Active implantable medical device encapsulated in a biocompatible and insulating material

Abstract

The invention relates to an active implantable device comprising a printed circuit, components, and tracks. According to the invention, at least the components and the tracks which are suitable for developing a voltage with a DC component during use are buried in the printed circuit. The device further comprises an electrically insulating housing made of biocompatible material that entirely and seamlessly encapsulates the whole of the printed circuit, components and tracks.

Description

[0001] DESCRIPTION

[0002] TITLE: Active implantable medical device encapsulated in a biocompatible and insulating material.

[0003] The present invention relates to an active implantable device having a protective housing.

[0004] It finds a particularly interesting application in the field of implantable medical devices for which a hermetic housing is used to prevent the migration of pollutants towards the electronic components inside the housing.

[0005] State-of-the-art hermetic enclosures are made of glass, ceramic, metal, or a combination of these three material families. The hermeticity of these enclosures is tested with a gas, typically helium, either to qualify the process or for each product in quality control. There is a standardized test that relies on injecting helium into the enclosure and leak detection. When leaks are below a certain threshold, sufficient hermeticity is guaranteed.

[0006] The objective of "hermeticity" is multiple. It is to prevent the penetration of "polluting" substances into the housing because, over time, these pollutants can condense and become liquid. The presence of substances in the liquid phase accelerates oxidation-reduction phenomena which can become fatal for the device. Note that these polluting substances can also already be present in the housing when they are included, for example, in or on the electronics. Therefore, it is necessary to combine the use of a hermetic housing with precautions for cleaning, drying and absorption of polluting substances in order to eliminate electrochemical problems regardless of their source of contamination.

[0007] There are known sealed ceramic housings, for example aluminum oxide, or another biocompatible crystal, which have the advantage of being electrically insulating and perfectly hermetic to liquids and gases. The disadvantages that explain their virtual absence in the sector of active implantable medical devices, beyond sealed feedthroughs, are:

[0008] - extreme mechanical fragility,

[0009] - difficulty in shaping,

[0010] - a high cost.

[0011] The major drawback of glasses and ceramics, which are biocompatible electrical insulating materials, is their extreme fragility and mass. As a result, almost all hermetic enclosures are made of metal, almost exclusively titanium, which offers an optimum in terms of biocompatibility / cost / robustness / handling.

[0012] Waterproof titanium housings are known with sealed feedthroughs such as platinum / iridium alloy conductors coated with an alumina-type ceramic insulator and combined with a titanium flange. This represents almost all implantable electronics and, in any case, all long-term active implantable medical devices (>24 months) implanted in the last year. Titanium has the advantage of ensuring complete hermeticity to gas and liquid over the long term. The only disadvantage of titanium for certain applications, in particular for the transmission of energy and / or signals, is that it is electrically conductive and acts as an electromagnetic shield. Therefore, when one wishes to transmit energy and / or an electromagnetic signal, it is necessary to provide a device placed outside the titanium housing.Typically, an antenna is placed in a header, for example made of epoxy, and connected to the electronics via a waterproof feedthrough.

[0013] Biocompatible polymer materials are commonly used in "non-active" implantable medical devices, such as prostheses, due to their ease of processing, particularly by machining and molding. These materials are mainly elastomers, for example silicones, thermosets, for example epoxy resins or thermoplastics, for example polyetherketones (PEK). Attempts have been made for a long time to use such polymers to encapsulate electronics to constitute an active implantable medical device. Systematically, the devices produced have shown degraded long-term reliability due to defects of electrochemical origin. They can still be used for active implantable medical devices only in the very short term, i.e. use of less than 24 months or even 12 months. The long-term disadvantages are as follows:

[0014] - long-term non-hermeticity due to chemical absorption phenomena by diffusion, in particular of water, which ends up causing defects by electrochemical corrosion,

[0015] - degradation of thermal, UV, oxidation, humidity origin, leading to the loss of original mechanical properties, and / or electrical insulation and / or the release of encapsulated particles etc.

[0016] In fact, none of these materials are able to successfully pass the helium hermeticity test. The transport of gas in the volume of a polymer material is done by chemical diffusion according to a law called Fick's law. This is a diffusion phenomenon, i.e. the migration speed varies according to the gradient of the concentration rate of the substance. When the polymer is placed in a solvent (for example water), we end up finding water molecules throughout the volume, which is characterized by a mass gain rate of the order of a few % to several tens of %. It should be noted that the material is not necessarily porous in the "physical" sense of the term, since penetration only occurs by chemical diffusion in gaseous form and not in liquid form. Thus, only gaseous compounds are potentially internalized and / or released.In any case, the solvent may end up in liquid form in the housing after a second condensation step. This phenomenon is accelerated by the ambient temperature falling below the dew point (which depends on the humidity level, for example around 5000 ppm for a temperature of 0°C and 50 OOOppm for a temperature of 37°C). Then, a few "liquid" molecular layers (from three) are enough to create an environment conducive to electrochemical phenomena.

[0017] We know the document Nathaniel Dahan, "The application of PEEK to the packaging of implantable electronic devices" department of medical physics and bioengineering university college of London, 2013, relating to studies to eliminate or slow diffusion through the polymer, either by adjusting its composition or by adding a conformal coating on (or inside) the housings. These tests made it possible to slow the phenomenon by a few months, but not enough to envisage a long-term application of more than two years.

[0018] Other studies have consisted of trying to live with the penetration of a solution, by adding a desiccant and / or a conformal coating on the printed circuit (parylene type), by controlling the cleaning of contaminating ions on the surface which are necessary to start the oxidation-reduction phenomena (chloride or bromide), by using electrodes made of gold or other noble metal (eg "electroless nickel immersion gold" in English, ENIG), by reducing the voltage gradients by moving the tracks away etc. Again, the electrochemical phenomena are slowed down but not sufficiently for the intended application.

[0019] Thus, with the aim of reducing the electrochemical phenomena of electronic equipment used in harsh environments (humidity, temperature, etc.), silicone or parylene coatings are traditionally used. The advantage of silicone coating is its low cost of purchase and removal (cold casting). Its disadvantage is its "lack of adhesion" to the printed circuit board (or PCB) and the components or conductors. The silicone will become loaded with solvent (water) and will eventually form a film of solvent (water) on the surface of the printed circuit board over the long term. The product's lifespan is greatly improved because the silicone has transformed conduction in the volume into surface conduction. But over a long period of time, this does not completely solve the problem.

[0020] For parylene, the observation is the same. The deposition process is different since the parylene is sublimated and then deposited by adsorption on the surface of the PCB. It is then condensed and then polymerized to form a very thin and very uniform layer, which penetrates into all the corners of the electronic PCB and its components. Apart from the fact that the process is very expensive (because the deposition is very long when the thickness is significant), the observation is the same as for silicone... In addition to the problem of adhesion to the surface (difficulty adhering to metals, delamination by delamination), parylene is fragile when it is too thick: it cracks. In the long term, the failure rate due to electrochemical phenomena is still too high for implantable medical applications. Despite all these attempts, electrochemical phenomena still appear in the long term.The main electrochemical phenomena causing defects are corrosion of the tracks / electrodes, the appearance of short circuits due to dendritic growth between tracks / electrodes, the appearance of functionally unacceptable parasitic signals (leakage currents), etc.

[0021] The present invention aims to increase the intrinsic reliability of active implantable medical devices over the long term.

[0022] Another aim of the invention is to increase the safety of people in the long term, in particular by guaranteeing electrical and / or chemical insulation through the absence of the release of toxic substances.

[0023] The invention also aims to reduce the cost and mass of active implantable medical devices.

[0024] At least one of the goals is achieved with an active implantable medical device comprising a printed circuit board (PCB), components and tracks.

[0025] According to the invention, at least the components and tracks likely to develop a voltage with a DC component during use are buried totally or partially in the printed circuit. And the device comprises an electrically insulating housing made of biocompatible material completely and without discontinuity of material encapsulating the entire printed circuit, components and tracks.

[0026] With the device according to the invention, two envelopes are put in place, a first envelope of the printed circuit around the electronics and a second envelope which is the electrically insulating housing.

[0027] The first envelope is the fact of burying the electronics in the printed circuit board in such a way as to eliminate any creepage and any clearance lines. More precisely, at least the components and tracks subjected to an electric field gradient with a continuous component are buried. By burying, we mean that the same material used as a support for the printed circuit board is also used as an insulating layer for the surface of the printed circuit board, leaving the components inside and in direct contact between the support and the insulating layer. Using the same material as the support means using a layer whose adhesion is free from surface defects (non-adhesion, delamination, etc.). The support for the printed circuit board is, for example, a glass fiber reinforced epoxy type FR.4.

[0028] With the burial according to the invention, two conductive elements of a component (track or electrode) or between components cannot be connected by a direct line either in the air or along a surface. In other words, for each pair of conductors in an electrical circuit, there is neither a clearance line nor a creepage line.

[0029] These creepage and clearance lines, when they are on the surface of a printed circuit, transform into electrical conduction lines in the presence of pollutants and condensed water vapor. They can thus cause defects in the printed circuit. The electrochemical phenomena causing the defects appear in the long term in the presence of a polarization voltage (DC component, for "Direct Current" in English). These phenomena originate on the surface of the printed circuits and become negligible in the absence of a DC component. The DC component can be functional (at the terminals of a capacitor, a DC power supply, etc.) or parasitic (self-generated by battery effect in the presence of a metal / metal junction).

[0030] The first envelope makes the electronics robust against surface defects but not intrinsically biocompatible. Since the first envelope considerably reduces the risks of an electrical malfunction of the printed circuit due to pollutants, the invention provides a second biocompatible envelope making the assembly biocompatible, therefore implantable in the long term. But advantageously according to the invention, instead of using a titanium envelope, a biocompatible insulating case is used. Titanium has the advantage of being perfectly hermetic but the disadvantage of being conductive (blocking of transmission signals between the inside and the outside). Many biocompatible insulating materials are known. They have the advantage of allowing the passage of electromagnetic signals but the disadvantage of being less hermetic than titanium.But this disadvantage is largely offset by the fact that the printed circuit becomes a volumetric object capable of protecting the buried components from possible substances which might pass through the biocompatible insulating material.

[0031] The device according to the invention makes it possible to be satisfied with a non-hermetic housing according to current standards. The migration of a gaseous substance by a diffusion process according to Fick's law is accepted. Thus, current helium tests become obsolete for this type of "non-hermetic" housing.

[0032] Another advantage of replacing the titanium casing with an electrically insulating casing is also to allow for a more isotropic antenna radiation pattern since the casing will not act as an electromagnetic "screen".

[0033] With the continuity of material all around the buried electronics, the latter is completely isolated from its environment, thus guaranteeing an absence of particulate release and electrical insulation.

[0034] The solution according to the invention makes it possible to make any implantable device intelligent since it is now possible to integrate remote communication means and radiofrequency power supply means. Any implantable device is, for example, a knee, femur, vertebrae or any other type of prosthesis. There is no electrical contact between the buried electronics and the environment outside the housing.

[0035] According to an advantageous characteristic of the invention, the biocompatible material may comprise a polymer from the family of polyetherketones (PEK), a polyaryletherketone (PAEK) or a polyetheretherketone (PEEK).

[0036] The use of a PEK polymer allows for all functions such as electrical insulation, shaping and biocompatibility. A PEK polymer also has a proven level of reliability superior to other solutions in terms of high melting temperature, thermoplastic behavior, ductility, hardness, elasticity over a certain deformation range, etc. In particular, PEK allows for a minimum material thickness, which improves the level of integration, without degrading the other characteristics necessary for insulation. The polymer can be a polyetherketone, a polyaryletherketone (PAEK) or a polyetheretherketone (PEEK).

[0037] According to the state of the art, for a given geometry and design, the characteristic time constant of the probability of a defect appearing ("time to failure" in English), follows the Arrhenius law. This empirical law contains parameters (proportional factor or exponential factor of an activation energy) which depend on the design choices. The speed of appearance of defects varies exponentially with the temperature. Thus, it is possible during a qualification step to accelerate the aging process by increasing the temperature. We then understand the double interest of using high-temperature materials such as PEK polymers. They allow both to improve reliability because they themselves are less subject to aging effects and they allow accelerated aging tests to be carried out during the development and qualification of the design.

[0038] According to the invention, the biocompatible material may comprise biocompatible epoxy resin. Such a material has the advantage of being simple to implement.

[0039] According to the invention, the biocompatible material may comprise silicone or ultra-high-molecular-weight polyethylene (UHMWPE). The latter has a lower melting temperature than PEK (<136°C) and may be lower than the maximum temperature acceptable for embedded electronics. Note that, on the other hand, UHMWPE is less reliable than PEK over the very long term.

[0040] According to an advantageous characteristic of the invention, only the components and tracks likely to develop a voltage with a DC component during use beyond their electrochemical potential are buried in the printed circuit. A threshold of 1.5V, corresponding in particular to the electrochemical potential of gold, can be set as a decision criterion for an acceptable DC component level. Otherwise, all the components and tracks can be buried in the printed circuit, regardless of their constituent material.

[0041] With burial, we ensure that no pair of electrical tracks with a potential difference with a DC component is exposed, i.e. without clearance. This means, for example, that all capacitors, diodes, transistors, voltage regulators, DC power supplies, etc. are buried. A component without a DC component, for example an inductor coil carrying an alternating current, may not be buried. For reasons of integration and space reduction, however, it is preferable to bury it as well.

[0042] According to the invention, the electrically insulating housing can be produced by overmolding.

[0043] In fact, in order to ensure the continuity of the material of the case, it is possible to proceed by overmolding, taking care not to exceed the maximum temperature that the buried electronics can withstand, of the order of 175°C for a few minutes.

[0044] The electrically insulating housing can also be made by 3D printing or by welding several assemblies, for example two half-shells. Each of the half-shells can be made without discontinuity of material by injection under pressure using molds. Welding can be carried out by laser, ultrasound, friction or electromagnetic heating. The advantage of laser welding is that it allows perfect continuity of material without heating beyond the weld line and by perfectly controlling the temperature gradients. Typically, this makes it possible to reduce the distance between the buried electronics and the weld line and thus optimize the total size of the device and in particular its thickness without degrading its reliability.

[0045] According to the invention, all the components and all the tracks likely to develop a voltage with a continuous component during use are completely buried within the same material constituting the printed circuit. The device according to the invention may comprise a biocompatible sealed feedthrough comprising:

[0046] - a conductor made of biocompatible material; at least part of the conductor being buried in the printed circuit and connected to a track capable of developing a voltage with a direct component during use,

[0047] - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor.

[0048] Such a biocompatible sealed feedthrough can be considered a buried sealed feedthrough. This arrangement ensures end-to-end material continuity. This amounts to including the sealed feedthrough in the buried components of the buried electronics. For example, the sealed feedthrough is pre-mounted with the other components on a first printed circuit board, and the whole thing is buried in the final printed circuit board with layers of FR.4 epoxy (matrix or prepreg). In this case, the sealed feedthrough is preferably a surface-mounted component and not a through-hole component. Material continuity is then ensured by the epoxy resin of the printed circuit board.

[0049] In a non-buried context of the biocompatible sealed crossing, the device according to the invention may comprise:

[0050] - a connection track made on the printed circuit in a non-buried manner,

[0051] - a biocompatible watertight crossing comprising:

[0052] - a conductor made of biocompatible material connected to the connection track;

[0053] - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor.

[0054] With such an arrangement, a gap may exist between the biocompatible sealed feedthrough and the PCB, this gap can be filled with a biocompatible insulating material, such as a heat-cured epoxy resin, ideally the same material as the PCB. Ideally, the flange is made of the same material as the enclosure.

[0055] Tracks and components are active elements participating in the electronic functions implemented by the printed circuit assembly.

[0056] One or more sealed feedthroughs can be provided. A sealed feedthrough can be an electrode.

[0057] To ensure sufficient sealing between the housing and the sealed feedthrough, the assembly consisting of the buried electronics and the sealed feedthrough can be overmolded. In other words, the housing is made over the assembly.

[0058] A case can also be produced by 3D printing, under conditions that are essentially identical to those for overmolding.

[0059] Preferably, a sealed feedthrough is produced separately. This sealed feedthrough is composed of at least one conductor and a flange. The assembly of the sealed feedthrough can be carried out using a method that guarantees the absence of creepage with a very high reliability rate. In a preferred embodiment, this assembly is carried out by overmolding the conductor with the biocompatible insulating material. The overmolding conditions are defined such that long-term reliability is guaranteed for a given mission profile (temperature, pressure, mechanical stresses, etc.). In a preferred embodiment, the material used for the flange is the same material as that used for the housing.

[0060] It is observed that compared to a conventional sealed feedthrough based on ceramic as an insulator and a metal flange for example, the flange here is at the same time the object ensuring sealing, electrical insulation and material continuity. The ceramic part has been eliminated, which reduces manufacturing costs and improves the long-term robustness of the device.

[0061] Thus, in a preferred embodiment, it is possible to assemble the sealed feedthrough with the housing while ensuring perfect continuity of material. The advantage of using identical polymer materials makes it possible to ensure good welding between the housing and the flange, for example by ultrasound, or friction, or electromagnetic heating, or even in a preferred solution by laser welding. Advantageously, at least a second conductor can be provided in the same biocompatible sealed feedthrough or in another biocompatible sealed feedthrough. This second conductor can be electrically connected to a track of the printed circuit by a face distinct from the face where the first conductor is connected. The two conductors can constitute a dipole capable of conducting a DC voltage.In order to reduce the effectiveness of creepage lines that would appear in the long term as a result of delamination phenomena, it is therefore planned to place the connection points of the conductors as far apart as possible. By placing the two conductors on two different sides of the printed circuit, the distance is increased as much as possible, which reduces both the importance of the creepage line and the DC field gradient.

[0062] According to one embodiment, the electrically insulating housing may comprise a through hole intended to fix the implantable device to the living tissue (generally a muscle) or several through holes intended to fix the implantable device to the living tissue (generally a muscle) and prevent any translational and / or rotational movement.

[0063] The hole allows the device to be fixed to a muscle to prevent subcutaneous or submuscular displacement. Having several holes prevents any translational or rotational movement of the device, as well as the risk of twisting or even tearing of the tissues. In the case of a polymer housing, it is possible to produce a housing in which at least one through hole is made, with a typical diameter of around 1 mm.

[0064] When the biocompatible material is a polymer from the polyetherketone (PEK) family, or more precisely polyaryletherketone (PAEK), this biocompatible material can be a natural material loaded with carbon with a mass loading rate of less than or equal to 1%, or even less than 0.1%, or even less than 100 ppm. This loading rate of the biocompatible material must be lower than the rate beyond which there is electrical percolation, because the biocompatible material would then become electrically resistant, or even electrically conductive and no longer electrically insulating. The mechanical properties would also be altered. Preferably, the load is pure and amorphous carbon, in the form known as "carbon black". A material with a low carbon loading is intended to:

[0065] - the preservation of exceptional mechanical and thermal properties,

[0066] - the preservation of “insulating” type electrical properties, and the significant increase in the absorption of an electromagnetic wave in the infrared or near infrared band, which facilitates welding operations.

[0067] Advantageously, the device may comprise at least one feed coil or antenna intended to receive energy by magnetic coupling and to power components of the printed circuit; the feed coil or antenna being buried in the printed circuit.

[0068] Such a coil or antenna receives energy to power the implantable electronics. It is possible to have an active implantable medical device that has either an energy transfer function, a signal transfer function, or both. In the case of energy transfer, there are, in addition to the constraints linked to the medical application, thermal constraints. Indeed, the device must not heat the living tissue with which it is in contact by more than two Kelvin. The thermal issue depends on the performance of the device in terms of efficiency, but also on its surface area. Indeed, it is recognized by those skilled in the art that the body is capable of adapting in order to absorb the excess energy dissipated in the device as long as the surface density of thermal power remains below a threshold of the order of 400 W / m 2The device according to the invention makes it possible to offer a reduced thickness than the devices of the prior art.

[0069] In one embodiment, if the power to be transmitted is not too high, for example < 5W, or even <2W, or even <1W, it is possible to integrate the antenna into the thickness of the buried electronics.

[0070] The antenna and / or coil, which is capable of transferring energy and / or a signal into the buried part, is buried with the rest of the electronics. This is to ensure a first complete electrical isolation with the printed circuit.

[0071] The printed circuit may comprise several layers, a first layer carrying a first feed coil or antenna, a second layer carrying a second feed coil or antenna, and a third layer disposed between the first and second layers and carrying components to be powered.

[0072] We can then have several layers with different functions. We alternate layers of winding, layers of electronics and layers of winding to achieve symmetry. The advantage of symmetry is to guarantee better long-term reliability of the printed circuit because it eliminates internal thermomechanical constraints on the printed circuit.

[0073] Alternatively, the feed coil or antenna can be positioned away from the PCB. When the power to be transmitted is greater than 1W, or even 2W, or even 5W, it is possible to place the device electronics and the coil / antenna side by side.

[0074] According to another aspect of the invention, there is provided a system comprising a first active implantable device as described above and a second implantable device, the two devices being connected to each other by a conductive cable made of biocompatible material covered with a covering sheath made of a polymer from the family of polyetherketones (PEK), polyaryletherketones (PAEK) or polyetheretherketone (PEEK).

[0075] The first device may be a medical device and the second device may be a probe for capturing an electrophysiological signal, or for supplying electrical energy to the patient or to another implantable device in the form of current or voltage, or both. This is the case, for example, for a pacemaker, an implantable defibrillator, a neurostimulator, a transcutaneous energy transfer device, a heart pump, an insulin pump, a hormone pump, an ascites pump, a cochlear implant, a hearing aid, etc. In these specific cases, it is necessary to be able to electrically interface two implantable devices or two modules of an implantable device. At least one of the two devices has the characteristics of the device according to the invention, allowing it to transmit energy and / or signals with an extracorporeal device.

[0076] To ensure excellent adhesion, the biocompatible material of the housing can be a polymer from the polyetherketone (PEK) family, or more precisely polyaryletherketone (PAEK) family, and the material of the printed circuit in which part of the conductor is buried can be a hot-cured epoxy resin.

[0077] The conductor cable may be a multi-strand conductor.

[0078] According to a first possibility of the invention, at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with:

[0079] - of a driver, and

[0080] - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor. Advantageously, the conductor of the sealed bushing is electrically connected to the conductive cable in a stripped area, a layer of hot-cured epoxy resin being deposited by overmolding in the stripped area to ensure continuity of material between the flange and the covering sheath.

[0081] Epoxy resin can cover part of the cover sleeve and part of the flange.

[0082] According to a second possibility of the invention, at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with:

[0083] - of a driver, and

[0084] - a flange made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor. And the conductor of the sealed bushing is electrically connected to the conductive cable in a stripped area, a biocompatible heat-shrinkable sheath made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family covering the stripped area to ensure material continuity between the flange and the covering sheath. A laser weld is made between the heat-shrinkable sheath and the covering sheath, and between the heat-shrinkable sheath and the flange.

[0085] Laser welding can be performed between the heat shrink tubing and the cover tubing, and between the heat shrink tubing and the flange.

[0086] The heat shrink tubing covers both part of the cover sleeve and part of the flange.

[0087] According to a third possibility of the invention, at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with:

[0088] - of a driver, and

[0089] - a flange made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor. And the conductor of the sealed bushing is electrically connected to the conductive cable in a stripped area. A biocompatible heat-shrinkable sleeve made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family covers the stripped area to ensure material continuity between the flange and the covering sleeve. A laser weld is made between the heat-shrinkable sleeve and the covering sleeve, and between the heat-shrinkable sleeve and the flange. A layer of heat-cured epoxy resin covers the biocompatible heat-shrinkable sleeve.

[0090] The biocompatible heat-shrinkable tubing is welded to both the flange and the cover sleeve to eliminate leakage lines. Advantageously, the heat-cured epoxy resin layer is deposited by overmolding the sealed feedthrough and a portion of the heat-shrinkable tubing to mechanically hold the assembly together.

[0091] According to the invention, the same electrically insulating housing made of biocompatible material can completely and without discontinuity of material encapsulate the first active implantable device, the second implantable device, and the conductive cable; the housing having the function of a covering sheath around the conductive cable.

[0092] Thus the first device, conductor and second device assembly comprises the same and unique encapsulation material.

[0093] The device according to the invention can be described as a semi-sealed assembly. The use of a polymer to make the housing makes the standard helium test inapplicable since the gas penetrates by diffusion through the housing.

[0094] The device according to the invention tends to eliminate the appearance of a creepage line between the inside of the housing and the outside of the housing. The possible presence of a creepage line therefore means that the semi-sealed housing is not electrically insulated and that it does not ensure its function of protection against particulate release. A creepage line can be characterized by a continuous surface between the inside of the housing and the outside of the housing whose thickness would be greater than three layers of solvent, 2 to 3 nm for water. It is thus possible to quantify the importance of the creepage line, for a given housing thickness, by its useful section. When the device is placed in a solvent (for example water), the creepage line will fill with said solvent, characterized by a known electrical conductivity. There is then equivalence between the importance of such a creepage line and the electrical admittance (the inverse of the resistance).Thus, the quality of the semi-sealed encapsulation can be estimated by an impedance measurement, and in particular by a DC resistance measurement, between at least one of the electrodes of the device placed in a conductive solvent and another electrode placed in said solvent.

[0095] A real-time diagnostic system for the insulation status of an implantable device is thus provided, comprising an encapsulation case made of biocompatible insulating material. This device may be as described above according to the invention.

[0096] The system includes:

[0097] - an implantable controller which is electrically connected to the implantable device via a conductor covered with a biocompatible insulating material,

[0098] - an external implantable electrode, external to the encapsulation box.

[0099] The controller is configured to: - either inject a direct current between the conductor and the electrode, measure a voltage between the conductor and the electrode, and signal the presence of a creepage line when the measured voltage exceeds a predetermined threshold,

[0100] - either apply a direct voltage difference between the conductor and the electrode, measure a current between the conductor and the electrode, and signal the presence of a leakage line when the measured current exceeds a predetermined threshold.

[0101] This technique makes it possible to control the quality of the sealing and / or electrical insulation of the device either during its development (process qualification), or during its manufacture (quality control), or even during its use since it is located in the body in a humid environment.

[0102] The conductor and the electrode are of course insulated from each other. When the device is a processing unit for a heart pump, the electrode can, for example, be the mechanical ground of the heart pump.

[0103] Other advantages and characteristics of the invention will appear on examining the detailed description of a non-limiting embodiment, and the appended drawings, in which:

[0104] [Fig. 1] Figure 1 is a schematic sectional view of an active implantable medical device comprising components embedded in a printed circuit and a biocompatible insulating housing according to the invention,

[0105] [Fig. 2] Figure 2 is a schematic perspective view of creepage lines and clearance lines on a printed circuit board,

[0106] [Fig. 3] Figure 3 is a schematic sectional view illustrating a sealed feedthrough fixed on a non-buried track of the printed circuit according to the invention, [Fig. 4] Figure 4 is a schematic sectional view illustrating a sealed feedthrough partially buried in the printed circuit according to the invention, [Fig. 5] Figure 5 is a schematic sectional view of two devices encapsulated together according to the invention,

[0107] [Fig. 6] Figure 6 is a schematic sectional view of a junction between a cable and a sealed bushing using an epoxy resin according to the invention, [Fig. 7] Figure 7 is a schematic sectional view of a junction between a cable and a sealed bushing using a heat-shrinkable sheath according to the invention,

[0108] [Fig. 8] Figure 8 is a schematic sectional view of a junction between a cable and a sealed bushing using an epoxy resin and a heat-shrinkable sheath according to the invention,

[0109] [Fig. 9] Figure 9 is a schematic sectional view of a housing formed by two half-shells incorporating fixing holes according to the invention, and

[0110] [Fig. 10] Figure 10 is a schematic view illustrating the self-diagnostic measurement of the insulation of the device from a single electrode according to the invention.

[0111] The embodiments which will be described below are in no way limiting; it will be possible in particular to implement variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0112] In particular, all the variants and embodiments described are intended to be combined with each other in all combinations where there is no technical obstacle to this.

[0113] In the figures, elements common to several figures retain the same reference.

[0114] Although the invention is not limited thereto, we will now describe an active implantable device equipped with a housing based on biocompatible insulating material from the polyetherketone (PEK) family or more precisely polyaryletherketones (PAEK).

[0115] In Figure 1, the active implantable device 1 according to the invention can be seen overall. The printed circuit 2 is not only a substrate on which components are installed, but a volume material in which electronic components 3 and tracks 4 are buried.

[0116] The printed circuit board 2 is made of FR4 type glass fiber reinforced epoxy. This same material is used both as a support for the printed circuit board and as an insulating layer for the surface of the printed circuit board, leaving the components inside and in direct contact between the support and the insulating layer. Using the same material as the support means using a layer whose adhesion is free from surface defects.

[0117] In the example of Figure 1, all the components are completely buried in the volume of the printed circuit 2. But it is possible to consider burying only some of these components and specifically the elements likely to develop a voltage with a DC component between two tracks in use and in particular beyond a threshold of 1.5V. This means, for example, that all capacitors, diodes, transistors, voltage regulators, DC power supplies and connected tracks must be buried. An inductance coil or an antenna carrying an alternating current may not be buried.

[0118] The technology for burying elements in a printed circuit is known to those skilled in the art and was initially developed to increase the degree of integration of electronics, but its function has been diverted here since it makes it possible to eliminate any creepage line and any clearance line as defined in Figure 2.

[0119] In Figure 1, there is also a housing 5 which completely encloses, without discontinuity of material, the printed circuit 2. A space 52, for example with air, may exist between the housing 5 and the printed circuit 2, in particular when the printed circuit is held by pads. This space may not exist totally or partially when the housing is for example obtained by overmolding. The housing 5 is made of a biocompatible insulating material such as polyetherketone (PEK) or more precisely a polyaryletherketone (PAEK) which is a thermoplastic polymer that a person skilled in the art knows how to machine, extrude or inject. The assembly comprising the printed circuit, the components and the tracks can be covered by overmolding with PEK at a temperature above the glass transition temperature and for a duration allowing the integrity of the electronics of the printed circuit to be preserved.

[0120] The function of the housing 5 is to provide the biocompatible character that the printed circuit 2 does not necessarily possess, to serve as a barrier against any pollutant when the device is implanted in a body, to guarantee electrical insulation between the printed circuit and the patient's body, and to allow any transmission of electromagnetic energy (radiofrequency communication and / or energy transfer) between the inside and the outside of the housing.

[0121] In Figure 2 is illustrated a conventional printed circuit which is a flat insulating substrate 6 on which tracks 7 are mounted. Pollutants and / or water vapor can settle on the surface of the flat insulating substrate 6 and create by their presence unwanted conduction lines between the tracks 7. To reduce this phenomenon, barriers 8 and spacings 9 can be made on a substrate to extend the length of the creepage lines 10 and the clearance lines 11. A clearance line represents the shortest distance path in the air between two conductors. A creepage line represents the shortest distance path along a surface between two conductors.

[0122] The barriers 8 and the spacings 9 are not sufficient to prevent the long-term occurrence of defects in the presence of pollutants and a bias voltage. The solution of the present invention is to bury all the components, active and passive, and tracks inside the printed circuit. The same material is used all around the components and tracks. Thus, creepage lines and clearance lines are eliminated. For each pair of conductors in an electrical circuit, there is neither clearance line nor creepage line. The addition of a simple conformal coating on the surface makes it possible to eliminate clearance lines but not creepage lines due to poor adhesion phenomena at the interface with the insulating flat substrate 6. Using the same material as the insulating flat substrate 6 to act as a coating makes it possible to eliminate both clearance lines and creepage lines.It is in this sense that we speak of continuity of material, for example FR.4, at the level of the printed circuit 2 as illustrated in Figure 1. In this case, the continuity of material of the printed circuit 2 protects the tracks 4 and the buried components 3 from all electrochemical phenomena. But since this material of the printed circuit 2 is generally not biocompatible, and since double electrical insulation must be ensured, the continuity of material of the printed circuit 2 alone is not sufficient to guarantee long-term reliability. Continuity of material is also required at the level of the housing 5 in Figure 1, but with a different material, for example PAEK, electrically insulating and biocompatible. Then, the continuity of material of the housing 5 protects the patient from all electrical risks and particulate releases.

[0123] Figure 3 illustrates a connection between one of the tracks 4 of the printed circuit 2 and a biocompatible sealed feedthrough 12A which can be used to connect the device according to the invention to another implantable device.

[0124] The biocompatible sealed feedthrough 12A comprises at least one conductor 13A and a flange 14A. The conductor 13A may be made of copper or silver-coated copper, or any other conductive material, or preferably be made of a biocompatible material, for example a platinum / iridium alloy, or gold. The flange 14A is made of an electrically insulating material, identical to that of the housing 5. The biocompatible sealed feedthrough 12A was produced prior to assembly on the printed circuit 2 by following a process known to those skilled in the art such that, even if there is an interface between the two different materials (conductor 13A and flange 14A), there is no creepage path. To eliminate the creepage path despite the absence of material continuity, the sealed feedthrough is generally produced by overmolding the material of the flange 14A around the conductor 13A at high pressure and high temperature.The choice of a PEK material and in particular PAEK is particularly well suited for this. The melting temperature of a PEK and in particular of a PAEK is too high to be able to carry out this operation in the presence of electronics and this is the reason why the sealed feedthrough 12A is produced prior to the assembly of the printed circuit 2.

[0125] The assembly between a 12A biocompatible sealed feedthrough and the printed circuit 2 can be carried out using two different processes which will be detailed below.

[0126] In a first method according to Figure 3, the printed circuit 2 is produced in a first step as described previously with buried components and tracks, except that at least the track 4A, called the connection track to be connected to the sealed feedthrough, is not buried. The latter is extended to one end of the printed circuit 2 so that it can be electrically connected to the conductor 13A. Preferably, the printed circuit 2 is through-hole so that the track 4A and the conductor 13A can be soldered, for example on the lower face.

[0127] In Figure 3, the conductor 13A is in the shape of an inverted “L”. A first vertical part passes through an extended layer of the printed circuit 2 to reach perpendicularly the track 4A arranged on the lower face of this extended layer. The second horizontal part of the conductor 13A in Figure 3 extends beyond the housing 5. The flange 14A completely envelops the entire part of the conductor 13A located between the extended layer and an internal face of the housing 5.

[0128] Generally speaking and for all the embodiments according to the invention, the flange can be contained inside the housing or be taken in the thickness of the housing as a constituent element of this housing.

[0129] The watertight crossing has a particular shape with the following advantageous constraints:

[0130] - Position the flange 14A on the printed circuit 2 so that the conductor 13A is in through contact with the track 4A, and / or

[0131] - the height of the flange 14A is substantially identical to that of the printed circuit 2, and / or

[0132] - flange 14A is used as a well to make a double pour of insulating material (on top and bottom).

[0133] Once the biocompatible sealed feedthrough 12A is soldered onto the printed circuit board 2, the presence of creepage lines is observed both on the top and on the bottom of the printed circuit board 2, at the interfaces between the material of the flange 14A and the printed circuit board 2. It is necessary in an additional step to eliminate these creepage lines. For this, the known process of “resin fill” or “back filling” can be used by pouring an insulating material 200 alternately from above and from below. As we have seen previously, this pouring will eliminate the clearance lines but not necessarily the creepage lines since there are always interfaces between the material 200 and the material 2 and the material 14A.But if a hot-cured epoxy resin is correctly chosen as material 200, then it is known to those skilled in the art that it will be possible to eliminate both the creepage line between the material 200 and the material of the printed circuit 2, itself being an epoxy resin. What is less known to those skilled in the art is that the combined use of a hot-cured epoxy resin and a PEK, and more particularly a PAEK, also makes it possible to eliminate the creepage lines between the flange 14A and the printed circuit 2. It is thus possible to introduce a biocompatible sealed feedthrough into a printed circuit 2 in which there is no longer a creepage line.

[0134] In a second method more advantageous than the first, the assembly in Figure 4 of the sealed feedthrough 12B is carried out during the manufacture of the printed circuit 2. In this second method, the sealed feedthrough becomes a component that is buried in the printed circuit 2 and the “back filling” or “resin fill” operation is eliminated, as well as the use of the heat-cured epoxy resin material 200. In this case, the biocompatible sealed feedthrough 12B has a different shape since the electrical contact between the at least one track 4B and one end of the conductor 13B is made using the SMD (surface-mounted component) soldering process. The conductor 13B extends from the track 4B to one end outside the housing 5 via the printed circuit 2 and the flange 14B. The conductor 13B is “Z” shaped with one end in the printed circuit and the other end outside the housing.The flange 14B is in the shape of an inverted "T" with a foot entirely contained in the printed circuit 2. The flange 14B does not need to form a well since the elimination of the creepage lines is carried out during the production of the printed circuit 2, the material of which is an epoxy resin capable of adhering hot to the material of the flange 14B during the manufacturing step of the printed circuit 2. It is understood that the choice of materials and manufacturing processes is one of the keys to the success of the operation in order to guarantee the elimination of creepage lines. This is why the choice of the material 14B among PEK and more particularly PAEK is important and forms part of the invention.

[0135] In order to now guarantee the continuity of material at the level of the housing 5, it is preferable that the at least one conductor 13A, 13B is surrounded by a flange 14A, 14B whose material is identical to that of the housing 5. For example a PEK and more precisely a PAEK. The biocompatible sealed feedthrough 12A, 12B can be assembled to the housing 5 according to a method known to those skilled in the art so that the latter has a continuity of material. The assembly is preferably carried out by laser welding between the flange 14 and the housing 5.

[0136] When at least one second conductor is required, for example to connect the medical device to a bipolar cable, then either this second conductor is placed in the same flange 14A, 14B as the first conductor 13A, 13B, or a second biocompatible sealed feedthrough is preferably placed near the biocompatible sealed feedthrough 12 in order to facilitate assembly of the cable.

[0137] In Figure 5, two printed circuits 15 and 16 are seen, of the same nature as the printed circuit 2 according to the invention, connected together by conductive cables 17. The cables 17 are intended to be connected to the conductors of the sealed feedthroughs 13A, 13B. Each of the printed circuits is produced according to the invention. It is observed that when there are at least two biocompatible sealed feedthroughs, although there is no creepage line likely to degrade the long-term reliability of the printed circuits, there potentially remains a creepage line between the two conductors of the two biocompatible sealed feedthroughs. When there is a direct voltage between the at least two conductors, there is a risk of degradation of the conductors by electrochemical phenomena described above, for example by corrosion. This is all the more critical when the voltage is high.However, when we want to transmit energy, we will tend to choose the highest possible voltage to reduce current and losses. A first possibility is to never use DC voltage, but for example an AC voltage. The disadvantage of this obvious solution is that we must add DC / AC and AC / DC converters on either side of the line, which adds losses and reduces the available space. There is another solution, the subject of the invention, which consists of extending the continuity of material along the entire length of the active implantable medical device 1. In Figure 5, the active implantable medical device comprises the assembly consisting of the two printed circuits 15 and 16 and the conductive cables 17. To ensure the continuity of material, this assembly is covered with the same biocompatible insulating case 18.To do this, it is possible to use, for example, a conductive cable made of biocompatible material covered with a sheath made of a material identical to that of the housing 5, for example a PEK or more precisely a PAEK. This cable technology is known to those skilled in the art, in particular for its robustness and intrinsic reliability. The conductor is preferably a multi-strand conductor in order to ensure long-term reliability of the cable and its connectors, in particular at the electrical junction with the biocompatible sealed feedthrough. The multi-strand conductor can be covered by an extrusion process according to a process known to those skilled in the art.

[0138] The assembly between the covered multi-stranded conductor and the conductor of the biocompatible sealed feedthrough 12A, 12B requires some precautions in order to eliminate a creepage distance. The electrical connection can be made in different ways, for example by tightening with a screw, or crimping, or by laser welding. Once the electrical contact is made, the creepage distance must be eliminated by adding a new electrical insulation without creepage distance. We can again proceed in three different ways, shown respectively in figures 6, 7 and 8.

[0139] The first possibility is to overmold the PAEK-covered cable and the PAEK flange of the sealed feedthrough with a heat-cured epoxy resin. As we have seen previously, it is possible to obtain an overmold without creepage distance with this solution. However, the mechanical forces that will occur at the cable will possibly lead to the appearance of a creepage distance in the long term, unless the volume of the overmold is very large. In Figure 6, we can see a conductor cable 19 covered with a covering sheath 20, a conductor 21 (of type 13A or 13B) and a flange 22 (of type 14A or 14B) of a biocompatible sealed feedthrough of type 12A or 12B. The two conductors 19 and 21 are connected at point 23. To do this, a stripped area (without covering sheath 20 and without flange 22) was made at the end of the two conductors 19 and 21.In this first solution, the stripped area is filled with a hot-cured epoxy resin 24. This epoxy resin covers the ends of the covering sheath 20 and the flange 22.

[0140] The second possibility is to use, in accordance with Figure 7, a biocompatible heat-shrinkable sheath 26 made of a material identical to that of the housing 5, for example a PEK or more precisely a PAEK. Such sheaths are known to those skilled in the art. The sheath 26, once retracted, covers the ends of the covering sheath 20 and the flange 22 and ensures the elimination of the clearance lines. The additional use of welding, for example laser welding, between the sheath 26 and, on the one hand, the flange 22 of the biocompatible sealed feedthrough and, on the other hand, the covering sheath 20, makes it possible to eliminate the leakage lines. In Figure 7, the same elements as those in Figure 6 bear the same references. In this solution, the stripped area 25 is not filled and may contain air.

[0141] Preferably, the insulating materials are identical, particularly PEK and more specifically PAEK. In this second solution, there are no longer any creepage lines, but for certain applications there remains a risk of long-term failure. Indeed, since the cable is flexible, it is possible that the electrical connection 23 between the cable 19 and the conductor 21 of the sealed bushing could break in the long term.

[0142] In order to eliminate this risk, in a third preferred solution according to Figure 8, the two methods presented above are combined. First, the conductor cable 19 is electrically welded to the conductor 21 of the sealed bushing. Then the PAEK heat-shrinkable sheath 26 placed on the PAEK covering sheath 20 of the cable and on the flange 22 of the PAEK sealed bushing is reduced in order to eliminate the clearance line. The heat-shrinkable sheath 26 is then laser-welded on the one hand with the covering sheath 20 and on the other hand with the flange 22 in order to eliminate the creepage line. Then the whole is overmolded with a small volume of heat-cured epoxy resin 24.In a preferred solution, the heat-shrinkable sheath 26 made of PAEK is located between the inside at 26a and the outside at 26b of the epoxy resin overmolding 24, which allows it to absorb the mechanical energy of torsion or tension of the cable and to act as a strain relief flange. In Figure 8, the same elements as those in Figures 6 and 7 bear the same references. In this third solution, the stripped area 25 is covered by the heat-shrinkable sheath 26, then the whole is overmolded by the heat-cured epoxy resin 24.

[0143] It is understood from Figure 5 that, if this solution is implemented on each side of the cable 17, then an active implantable medical device 1 is provided whose continuity of material of the biocompatible insulating housing 18 is ensured from end to end and with long-term reliability compatible with the intended application. Such configurations can occur for example, and in a non-limiting manner, between a transcutaneous energy transfer device and a cardiac assistance pump.

[0144] Figure 9 shows a device according to the invention in sectional view with an illustration of fixing holes 27, 28 and 29 through a housing 30. The housing 30 is of the same nature as the housing 5 but with fixing holes. This device can include all the features as described in the other figures. At least one, or even at least two, or even at least three holes are provided allowing mechanical fixing of the housing 30 to human tissue by simple sewing. A hole is for example 1 mm in diameter and crosses the entire height of the housing. The holes 27 and 28 pass through the housing 30 and the printed circuit 31 (of the same nature as the printed circuit 2 but with through holes) without damaging the electronic components 32 (of the same nature as the components 3). Adding a hole in a printed circuit is known to those skilled in the art for fixing it in a housing.These holes are obtained by making studs 33, 34 in the housing 30 between which the printed circuit is embedded. These studs are drilled in the middle so that a hole exists in the entire housing. The housing is then made by assembling two PAEK half-shells. In order to ensure the absence of a creepage line, continuity of material is guaranteed by welding the two PAEK half-shells, for example with a laser. Note that it is not possible to achieve such a sealed geometry with a titanium housing, which explains why current titanium housings do not have a fixing system. Such a fixing system is placed on the "header" of titanium devices, but since this "header" is generally only on one side of the device, the fixing does not prevent rotation. The present invention aims to eliminate this problem and thus greatly improve the quality of the fixing and the durability of the implanted device.

[0145] A system is provided for real-time diagnosis of the state of health of a first device 35 (of the same nature as an implantable medical device 1), made of insulating polymer material as illustrated in FIG. 10. The objective is to determine the importance of a possible leakage line associated with the sealed feedthroughs of the device 35. This diagnosis can be carried out by another implantable device 36 connected to the first device 35 via a conductive cable 37 (of the same nature as the conductive cable 17) and a biocompatible sealed feedthrough 38 (of the same nature as the sealed feedthroughs 13A or 13B). In the case of an implantable medical device 35, this second device 36 may be a remote controller, for example the controller of a heart pump.To do this, it is sufficient to set up a measurement of the insulation impedance between one of the conductors of the sealed feedthrough 38, preferably the common potential, and an electrode 39 located elsewhere in the human body, for example the metal mass of a conventional titanium case. The conductor of the sealed feedthrough 38 and the metal mass then constitute a dipole of two electrodes. When the sealed feedthrough 38 is composed of at least two conductors, for example in the case of a transcutaneous energy transfer device, a single electrode can be formed at the level of the second device 36 using a star resistive bridge of at least two identical resistors (greater than 10 kOhm, or even 100 kOhm, or even 1 MOhm) connected to each of the at least two conductors 37 in order to constitute a common mode potential. It is this common potential which then constitutes the second electrode.The advantage of this solution is that it can be used to test, with a single device 36, the extent of a possible creepage line appearing on any of the conductive cables 37 and / or the conductors of the sealed feedthrough 38. The measurement is carried out, for example, by injecting a DC voltage between the two electrodes and measuring the DC current between the two electrodes in order to calculate an admittance. In order to prevent this DC voltage from generating electrochemical phenomena, it will be reduced. In any case, it should be less than 1.5VDC, or even less than IV, or even 500mV or even 100mV. It is also possible to use a DC generator whose polarity direction is regularly reversed, at a very low frequency of the order of 1Hz, or even 0.1Hz, or even 10mHz. There will then be no more electrochemical problems. The current measurement is then obtained by synchronous demodulation using a technique known to those skilled in the art.In normal operation, i.e. in the absence of creepage lines on one of the conductive cables 37 and / or the sealed feedthrough 38, the DC current must tend towards a zero or very low value. The measurement of the current is directly proportional to the importance of any creepage lines. When the current is too high, then the galvanic isolation is no longer ensured or a creepage line likely to degrade the long-term reliability is detected in one of the conductive cables 37 or the sealed feedthrough 38, whether at the level of the housing or the connecting cable, and a maintenance operation must be launched. The trigger threshold must be adapted according to the geometry of the design and in particular the length and surface area of ​​the active implantable medical device.

[0146] When the active implantable medical device is made entirely according to the invention, i.e. all the housings are made of PEK insulating material and more precisely PAEK, then a specific electrode can be used for measuring the creepage lines, by electrically connecting the patient's tissues by means of a biocompatible sealed feedthrough according to the invention.

[0147] In Figure 10, we see an example of insulation measurement with a megaOhmmeter 40 by connecting at least one conductor of the conductive cable 37, ideally the one which is connected to a common potential of the first device 35 (or to at least two conductors via the common mode resistance network as described previously) to an electrode of the megaOhmmeter, the other electrode 39 being connected to a reference potential connected to the patient's tissue via a biocompatible sealed feedthrough.

[0148] The reference potential is a conductor 39 outside the device 35 for which the diagnosis is carried out, this conductor 39 being able to be either of the same nature as the conductor 13A or 13B of a sealed feedthrough according to the invention, or the titanium casing of a conventional device.

[0149] The geometry, i.e. the surface area of ​​the external electrode and the distance from the device 35 is fixed in order to be able to compare the current values ​​obtained. For example, the surface area of ​​the external electrode may be substantially identical to the surface area of ​​the housing. The distance between the external electrode and the device 35 may be the square root of the surface area of ​​the housing. The acceptable leakage resistance threshold may be adjusted depending on the application. It is for example 1000 ohm, or even 1000 ohm, or even 1000 ohm, or even 1000 ohm. Thus the present invention can be seen both as the possibility of changing the nature of a medical device housing to enable it to transmit energy and / or information, but also as the possibility of making a purely mechanical prosthesis intelligent by adding medical device functionalities to it.

[0150] The invention has the following advantages:

[0151] - possibility of transmitting energy and / or information

[0152] - reduction of the thickness and / or mass of the active implantable medical device,

[0153] - introduction of the possibility of mechanical deformation,

[0154] - addition of mechanical fixing systems,

[0155] - limitation of the rise in temperature of living tissues,

[0156] - enables long-term reliability to be demonstrated over a short period of time, or even to detect a failure in situ,

[0157] - integration of a long-term active implantable medical device into a polymer prosthesis.

[0158] Of course, the invention is not limited to the examples just described. Many modifications can be made to these examples without departing from the scope of the present invention as described.

Claims

CLAIMS 1. Active implantable medical device comprising a printed circuit, components and tracks, characterized in that: - the components and tracks are completely buried in the printed circuit, this printed circuit being a volume material in which all the components and tracks are buried, and - it comprises an electrically insulating housing made of biocompatible material completely and without discontinuity of material encapsulating the entire printed circuit, components and tracks; the biocompatible material comprising a polymer from the family of polyetherketones (PEK), a polyaryletherketone (PAEK) or a polyetheretherketone (PEEK).

2. Device according to claim 1, characterized in that the biocompatible material comprises biocompatible epoxy resin.

3. Device according to claim 1, characterized in that the biocompatible material comprises silicone.

4. Device according to claim 1, characterized in that the biocompatible material comprises ultra-high-molecular-weight polyethylene (UHMWPE).

5. Device according to any one of the preceding claims, characterized in that all the components and all the tracks are completely buried within the same material constituting the printed circuit.

6. Device according to claim 5, characterized in that it comprises a biocompatible sealed crossing comprising: - a conductor made of biocompatible material; at least part of the conductor being buried in the printed circuit and connected to a track, - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor.

7. Device according to any one of claims 1 to 4, characterized in that it comprises: - a connection track made on the printed circuit in a non-buried manner, - a biocompatible watertight crossing comprising: - a conductor made of biocompatible material connected to the connection track; - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor.

8. Device according to claim 7, characterized in that it comprises a space between the biocompatible sealed crossing and the printed circuit, this space being filled with a biocompatible insulating material.

9. Device according to any one of the preceding claims, characterized in that the electrically insulating housing is produced by overmolding.

10. Device according to any one of claims 1 to 8, characterized in that the electrically insulating housing is produced by 3D printing.

11. Device according to any one of claims 1 to 8, characterized in that the electrically insulating housing is produced by welding several assemblies.

12. Device according to claim 11, characterized in that the welding is carried out by laser, ultrasound, friction or electromagnetic heating.

13. Device according to any one of the preceding claims, characterized in that the electrically insulating housing comprises one or more through holes intended to fix the implantable device to living tissue. through holes intended to fix the implantable device to living tissue and prevent any translational and / or rotational movement.

14. Device according to any one of the preceding claims, characterized in that when the biocompatible material is a polymer from the polyetherketone (PEK) family or a polyaryletherketone (PAEK), this biocompatible material is loaded with carbon with a mass loading rate of less than or equal to 1%, or even less than 0.1%, or even less than 100 ppm.

15. Device according to any one of the preceding claims, characterized in that it comprises at least one coil or power antenna intended to receive energy by magnetic coupling and power components of the printed circuit; the coil or power antenna being buried in the printed circuit.

16. System according to claim 15, characterized in that the printed circuit comprises several layers, a first layer carrying a first coil or a feed antenna, a second layer carrying a second coil or a feed antenna, and a third layer arranged between the first and the second layer and carrying components to be powered.

17. Device according to any one of claims 1 to 14, characterized in that it comprises at least one coil or antenna intended to receive energy by magnetic coupling and supply components of the printed circuit; the supply coil or antenna being arranged at a distance from the printed circuit.

18. System comprising a first active implantable device according to any one of the preceding claims and a second implantable device, the two devices being connected to each other by a conductive cable made of biocompatible material covered with a covering sheath made of a polymer from the family of polyetherketones (PEK), polyaryletherketones (PAEK) or polyetheretherketone (PEEK).

19. System according to claim 18, characterized in that the conductive cable is a multi-strand conductor.

20. System according to claim 18 or 19, characterized in that at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with: - of a driver, and - a polymer flange from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor, and in that the conductor of the sealed bushing is electrically connected to the conductive cable in a stripped area, a layer of hot-polymerized epoxy resin being deposited by overmolding in the stripped area to ensure continuity of material between the flange and the covering sheath.

21. System according to claim 18 or 19, characterized in that at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with: - of a driver, and - a flange made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor, and in that the conductor of the sealed bushing is electrically connected to the conductive cable in a stripped area, a biocompatible heat-shrinkable sheath made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family covering the stripped area to ensure continuity of material between the flange and the covering sheath; a laser weld being carried out between the heat-shrinkable sheath and the covering sheath, and between the heat-shrinkable sheath and the flange.

22. System according to claim 18 or 19, characterized in that at least one junction between the conductive cable and the first active implantable device or the second implantable device is made by means of a biocompatible sealed feedthrough fixed to the first active implantable device or to the second implantable device, this biocompatible sealed feedthrough being provided with: - of a driver, and - a flange made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family, made around the conductor, and in that the conductor of the sealed feedthrough is electrically connected to the conductive cable in a stripped area, a biocompatible heat-shrinkable sheath made of a polymer from the polyetherketone (PEK), polyaryletherketone (PAEK) or polyetheretherketone (PEEK) family covering the stripped area to ensure continuity of material between the flange and the covering sheath; a laser weld being made between the heat-shrinkable sheath and the covering sheath, and between the heat-shrinkable sheath and the flange, and in that a layer of hot-cured epoxy resin covers the biocompatible heat-shrinkable sheath.

23. System according to any one of claims 18 to 22, characterized in that the same electrically insulating housing made of biocompatible material completely and without discontinuity of material encapsulates the first active implantable device, the second implantable device, and the conductive cable; the housing having the function of covering sheath around the conductive cable.

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