WO2002058549A1

WO2002058549A1 - Endoluminal expandable implant with integrated sensor system

Info

Publication number: WO2002058549A1
Application number: PCT/DE2002/000234
Authority: WO
Inventors: Hagen Thielecke; Andrea Robitzki; Alexandra REININGER-MACK; Thomas Stieglitz; Oliver Scholz; Karl Konstantin Haase; Tim SÜSELBECK
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2001-01-26
Filing date: 2002-01-24
Publication date: 2002-08-01
Also published as: DE10103503A1

Abstract

The invention relates to an endoluminal expandable implant with integrated sensor system, especially a stent. The stent base (1) is at least substantially enclosed on its inner or outer diameter by a flexible and extensible film (2). In said film (2), a plurality of electrodes (4), a thinned semiconductor chip (6) with integrated electronics and conductor tracks (5) for linking the integrated electronics (6) with the electrodes (4) are arranged in the form of an array. The integrated electronics (6) is adapted to control the electrodes for registering impedance spectra in order to obtain spatially resolved impedance spectra across the surface of the film (2). Conductor tracks (5) that establish an electrical link at an angle to the longitudinal axis of the implant body (1) on the film (2) are produced from a flexible material and/or have a meandering structure. The inventive implant can be conventionally implanted and expanded and supplies proliferation parameters for the purpose of a reliable risk stratification.

Description

Endoluminal expandable implant with integrated sensors

Technical application area

The present invention relates to an endoluminal expandable implant, in particular a stent, made of a cylindrical, radially expandable implant body, which is at least largely enclosed on its inner or outer circumference by a flexible film, in which sensor elements and a thinned semiconductor chip with integrated

Electronics and conductor tracks for connecting the integrated electronics with the sensor elements are arranged. The implant can in particular be designed as a stent, the integrated sensor technology of which provides data for risk stratification, for therapy control and, if appropriate, for controlling a controlled release of active substance in the body.

PRIOR ART For the treatment of stenoses in patients with coronary artery disease, percutaneous transluminal coronary balloon angoplasty (PTCA) is used. In this technique, an expandable balloon is inserted into the vessel and inflated there for a certain period of time so that it expands the vessel at this point. An essential limitation of the PTCA is the occurrence of a relapse stenosis within a period of 3-6 months after the intervention. The occurrence of a relapse stenosis is essentially due to the following factors. Very early after balloon dilatation, the elastic bevels in the vessel wall perform a return movement that reduces the vessel lumen that was initially reached. The mechanism of balloon dilation also leads to severe damage to the endotelial cell layer, which results in unmasking of the subendothelial localized vascular wall structures. Thrombocytic adhesion, thrombocytic aggregation, further platelet activation and thrombus formation are consequences of this vascular wall injury. Activated platelets lead to the activation of proliferation-active cell systems through the release of growth factors, but on the other hand they can also result in early complications of PTCA, the thrombotic vascular occlusion, by promoting thrombus formation.

The compression and dissection of the stenosing plaque caused by the expansion of the balloon leads to a proliferation of smooth muscle cells in the media. These smooth muscle cells migrate from the media into the intima and cause a further, so-called late lumen loss, several weeks after the initial balloon expansion.

In order to reduce the undesired restoring movement of the vessel wall, vascular prostheses (stents) are implanted either after prior balloon expansion of the vessel or directly via a balloon dilatation catheter. The stent consists of a cylindrical, radially expandable implant body which supports the expanded vessel lumen after the implantation and, if appropriate, subsequent radial expansion. The reduction in the incidence of restenosis after stent placement is essentially explained by an additional lumen gain. After the stent implantation, there is renewed endothelialization of the dilated and stented vascular segment, which, depending on the length of the stent, is completed after about four weeks. Parallel to this endothelial lining of the vessel lumen, the implanted stent induces a proliferation stimulus on the vessel wall and leads to a lumen reduction in this area, which in some of the treated patients can lead to focal or diffuse, the entire stent length regarding in-stent stenosis. Due to non-invasive parameters, it is currently not possible to carry out a secure risk stratification that allows individual predictability for the development of restenosis after stent implantation.

From the prior art, only stents with integrated sensors are currently known, which are designed to measure flow parameters. The measured values acquired via the sensors are transmitted wirelessly to a receiver outside the vessel in which the stent is implanted or outside the body.

No. 6,053,873 shows such a stent with integrated electronics and sensors for flow measurement. An elastic coil is placed around the stent, which serves as an antenna for data transmission and for energy consumption for the operation of the electronics. The publication shows an embodiment of a stent in which the impedance of the blood flowing through the stent lumen is detected and for determining the Flow rate is used. For this impedance measurement, a plurality of axially spaced-apart electrode pairs, each of electrodes lying opposite one another, are arranged together with the electronics in a thin flexible film which is attached to the stent. However, the stent of US Pat. No. 6,053,873 cannot be used for safe risk stratification, since knowledge of the proliferation parameters is necessary for this. These cannot be reliably determined from the measured flow parameters.

US 5,967,986 also describes a stent with integrated electronics and sensors for measuring various physical or biological parameters, in particular for flow measurement. In one embodiment, two electrodes run approximately helically along the length of the stent at a constant distance, via which tissue growth in the stent can be detected. The sensors or electrodes as well as the associated electronics are arranged on a thin flexible film, which for the most part encloses the stent on its inner surface.

Even with the stent of this publication, no reliable proliferation parameters can be obtained after the implantation, which are necessary for a safe

Sufficient risk stratification. Furthermore, with this as well as with the stent of the aforementioned publication, there is the problem that expansion of the stent after implantation can damage the integrated sensor system.

Based on this prior art, the invention has for its object an endoluminal expandable implant with integrated sensor technology, in particular a stent, which enables safe risk stratification after implantation.

Presentation of the invention

The object is achieved with the implant according to claim 1. Advantageous embodiments of the implant are the subject of the subclaims.

The present endoluminal expandable implant, hereinafter also referred to as a stent according to the preferred embodiment, consists in a known manner of a cylindrical, radially expandable implant body. The structure of such an implant body is known to the person skilled in the art. The implant body is at least largely enclosed on its inner or outer circumference by a thin and flexible first film. Sensor elements, a thinned semiconductor chip with integrated electronics and conductor tracks for connecting the integrated electronics to the sensor elements are arranged in the film. The film is attached to the implant body in a suitable manner. In the present implant, the first film with the integrated sensor elements and the semiconductor chip is designed to be stretchable, so that it can follow a radial expansion of the implant at any time. The sensor elements are formed by a multiplicity of first electrodes arranged in an array-like manner distributed over the film surface. The integrated electronics is for

Control of the first electrodes for the recording of impedance spectra between the or each of the first electrodes designed to cover the area the first film - and thus the inner or outer circumference of the implant - to obtain spatially resolved impedance spectra. Furthermore, conductor tracks, which produce an electrical connection transversely to the longitudinal axis or axial direction of the implant body on the first film, are optionally formed from an expandable material and / or run in a meandering shape. If the electrodes and the at least one semiconductor chip are arranged in such a way that no electrical connections transverse to the longitudinal axis of the implant body on the first film are required, the latter measure is of course not necessary.

In the case of this implant, which is preferably designed as a stent, a plurality of electrodes, preferably at least 6 electrodes, are thus arranged on the first film in such a way that they are coated with the tissue or plaque material that surrounds the inner or outer wall of the stent , have electrical contact. The electrodes are electrically connected to the electronics of the semiconductor chip, which drives the electrodes to record the spatially resolved impedance spectra. In addition, the electronics are preferably for evaluation and / or transmission of the detected ones

Measurement data trained to an external receiver. In order to determine the spatial distribution of the tissue and plaque parameters in or around the stent, the impedance spectra are arranged at different locations of the stent between them

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provide. The stent can be implanted in a conventional manner and expanded within the vessel without endangering the electronic components and the measurement properties.

In a preferred embodiment of the present implant, a second thin film is provided, which optionally bears against the first film via a thin intermediate layer. Like the first film, the second film is designed to be elastic and stretchable. The second film carries a capacitor array and conductor tracks for connecting the capacitors of the capacitor array to one another and connects the capacitor array via an electrical contact to the first film for energy supply with the electronics of the semiconductor chip. The conductor tracks on the second film, which establish an electrical connection transversely, in particular perpendicularly, to the longitudinal axis of the implant body, are formed from an expandable material and / or run in a meandering shape. This second film with the capacitor array provides an energy store which stores the energy which may be transmitted wirelessly from an external energy source or which is obtained by internal energy conversion and, if required, makes it available to the electronics of the semiconductor chip. For this purpose, the second film, like the first film, is designed to be electrically insulating and carries a multiplicity of microcapacitors which are connected to one another by the conductor tracks. The dimensions of the implant with the two foils differ only insignificantly from a conventional implant without due to the small thickness of the foils integrated sensors. Such a capacitor array, the capacitors of which are distributed over the full inner or outer surface of the stent, enables a high storage capacity without noticeably reducing the lumen of the stent. On the other hand, this energy storage enables reliable operation of the integrated electronics. Due to the stretchable configuration of the second film and the stretchability of the conductor tracks due to the special material or meandering course, the stent can be expanded in the usual way after the implantation.

The electrical components arranged in the second film, i.e. the capacitor array and the conductor tracks can, for the same purpose, also be integrated directly in the first film and can be electrically insulated from the other components of the first film. In such an embodiment, no separate second film is required, but only a layer-like structure of the first film.

In a further advantageous embodiment, the substrate film (first film) of the electrode array consists of a piezoelectric material. Second electrodes, for example as a correspondingly structured electrode layer, are arranged on both sides of this film. These electrodes are separated from the first electrodes thereon, the sensor elements, by an insulation layer. This configuration enables a continuous power supply and thus continuous monitoring to be implemented independently of external energy sources. Due to pressure changes inside the stent, for example as a result of the pulse beat, the piezoelectric film is stretched, so that a change in the voltage between the second electrodes of the two film sides results. The converted energy is stored in the capacitor array after an AC / DC conversion or is used directly to supply energy to the semiconductor electronics. In this case, the energy is also managed by the electronics integrated in the semiconductor chip. The second electrodes, which extend perpendicular to the longitudinal axis of the implant body, ie in the direction of expansion, are in turn either designed to be stretchable and / or run in a meandering manner in this direction.

The first electrodes are preferably arranged on the first film in such a way that they are equidistant after the intended expansion of the stent. This enables a simplified evaluation of the measurement data with regard to the spatial distribution of the tissue parameters. The person skilled in the art knows the relationships for deriving these parameters from the spectral impedance measurements. The result of this is that biological tissues have characteristic electrical and dielectric properties that can be determined using impedance spectroscopy.

A semiconductor chip with an approximately rectangular shape is preferably applied or integrated into the first film, which has a greater longitudinal than transverse dimension. The semiconductor chip is oriented on the film in such a way that its longitudinal axis runs approximately parallel to the longitudinal axis of the implant body. This will create a Stress on the semiconductor chip is minimized by stretching the film transversely to the axial direction. If necessary, the stretchability of this film in the region of the semiconductor chip can also be reduced.

In a further advantageous embodiment, all electrodes lie on the film in each case on straight lines running parallel to the longitudinal axis of the implant body, a separate semiconductor chip with integrated electronics for controlling the electrodes on the respective line being provided for each of the lines. In this case there is no electrical connection between the individual electrical components on the film in the direction of expansion, i. H. required transversely to the longitudinal axis of the implant. All conductor tracks run parallel to the longitudinal axis of the implant, so that the electrical components are not stressed by an expansion of the film due to the expansion of the implant.

The electronics are preferably designed to evaluate and / or transmit measurement data to an external unit. For this purpose, a transmitting and receiving coil is wound helically or double helically around the implant body and connected to the electronics. The electronics can furthermore have outputs for controlling a microsystem, optionally arranged on the implant body, for releasing the active substance. Such a microsystem for drug release is disclosed in the parallel German patent application 100 63 612.8, the design features of which are preferably also implemented in the present implant. The electronics include Here is a program that controls the release of the active ingredient depending on the measured parameters. The microsystem of 100 63 612.8, which is arranged above an active substance reservoir which is preferably integrated in the implant, consists of a thin carrier substrate which consists of a material impermeable to the active substance and has one or more through openings for the active substance. A plurality of electrodes are arranged in the area of the through openings and are controlled via electronics integrated in the carrier substrate or directly via the electronics in the present first film. The through openings are designed as microgaps and / or microchannels, each with electrodes arranged on both sides, and covered on one side of the carrier substrate by a layer of an electroporous material.

According to a further embodiment of the present implant, a second stent body is arranged coaxially around the first stent body, the first and optionally second film lying between the two stent bodies. The inner stent body is expanded in such a way that it is pressed against the outer stent body, so that the entire system is under mechanical tension.

In order to allow tissue to penetrate into the stent, the first and optionally the second film are preferably perforated. Furthermore, these foils can be provided with a layer that is under tensile stress, so that the foils are always on the surface due to the tensile stress of the implant body. It goes without saying that the direction of the tensile stress must be selected appropriately for this, depending on whether the film is applied to the inner or the outer circumference of the stent body. Of course, widened sensor elements can also be arranged on the first film and connected to the electronics in order to be able to detect further biological or physical parameters if necessary.

Brief description of the drawings

The present implant is explained again below using exemplary embodiments in conjunction with the drawings without restricting the general inventive concept. Here show:

Fig. 1 shows a schematic representation of a

Stents with integrated sensors for recording the spatial distribution of tissue and plaque parameters according to one

Embodiment of the present invention;

Fig. 2 is a schematic representation of a flexible, stretchable film with an electrode array and integrated

Circuit (not to scale);

3 shows a schematic illustration of a flexible and stretchable film with a stretchable capacitor array; Fig. 4 is a block diagram of the integrated

Circuitry according to an embodiment of the present invention; Fig. 5 is a schematic representation of a

Stents according to another embodiment of the present invention;

6a shows an example of a piezoelectric film for energy conversion in a top view;

6b shows a schematic sectional illustration of a sensor structure with a piezoelectric film according to FIG. 6a as substrate material; Fig. 7 shows an example of an arrangement of the

Electrodes, conductor tracks and IC's on a stretchable film; and

8 shows an example of a stent with an applied sensor system that is under internal stress before and after radial stent expansion.

WAYS OF IMPLEMENTING THE INVENTION FIG. 1 schematically shows an illustration of a possible embodiment of a stent with integrated sensors for continuously recording the spatial distribution of tissue and plaque parameters after implantation of the stent. The stent has a radially expandable cylindrical stent body 1, on the outer surface of which, in this example, a stretchable, flexible thin film 2 is applied, which carries an electrode array, an integrated circuit and conductor tracks. On this first film 2, a second flexible and stretchable film 3 is applied, which is a microcapacitor array with conductor tracks for the corresponding connection of the individual capacitors wearing. The individual electrodes 4 of the electrode array of the film 2, which come into contact with tissue growing into the stent, can be seen very well in the figure. The stent itself is constructed in the usual way and consists, for example, of a wire mesh. The two foils 2 and 3 enclose the stent body 1 almost completely in this example. The attachment to the stent body and the connection between the foils can be carried out using adhesives known to the person skilled in the art.

In the case of a radial expansion of the stent shown in FIG. 1, the two films applied expand in the same way as the stent, without damaging the electrical components which are integrated in or on the films.

To produce a flexible, elastic electrode array, i. H. the first film 2 with the electrode array of the electrodes 4, 2 metal layers for the electrodes 4 and conductor tracks 5 are deposited and structured on an elastomer film. An ultra-thin flexible silicon chip 6 is produced using semiconductor technology and is connected to the elastomer film 2 by a known connection technology for flexible chips on flexible substrates. The chip 6 is designed as a narrow rectangle and is preferably applied to the electrode substrate 2 such that the edges of the narrow sides of the rectangle lie in the direction in which the electrode substrate 2 is stretched when the stent body 1 expands.

Techniques for connecting a thinned semiconductor chip to a film are, for example, from Aschbrenner et al. , Concepts for Ultra Thin Packaging Technologies, Proceedings. 4 ^th International Conference on Adhesive Joining and Coating Technology in Electronics Manufacturing, 2000, pages 16 - 19.

FIG. 2 shows a schematic representation of an example of an electrode array applied to a film 2 with associated conductor tracks 5 and the semiconductor chip 6. The film 2 is an elastic and electrically non-conductive elastomer film which can be stretched at least in one direction (indicated by the arrows). The exposed electrodes 4 of the electrode array can be seen on the film and are connected via conductor tracks 5 to the semiconductor chip 6, which controls the electrodes. In order to minimize the forces on the electrical connections between the electrode array and the semiconductor chip 6 during and after the stent expansion, the extensibility of the film 2 in the region in which the chip 6 is located can be reduced. This can vary depending

Elastomer material can be achieved, for example, by local light or heat treatment (e.g. using a laser).

The electrodes 4 are arranged so that they are equidistant after stent expansion. Furthermore, the conductor tracks 5, in areas in which they extend in the direction of expansion of the film 2, are meandering. This meandering course of the conductor tracks 5 enables the film 2 to be stretched in the specified direction without the conductor tracks 5 being damaged or interrupted thereby. The meandering course thus enables an elastic electrical connection of the electrodes 4 to the Semiconductor chip 6. Connections 7 for a system for drug release and connections 8 for supplying energy to semiconductor chip 6 can also be seen in the figure. The semiconductor chip 6 has electronics or an integrated circuit (IC) which controls the electrodes 4 of the electrode array for impedance spectroscopic measurement. The control takes place in such a way that a spatially resolved measurement of the impedance is achieved as a function of the wavelength.

Of course, the number of electrodes in this and the other examples can also be increased further, in order, for. B. to achieve a certain spatial resolution or to cover a larger area.

An example of a block diagram of the integrated circuit is shown in FIG. 4. The electrodes 4, which are on a line (here referred to as the longitudinal axis l..m) parallel to the longitudinal axis of the stent body, are each with a

Multiplexer connected. The multiplexers each connect two adjacent electrodes 4 of a longitudinal axis with impedance analyzers, which determine impedance spectra for the electrode pairs. The impedance spectra are either written into a memory located on chip 6 via a control circuit or sent telemetrically to a receiving unit outside the vessel. An analysis circuit can be used to determine events from the impedance spectra in which control signals are sent to a system for the controlled release of active substance. The circuit receives the energy inductively from an external energy source and / or from energy converters, which are located on the stent. The energy is buffered in a capacitor array. Energy is taken from the capacitor array to operate the circuit. The energy management is carried out by a power management module that is integrated in the semiconductor chip 6.

FIG. 3 shows an example of a film 3 with an array of metallized film capacitors 9. The film 3 again consists of an elastomer substrate on which the film capacitors 9 are produced by combined deposition and structuring of metal and polymer layers. Concepts for the deposition of materials for the production of monolithic film capacitors are described, for example, in Rzad et al. .

Advanced Materials for High Energy Density Capacitors, IEEE 35 ^h International Power Sources Symposium, 1992.

In this example, the individual film capacitors 9 are connected or connected to one another via conductor tracks 10 made of an elastic, electrically conductive material, preferably a polymer material. The connections 11 of the capacitor array are connected to the connections for the energy storage on the film 2 with the electrode array. The foils 2, 3 for the electrode and capacitor array are then placed together around the stent body 1. A thin wire is wound around the stent with the sensor system in the form of a double helix, whereby a transmitting and receiving coil is formed. The ends of the coil are connected to the corresponding inputs on the semiconductor chip 6. g TJ m ß ß ß ri o ß TJ Φ rH ^ F Φ φ Φ ^ ß rd. SH

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Compression of this film 13 on the stent generates a voltage across the electrodes 14 via the piezoelectric effect, with which the semiconductor chip 6 can be operated and / or the capacitor array can be charged. With this integrated piezoelectric energy converter, the sensors can be operated for a long time independently of external energy sources.

In a further exemplary embodiment, a separate integrated circuit (6a-6d) is used for the electrodes 4, which are located on a line or axis parallel to the longitudinal axis of the stent body 1, for control and data acquisition. This arrangement makes it possible to dispense with stretchable conductor tracks within the electrode structure or to reduce the number thereof. The ICs (6a - 6d) of each axis are connected, for example, to a common transmitting and receiving coil and communicate with an external unit. Figure 7 shows one

Embodiment in which no separate foils are provided for the electrode array and the capacitor array. Rather, the electrodes of the electrode array are arranged on the same film 2 as the capacitor array. Of course, the conductor tracks 10 of the capacitor array are insulated from the electrodes 4 and conductor tracks 5 of the electrode array by a corresponding intermediate layer. In this example, the film is stretched when the stent expands perpendicular to the course of the conductor tracks 5 shown in the figure. FIG. 8 finally shows schematically an example of a stent in which the sensor system 18, consisting of the film 2 with the electrode array and optionally a further film with the capacitor array, is provided with a layer which is under tensile stress. This layer is deposited on the film 2 during the manufacture of the electrode array. As a result of this tension, the film itself takes on a cuff shape. The cuff is widened or compressed and placed around a stent body 1 or pushed into a stent body 1. A cuff 18 (sensor system) pushed over the stent body 1 can be seen in the example in FIG. 8a. The sensor system is stuck on the stent body due to its inherent tension. When the cuff is attached to the inner circumference of the stent body, the applied layer must of course cause an external tension. With radial expansion of the stent, the cuff expands, as can be seen in partial illustration b of FIG. 8. Due to the inherent tension, however, the cuff still lies securely on the stent body. The electrodes are arranged in this sensor system so that they have the desired position in the expanded state.

In addition to electrodes, other detectors for tissue or plaque characterization can of course also be arranged on the film or films. It is also possible to arrange additional sensors for other biological or physical parameters. In this case, the electronics of the Semiconductor chips can be adapted accordingly to the measurement tasks.

Even if individual aspects of the possible configurations of the electrode array and of the capacitor array and the underlying substrate foils are given in the preceding exemplary embodiments, the person skilled in the art will understand that these individual configurations can be combined with one another as desired. For example, both the capacitor array and the electrode array can be arranged on a common film, which can additionally consist of a piezoelectric material with corresponding electrodes for reducing the voltage. The piezoelectric film, a film for the electrode array and a film for the capacitor array can also be used separately. The arrangement of the electrodes of the electrode array is not restricted to specific patterns or distances. Rather, they depend on the desired spatial resolution. Furthermore, the interconnection of the individual electrodes for recording the impedance spectra can be carried out in different ways, as is known to the person skilled in the art. Both two-pole, three-pole and four-pole arrangements are suitable for such a task.

LIST OF REFERENCE NUMBERS

Stent body first stretchable film second stretchable film first electrodes first conductor tracks semiconductor chip connections for a system for drug release connections for a system for energy supply film capacitor second conductor tracks connection surface second stent body piezoelectric film second electrodes connection surface rear connection surface front side passivation layer sensor system

Claims

claims

1. Endoluminal expandable implant, in particular a stent, made of a cylindrical, radially expandable implant body (1), which is at least largely enclosed on its inner or outer circumference by a thin and flexible first film (2), in the sensor elements (4) and a thinned semiconductor chip (6) with integrated electronics and conductor tracks (5) for connecting the integrated electronics to the sensor elements (4), characterized in that the first film (2) is designed to be stretchable, the sensor elements made of a plurality of the surface of the film is distributed and the first electrodes (4) are formed and the integrated electronics for controlling the first electrodes (4) are designed to record spatially resolved impedance spectra, with conductor tracks (5), if necessary, which make an electrical connection transverse to the longitudinal axis of the Manufacture the implant body (1) on the first film (2) from a stretchable aren material exist and / or meandering.

2. Implant according to claim 1, characterized in that a second film (3), which is designed to be elastic and stretchable, optionally bears against the first film (2) via an intermediate layer, wherein the second film (3) carries a capacitor array and conductor tracks (10) for connecting the capacitors (9) of the capacitor array to one another and the electrical contact to the first film (2)

Capacitor array for power supply with the electronics of the semiconductor chip (6) connects, the conductor tracks (10) on the second film (3), which establish an electrical connection transverse to the longitudinal axis of the implant body (1), consist of an expandable material and / or meandering run.

3. Implant according to claim 1, characterized in that the first film (2) carries a capacitor array and conductor tracks (10) for connecting the capacitors (9) of the capacitor array to one another, the capacitor array being connected to the electronics of the semiconductor chip (6) for energy supply and the conductor tracks (10), which produce an electrical connection perpendicular to the longitudinal axis of the implant body (1), consist of an expandable material and / or run in a meandering shape.

4. Implant according to one of claims 1 to 3, characterized in that the first film (2) consists of a piezoelectric material (13) with bilaterally arranged second electrodes (14) by an insulation layer (17) against the first Electrodes (4) are insulated, being electrical Voltages which are present due to the expansion or compression of the first film (2) due to the piezoelectric effect between the second electrodes (14), via electrical connections for charging the capacitor array and / or

Power supply of the semiconductor chip (6) and second electrodes (14), which extend transversely to the longitudinal axis of the implant body (1) on the first film (2), consist of an expandable material and / or run in a meandering shape.

5. Implant according to one of claims 1 to 4, characterized in that the first electrodes (4) are arranged on the first film (2) such that they are equidistant after the intended expansion of the implant body (1).

6. Implant according to one of claims 1 to 5, characterized in that the semiconductor chip (6) has an approximately rectangular plan shape with a larger longitudinal than transverse axis, the longitudinal axis of the semiconductor chip (6) approximately parallel to

Longitudinal axis of the implant body (1) runs.

7. Implant according to one of claims 1 to 6, characterized in that the extensibility of the first film (2) in

Area of the semiconductor chip (6) is reduced.

8. Implant according to one of claims 1 to 7, characterized in that the first electrodes (4) are arranged on a plurality of lines running parallel to one another and to the longitudinal axis of the implant body (1), a separate semiconductor chip with integrated electronics for each of the lines Control of the electrodes (4) is provided on the respective line and the conductor tracks (5) between the electrodes (4) and the semiconductor chips only run parallel to the lines.

9. Implant according to one of claims 1 to 8, characterized in that the electronics are designed to evaluate and / or transmit measurement data to an external unit.

10. Implant according to claim 9, characterized in that the electronics comprise at least one impedance analyzer, a multiplexer, a memory, a transmitting and receiving unit and a power management module.

11. Implant according to claim 10, characterized in that the electronics each have a multiplexer for a fixed number of electrodes (4) from the plurality of electrodes of the first film (2).

12. Implant according to one of claims 1 to 11, characterized in that a transmitting and receiving coil is helically or double helically wound around the implant body (1) and connected to the electronics.

13. Implant according to one of claims 1 to 12, characterized in that the electronics have outputs for controlling a unit for drug release arranged on the implant body (1).

14. Implant according to one of claims 1 to 13, characterized in that a further cylindrical and radially expandable implant body (12) is arranged coaxially above the first implant body (1), the first (2) and optionally second film (3) between the first (1) and the further implant body (12) lie and the first

Implant body (1) is mechanically clamped by expansion against the further implant body (12).

15. Implant according to one of claims 1 to 14, characterized in that the first (2) and / or second film (3) are perforated.

16. Implant according to one of claims 1 to 15, characterized in that the first film (2) is provided with a layer which is under tensile stress, so that the film (2) will contact the surface of the implant body at any time due to the tensile stress

(1) creates.

17. Implant according to one of claims 1 to 16, characterized in that further sensor elements on the first film

(2) are arranged and connected to the electronics of the semiconductor chip (6).