Medical instrument with a piezoelectric sensor stack, and method for producing same

Abstract

The invention relates to a medical instrument (1) with a distal end (2), which is designed to be introduced into the body of a patient, and a sensor unit, which is arranged at the distal end and is designed to detect a physical measurement variable and convert same into an electric measurement signal. The sensor unit, in the form of a layered sensor stack (4), comprises a first section (4a) and a second section (4b), each of which comprises multiple functional layers lying one over the other. The first section (4a) has at least one first insulating layer (6) which at least partly covers the distal end, a first electrode layer (7), a piezo layer (9), a second electrode layer (10), a second insulating layer (13), and a conductive electric shielding layer (14). The second section (4b) has at least one insulating layer (16) and a first conductor path (17) and a second conductor path (18) on the at least one insulating layer.

Description

[0001] MEDICAL INSTRUMENT WITH A PIEZOELECTRIC SENSOR STACK AND MANUFACTURING METHOD THEREFOR

[0002] FIELD OF APPLICATION AND STATE OF THE ART

[0003] The invention relates to a medical instrument with a sensor stack and a method for producing such a medical instrument.

[0004] A medical instrument in the form of a catheter with a sensor unit for detecting and converting a physical measurement variable is known, for example, from WO 2017 / 013224 A1. The sensor unit is designed as an ultrasound transducer and is used for ultrasound-based location of the catheter tip in a patient's body, also known as tracking. The sensor unit is formed from several film-like, stacked functional layers and can therefore also be referred to as a sensor stack. The sensor stack is manufactured by bonding the individual functional layers layer by layer, which is also known as lamination. For application, the laminated sensor stack is provided with an adhesive layer, wrapped around the catheter tip, and adhered to the catheter tip using the adhesive layer.

[0005] Furthermore, from DE 10 2018 220 606 A1 a medical instrument is known which can be designed, for example, as a cannula and has a sensor unit at a distal end which is designed to detect a physical measurement variable and to convert it into an electrical measurement signal.

[0006] A disadvantage of state-of-the-art medical instruments with a sensor unit is often insufficient measurement value acquisition and thus low signal strength, which, for example, makes it difficult for the medical instrument to navigate within a patient's body to a target area. Furthermore, the production of appropriately designed medical instruments is generally very time-consuming and costly. TASK AND SOLUTION

[0007] The object of the invention is therefore to provide a medical instrument and a method for producing a medical instrument which, in particular, partially or completely avoid the disadvantages mentioned in the introduction.

[0008] This object is achieved by a medical instrument having the features according to independent claim 1 and a method according to claim 16. Preferred embodiments of the invention are the subject of the dependent claims. The wording of all claims is hereby incorporated into the present description by express reference.

[0009] According to a first aspect, the invention relates to a medical instrument with a distal end intended for insertion into the body of a patient. The medical instrument can, in particular, be a catheter, a cannula, or another medical instrument intended for insertion into the body of a patient, at least in part. The distal end can therefore, in particular, be a catheter tip or a cannula tip.

[0010] The medical instrument has a sensor unit arranged at the distal end. The sensor unit is configured to detect a physical measurement variable and convert it into an electrical measurement signal and is constructed in the form of a layered sensor stack. The sensor stack can be configured to detect, for example, a temperature, a hydrostatic pressure, or another physical measurement variable of therapeutic and / or diagnostic interest. Preferably, the sensor stack, in particular the piezoelectric layer of the first section, is configured to detect and convert ultrasonic pulses and thus preferably forms an ultrasonic transducer.

[0011] The sensor stack has a first section and a second section. The first section can also be referred to as the sensor section within the meaning of the present invention. The second section can also be referred to as the contact section within the meaning of the present invention, in which electrical signals generated in the first section of the sensor stack can be picked up or diverted.

[0012] Preferably, the first section is a distal section of the sensor stack, and the second section is a proximal section of the sensor stack. In other words, the sensor stack can be arranged on the medical instrument such that the first section is arranged distally at the distal end of the medical instrument, and the second section is arranged proximally at the distal end of the medical instrument.

[0013] Furthermore, the first section and the second section are preferably arranged one behind the other, in particular directly behind the other. Particularly preferably, the first section and the second section are formed integrally and connected to one another. Alternatively, the first section and the second section can be formed separately from one another and connected to one another, in particular by a material bond.

[0014] In particular, the sensor stack may consist of the first section and the second section.

[0015] The sensor stack is preferably produced by means of a printing process, in particular offset printing, inkjet printing, screen printing, aerosol jet printing, spray coating or dip coating.

[0016] The first section and the second section of the sensor stack each comprise a plurality of functional layers arranged one above the other, in particular arranged directly or not directly above the other. The functional layers are applied, in particular printed, layer by layer, overlapping one another at least in sections, in particular only in sections or completely.

[0017] The first section has at least the following functional layers: a first insulation layer covering the distal end of the medical instrument at least in sections, in particular only in sections or completely, ie continuously or contiguously, and electrically insulating, an electrically conductive first electrode layer applied, in particular printed, to the first insulation layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, a piezoactive piezo layer applied, in particular printed, to the first electrode layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, a piezo-layer applied, in particular printed, to the piezo layer at least in sections, in particular only in sections or completely, iecontinuously or coherently applied, in particular printed, electrically conductive second electrode layer, an electrically insulating second insulation layer applied, in particular printed, at least in sections, in particular only in sections or completely, ie continuously or coherently, to the second electrode layer and a shielding layer applied, in particular printed, at least in sections, in particular only in sections or completely, ie continuously or coherently, to the second insulation layer.

[0018] The first insulation layer may or may not directly cover the distal end of the medical instrument.

[0019] Furthermore, the first electrode layer can be applied, in particular printed, directly or not directly onto the first insulation layer and / or the piezoelectric layer can be applied, in particular printed, directly or not directly onto the first electrode layer and / or the second electrode layer can be applied, in particular printed, directly or not directly onto the piezoelectric layer and / or the second insulation layer can be applied, in particular printed, directly or not directly onto the second electrode layer and / or the shielding layer can be applied, in particular printed, directly or not directly onto the second insulation layer.

[0020] The second section has at least the following functional layers: an insulating layer covering the distal end of the medical instrument at least in sections, in particular only in sections or completely, ie continuously or contiguously, and electrically insulating, an electrically conductive first conductor track applied, in particular printed, to the insulating layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, and an electrically conductive second conductor track applied, in particular printed, to the insulating layer at least in sections, in particular only in sections or completely, ie continuously or contiguously.

[0021] The insulation layer may or may not directly cover the distal end of the medical instrument.

[0022] Furthermore, the first conductor track can be applied, in particular printed, directly or not directly to the insulation layer and / or the second conductor track can be applied, in particular printed, directly or not directly to the electrically insulating insulation layer. Preferably, the first conductor track and the second conductor track are applied, in particular printed, to different sections of the insulation layer. For the purposes of the present invention, the term "distal" is understood to mean located further away from the center of the body of a person, in particular a medical professional, who uses the medical instrument as intended.

[0023] For the purposes of the present invention, the term “proximal” is to be understood as being closer to the center of the body of a person, in particular a medical professional, who uses the medical instrument as intended.

[0024] In the context of the present invention, the term “sensor stack” is to be understood as a sensor unit constructed layer by layer from several functional layers, in particular in the form of a film or foil.

[0025] In the context of the present invention, the term “piezoactive piezo layer” is to be understood as a layer on which a voltage is generated under the influence of mechanical pressure (piezoelectric effect).

[0026] The shielding layer preferably serves to shield the remaining functional layers, in particular the first section, preferably the piezoelectric layer, of the sensor stack from electrical and / or magnetic fields. Such fields can disrupt the measurement acquisition and / or measurement conversion and / or measurement derivation. The shielding layer enables the sensor stack to function as smoothly as possible.

[0027] The first conductor track and the second conductor track of the second section serve to divert the electrical measurement signals of the first section, in particular the piezoelectric layer of the first section, toward a proximal end of the medical instrument. Starting from this proximal end, the first conductor track and the second conductor track can be electrically conductively contacted or contactable with an evaluation unit for evaluating the electrical measurement signals of the first section, in particular the piezoelectric layer of the first section.

[0028] More preferably, the first insulation layer of the first section and the insulation layer of the second section are of identical design. In particular, the first insulation layer of the first section and the insulation layer of the second section are of one-piece construction. Alternatively, the first insulation layer of the first section and the insulation layer of the second section can be formed separately from one another and connected to one another, in particular by a material fit. The second section of the sensor stack is preferably free of a further insulation layer, in particular one applied, in particular printed, to the first conductor track and / or second conductor track, and free of an electrically shielding shielding layer. In other words, the first conductor track and the second conductor track of the second section are each preferably an exposed conductor track.This advantageously makes it possible to establish contact, for example, with an amplifier unit which is designed to amplify the measurement signals of the sensor stack, and / or with an evaluation unit, in particular one connected downstream of the amplifier unit, which is designed to evaluate the electrical measurement signals.

[0029] Further preferably, the first electrode layer of the first section and the first conductor track of the second section are formed as a single, connected piece. A single-piece design of the first electrode layer and the first conductor track has the advantage, in principle, that electrical signals generated in the first section of the sensor stack can be picked up more quickly.

[0030] Alternatively, the first electrode layer can be applied separately from the first conductor track, in particular printed, and electrically contacted therewith.

[0031] Furthermore, the second electrode layer of the first section and the second conductor track of the second section are preferably formed as a single, continuous piece. A single-piece design of the second electrode layer and the second conductor track (also) has the advantage, in principle, that electrical signals generated in the first section of the sensor stack can be picked up more quickly.

[0032] Alternatively, the second electrode layer can be applied separately from the second conductor track, in particular printed, and electrically contacted therewith.

[0033] The functional layers of the first section and / or second section can independently of one another have a layer thickness of 1 pm to 30 pm, in particular of 0.5 pm to 20 pm, preferably of 1 pm to 10 pm.

[0034] In one embodiment of the invention, the first electrode layer and the second electrode layer are formed differently, in particular at least in sections, for example only in sections or continuously. Alternatively, the first electrode layer and the second electrode layer can be formed identically, in particular at least in sections, for example only in sections or continuously.

[0035] Furthermore, the first electrode layer, in particular only the first electrode layer, can be formed as a single piece or in the form of layer sections formed separately from one another. Furthermore, the second electrode layer, in particular only the second electrode layer, can be formed as a single piece or in the form of layer sections formed separately from one another.

[0036] Furthermore, the first electrode layer can be formed in a single, continuous layer, and the second electrode layer can be formed in the form of layer sections formed separately from one another. Alternatively, the first electrode layer can be formed in the form of layer sections formed separately from one another, and the second electrode layer can be formed in a single, continuous layer. Alternatively, the first electrode layer and the second electrode layer can each be formed in a single, continuous layer or each be formed in the form of layer sections formed separately from one another.

[0037] Furthermore, the first electrode layer can have a layer thickness of 0.1 pm to 30 pm, in particular 0.5 pm to 10 pm, preferably 1 pm to 2 pm. The second electrode layer can further have a layer thickness of 0.1 pm to 30 pm, in particular 0.5 pm to 10 pm, preferably 1 pm to 2 pm.

[0038] In principle, any electrically conductive material is suitable for the first electrode layer and the second electrode layer.

[0039] Preferably, the first electrode layer and the second electrode layer each comprise a printable conductive material or preferably each consist of such a material. In particular, at least one of the two electrode layers comprises or consists of a material that can be very finely structured, in particular in the micrometer range, for example, with a line width of 100 pm.

[0040] More preferably, the first electrode layer and the second electrode layer independently comprise an electrically conductive material or consist of an electrically conductive material selected from the group consisting of electrically conductive polymers, electrically conductive metals, and combinations thereof. Regarding suitable electrically conductive polymers and electrically conductive metals, reference is made to the following explanations. If the first electrode layer and / or the second electrode layer are formed in the form of layer sections formed separately from one another, the respective layer sections of the first electrode layer and / or second electrode layer can independently comprise an electrically conductive material or consist of an electrically conductive material selected from the aforementioned group.

[0041] In a further embodiment of the invention, the first electrode layer and the second electrode layer independently comprise an electrically conductive material or independently consist of an electrically 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 electrically conductive materials.

[0042] In a further embodiment of the invention, the first electrode layer comprises an electrically conductive metal, in particular an electrically conductive and nanoscale metal and / or an electrically conductive and microscale metal, or carbon, and the second electrode layer comprises an electrically conductive polymer, or vice versa. Alternatively, the first electrode layer and the second electrode layer can be made of the respective aforementioned electrically conductive materials. The electrically conductive metal can in particular be selected from the group consisting of silver, preferably nanoscale silver and / or microscale silver, gold, platinum, indium, tin, copper, and combinations of at least two of the aforementioned electrically conductive metals.The electrically conductive polymer can in particular be selected from the group consisting of polythiophene, preferably poly(3,4-ethylenedioxythiophene), polypyrrole, doped polyethylene, polyaniline and combinations of at least two of the aforementioned electrically conductive polymers.

[0043] For the purposes of the present invention, the term “nanoscale metal” is understood to mean a metal having a particle diameter, in particular an average particle diameter, of 1 nm to 1000 nm, in particular 10 nm to 500 nm, preferably 50 nm to 250 nm.

[0044] For the purposes of the present invention, the term "microscale metal" refers to a metal with a particle diameter, in particular an average particle diameter, of 1 pm to 100 pm, in particular 3 pm to 50 pm, preferably 5 pm to 30 pm. In particular, the first electrode layer and / or the second electrode layer can be made of a paste containing a nanoscale metal and / or a microscale metal.

[0045] In a further embodiment of the invention, the electrically conductive metal, in particular electrically conductive and nanoscale metal and / or electrically conductive and microscale metal, is silver, and the conductive polymer is poly(3,4-ethylenedioxythiophene). In other words, in a further embodiment 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 can consist of the respective aforementioned materials. The use of silver, in particular nanoscale silver, has the advantage that it can be applied, in particular printed, for example by screen printing, in particularly fine structures.The silver can, for example, have a diameter, in particular an average diameter, of 0.5 pm to 30 pm, in particular 1 pm to 20 pm, preferably 5 pm to 15 pm. The use of poly(3,4-ethylenedioxythiophene) can advantageously prevent breakdowns of the piezoelectric layer located between the first electrode layer and the second electrode layer during polarization with high voltage. Furthermore, an electrode layer with or made of poly(3,4-ethylenedioxythiophene) advantageously has a self-healing effect in the event of an electrical breakdown, in that the layer closes itself again at the affected area due to the resulting heat development. Furthermore, the smooth surface of poly(3,4-ethylenedioxythiophene) has a positive effect on preventing voltage breakdowns. Overall, the risk of a permanent short circuit between the electrode layers can thus be eliminated.

[0046] The piezo layer can be formed in one piece or in the form of layer sections formed separately from one another.

[0047] Furthermore, the piezo layer can have a layer thickness of 0.5 pm to 30 pm, in particular 1 pm to 20 pm, preferably 1 pm to 10 pm.

[0048] Furthermore, all piezoresistive materials, in particular piezoresistive polymers, piezoresistive ceramics, and combinations thereof, are generally suitable for the piezoelectric layer. The piezoresistive polymers can be homopolymers or copolymers, in particular bi- and / or terpolymers, in particular as described below. In a further embodiment of the invention, the piezoelectric 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)),

[0049] Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-T rFE-CFE)), lead zirconate titanate (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AIN), and combinations of at least two of the aforementioned materials. If the piezoelectric layer is formed in the form of separate layer sections, the layer sections can independently comprise a material or consist of a material selected from the aforementioned group.

[0050] Preferably, the piezo layer comprises poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) or consists of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)).

[0051] Furthermore, the piezoelectric layer can be applied, in particular printed, continuously in the circumferential direction of the distal end of the medical instrument. The remaining functional layers, in contrast, can be applied, in particular printed, only in sections on the distal end of the medical instrument. This advantageously enables uniform measurement value acquisition in the circumferential direction. As a result, the measurement value acquisition is independent of the angular orientation of the distal end of the medical instrument, for example, relative to an ultrasound source. This allows for further improved measurement value acquisition and, in particular, improved localization, for example, ultrasound-based localization, of the medical instrument.

[0052] Furthermore, the first conductor track, in particular only the first conductor track, can be formed as a single piece or in the form of layer sections formed separately from one another. Furthermore, the second conductor track, in particular only the second conductor track, can be formed as a single piece or in the form of layer sections formed separately from one another.

[0053] Furthermore, the first conductor track can be integrally connected and the second conductor track can be formed in the form of layer sections that are formed separately from one another. Alternatively, the first conductor track can be formed in the form of layer sections that are formed separately from one another and the second conductor track can be integrally connected. Alternatively, the first conductor track and the second conductor track can each be integrally connected or each be formed in the form of layer sections that are formed separately from one another. Furthermore, the first conductor track can have a layer thickness of 0.1 pm to 30 pm, in particular 0.5 pm to 10 pm, preferably 1 pm to 2 pm. The second conductor track can furthermore have a layer thickness of 0.1 pm to 30 pm, in particular 0.5 pm to 10 pm, preferably 1 pm to 2 pm.

[0054] Furthermore, the first conductor track and the second conductor track can be designed differently, in particular at least in sections, for example only in sections or continuously.

[0055] Alternatively, the first conductor track and the second conductor track can be of identical design, in particular at least in sections, for example only in sections or continuously.

[0056] In principle, any conductive material is suitable for the first and second conductor tracks. However, conductive materials with the lowest possible electrical resistivity, a certain degree of flexibility, and good adhesion, especially to the insulation layer of the second section, are preferred.

[0057] In a further embodiment of the invention, the first conductor track and the second conductor track each comprise an electrically conductive metal, in particular an electrically conductive and nanoscale metal and / or an electrically conductive and microscale metal. In particular, the first conductor track and the second conductor track can each consist of such a metal.

[0058] Preferably, the first conductor track and the second conductor track independently comprise an electrically conductive metal, in particular silver, preferably nanoscale silver and / or microscale silver, gold, platinum, indium, tin, copper, or combinations of at least two of the aforementioned metals. If the first conductor track and / or the second conductor track are formed in the form of layer sections formed separately from one another, the respective layer sections of the first conductor track and / or second conductor track can independently comprise a material or consist of a material selected from the aforementioned group.

[0059] The first conductor track and / or the second conductor track preferably comprise / comprising silver, in particular nanoscale silver. In particular, the first conductor track and / or the second conductor track can be made of silver, in particular nanoscale silver. The silver preferably has a diameter, in particular an average diameter, of 1 nm to 1000 nm, in particular 10 nm to 500 nm, preferably 50 nm to 250 nm. Correspondingly designed conductor tracks advantageously exhibit reduced brittleness and increased bendability or flexibility. A further advantage is that, in the case of silver, the first conductor track and the second conductor track adhere better to a functional layer, in particular an insulating layer, lying beneath the conductor tracks with respect to a layer thickness direction D of the sensor stack.

[0060] In a further embodiment of the invention, the sensor stack, in particular the first section and / or second section of the sensor stack, further comprises an adhesive layer. The adhesive layer preferably serves for the integral connection, in particular by gluing, of the sensor stack to the medical instrument. The adhesive layer is preferably arranged, in particular directly or indirectly, between the first insulation layer of the first section and the surface of the medical instrument and / or, in particular directly or indirectly, between the insulation layer of the second section and the surface of the medical instrument.

[0061] In particular, the first section of the sensor stack may comprise an adhesion layer which is arranged, in particular directly or not directly, between the first insulation layer and the surface of the medical instrument.

[0062] Preferably, the adhesion layer is arranged with respect to a layer thickness direction D of the sensor stack, in particular directly or not directly, below the first insulation layer of the first section.

[0063] Further preferably, the adhesive layer of the first section is applied directly to the medical instrument, in particular printed thereon.

[0064] Furthermore, in particular (also) the second section of the sensor stack can have an adhesion layer which is arranged, in particular directly or not directly, between the insulation layer and the surface of the medical instrument.

[0065] Preferably, the adhesion layer is arranged with respect to a layer thickness direction D of the sensor stack, in particular directly or not directly, below the insulation layer of the second section.

[0066] Further preferably, the adhesive layer of the second section is (also) applied directly to the medical instrument, in particular printed. Furthermore, the adhesive layer described in the preceding paragraphs can be formed as a single piece or in the form of separate layer sections.

[0067] Furthermore, the adhesion layer of the first section, in particular only of the first section, can be formed as a single piece or in the form of layer sections formed separately from one another. Furthermore, the adhesion layer, in particular only of the second section, can be formed as a single piece or in the form of layer sections formed separately from one another.

[0068] Furthermore, the adhesion layer of the first section can be formed as a single piece, and the adhesion layer of the second section can be formed as separate layer sections. Alternatively, the adhesion layer of the first section can be formed as separate layer sections, and the adhesion layer of the second section can be formed as a single piece. Alternatively, the adhesion layer of the first section and the adhesion layer of the second section can each be formed as a single piece, or each can be formed as separate layer sections.

[0069] Furthermore, the adhesion layer of the first section and the adhesion layer of the second section can be formed integrally.

[0070] Alternatively, the adhesive layer of the first section can be applied separately from the adhesive layer of the second section, in particular printed, and bonded thereto.

[0071] Furthermore, the adhesion layer, in particular of the first section and / or second section, can have a layer thickness of 1 pm to 50 pm, in particular 2 pm to 30 pm, preferably 5 pm to 15 pm.

[0072] In a further embodiment of the invention, the adhesion layer, in particular of the first section and / or second section of the sensor stack, comprises an electrically conductive metal, in particular an electrically conductive and microscale metal. The metal is preferably selected from the group consisting of silver, gold, platinum, indium, tin, copper, and combinations of at least two of the aforementioned metals. If the adhesion layer is formed in the form of layer sections formed separately from one another, the layer sections can independently comprise a metal or consist of a metal selected from the aforementioned group.

[0073] In a further embodiment of the invention, the metal of the adhesion layer, in particular of the first section and / or second section, is silver, in particular microscale silver. The silver preferably has a diameter, in particular an average diameter, of 0.5 pm to 30 pm, in particular 1 pm to 20 pm, preferably 5 pm to 15 pm. A correspondingly designed adhesion layer is advantageously characterized by reduced brittleness and increased pliability or flexibility.

[0074] In a further embodiment of the invention, the sensor stack, in particular the first section and / or second section, preferably the second section, of the sensor stack, further comprises an anti-corrosion layer. This advantageously protects the conductor tracks from corrosion, particularly in the area of ​​contact with other materials, during signal transmission, and ensures a long-term constant electrical contact resistance and low contact resistance.

[0075] The anti-corrosion layer is preferably applied, in particular printed, above the first conductor track and the second conductor track with respect to a layer thickness direction D of the sensor stack, in particular directly or not directly.

[0076] The anti-corrosion layer can be formed as a single, continuous layer. Alternatively, the anti-corrosion layer can be formed as separate layer sections.

[0077] Furthermore, the anti-corrosion layer can have a layer thickness of 0.5 pm to 30 pm, in particular 1 pm to 20 pm, preferably 2 pm to 10 pm.

[0078] In principle, all non-corrosive and conductive materials are suitable for the anti-corrosion layer.

[0079] In a further embodiment of the invention, the anti-corrosion layer comprises or consists 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. If the anti-corrosion layer is formed in the form of layer sections formed separately from one another, the layer sections can independently comprise or consist of a material selected from the aforementioned group.

[0080] The anti-corrosion layer preferably comprises conductive carbon. In particular, the anti-corrosion layer can consist of conductive carbon. Carbon has proven particularly advantageous for preventing corrosion and thus ensuring a constant electrical contact resistance over time. Furthermore, carbon is softer than the aforementioned precious metals, for example, and can therefore conform better to a contact.

[0081] In a further embodiment of the invention, the sensor stack, in particular the first section and / or second section, in particular only the first section, of the sensor stack, has a biocompatible cover layer. The cover layer is preferably arranged on the outside with respect to a layer thickness direction D of the sensor stack. The cover layer is preferably applied, in particular printed, above the shielding layer with respect to a layer thickness direction D of the sensor stack, in particular directly or not directly. Accordingly, the biocompatible cover layer can preferably form a (final) outer layer of the sensor stack, in particular of the first section of the sensor stack.

[0082] The biocompatible top layer advantageously prevents direct contact of the remaining functional layers with the patient's body. This counteracts any undesirable chemical and / or biological interactions and thus any potential adverse effects on the patient's health.

[0083] The biocompatible cover layer can be formed as a single, continuous piece. Alternatively, the biocompatible cover layer can be formed as separate layer sections.

[0084] Furthermore, the biocompatible cover layer can have a layer thickness of 1 pm to 30 pm, in particular 2 pm to 20 pm, preferably 5 pm to 15 pm.

[0085] In principle, all biocompatible and, in particular, electrically insulating materials are suitable for the biocompatible cover layer. Preferably, the biocompatible cover 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 combinations of at least two of the aforementioned materials. If the cover layer is formed in the form of separately formed layer sections, the layer sections can independently comprise or consist of a material selected from the aforementioned group.

[0086] The first insulation layer of the first section of the sensor stack can be formed in one piece or in the form of several layer sections formed separately from one another.

[0087] Furthermore, the first insulation layer of the first section and / or the insulation layer of the second section of the sensor stack can have a layer thickness of 1 pm to 50 pm, in particular 2 pm to 30 pm, preferably 4 pm to 20 pm.

[0088] Furthermore, the second insulation layer of the first section of the sensor stack can be formed in one piece or in the form of several layer sections formed separately from one another.

[0089] Furthermore, the second insulation layer of the first section can have a layer thickness of 1 pm to 50 pm, in particular 5 pm to 40 pm, preferably 10 pm to 30 pm.

[0090] Furthermore, the insulation layer of the second section of the sensor stack can be formed in one piece or in the form of several layer sections formed separately from one another.

[0091] Furthermore, the insulation layer of the second section can have a layer thickness of 1 pm to 50 pm, in particular 5 pm to 40 pm, preferably 10 pm to 30 pm.

[0092] Furthermore, the first insulation layer and the second insulation layer of the first section and the insulation layer of the second section can be designed differently, in particular at least in sections, for example only in sections or continuously.

[0093] Alternatively, the first insulation layer and the second insulation layer of the first section and the insulation layer of the second section can be of identical design, in particular at least in sections, for example only in sections or continuously.

[0094] In principle, all non-conductive materials are suitable for the first insulation layer and the second insulation layer of the first section, as well as the insulation layer of the second section. These non-conductive materials can, in particular, be UV-curing materials and / or thermally curing materials. These materials have the advantage of rapid curing, thus shortening the manufacturing time of the sensor stack and, in particular, the medical instrument.

[0095] In a further embodiment of the invention, the first insulation layer and the second insulation layer of the first section and the insulation layer of the second section independently of one another comprise an electrically insulating material which is selected from the group consisting of UV-curing materials, in particular polyester resins, thermally curing materials, in particular as previously mentioned, 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 insulation layer and / or the second insulation layer of the first section and / or the insulation layer of the second section are formed in the form of layer sections formed separately from one another, the respective layer sections of the first insulation layer and / or second insulation layer of the first section and / or the insulation layer of the second section can independently of one another comprise a material or consist of a material selected from the aforementioned group.

[0096] Preferably, the first insulation layer of the first section and the insulation layer of the second section comprise or consist of the same material at least in sections, in particular only in sections or continuously. The material is preferably polyethylene naphthalate (PEN). This advantageously enables high temperature resistance and, in particular, good adhesion for the printing process. Regarding alternative materials that may be considered, reference is made to the above statements regarding the insulation layers.

[0097] Furthermore, the second insulation layer of the first section and / or the insulation layer of the second section preferably comprise / comprises a UV-curing material, preferably a polyester resin, or consist / consists of such a material.

[0098] The use of UV-curing materials, in particular polyester resin, for forming the second insulation layer of the first section and / or the insulation layer of the second section has proven particularly advantageous for reducing capacitive effects and protecting against breakage of the functional layers, in particular the electrode layers and conductor tracks. This advantageously enables bending of the sensor unit, especially when applied to a curved surface of the medical instrument, without loss of integrity of the functional layers, in particular the electrode layers and / or the conductor tracks. A further advantage is improved adhesion for immediately adjacent functional layers, in particular the shielding layer of the first section.In addition, UV-curing materials, especially polyester resin, do not interact with underlying functional layers immediately after application, especially printing, which means that the sensor properties are not negatively affected.

[0099] Furthermore, the second insulation layer of the first section serves as an electrically insulating layer between the shielding layer and the electrode layers of the first section, in particular the second electrode layer. The thickness of the second insulation layer of the first section can be used to specifically influence the distance between the shielding layer and the electrode layers, possible capacitances, and the size of the sensor unit.

[0100] For example, the second insulation layer of the first section can have a layer thickness of 1 pm to 50 pm, in particular of 5 pm to 40 pm, preferably of 10 pm to 30 pm.

[0101] Furthermore, the second insulation layer can be formed as a single, continuous layer or in the form of several, for example two or three, separate sub-layers.

[0102] The shielding layer can be formed in one piece or in the form of several layer sections formed separately from one another.

[0103] In principle, any electrically conductive material is suitable for the electrically shielding layer. However, electrically conductive materials with the lowest possible electrical resistivity and good adhesion are preferred.

[0104] In a further embodiment of the invention, the shielding layer comprises a material, in particular an electrically conductive material, or consists of a material, in particular an electrically conductive material, which is selected from the group consisting of carbon, conductive polymer, in particular polypyrrole, doped polyethylene, polyaniline or polythiophene, preferably poly(3,4-ethylenedioxythiophene), conductive metals, in particular gold, platinum, indium, tin, copper, or silver, preferably nanoscale silver, and combinations of at least two of the aforementioned materials, in particular electrically conductive materials. If the shielding layer is formed in the form of several layer sections formed separately from one another, the layer sections can comprise a material or consist of a material selected from the aforementioned group.

[0105] The shielding layer preferably comprises a conductive metal, in particular silver.

[0106] Furthermore, at least one second applied, in particular printed, sensor stack can be provided at the distal end of the medical instrument, which is arranged at a distance from the sensor stack in the longitudinal direction of the distal end. The second sensor stack is preferably structurally identical to the sensor stack.

[0107] Due to the longitudinally spaced arrangement of the second sensor stack, not only the position of the distal end but also its angular position, in particular with respect to an existing ultrasound field, can be determined. Thus, advantageously, not only the position of the distal end is located, but also the orientation is located, which in particular allows a conclusion to be drawn about a 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 subsequently applied, in particular imprinted, to the distal end of the medical instrument. Alternatively, the second sensor stack can be applied, in particular printed, directly to the distal end.With regard to the functional layers (including their arrangement) of the second sensor stack, in order to avoid repetition, reference is made to the relevant disclosure in connection with the (first) sensor stack, which applies accordingly to the second sensor stack.

[0108] According to a second aspect, the invention relates to a method for producing a medical instrument according to the first aspect of the invention, in which functional layers are applied, in particular printed, to the distal end of the medical instrument to form the sensor stack.

[0109] By applying, in particular printing, the functional layers to the distal end of the medical instrument, the complex positioning of a separately manufactured sensor stack at the distal end and the separate creation of a joint between the distal end and the sensor stack can be dispensed with. Instead, the functional layers of the sensor stack are applied, in particular printed, directly onto a wall section of the distal end of the medical instrument. This also prevents air pockets between the sensor stack and the wall section, which is advantageous both with regard to a secure connection of the sensor stack to the distal end of the medical instrument and with regard to the measurement sensitivity of the sensor stack.

[0110] When applying, in particular printing, the functional layers to the medical instrument, it is further advantageous that the use of a carrier layer and / or stiffening layer is dispensed with. Instead, a first functional layer with respect to a layer thickness direction D of the sensor tack, in particular the adhesive layer of the first and / or second section or the first insulation layer of the first section and / or the insulation layer of the second section, is applied, in particular printed, to the medical instrument, onto which all further functional layers are subsequently applied, in particular printed.

[0111] The sensor stack is preferably formed using a printing process, in particular screen printing. Screen printing has the advantage of providing good long-term process stability at low cost. As an alternative to screen printing, the sensor stack can also be formed using other printing processes such as offset printing, inkjet printing, aerosol jet printing, spray coating, or dip coating.

[0112] Furthermore, the first electrode layer and / or the second electrode layer of the sensor stack can be made of a metal-containing paste, in particular a paste containing nanoscale metal, preferably nanoscale silver, and / or microscale metal, preferably microscale silver. Alternatively, a conductive metal, such as gold, platinum, indium, tin, or copper, can be applied to a foil to form the first electrode layer and / or second electrode layer.

[0113] Furthermore, the first conductor track and / or the second conductor track of the sensor stack can be made of a metal-containing paste, in particular a paste containing nanoscale metal, preferably nanoscale silver, and / or microscale metal, preferably microscale silver.

[0114] Alternatively, to form the first electrode layer and / or second electrode layer and / or first conductor track and / or second conductor track, a conductive metal, such as gold, platinum, indium, tin, or copper, can be applied to a foil and shaped to a suitable line width by structuring and / or etching. Additional functional layers can subsequently be applied, in particular printed, or applied using thin-film technology (evaporation or sputtering). With regard to further features and advantages of the method, in particular with regard to the medical instrument, the sensor stack, and the functional layers, reference is made in full to the statements made in the context of the first aspect of the invention. The features and advantages described there, in particular with regard to the medical instrument, the sensor stack, and the functional layers, also apply mutatis mutandis to the method according to the second aspect of the invention.

[0115] According to a third aspect, the invention relates to a method for producing a medical instrument according to the first aspect of the invention, in which the functional layers are produced using a carrier layer and / or stiffening layer as a separate sensor stack and then the separately produced sensor stack is applied, in particular printed, to the distal end of the medical instrument with removal of the carrier layer and / or stiffening layer.

[0116] For the purposes of the present invention, the term “carrier layer” is to be understood as a layer to which all further functional layers are applied, preferably with the exception of the adhesion layer, which is preferably applied on the side opposite the functional layer side of the carrier layer. For the purposes of the present invention, the carrier layer can also be referred to as a substrate layer. The carrier layer is preferably film-shaped. The carrier layer is preferably designed to be printable and, in particular, to withstand temperatures in a drying process without significant 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.

[0117] The stiffening layer can also be referred to as a liner layer within the meaning of the present invention. The stiffening layer is preferably film-shaped. More preferably, the stiffening layer has a greater layer thickness than the substrate layer. In particular, the stiffening layer can have a layer thickness that is at least 2 times greater than the layer thickness of the carrier layer. For example, the stiffening 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. This advantageously gives the entire structure the necessary rigidity to be processable, for example, in a screen printing process. Furthermore, the stiffening layer can, in particular, cover an adhesive layer applied to a backside of the carrier layer and thereby prevent unwanted sticking of the substrate layer.The stiffening layer can also be coated, for example with a silicone. This advantageously prevents permanent bonding between the stiffening layer and the carrier layer.

[0118] In principle, the carrier layer and the stiffening layer can have a different material or be made of a different material.

[0119] Preferably, however, the carrier layer and the stiffening layer comprise or consist of the same material. In particular, the material of the carrier layer has the same thermal expansion coefficient as the material of the stiffening layer.

[0120] The material of the carrier layer can in particular be selected from the group consisting of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethersulfone (PES), polysulfone (PSU), polyimide (PI), polycarbonate (PC), polyethyleneimine (PEI) and combinations of at least two of the aforementioned polymers.

[0121] The material of the stiffening layer can in particular 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 combinations of at least two of the aforementioned polymers.

[0122] Polyethylene naphthalate (PEN) is particularly preferred as the material for the carrier layer and the stiffening layer. Alternatively, polyethylene terephthalate (PET) may be preferred as the material for the carrier layer and the stiffening layer.

[0123] Preferably, the adhesive layer described in detail in the context of the first aspect of the invention is exposed by removing the carrier layer and / or stiffening layer.

[0124] With regard to further features and advantages of the method, in particular with regard to the medical instrument, the sensor stack, and the functional layers, reference is made in full to the statements made in the context of the first and second aspects of the invention. The features and advantages described there, in particular with regard to the medical instrument, the sensor stack, and the functional layers, also apply mutatis mutandis to the method according to the third aspect of the invention.

[0125] According to a fourth aspect, the invention relates to a sensor unit. The sensor unit is configured to detect a physical measurement variable and convert it into an electrical measurement signal and is designed in the form of a layered sensor stack with a first section and a second section.

[0126] The first section and the second section each have a plurality of functional layers arranged one above the other, in particular directly or not directly.

[0127] The functional layers are applied to one another in layers, at least in sections, overlapping one another, in particular printed.

[0128] The first section has at least the following functional layers: a first insulation layer covering the distal end of the medical instrument at least in sections, in particular only in sections or completely, ie continuously or contiguously, and electrically insulating, an electrically conductive first electrode layer applied, in particular printed, to the first insulation layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, a piezoactive piezo layer applied, in particular printed, to the first electrode layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, a piezo-layer applied, in particular printed, to the piezo layer at least in sections, in particular only in sections or completely, iecontinuously or coherently applied, in particular printed, electrically conductive second electrode layer, an electrically insulating second insulation layer applied, in particular printed, at least in sections, in particular only in sections or completely, ie continuously or coherently, to the second electrode layer and an electrically shielding shielding layer applied, in particular printed, at least in sections, in particular only in sections or completely, ie continuously or coherently, to the second insulation layer.

[0129] The second section has at least the following functional layers: an insulating layer covering the distal end of the medical instrument at least in sections, in particular only in sections or completely, ie continuously or contiguously, and electrically insulating, an electrically conductive first conductor track applied, in particular printed, to the insulating layer at least in sections, in particular only in sections or completely, ie continuously or contiguously, and an electrically conductive second conductor track applied, in particular printed, to the insulating layer at least in sections, in particular only in sections or completely, ie continuously or contiguously.

[0130] With regard to further features and advantages of the sensor unit, reference is made in full to the statements made in the previous description, in particular to the first aspect of the invention. The features and advantages described therein with regard to the sensor unit also apply mutatis mutandis to the sensor unit according to the fourth aspect of the invention.

[0131] Further advantages and features of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are illustrated schematically with reference to the drawings.

[0132] Fig. 1 shows a schematic, partially cut-off perspective view of an embodiment of a medical instrument according to the invention in the region of a distal end,

[0133] Fig. 2 shows in a schematically simplified cross-sectional view the medical instrument according to Fig. 1 along a section line ll-ll according to Fig. 1,

[0134] Fig. 3 shows a partially cut-off schematically simplified longitudinal section of the medical instrument according to Figs. 1 and 2 in the area of ​​the distal end,

[0135] Fig. 4 shows schematically a first section of a sensor stack of the medical instrument according to Figs. 1 to 3,

[0136] Fig. 5 shows schematically a second section of a sensor stack of the medical instrument according to Figs. 1 to 3 and

[0137] Fig. 6 shows a partially cut-off schematic side view of another embodiment of a medical instrument according to the invention, wherein individual components are shown schematically in a highly simplified manner to illustrate a basic structure. Fig. 1 schematically shows a medical instrument 1, for example in the form of a cannula. The medical instrument is only visible in the region of a distal end, which is intended for insertion into a patient's body. The distal end 2 can, for example, be a cannula tip, which has a piercing section 3 on the front side, which is designed in a basically known manner and is ground at an angle. A proximal end, not visible, has a basically known structure. The medical instrument 1 has a sensor unit 4, which is designed to detect a physical measurement variable and convert it into electrical measurement signals.The sensor unit 4 is arranged at the distal end 2 and is shown schematically in a highly simplified manner, particularly with reference to Figs. 1 to 3.

[0138] Preferably, the sensor unit 4 is designed in the form of an ultrasound transducer, as will be described in more detail below, which enables ultrasound-based localization of the tip 2 of the medical instrument 1 within a patient's body. This allows medical personnel to navigate the tip 2 within the patient's body during a therapeutic and / or diagnostic procedure. Suitable ultrasound-based methods for this purpose are generally known and are also referred to as tracking. Therefore, tracking as such need not be discussed in detail here.

[0139] The sensor unit is designed in the form of a layered sensor stack 4. The sensor stack 4 has a first section 4a and a second section 4b. The section 4a, which can also be referred to as the sensor section, preferably forms a distal section of the sensor stack 4. The section 4b, which can also be referred to as the contact section, preferably forms a proximal section of the sensor stack 4.

[0140] Furthermore, the first section 4a and the second section 4b are preferably arranged one behind the other, in particular directly behind the other. Particularly preferably, the first section 4a and the second section 4b are formed integrally. Alternatively, the first section 4a and the second section 4b can be formed separately from one another and connected to one another, in particular by a material bond.

[0141] Section 4a and section 4b each have a plurality of functional layers arranged one above the other (cf. Figs. 4 and 5). The functional layers are applied, in particular printed, layer by layer, at least partially overlapping one another. The sensor stack 4 is preferably produced using a printing process. Examples of suitable printing processes for producing the sensor stack 4 include screen printing, injection printing, dispensing, and / or stamp printing techniques. To form the individual functional layers of the sensor stack 4, which will be described in more detail below, materials with corresponding electrical and / or electronic functional properties are printed from a liquid and / or pasty form using the printing process. The functional layers are not shown to scale. For suitable layer thicknesses, reference is made to the general description.To achieve appropriate layer thicknesses, individual materials can be printed multiple times on top of each other to form one of the functional layers.

[0142] In the embodiment according to Figs. 1 to 5, the sensor stack 4 is applied, in particular printed, directly to a wall section 5 of the distal end 2 and thus firmly connected to the distal end 2. This eliminates the need for a separate application of a previously manufactured sensor stack, which significantly simplifies the manufacture of the medical instrument 1. Furthermore, air pockets between the wall section 5 and the sensor stack 4, such as those that can occur, for example, when a sensor stack is otherwise conventionally glued on, are avoided.

[0143] The layered structure of the sensor stack 4 and its sections 4a and 4b will be discussed in more detail below with reference to Figs. 4 and 5.

[0144] Thus, the first section 4a of the sensor stack 4 has a first insulation layer 6, which comprises an electrically insulating material or is formed from an electrically insulating material. The first insulation layer 6 is preferably printed directly onto the wall section 5. Accordingly, the first insulation layer 6 preferably forms a lowermost layer of the first section 4a.

[0145] Furthermore, the first section 4a has a first electrode layer 7 printed, in particular directly, onto the insulation layer 6. The first electrode layer 7 comprises an electrically conductive material or is formed from an electrically conductive material.

[0146] Furthermore, the first section 4a has a piezoactive piezo layer 9 printed onto the first electrode layer 7, in particular directly. The piezo layer 9 preferably converts ultrasonic pulses to be detected into corresponding electrical measurement signals in a generally known manner. Accordingly, the piezo layer 9 preferably forms an actual ultrasonic transducer of the sensor stack 4, with the remaining functional layers, for example, serving for electrical insulation or signal dissipation. The piezo layer 9 can in particular 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)),

[0147] Poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)), lead zirconate titanates (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AIN) and combinations of at least two of the aforementioned materials.

[0148] Furthermore, the first section 4a has an electrically conductive second electrode layer 10 printed onto the piezoelectric layer 9, in particular directly, which (likewise) comprises an electrically conductive material or is made of an electrically conductive material. The second electrode layer 10 and the first electrode layer 7 preferably independently comprise an electrically conductive material or preferably independently consist of an electrically 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 combinations of at least two of the aforementioned electrically conductive materials.

[0149] Preferably, the first electrode layer 7 and the second electrode layer 10 are formed differently. Preferably, the first electrode layer 7 comprises an electrically conductive metal, in particular an electrically conductive and nanoscale metal and / or an electrically conductive and microscale metal, or carbon, and the second electrode layer 10 comprises an electrically conductive polymer. Particularly preferably, the metal is silver and the polymer is poly(3,4-ethylenedioxythiophene).

[0150] As can be further seen from Fig. 4, the first section 4a also has a second insulation layer 13, which comprises an electrically insulating material or is formed from an electrically insulating material. The second insulation layer 13 is printed onto the second electrode layer 10 and the underlying functional layers. The second insulation layer 13 is preferably printed directly onto the second electrode layer 10. Furthermore, the second insulation layer 13 can be wrapped around the end face of the electrode layers 7, 10 and the piezoelectric layer 9, particularly in the area of ​​the latter.

[0151] The electrically insulating material of the first insulation layer 6 and the electrically insulating material of the second insulation layer 13 can be selected independently of one another from the group consisting of UV-curing materials, in particular polyester resins, thermally curing 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. Furthermore, the first section 4a has a shielding layer 14, which is printed directly onto the second insulation layer 13 and electrically and / or magnetically shields it and the additional functional layers located beneath it in a layer thickness direction D.The shielding layer 14 can, in particular, serve to shield the piezoelectric layer 9 against electrical and / or magnetic fields that could impair signal detection, conversion, and / or dissipation. The shielding layer 14 can, in particular, comprise or consist of a material selected from the group consisting of carbon, conductive polymers, in particular polypyrrole, doped polyethylene, polyaniline, or polythiophene, preferably poly(3,4-ethylenedioxythiophene), conductive metals, in particular gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and combinations of at least two of the aforementioned materials.

[0152] In addition, the first section 4a can have a biocompatible cover layer 15, which is arranged on the outside with respect to the layer thickness direction D. Accordingly, the biocompatible cover layer 15 forms an outer shell of the sensor stack 4. The cover layer 15 comprises a biocompatible material or is formed from a biocompatible material. The material can, for example, be selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), and combinations of at least two of the aforementioned materials. The biocompatible cover layer 15 prevents the remaining functional layers of the sensor stack 4 from coming into contact with the patient's body, which could potentially be accompanied by harmful chemical and / or biological interactions.

[0153] The second section 4b of the sensor stack 4 has an insulation layer 16. The insulation layer 16 is preferably printed directly onto the wall section 5 of the medical instrument 1. Accordingly, the insulation layer 16 forms a bottom layer of the second section 4b. The insulation layer 16 and the first insulation layer 6 of the first section 4a are preferably of identical design. In particular, the first insulation layer 6 of the first section 4a and the insulation layer 16 of the second section 4b are integrally formed. Alternatively, the first insulation layer 6 of the first section 4a and the insulation layer 16 of the second section 4b can also be formed separately from one another and connected to one another, in particular by a material bond. Furthermore, an electrically conductive first conductor track 17 is provided, which is printed in sections, in particular directly, onto the insulation layer 16.The first conductor track 17 can be formed integrally with the first electrode layer 7. Alternatively, the first conductor track 17 can be printed separately from the first electrode layer 7 and electrically contacted therewith.

[0154] Furthermore, the second section 4b has a second conductor track 18 printed on the insulation layer 16, in particular directly, in sections, wherein the second conductor track 18 is printed on another section of the insulation layer 16, in particular directly.

[0155] The first conductor track 17 and the second conductor track 18 each preferably comprise a conductive metal, in particular a conductive and nanoscale metal, or are formed from such a metal. The metal is preferably silver. In particular, the first conductor track 17 and the second conductor track 18 can be of identical design.

[0156] The first conductor track 17 and the second conductor track 18 serve to divert the electrical measurement signals of the piezoelectric layer 9 toward a proximal end of the medical instrument 1 (not shown in detail). The conductor tracks 17, 18 are preferably spaced apart from one another and routed along the insulation layer 16 toward the proximal end. Starting from this proximal end, the conductor tracks 17, 18 can be electrically conductively contacted with an evaluation unit for evaluating the electrical measurement signals of the piezoelectric layer 9.

[0157] Furthermore, the second section 4b can have an anti-corrosion layer 19. The anti-corrosion layer 19—as shown—can be formed in the form of separately formed layer sections 19a, 19b, and 19c. Alternatively, the anti-corrosion layer 19 can also be formed as a single, continuous piece. The anti-corrosion layer 19 is printed above the first conductor track 17 and the second conductor track 18 with respect to the layer thickness direction of the sensor stack 4. The anti-corrosion layer 19 can, for example, 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. As illustrated in Fig. 2, the medical instrument 1 in the present case has an approximately circular hollow cross-section.Preferably, at least the piezoactive piezo layer 9 is printed continuously and gap-free in the circumferential direction of the distal end 2. Accordingly, the piezo layer 9 preferably surrounds the circular wall section 5 shown in Fig. 2, preferably without gaps. This is particularly advantageous with regard to ultrasound-based tracking of the tip 2 in that a gap-related signal drop is avoided. Such a signal drop is detectable in the prior art, especially when a conventional sensor stack is wrapped around a cannula tip and glued to the cannula tip, forming a gap at the front end. If such a gap is aligned parallel to the direction of incidence of an ultrasound, a signal drop and thus an impairment of tracking cannot be easily avoided.The piezoelectric layer, which is printed in this case in a continuous, gap-free manner along the circumferential direction of the distal end 2, counteracts this. In particular, with the exception of the conductor tracks 17, 18, the remaining functional layers of the sensor stack 4 can also be printed circumferentially, so that the sensor stack 4 has a circular cross-section.

[0158] Fig. 6 shows a further embodiment of the medical instrument 1, which essentially corresponds to the embodiment previously described with reference to Figs. 1 to 5. To avoid repetition, reference is therefore made to the disclosure in connection with this embodiment. The following only discusses the essential differences between the embodiment shown in Fig. 6 and the previous embodiment.

[0159] The medical instrument 1 shown in Fig. 6 is partially cut away and shown in a highly simplified side view. The medical instrument is preferably in the form of a cannula 1. In contrast to the previously described embodiment, the medical instrument 1 has two sensor stacks. These sensor stacks 4 can either be printed directly onto the distal end 2 of the medical instrument 1 or printed separately and then applied to the distal end 2. Otherwise, the structure of the functional layers of the sensor stacks 4 corresponds to the structure of the previously described sensor stack 4 shown in Figs. 1 to 5. The two sensor stacks 4 are arranged at a distance from one another in the longitudinal direction L of the distal end 2. This type of arrangement can be used, for example, to determine the orientation of the distal end 2 using ultrasound.To simplify matters, each of the two sensor stacks 4 can be "tracked" using generally known methods, for example, ultrasound-based. If the respective position of both sensor stacks 4 is known, this allows a direct conclusion to be drawn about the orientation of the distal end 2.

[0160] In addition, an amplifier unit 20 is provided at the distal end 2. In this case, the amplifier unit 20 serves to amplify the measurement signals of the two sensor stacks 4. In an embodiment not shown in detail in the drawing, only one sensor stack can be provided and electrically connected to the amplifier unit for signal amplification. In this case, the amplifier unit 20 is electrically connected to the two sensor stacks 4 by means of signal lines (not shown in detail) and is designed in the form of a printed circuit. The printed circuit 20 can be connected to an evaluation unit for evaluating the amplified measurement signals by means of a further signal line 21. In this case, the printed circuit 20 is printed directly onto the wall section 5 of the distal end 2.In an embodiment not shown in detail in the drawing, the printed circuit 20 can first be printed separately and then applied to the wall section 5.

[0161] As indicated by the two dashed lines in Fig. 6, both sensor stacks 4, the printed circuit 20, and the signal lines extending between these components are covered by a metallic shielding layer 14 and / or a biocompatible cover layer 15. The shielding layer 14 and / or the cover layer 15 cover the entire distal end 2 of the medical instrument 1, with the exception of a piercing section not shown in detail in the drawing.

[0162] With regard to further features and advantages of the embodiments of a medical instrument according to the invention shown in Figs. 1 to 6, reference is made in full to the general description.

Claims

Claims. A medical instrument with a distal end intended for insertion into a patient's body and a sensor unit arranged at the distal end, which is configured to detect a physical quantity and convert it into an electrical measurement signal, wherein the sensor unit is designed in the form of a layered sensor stack with a first section and a second section, wherein the first section and the second section each have several superimposed functional layers, wherein the functional layers are applied layer by layer, in particular printed, at least partially overlapping, wherein the first section has at least the following functional layers: - a first insulating layer that covers at least part of the distal end of the medical instrument and is electrically insulating, - an electrically conductive first electrode layer applied at least partially to the first insulating layer, - a piezoactive piezo layer applied at least partially to the first electrode layer, - an electrically conductive second electrode layer applied at least partially to the piezo layer, - an electrically insulating second insulating layer applied at least partially to the second electrode layer and - a shielding layer applied at least partially to the second insulating layer and the second section having at least the following functional layers: - an electrically insulating insulating layer that covers at least part of the distal end of the medical instrument, - an electrically conductive first conductor track applied at least partially to the insulating layer and - an electrically conductive second conductor applied at least partially to the insulating layer. Medical instrument according to claim 1, characterized in that the first electrode layer and the second electrode layer are configured differently. A medical instrument according to claim 1 or 2, characterized in that the first electrode layer and the second electrode layer independently comprise an electrically 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 combinations of at least two of the aforementioned electrically conductive materials. A medical instrument according to any one of the preceding claims, characterized in that the first electrode layer comprises an electrically conductive metal, in particular a conductive and nanoscale metal, or carbon, and the second electrode layer comprises an electrically conductive polymer.A medical instrument according to claim 4, characterized in that the electrically conductive metal is silver and the conductive polymer is poly(3,4-ethylenedioxythiophene). A medical instrument according to any of the preceding claims, characterized in that the piezoelectric 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 titanates (PZT), lead magnesium niobate (PMN), zinc oxide (ZnO), aluminum nitride (AlN), and combinations of at least two of the aforementioned materials.A medical instrument according to any 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 and nanoscale metal. A medical instrument according to any of the preceding claims, characterized in that the sensor stack further comprises an adhesion layer arranged between the first insulating layer of the first section and the surface of the medical instrument and / or between the insulating layer of the second section and the surface of the medical instrument. A medical instrument according to claim 8, characterized in that the adhesion layer comprises an electrically conductive metal, in particular an electrically conductive and microscale metal. A medical instrument according to claim 7 or 9, characterized in that the metal is silver. A medical instrument according to any one of the preceding claims, characterized in that the second section further comprises an anti-corrosion layer applied above the electrically conductive first conductor and the electrically conductive second conductor with respect to a layer thickness direction D of the sensor stack. A medical instrument according to claim 10, characterized in that the anti-corrosion 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.Medical instrument according to one of the preceding claims, characterized in that the sensor stack, in particular the first section of the sensor stack, has a biocompatible cover layer which is arranged externally with respect to a layer thickness direction D of the sensor stack.Medical instrument according to one of the preceding claims, characterized in that the electrically insulating first insulating layer and the electrically insulating second insulating layer of the first section and the electrically insulating insulating layer of the second section independently comprise an electrically insulating material selected from the group consisting of UV-curing materials, in particular polyester resins, thermally curing 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. Medical instrument according to one of the preceding claims, characterized in that the shielding layer comprises a material, in particular an electrically conductive material, selected from the group consisting of carbon, conductive polymers, in particular polypyrrole, doped polyethylene, polyaniline or polythiophene, preferably poly(3,4-ethylenedioxythiophene), conductive metals, in particular gold, platinum, indium, tin, copper, silver, preferably nanoscale silver, and combinations of at least two of the aforementioned materials.Method for manufacturing a medical instrument according to one of the preceding claims, wherein the functional layers are applied to the distal end of the medical instrument to form the sensor stack, in particular by printing, or the functional layers are manufactured as a separate sensor stack using a carrier layer and / or stiffening layer, and subsequently the separately manufactured sensor stack is applied to the distal end of the medical instrument after removing the carrier layer and / or stiffening layer.

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