5 μm to 40 μm, and preferably 10 μm to 30 μm.

[0108] Furthermore, the second insulating layer can be embodied as an integral continuous layer or in the form of several partial layers, for example two or three partial layers embodied separately from one another.

[0109] The shielding layer can be embodied as a single continuous layer or as a plurality of layer portions embodied separately from one another.

[0110] In principle, all conductive materials are suitable for the electrically insulating shielding layer, but conductive materials with as low an electrical resistivity as possible and good adhesion are preferred.

[0111] In a further configuration of the invention, the shielding layer comprises or consists of a material, in particular a conductive material, selected from the group consisting of carbon, a conductive polymer, in particular polypyrrole, doped polyethylene, polyaniline or polythiophene, preferably poly(3,4-ethylenedioxythiophene), a conductive metal, in particular gold, platinum, indium, tin, copper or silver, preferably nanoscale silver, and a combination of at least two of the aforementioned materials, in particular a combination of at least two of conductive materials. If the shielding layer is embodied in the form of a plurality of layer parts embodied separately from one another, the layer parts may comprise or consist of a material selected from the aforementioned group.

[0112] Preferably, the shielding layer comprises a conductive metal, especially silver.

[0113] Furthermore, at least one second applied, in particular printed, sensor stack may be provided at the distal end of the medical instrument, the second sensor stack being arranged at a distance from said sensor stack in the longitudinal direction of the distal end, preferably having an identical structure to said sensor stack.

[0114] As a result of the second sensor stacks being spaced apart in the longitudinal direction, it is possible to determine not only the position of the distal end, but also its angular alignment, in particular in relation to the existing ultrasound field. As a result, advantageously, it is possible not only to determine the position of the distal end, but also to determine the alignment, which in particular allows conclusions to be drawn about the feed direction of the distal end of the medical instrument in the patient's body. The second sensor stack can be formed separately, in particular printed, and then applied, in particular printed, to the distal end of the medical instrument. Alternatively, the second sensor stack can be directly, in particular printed, on the distal end. With regard to the functional layers of the second sensor stack (including their arrangement), reference is made to the relevant disclosure of the (first) sensor stack, which, in order to avoid repetition, applies correspondingly to the second sensor stack.

[0115] According to a second aspect, the present invention relates to a method for manufacturing a medical device according to the first aspect of the invention, in the process of which a functional layer is applied, in particular printed, to a distal end of the medical device during formation of a sensor stack.

[0116] By applying, in particular printing, the functional layer on the distal end of the medical device, it is possible in particular to avoid a complex positioning of a separately manufactured sensor stack at the distal end and a separate manufacture of a joint between the distal end and the sensor stack. Instead, the functional layer of the sensor stack is applied, in particular directly printed, directly on the wall of the distal end of the medical device. Furthermore, as a result, air inclusions between the sensor stack and the wall can be prevented. This is advantageous both in terms of a reliable connection of the sensor stack to the distal end of the medical device and in terms of the measurement sensitivity of the sensor stack.

[0117] It is also advantageous for the application of the functional layers to the medical device, in particular for the printing of the functional layers on the medical device, that the use of a carrier layer and / or a reinforcing layer is not necessary: ​​instead, a first functional layer, in particular the adhesive layer of the first and / or second part or the first insulating layer of the first part and / or the insulating layer of the second part, is applied, in particular printed, to the medical device in relation to the layer thickness direction D of the sensor stack, and then all further functional layers are applied, in particular printed, to this first functional layer.

[0118] Preferably, the sensor stack is realized by a printing method, in particular by screen printing. Screen printing has the advantage that it offers good long-term process stability at low cost. As an alternative to screen printing, the sensor stack can also be realized by other printing methods, such as offset printing, inkjet printing, aerosol jet printing, spray coating or dip coating.

[0119] Furthermore, the first and / or second electrode layer of the sensor stack can be manufactured from a metal-containing paste, in particular a paste containing a nanoscale metal, preferably nanoscale silver, and / or a microscale metal, preferably microscale silver. Alternatively, a conductive metal, such as gold, platinum, indium, tin or copper, can be applied to a film to embody the first and / or second electrode layer.

[0120] Furthermore, the first conductor track and / or the second conductor track of the sensor stack may be manufactured from a metal-containing paste, in particular a paste comprising a nanoscale metal, preferably nanoscale silver, and / or a microscale metal, preferably microscale silver.

[0121] Alternatively, a conductive metal, for example gold, platinum, indium, tin or copper, can be applied to the film and shaped to a suitable line width by structuring and / or etching in order to realise the first and / or second electrode layer and / or the first and / or second conductor track. Further functional layers can then be applied, in particular printed, or by thin film techniques (evaporation or sputtering).

[0122] For further features and advantages of the method, in particular those relating to the medical device, the sensor stack and the functional layer, reference is made in full to the description given within the scope of the first aspect of the invention. The features and advantages described therein, in particular with regard to the medical device, the sensor stack and the functional layer, apply analogously to the method according to the second aspect of the invention.

[0123] According to a third aspect, the present invention relates to a method for manufacturing a medical device according to the first aspect of the invention, wherein a functional layer is manufactured as a separate sensor stack using a carrier layer and / or a reinforcing layer, and the separately manufactured sensor stack is then applied, in particular printed, to a distal end of the medical device, the carrier layer and / or the reinforcing layer being removed in the process.

[0124] In the sense of the present invention, the term "carrier layer" should be understood to mean the layer to which all further functional layers are applied, with the exception of the adhesive layer, which is preferably applied on the side of the carrier layer opposite to the functional layer side. The carrier layer may also be called the substrate layer in the sense of the present invention. The carrier layer is preferably designed like a film. Preferably, the carrier layer is embodied to allow printing thereon and, in particular, to withstand the temperatures in the drying process without a significant amount of shrinkage. In particular, the carrier layer can have a layer thickness of 10 μm to 500 μm, in particular 20 μm to 250 μm, preferably 50 μm to 150 μm.

[0125] The reinforcing layer may also be called a liner layer in the sense of the present invention. The reinforcing layer is preferably designed like a film. More preferably, the reinforcing layer has a layer thickness greater than that of the substrate layer. In particular, the reinforcing layer may have a layer thickness at least twice as large as that of the carrier layer. For example, the reinforcing layer may have a layer thickness of 10 μm to 500 μm, in particular 20 μm to 250 μm, preferably 50 μm to 150 μm. As a result, the entire structure is advantageously provided with the necessary rigidity to be processable, for example within the scope of a screen printing process. Furthermore, the reinforcing layer may in particular cover an adhesive layer applied to the back side of the carrier layer, thereby preventing unwanted adhesive bonding of the substrate layer.

[0126] The reinforcing layer may be coated, for example with silicone, which advantageously prevents a permanent adhesive bond between the reinforcing layer and the carrier layer.

[0127] In principle, the carrier layer and the reinforcing layer may comprise or consist of different materials.

[0128] Preferably, however, the carrier layer and the reinforcing layer comprise or consist of the same material, in particular the material of the carrier layer has the same coefficient of thermal expansion as the material of the reinforcing layer.

[0129] In particular, the material of the carrier layer may be selected from the group consisting of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC), polyethyleneimine (PEI), and a combination of at least two of the aforementioned polymers.

[0130] In particular, the material of the reinforcing layer may be selected from the group consisting of paper, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC), polyethyleneimine (PEI), and a combination of at least two of the aforementioned polymers.

[0131] Polyethylene naphthalate (PEN) is particularly preferred as the material for the carrier layer and the reinforcing layer, or polyethylene terephthalate (PET) is preferred as the material for the carrier layer and the reinforcing layer.

[0132] Suitably the adhesive layer as detailed within the first aspect of the invention is exposed by removal of the carrier layer and / or the stiffening layer.

[0133] With regard to further features and advantages of the method, in particular with regard to the medical device, the sensor stack and the functional layer, reference is made in full to the description given within the scope of the first and second aspects of the invention, where the features and advantages described therein, in particular with regard to the medical device, the sensor stack and the functional layer, apply analogously to the method according to the third aspect of the invention.

[0134] According to a fourth aspect, the present invention relates to a sensor unit.

[0135] The sensor unit is configured to capture a measured physical variable and convert the measured physical variable into an electrical measurement signal, said sensor unit being in the form of a sensor stack arranged in layers having a first part and a second part.

[0136] The first part and the second part each comprise a number of functional layers arranged one on top of the other, in particular directly or not directly on top of each other.

[0137] The functional layers are applied, in particular printed, in layer-by-layer onto one another so as to at least partially cover one another.

[0138] The first part comprises at least the following functional layers: a first insulating layer that at least partially, in particular only partially or entirely, i.e. entirely or continuously covers and electrically insulates the distal end of the medical device; a conductive first electrode layer applied at least partially, in particular only partially or entirely, i.e. entirely or continuously, to the first insulating layer, in particular printed; a piezoelectrically active piezo layer applied at least partially, in particular only partially or entirely, i.e. entirely or continuously, to the first electrode layer, in particular printed; a conductive second electrode layer applied at least partially, in particular only partially or entirely, i.e. entirely or continuously, to the piezo layer, in particular printed, an electrically insulating second insulating layer applied at least partially, in particular only partially or entirely, i.e. entirely or continuously, to the second electrode layer, in particular printed; and an electrically shielding layer applied at least partially, in particular only partially or entirely, ie entirely or continuously, to the second insulating layer, in particular printed.

[0139] The second part comprises at least the following functional layers: an insulating layer that at least partially, in particular only partially or entirely, i.e. entirely or continuously covers and electrically insulates the distal end of the medical device; a conductive first conductor track applied at least partially, in particular only partially or entirely, i.e. entirely or continuously, to the insulating layer, in particular printed, and a conductive second conductor track applied at least partially, in particular only partially or entirely, ie entirely or continuously, to the insulating layer, in particular printed.

[0140] With regard to further features and advantages of the sensor unit, full reference is made to the descriptions given within the above description, in particular with regard to the first aspect of the invention: the features and advantages described therein in relation to the sensor unit apply analogously to the sensor unit according to the fourth aspect of the invention.

[0141] Further advantages and features of the invention emerge from the claims and the following description of preferred exemplary embodiments of the invention, which are illustrated diagrammatically with the aid of the drawings. [Brief description of the drawings]

[0142] [Figure 1] 1 is a schematic perspective, partially cut-away view of an embodiment of a medical device according to the invention in the region of its distal end; [Diagram 2] 2 is a schematic simplified cross-sectional view of the medical device according to FIG. 1 taken along the section line II-II according to FIG. 1; [Diagram 3] FIG. 3 shows a schematic, partially cut away and simplified longitudinal section of the medical device according to FIGS. 1 and 2 in the region of the distal end. [Figure 4] FIG. 4 is a schematic diagram of a first part of a sensor stack of the medical device according to FIGS. 1 to 3; [Diagram 5] FIG. 4 is a schematic diagram of a second part of the sensor stack of the medical device according to FIGS. 1 to 3; [Figure 6] FIG. 2 is a schematic cutaway side view of a further embodiment of a medical device according to the invention, in which the individual components are depicted diagrammatically and in a highly simplified manner in order to clarify the basic structure; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0143] FIG. 1 shows a schematic representation of a medical device 1, for example in the form of a cannula. Only the region of the distal end of the medical device, which is provided for insertion into the patient's body, is visible. The distal end 2 can, for example, be a cannula tip, which is embodied in a manner known in principle at the end face and is provided with a beveled puncture 3. The proximal end, which is not visible here, has a structure known in principle. The medical device 1 comprises a sensor unit 4, which is arranged to capture a measured physical variable and convert this into an electrical measurement signal. The sensor unit 4 is arranged at the distal end 2 and is depicted in a schematic and rather simplified manner, in particular on the basis of FIGS. 1 to 3.

[0144] Preferably, the sensor unit 4 is embodied in the form of an ultrasound transducer, as not yet described in detail, and allows ultrasound-based localization of the tip 2 of the medical instrument 1 within the patient's body. This allows medical staff to navigate the tip 2 within the patient's body during therapeutic and / or diagnostic procedures, ultrasound-based methods suitable for this purpose being known in principle and also called tracking. Such tracking therefore does not need to be described in further detail here.

[0145] The sensor unit is embodied in the form of a sensor stack 4 built up layer by layer. The sensor stack 4 comprises a first part 4a and a second part 4b. The part 4a, which may also be called the sensor part, preferably forms the distal part of the sensor stack 4. The part 4b, which may also be called the contact part, preferably forms the proximal part of the sensor stack 4.

[0146] Furthermore, the first part 4a and the second part 4b are preferably arranged successively, in particular directly successively. Particularly preferably, the first part 4a and the second part 4b are embodied in a continuous and integral manner. Alternatively, the first part 4a and the second part 4b can be embodied separately from one another and can be connected to one another, in particular glued in a continuous manner.

[0147] Parts 4a and 4b each comprise a number of functional layers arranged one on top of the other (see Fig. 4 and Fig. 5). In this case, the functional layers are applied, in particular printed, on one another in layers, so as to at least partially cover one another. In this case, the sensor stack 4 is preferably produced by a printing method. For example, screen printing techniques, inkjet printing techniques, dispensing printing techniques and / or block printing techniques come into consideration as printing methods for producing the sensor stack 4. To embody the individual functional layers of the sensor stack 4, which have not yet been described in detail, materials having suitable electrical and / or electronic functional properties are printed, initially in liquid and / or pasty form, by a printing method. The functional layers are not drawn to scale. For suitable layer thicknesses, please refer to the general description. To achieve suitable layer thicknesses, the individual materials can be printed on one another several times to form one of the functional layers.

[0148] In this case, the sensor stack 4 is applied, in particular directly printed, in the embodiment according to figures 1 to 5 directly to the wall 5 of the distal end 2 and is therefore securely connected to the distal end 2. As a result, in particular it becomes possible to manage the sensor stack produced separately in a previous step without a separate application, which significantly facilitates the production of the medical device 1. Furthermore, the inclusion of air between the wall 5 and the sensor stack 4, which can occur when gluing the sensor stack, for example conventionally with an adhesive, is prevented.

[0149] The layer-by-layer structure of the sensor stack 4, or its parts 4a, 4b, is explained in more detail below on the basis of FIGS.

[0150] Thus, the first portion 4a of the sensor stack 4 comprises a first insulating layer 6 which comprises or is formed from an electrically insulating material. Preferably, the first insulating layer 6 is printed directly onto the wall 5. The first insulating layer 6 therefore preferably forms the bottom layer of the first portion 4a.

[0151] Furthermore, the first part 4a comprises a first electrode layer 7 printed, in particular directly printed, on the insulating layer 6. The first electrode layer 7 comprises or is formed from an electrically conductive material.

[0152] Furthermore, the first part 4a comprises a piezoelectrically active piezo layer 9 printed, in particular directly printed, on the first electrode layer 7. The piezo layer 9 converts, in a manner known in principle, preferably ultrasonic pulses to be captured into suitable electrical measurement signals. The piezo layer 9 thus preferably forms the actual ultrasonic transducer of the sensor stack 4, in contrast the remaining functional layers for example play a role in electrical insulation or in signal conduction. In particular, the piezo layer 9 may comprise or consist of a material selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), lead zirconate titanate (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AlN), and a combination of at least two of the aforementioned materials.

[0153] Furthermore, the first part 4a comprises a conductive second electrode layer 10 which is printed, in particular directly printed, on the piezo layer 9 and which (also) comprises or is made of a conductive material.

[0154] The second electrode layer 10 and the first electrode layer 7 preferably comprise or consist, independently of each other, of a conductive material selected from the group consisting of polypyrrole, doped polyethylene, polyaniline, polythiophene, preferably poly(3,4-ethylenedioxythiophene), gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and a combination of at least two of the aforementioned conductive materials.

[0155] Preferably, the first electrode layer 7 and the second electrode layer 10 have different embodiments. Suitably, the first electrode layer 7 comprises a conductive metal, in particular a conductive nanoscale metal and / or a conductive microscale metal, or carbon, and the second electrode layer 10 comprises a conductive polymer. Particularly preferably, the metal is silver and the polymer is poly(3,4-ethylenedioxythiophene).

[0156] As is further evident from Fig. 4, the first part 4a further comprises a second insulating layer 13 which comprises or is formed from an electrically insulating material. The second insulating layer 13 is printed on the second electrode layer 10 and the functional layer therebelow. In this case, the second insulating layer 13 is preferably printed directly on the second electrode layer 10. Furthermore, in particular in the region of the electrode layers 7, 10 and the piezo layer 9, the second insulating layer 13 can be guided around these on the end side.

[0157] The electrically insulating material of the first insulating layer 6 and the electrically insulating material of the second insulating layer 13 may be selected independently from the group consisting of ultraviolet curing materials, in particular polyester resins, thermosetting materials, plastics, in particular polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC) or polyetherimide (PEI), and combinations of at least two of the aforementioned electrically insulating materials.

[0158] Furthermore, the first part 4a comprises a shielding layer 14 printed, in particular directly printed, on the second insulating layer 13, which electrically and / or magnetically shields the second insulating layer 13 and further functional layers therebelow in the layer thickness direction D. In particular, the shielding layer 14 may serve to shield the piezo layer 9 from electric and / or magnetic fields that may adversely affect the capture, conversion and / or derivation of signals. In particular, the shielding layer 14 may comprise or consist of a material selected from the group consisting of carbon, a conductive polymer, in particular polypyrrole, doped polyethylene, polyaniline or polythiophene, preferably poly(3,4-ethylenedioxythiophene), a conductive metal, in particular gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and a combination of at least two of the aforementioned materials.

[0159] Furthermore, the first portion 4a may comprise a biocompatible capping layer 15 arranged on the outside with respect to the layer thickness direction D. The biocompatible capping layer 15 thus forms an outer sleeve of the sensor stack 4. The capping layer 15 comprises or is formed of a biocompatible material. For example, the material may be selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), and a combination of at least two of the aforementioned materials. The biocompatible capping layer 15 prevents contact between the remaining functional layers of the sensor stack 4 and the patient's body, which may involve adverse chemical and / or biological interactions.

[0160] The second portion 4 b of the sensor stack 4 comprises an insulating layer 16 .

[0161] Preferably, the insulating layer 16 is printed directly on the wall 5 of the medical device 1. The insulating layer 16 thus forms the bottom layer of the second part 4b. The insulating layer 16 and the first insulating layer 6 of the first part 4a preferably have the same embodiment. In particular, the first insulating layer 6 of the first part 4a and the insulating layer 16 of the second part 4b are embodied continuously and integrally. However, alternatively, the first insulating layer 6 of the first part 4a and the insulating layer 16 of the second part 4b can also be embodied separately from each other and connected to each other, in particular glued together.

[0162] Furthermore, electrically conductive first conductor tracks 17 are provided which are partially printed, in particular directly printed, on the insulating layer 16. The first conductor tracks 17 can be embodied in one piece and continuous with the first electrode layer 7. Alternatively, the first conductor tracks 17 can be printed separately from the first electrode layer 7 and are in electrical contact with it.

[0163] Furthermore, the second part 4b comprises a second conductor track 18, which is partially printed, in particular directly printed, on the insulating layer 16 and which is also printed, in particular directly printed, on another part of the insulating layer 16.

[0164] Preferably, the first conductor track 17 and the second conductor track 18 each comprise or are formed from a conductive metal, in particular a conductive nanoscale metal. Preferably, the metal is silver. In particular, the first conductor track 17 and the second conductor track 18 can have the same embodiment.

[0165] The first conductor track 17 and the second conductor track 18 serve to conduct the electrical measurement signal from the piezo layer 9 in the direction of a proximal end (not depicted in detail here) of the medical device 1. In this case, the conductor tracks 17, 18 are preferably spaced apart from one another and guided on the insulating layer 16 in the direction of the proximal end. Starting from this proximal end, the conductor tracks 17, 18 can be brought into electrically conductive contact with an evaluation unit for evaluating the electrical measurement signal from the piezo layer 9.

[0166] The second portion 4b may also be provided with a corrosion protection layer 19.

[0167] The corrosion protection layer 19 can be embodied in the form of layer portions 19a, 19b and 19c embodied separately from one another as shown. Alternatively, the corrosion protection layer 19 can be embodied continuously and integrally. With respect to the layer thickness direction of the sensor stack 4, the corrosion protection layer 19 is printed on the first conductor track 17 and the second conductor track 18. For example, the corrosion protection layer 19 can comprise or consist of a material selected from the group consisting of carbon, precious metals, in particular gold and / or platinum, and combinations of at least two of the aforementioned materials.

[0168] As is evident from FIG. 2, the medical device 1 has in this embodiment an approximately annular hollow cross section. Preferably, at least the piezoelectrically active piezo layer 9 is printed continuously and without gaps in the circumferential direction of the distal end 2. The piezo layer 9 therefore preferably surrounds the annular wall 5 visible in FIG. 2 all around without gaps. This is particularly advantageous in that gap-induced signal drops are avoided with regard to ultrasound-based tracking of the tip 2. In the prior art, such signal drops are determined in particular whenever a conventional sensor stack is wound mainly around the cannula tip and adhesively bonded to the cannula tip with gaps on the end face side. If such gaps are arranged parallel to the direction of ultrasound incidence, a drop in the signal and thus a negative effect on tracking cannot be easily avoided. This is countered by the piezo layer, which is now printed continuously and without gaps in the circumferential direction of the distal end 2. In particular, the remaining functional layers of the sensor stack 4 can be printed all around in the circumferential direction, in particular with the exception of the conductor tracks 17, 18, so that the sensor stack 4 has an annular cross section.

[0169] Figure 6 shows a further embodiment of a medical device 1 which substantially corresponds to the embodiment described above on the basis of figures 1 to 5. Therefore, in order to avoid repetition, reference is made to the present disclosure in the context of this embodiment. Only the essential differences between the embodiment according to figure 6 and the previous embodiment are described below.

[0170] The medical device 1 evident from FIG. 6 is depicted in a partially cut and somewhat simplified side view. This medical device is preferably embodied in the form of a cannula 1. In contrast to the above-mentioned embodiment, the medical device 1 comprises two sensor stacks. These sensor stacks 4 are either printed directly on the distal end 2 of the medical device 1 or printed separately and subsequently applied to the distal end 2. Otherwise, the structure of the functional layers of the sensor stacks 4 corresponds to the structure of the sensor stacks 4 described above and depicted in FIGS. 1 to 5. The two sensor stacks 4 are arranged spaced apart from each other in the longitudinal direction L of the distal end 2. For example, as a result of this type of arrangement, an ultrasound-based determination of the alignment of the distal end 2 can be performed. For this purpose, expressed in a simplified manner, each of the two sensor stacks 4 can be "tracked" on an ultrasound basis, for example based on methods known in principle. As a result, once the respective positions of both sensor stacks 4 are known, the alignment of the distal end 2 can be immediately deduced.

[0171] Furthermore, an amplification unit 20 arranged at the distal end 2 is provided.

[0172] In the present example, the amplification unit 20 serves to amplify the measurement signals from the two sensor stacks 4. In the case of embodiments not depicted in detail in the drawings, there is only one sensor stack, which may be electrically conductively connected to the amplification unit for the purpose of signal amplification. In the present example, the amplification unit 20 is electrically conductively connected to both sensor stacks 4 by signal lines not labeled in detail and is embodied in the form of a printed circuit. The printed circuit 20 is connectable by a further signal line 21 to an evaluation unit for evaluating the amplified measurement signals. In the present example, the printed circuit 20 is printed directly on the wall 5 of the distal end 2. In the case of embodiments not depicted in detail in the drawings, the printed circuit 20 may first be printed separately and then applied to the wall 5.

[0173] 6 by the two dashed lines, the two sensor stacks 4, the printed circuit 20, and the signal lines running between these components are currently covered by a metallic shielding layer 14 and / or a biocompatible capping layer 15. In this case, the shielding layer 14 and / or capping layer 15 covers the entire distal end 2, except for the puncture portion of the medical device 1, which is not depicted in detail in the drawings.

[0174] For further features and advantages of the embodiment of the medical device according to the invention as depicted in Figures 1 to 6, please refer to the general description.

Claims

1. 1. A medical instrument having a distal end adapted for insertion into a patient's body and a sensor unit arranged at said distal end and configured for capturing a physical variable to be measured and converting said physical variable into an electrical measurement signal, the sensor unit being in the form of a layered sensor stack having a first portion and a second portion; the first portion and the second portion each comprise a plurality of functional layers disposed one above the other; said functional layers being applied to one another in layers at least partially covering one another, in particular by printing, The first part comprises at least the following functional layers: a first insulating layer at least partially covering and electrically insulating the distal end of the medical device; a conductive first electrode layer applied at least partially to the first insulating layer; a piezoelectrically active piezo layer applied at least partially to the first electrode layer; a conductive second electrode layer applied at least partially to the piezo layer; a second insulating layer applied at least partially to the second electrode layer and being electrically insulating; a shielding layer applied at least partially to the second insulating layer; The second portion comprises at least the following functional layers: an insulating layer at least partially covering and electrically insulating the distal end of the medical device; a conductive first conductor track applied at least partially to said insulating layer; and a conductive second conductor track applied at least partially to said insulating layer.

2. The medical device of claim 1 , wherein the first electrode layer and the second electrode layer have different morphologies.

3. 3. The medical device according to claim 1 or 2, characterized in that the first electrode layer and the second electrode layer, independently of each other, comprise a conductive material selected from the group consisting of polypyrrole, doped polyethylene, polyaniline, polythiophene, preferably poly(3,4-ethylenedioxythiophene), gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and a combination of at least two of the aforementioned conductive materials.

4. 4. The medical device according to claim 1 , characterized in that the first electrode layer comprises a conductive metal, in particular a conductive nanoscale metal, or carbon, and the second electrode layer comprises a conductive polymer.

5. 5. The medical device of claim 4, wherein said conductive metal is silver and said conductive polymer is poly(3,4-ethylenedioxythiophene).

6. 6. The medical device according to any one of claims 1 to 5, characterized in that the piezo layer comprises a material selected from the group consisting of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), lead zirconate titanate (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AlN), and a combination of at least two of the aforementioned materials.

7. 7. Medical device according to any one of the preceding claims, characterized in that the first conductor track and the second conductor track each comprise an electrically conductive metal, in particular an electrically conductive nanoscale metal.

8. 8. The medical device of claim 1 , wherein the sensor stack further comprises an adhesive layer disposed between the first insulating layer of the first portion and a surface of the medical device and / or between the insulating layer of the second portion and a surface of the medical device.

9. 9. The medical device according to claim 8, characterized in that the adhesive layer comprises a conductive metal, in particular a conductive microscale metal.

10. 10. The medical device according to claim 7 or 9, characterized in that the metal is silver.

11. 11. The medical device according to claim 1, wherein the second part further comprises a corrosion protection layer applied above the first conductive conductor track and the second conductive conductor track in a layer thickness direction D of the sensor stack.

12. 12. The medical device according to claim 11, characterized in that the anticorrosive layer comprises a material selected from the group consisting of carbon, precious metals, in particular gold and / or platinum, and combinations of at least two of the aforementioned materials.

13. 13. The medical device according to claim 1, characterized in that the sensor stack, in particular the first part of the sensor stack, comprises a biocompatible capping layer arranged externally with respect to a layer thickness direction D of the sensor stack.

14. 14. The medical device according to claim 1, characterized in that the first and second electrically insulating layers of the first part and the second electrically insulating layer of the second part, independently of one another, comprise an electrically insulating material selected from the group consisting of UV-curable materials, in particular polyester resins, thermosetting materials, plastics, in particular polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC) or polyetherimide (PEI), and combinations of at least two of the aforementioned electrically insulating materials.

15. 15. The medical device according to any one of claims 1 to 14, characterized in that the shielding layer comprises a material, in particular a conductive material, selected from the group consisting of carbon, a conductive polymer, in particular polypyrrole, doped polyethylene, polyaniline or polythiophene, preferably poly(3,4-ethylenedioxythiophene), a conductive metal, in particular gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and a combination of at least two of the aforementioned materials.

16. A method for manufacturing a medical device according to any one of claims 1 to 15, comprising the steps of: the functional layer is applied, in particular printed, to the distal end of the medical device, forming in the process the sensor stack, or A method in which the functional layer is manufactured as a separate sensor stack using a carrier layer and / or a reinforcing layer, and the separately manufactured sensor stack is then applied to the distal end of the medical device, and the carrier layer and / or the reinforcing layer are removed in the process.

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