Low-voltage deformable navigation guide

Abstract

Low-voltage deformable navigation guide. This description concerns a navigation guide for a fluidic circuit comprising successively a distal portion (1), a central portion (2), and a proximal portion (3). The distal portion (1) comprises a substrate (10) whose first principal face (10a) is covered by one or more active blocks (11), arranged at a first distance from the first end of the distal portion (1), and whose second principal face (10b) is covered by one or more active blocks (11), arranged at a second distance from the first end of the distal portion (1). The first distance is different from the second distance, whereby the distal portion (1) exhibits a non-zero curvature. Figure for the abstract: Fig. 3

Description

Title of the invention: Low-voltage deformable navigation guide. Technical field.

[0001] The present description relates generally to devices for navigation in a fluid, for example devices for arterial navigation (endovascular surgery), or for navigation in branching systems such as plumbing pipes or air conditioning circuits. Previous technique

[0002] In the context of endovascular surgery, in order to reach a target blood vessel (such as an artery, for example), surgeons use guides to navigate through the arterial circuit.

[0003] A guide connects the target artery with the outside: it allows, for example, the delivery of a balloon catheter and a stent in the case of a stenosis.

[0004] However, since they are not steerable, they must be introduced using pre-shaped selective angiography catheters or pre-shaped probes. The catheters are chosen according to the shape of the artery: curved, S-shaped, etc. For example, the catheters may be those referenced under the names 'Head Hunter 1', 'Cobra 1', 'Simmons Sidewinder 2', 'Vertebral', 'Berenstein', 'Multipurpose A'. There is no universal navigation guide: each catheter corresponds to a specific shape.

[0005] Target artery anchoring is one of the critical steps, particularly during minimally invasive surgery (MIS). Even with experience, surgeons generally need several attempts before successfully anchoring an artery (i.e., successfully inserting the guidewire from one artery into a second artery). Such attempts increase operating time and / or the risk of injury and can lead to postoperative complications.

[0006] To facilitate hooking, a guidewire with a slightly curved overhang (between 30° and 50°), forming a hook, can be used. The selective angiography catheter allows the guidewire to reach the target artery, and the curvature of the guidewire enables hooking. The drawback of the hook is that its curvature is not adjustable. The hook shape makes advancing the device through the vascular system more difficult, particularly when the guidewire is moving against the flow. Furthermore, if the angle between the two arteries is too large and the hook angle is too small, hooking the target artery becomes very difficult.

[0007] To overcome this drawback, devices comprising an electroactive polymer-based active block have been designed. For example, in the article by Q. Jacquemin et al. (“Design of a new electroactive polymer based continuum actuator for endoscopy surgical robots,” 2020, IEEE / RSJ International Conference on Intelligent Robots and Systems (IROS)), the actuator's active block is positioned on a 25 µm thick PEN substrate, the electrodes are made of PEDOT:PSS, and the 6 µm electroactive polymer layer is made of P(VDF-TrFE-CTFE). By applying voltages greater than 50 V / µm, it is possible to bend the device proportionally to the applied electric field. The device is 5 cm long and 4 mm wide.

[0008] Thus, it would be possible to manufacture a navigation guide comprising a substrate covered by an active block. When a voltage is applied to the active block, it deforms mechanically and causes the substrate to bend.

[0009] However, such devices are still too bulky for arterial navigation. Furthermore, the device can be either straight or curved in only one direction, which is not conducive to navigation in a channel with complex geometry (particularly with passages where the device must be oriented in one direction and then the other). In addition, this type of device has a single curvature, which serves both for navigation and for anchoring to the artery.

[0010] Finally, the tensions applied to modify the shape of the end are still too high. Summary of the invention

[0011] There is a need for a device whose shape can be changed at low voltage, the device must be miniaturizable in order to be able to navigate in small fluidic systems, for example in blood vessels of the brain.

[0012] This objective is achieved by a fluidic circuit guide comprising successively a distal part, a central part, and a proximal part, the distal part comprising a first end and a second end in contact with the central part, the distal part comprising a substrate, a first principal face of which is covered by a first active block or a first group of active blocks, and a second principal face of which is covered by a second active block or a second group of active blocks, each active block comprising at least one electroactive layer, a first electrode, and a second electrode, the first active block or the first group of active blocks being disposed at a first distance from the first end of the distal part, and the second active block or the second group of active blocks being arranged at a second distance from the first end of the distal part, the first distance being different from the second distance, whereby the distal part has a non-zero curvature.

[0013] According to a particular embodiment, the active blocks comprise between 1 and 15 electroactive layers, preferably between 1 and 10 electroactive layers.

[0014] According to a particular embodiment, the electroactive layers of the active blocks are made of polymer, for example a piezoelectric polymer, an electrostrictive polymer or a ferroelectric polymer, of ceramic, for example PZT or SBN, or a composite material comprising a polymer matrix and ceramic particles.

[0015] According to a particular embodiment, the electroactive layers are made of PVDF or one of its copolymers or terpolymers, such as P(VDF-TrFe) or PVDF-TrFE-CFE.

[0016] According to a particular embodiment, the electroactive layers have a thickness of between 3 and 50 pm, preferably between 3 and 10 pm.

[0017] According to a particular embodiment, the substrate is made of polyimide.

[0018] According to a particular embodiment, the first electrodes and the second electrodes are made of an electrically conductive polymer, preferably PEDOT-PSS.

[0019] According to a particular embodiment, the first distance and / or the second distance are between 0 and 15 cm, preferably between 1 mm and 3 cm.

[0020] According to a particular embodiment, the active blocks of the first group of active blocks are identical or different from the active blocks of the second group of active blocks, the active blocks of the first group of active blocks being arranged opposite the active blocks of the second group of active blocks.

[0021] This goal is also achieved by a method of using a navigation guide comprising at least the following steps: - provide a navigation guide as defined previously, the distal part of the guide having a non-zero curvature, in the absence of applied tension, - apply a voltage, preferably between 10 and 200 V / pm, even more preferably between 10 V and 60 V / pm, to the organic electroactive layers, whereby the curvature of the distal part decreases, for example, until it is zero. Brief description of the drawings

[0022] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0023] [Fig.1] represents, schematically and in top view, a navigation guide according to a particular embodiment of the invention;

[0024] [Fig.2] schematically and in cross-section represents the distal part of a navigation guide comprising a substrate whose main faces are each covered by an active block, according to another particular embodiment of the invention;

[0025] Figure 3 schematically represents, in cross-section, the distal part of a guide navigation comprising a substrate, one of whose main faces is covered by an active block and the other main face of which is covered by several active blocks, according to another particular embodiment of the invention;

[0026] [Fig.4] represents, schematically and in three dimensions, the distal part of a navigation guide comprising a substrate whose main faces are covered by several portions of active blocks, according to another particular embodiment of the invention;

[0027] Figure 5 schematically represents, in cross-section, the distal part of a guide navigation comprising a substrate whose main faces are covered by several portions of active blocks, according to another particular embodiment of the invention;

[0028] Figure 6 schematically represents, in cross-section, the distal part of a guide navigation comprising a substrate whose main faces are covered by several portions of active blocks, according to another particular embodiment of the invention;

[0029] [Fig.7] schematically and in cross-section represents the distal end of a navigation guide in the absence of applied tension (position 1) and by applying different tensions (position 2 and position 3), according to another particular embodiment of the invention;

[0030] [Fig.8A] schematically and in cross-section represents the distal end of a navigation guide, curved in the absence of applied tension, according to another particular embodiment of the invention;

[0031] [Fig.8B] schematically represents the distal end of a navigation guide, curved when a tension is applied, according to another particular embodiment of the invention;

[0032] [Fig.9A], [Fig.9B], [Fig.9C] and [Fig.9D] schematically represent different geometries that can be obtained with a distal part of a navigation guide, in the absence of applied tension ([Fig.9A]) and by applying different tensions (figures 9B, 9C, 9D) according to different particular embodiments of the invention;

[0033] [Fig.1OA], [Fig.1OB], [Fig.1OC] and [Fig.1OD] schematically represent the position and shape of a navigation guide in a fluidic system according to different stages of a navigation process, according to another particular embodiment of the invention.

[0034] The different elements are not necessarily on a uniform scale in order to make the figures more legible. Description of the implementation methods

[0035] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0036] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0037] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0038] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0039] When referring to an active or electroactive element, this means an element that can be electrically activated. In particular, under the action of an electric field (application of a voltage, for example), a mechanical deformation of the element is obtained.

[0040] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0041] Subsequently, we will describe in more detail the devices for arterial navigation; however, the device can be used for any type of navigation in a fluid, for example for navigation in various branched systems (plumbing pipe or air conditioning circuit for example).

[0042] We will now describe the navigation guide in more detail with reference to the attached figures.

[0043] As shown in [Fig. 1], the navigation guide comprises three main parts: the distal part 1 (also called the end), the transition zone 2 (also called junction, central part or central core) and the proximal part 3 (also called body).

[0044] The distal portion 1 comprises a first zone, the so-called actuator zone, and a second zone 1b, the so-called overhang zone (or simply overhang or hook). The actuator zone 1a is positioned between the transition zone 2 and the overhang 1b.

[0045] The actuator zone la is connected and electrically linked to the guide wire body 3 by a junction 2. The overhang 1b and the actuator part la are controllable parts. The overhang 1b is an extension of the actuator zone la. The overhang zone 1b is controlled by a person (a surgeon, for example) and can be bent at will, in either direction, to facilitate hooking, for example, with a target artery. The guide wire thus allows easier navigation from one artery to another thanks to the distal end 1, which can be oriented under the action of an electric field. It is also possible to have an overhang 1b that is not electrically connected and therefore not controllable. In this case, it retains a permanently hooked shape.

[0046] The distal part 1 comprises two ends: a first end is free. In other words, it is not connected to any other elements. The second end is in contact with the central part 2.

[0047] As shown in Figures 1 to 6, the distal end 1 comprises a substrate 10 having a first principal face 10a and a second principal face 10b.

[0048] The first main face 10a of the substrate 10 is covered by a first active block 11 or by a first group of active blocks 11. The second face 10b of the substrate 10 is covered by a second active block 11 or by a second group of active blocks 11.

[0049] The active blocks 11 are also called electroactive blocks. Each active block 11 can comprise one or more active layers 103 (or electroactive layers). In other words, an active block 11 corresponds to one or more 'stacks', each 'stack' being formed by a unit stack comprising an active layer 103 arranged between two electrodes.

[0050] The first active block 11 or the first group of active blocks 11 is at a first distance dl from the end of the distal part 1 and the second active block 11 or the second group of active blocks 11 is at a second distance d2 from the end of the distal part 1. The first distance dl is different from the second distance d2.

[0051] One of the first distance dl or the second distance d2 is greater by at least 10% and preferably by at least 50% than the other of the first distance dl or the second distance d2.

[0052] Preferably, the first distance dl and / or the second distance d2 are between 0 and 15 cm, preferably between 1 mm and 15 cm, even more preferably between 1 mm and 3 cm, and preferably between 0.5 and 1.5 cm. At least one of the first or second distances is strictly greater than 0 (i.e., non-zero). Preferably, both distances are strictly greater than 0 to allow for a more flexible overhang for the guide.

[0053] A guide is thus formed in which the electroactive blocks 11 are arranged, on either side of the substrate 10, asymmetrically (with respect to the plane of the substrate 10).

[0054] The offset of the stacks on either side of the substrate 10 means that, in the absence of an electric field, the overhang 1b is curved. Indeed, this geometric asymmetry of the hook 1b induces a prestress in the substrate 10 and therefore a deformation when it is at rest. The prestresses can also be influenced by the difference in thermal coefficient, as well as the evaporation of solvents during the manufacturing process.

[0055] If the stacks were placed opposite each other, on either side of the substrate 10, symmetrically these stresses would cancel each other out and therefore the guide would be planar.

[0056] Thus, the overhang 1b exhibits a non-zero curvature when no voltage is applied (position 1 in [Fig. 7]). In particular, the overhang 1b forms an angle 0C between 20° and 150° with respect to the actuator part la, more preferably between 20° and 100° and even more preferably between 20° and 90°, with the part la ([Fig. 8A]). The actuator part la has a zero angle with respect to the junction part 2 (in other words, the actuator part is not curved).

[0057] When a voltage is applied to the active blocks 11 (i.e. to the organic electroactive layers 103), the substrate 10 is mechanically deformed, creating tension and compression zones on the faces 10a, 10b of the substrate 10, which leads to a change in the radius of curvature.

[0058] When a tension is applied to the overhang 1b, it straightens (in the opposite direction to the prestress). The curvature decreases until it is zero (position 2, [Fig.7]) or even until it changes direction for larger fields, i.e. the sample bends in the other direction (position 3, [Fig.7]).

[0059] The controllable overhang 1b can take all positions between positions 1 and 3, passing through position 2.

[0060] The end of the guide can thus be oriented in two directions: the bending can be done in one direction or the other.

[0061] When a voltage is applied in the actuator part la, the actuator part la bends and forms an angle 0a with the junction 2 ([Fig.8B]).

[0062] The presence of several portions of active PN blocks can allow, by applying tension to the active blocks, the formation of larger angles between the distal portion 1 and the body of the guide 3 and / or the obtaining of several deformation configurations of the distal portion 1. The actuated length is adjustable. This can be particularly advantageous, when it is necessary to navigate in a complex fluidic system with curved and straight areas.

[0063] An active block portion corresponds to a segment of the distal part 1 on which there may be 1 or 2 active blocks (either on face 10a or on face 10b of the substrate or on both).

[0064] For example, when the device comprises several PN portions of active blocks, the distal part 1 of the guide (in particular the overhang 1b) is curved ([Fig. 9A]). By applying electrical voltages to the actuator area, it is possible to modify the shape of the guide as shown in Figures 9B, 9C and 9D.

[0065] This type of control is particularly advantageous since the applied voltages make it possible to generate several (for example two) different curvatures consecutively.

[0066] Even if a portion of active PN blocks can be activated in both directions, it is possible to connect or activate only one of the two sides depending on the use of the guide.

[0067] The voltage applied to each active block 11 is preferably between 10 V / pm and 200 V / pm, and preferably between 10 V / pm and 100 V / pm. It may be less than 60 V / pm. Such voltages are sufficient to modify the shape of the distal part 1, that is to say, to bend the part 1a for navigation, and to straighten or even reverse the curve of the overhang 1b.

[0068] We will now describe in more detail the different elements of the device.

[0069] As previously stated, at least one active block 11 is arranged on each side of the substrate 10.

[0070] According to an alternative embodiment, shown in [Fig.2], a single active block 11 is disposed on the first face 10a of the substrate 10 and a single active block 11 is disposed on the second face 10b of the substrate 10. The active blocks 11 are offset from each other, so as not to be at the same distance from the first end of the distal part 1.

[0071] According to another embodiment, shown in [Fig.3], a single active block 11 is arranged on the first face 10a of the substrate 10 and several active blocks 11 are arranged on the second face 10b of the substrate 10.

[0072] According to another embodiment, shown in Figures 4 to 6, each of the faces 10a, 10b of the substrate 10 is covered by several active blocks 11. According to this embodiment, the second distance d2 corresponds to the distance between the active block 11 of the second face 10b closest to the first end of the distal part 1 and the first end of the distal part 1.

[0073] According to this variant, the first distance dl corresponds to the distance between the active block 11 of the first face 10a closest to the first end and the first end of distal part 1. Still according to this variant, the second distance d2 corresponds to the distance between the active block of the second face 10b closest to the first end of distal part 1 and the first end of distal part 1.

[0074] The active blocks 11 can be arranged in the form of portions of active blocks PN (at least two), each portion of active blocks PN comprising at least one active block 11. In other words, a portion of active blocks PN can comprise: - a single active block 11, or - two active blocks 11, each active block 11 being positioned on either side of the substrate 10, on each of the faces 10a and 10b: a portion PN then comprises two active blocks 11 arranged opposite each other.

[0075] For example, as shown in [Fig.4], the device comprises 4 portions of active blocks: PI, P2, P3 and P4. Each portion of active blocks comprises an active block 11 arranged on either side of the substrate.

[0076] The guide may comprise between 2 and 5 portions of active blocks. By between X and Y, it is meant here and subsequently that the boundaries are included.

[0077] It is possible to position the majority of the active blocks 11 of the different portions PN on the same side of the substrate to increase the angle between part 1a and part 1b.

[0078] The active blocks 11 of the different portions PN can be arranged, randomly or regularly, on the two faces 10a, 10b of the substrate 10.

[0079] The active blocks 11 can be operated independently of each other.

[0080] The substrate 10 is a flexible substrate, that is to say, it can deform when the piezoelectric stack is subjected to a voltage. The material is chosen so as to allow reversible deformation.

[0081] The substrate 10 is, for example, a polymer such as polyimide (PI) or poly(ethylene naphthalate) (PEN). It can also be a polyarylate (PAR). It could also be a natural, bio-based material.

[0082] The substrate 10 has a small thickness, typically between 15 µm and 1 mm, preferably between 15 µm and 75 µm, and even more preferably between 20 µm and 50 µm, for example 25 µm. With such thicknesses, the substrate can be easily deformed while still supporting the electroactive stack(s) and / or allowing navigation within the target fluidic circuit.

[0083] For arterial navigation, the substrate 10 has a length, for example, between 10 and 100 mm, preferably between 15 and 60 mm, particularly for a device with a single electroactive block. For navigation in plumbing or air conditioning circuits, the dimensions will be adapted to those of the pipes / circuits.

[0084] The substrate 10 has a width, for example, between 0.1 mm and 5 mm, preferably between 0.2 and 3 mm. For navigation in plumbing or air conditioning circuits, the dimensions will be adapted to those of the pipes / circuits.

[0085] The length / width ratio is preferably between 2 and 150, even more preferably between 5 and 100, for example between 50 and 100. The higher the ratio, the lower the tension required to deform the substrate 10 of the distal part 1.

[0086] The distance 'li' between two consecutive portions of active blocks PN and PN-1 is, for example, between 0.1 and 5 mm, preferably between 2 and 4 mm.

[0087] The distal part 1 has a length of, preferably, between 1 and 17 cm, and preferably between 1 and 15 cm, more preferably between 1 and 7 cm, and very preferably between 1 and 4 cm.

[0088] The length of the distal part 1 corresponds to the sum of the lengths of the different active blocks, the different inter-active block distances and the extreme length.

[0089] In the case where the multilayer active block 11 terminates with an electroactive layer, the latter acts as an encapsulation layer and protects the upper electrode.

[0090] Each active block linked a length denoted 'la', for example, between 0.5 and 4 cm, preferably between 1.5 and 3 cm.

[0091] Each active block, for example, has a width between 0.1 mm and 3 cm, preferably between 0.1 and 1 mm, and more preferably between 0.2 and 1 mm. With such widths, arterial navigation is possible.

[0092] The different active blocks 11 may have identical or different dimensions, an identical or different number of electroactive layers.

[0093] For example, as shown in [Fig. 6], the device comprises three portions of active blocks PI, P2, and P3. Portion PI comprises a single active block, and portions P2 and P3 each comprise an active block 11 arranged on either side of the flexible substrate 10. The first portion of active blocks PI comprises an active block 11 formed of one stack (i.e., the active block comprises one electroactive layer 103). The second portion P2 of active blocks comprises active blocks 11, each having four stacks (i.e., the active blocks each have four electroactive layers). The third portion P3 of active blocks comprises active blocks 11, each having two stacks (i.e., each active block 11 comprises two electroactive layers). The dimensions (in particular, length and thickness) of the active blocks 11 are different in these portions.

[0094] Preferably, the active blocks 11 comprise between 1 and 15 electroactive layers 103, and even more preferably between 1 and 10 layers 103, and even more preferably between 4 and 8 electroactive layers 103. When the active block 11 comprises several electroactive layers 103, the active block 11 is formed by a stack comprising an alternation of electroactive layers 103 and electrodes 101, 102. The stack begins with a first electrode 101 and ends with a second electrode 102, except in the case where a dielectric layer is used for encapsulation.

[0095] When the active block 11 comprises a single active layer 103, this is arranged between a first electrode 101 and a second electrode 102.

[0096] When the active block 11 comprises several electroactive layers 103, it also comprises several first electrodes 101 and several second electrodes 102. The first electrodes 101 and the second electrodes 102 are positioned on either side of each electroactive layer 103. The active block 11 is formed of an electroactive stack.

[0097] Each electroactive layer 103 has a thickness 'ed', for example, of between 1 and 50 pm, preferably between 3 and 15 pm, preferably between 3 and 10 pm. With such thicknesses, the applied voltages can be relatively low.

[0098] Electroactive materials are materials that deform under the application of an electric field.

[0099] The electroactive material can be chosen, for example, from polymers (conductive, piezoelectric, ferroelectric, electrostrictive, ionic, etc.), ceramics (in particular lead zirconate titanate (PZT) or Sr-Ba-Nb oxide (SBN)), shape memory materials, and rheological fluids. It can also be a composite material, for example a polymer material comprising ceramic particles (in particular PZT or BaTiO3 particles).

[0100] Preferably, each electroactive layer 103 is an organic electroactive layer. Each electroactive layer preferably comprises a polymeric matrix of PVDF, a PVDF copolymer, or a PVDF terpolymer. This may be a copolymer of vinylidene fluoride and at least one other monomer copolymerizable with VDF. Advantageously, the copolymer comprises at least 50 mol%, preferably at least 70 mol%, and even more preferably at least 80 mol% of VDF.

[0101] By way of illustration, the copolymerizable monomer(s) are, for example, chosen from chlorotrifluoroethylene (CTFE), chlorofluoroethylene (CFE), hexafluoropropylene (HFP), trifluoroethylene (VF3), methyl methacrylate (MMA), tetrafluoroethylene (TFE), and perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE).

[0102] For example, the copolymer is a copolymer of poly(vinylidene fluoride-trifluoroethylene) PVDF / TrFe, also noted as P(VDF-TrFe) or PVDF-CTFE.

[0103] It can also be a terpolymer. For example, a PVDF / TRFE / CTFE or PVDF / TRFE / CFE terpolymer might be chosen. Such materials are called electrostrictive materials.

[0104] According to another embodiment, the polymer is not a ferroelectric polymer: it may be PVDF-HFP.

[0105] In particular, a piezoelectric material (such as P(VDF-TrFE)) or an electrostrictive material (such as PVDF-TrFE-CTFE) may be chosen.

[0106] As previously stated, the organic electroactive layer 103 can be a composite material. For example, the layer may comprise, in addition to the polymer matrix, ferroelectric particles and, optionally, PEDOT:PSS particles in order to increase the relative permittivity of the material and thus improve its electrical behavior.

[0107] For example, ferroelectric particles are made of BaTiO3 (BTO), PZT (lead zirconate titanate), AIN, ZnO, or SBN (Sr-Ba-Nb oxide) or SBT (Sr-Ba-Ti oxide). Such particles are used, for example, with a crosslinkable epoxy matrix. The resulting layer has a certain stiffness, which allows the electrical impulse to be efficiently converted into mechanical displacement.

[0108] The electrodes 101, 102 have, for example, a thickness 'ec' between 0.1 and 10 pm, preferably between 0.1 and 3 pm, even more preferably between 1 and 2.5 pm.

[0109] Preferably, the electrodes 101, 102 are made of an electrically conductive polymer, preferably PEDOT-PSS (poly(3,4-ethylenedioxythiophene).

[0110] The materials forming the different active blocks 11 may be identical or different. Preferably, they are identical. Even more preferably, each active block 11 comprises electrodes 101, 102 made of PEDOT-PSS and an electroactive layer made of P(VDF-TrFe), the whole being optionally covered by an encapsulation layer.

[0111] When using the navigation guide, depending on the desired shape, it is possible to apply no tension, or to apply one or more different tensions to the active blocks 11. With such a device, it is possible to have an end curved in one direction or the other, a straight shape or an S-shaped end.

[0112] According to one embodiment, each part of the navigation guide includes a substrate for supporting different elements (electrical tracks, electrical wires, active blocks).

[0113] Preferably, the body of the guide can be made of wires, optionally coated in a polymer material.

[0114] In the case where electrical tracks are used, the proximal part 3 (also called the body) and the transition zone 2 (also called the central core) each comprise a substrate. The substrate of the proximal part 3 and the substrate of the transition zone 2 may be identical or different. These substrates are preferably made of polymers such as PEN or PI. The thickness of these substrates is, for example, between 25 and 250 µm.

[0115] The substrate 10 of the distal part 1 is advantageously thinner than those of the central part 2 and proximal part 3 in order to be more easily deformed. According to another embodiment, the substrate 10 of the distal part 1 may have the same thickness as those of the central part 2 and proximal part 3.

[0116] Electrical connection means are arranged to carry the signal to the active blocks 11 positioned at the distal part 1.

[0117] Several solutions can be considered for routing the electrical signal in the body 3 of the navigation guide and / or in the core 2 of the navigation guide.

[0118] According to a first embodiment, the connection is made by means of electrical wires (i.e., electrically conductive wires). The wires are, for example, in an electrically insulating sheath. The wires may be braided or positioned concentrically.

[0119] According to another embodiment, the connection is made by means of electrical tracks (i.e., electrically conductive tracks). The tracks can be printed or deposited by another method (e.g., photolithography) onto the substrate. The tracks can be arranged on one side of the substrate or on both sides of the substrate.

[0120] The tracks can be made of a metal (gold or silver, for example) or of an electrically conductive polymer material. For example, the electrically conductive polymer material is PEDOT:PSS. It can also be a polymer in which electrically conductive particles are dispersed, for example, carbon or gold particles. Advantageously, the particles have a larger dimension of less than 300 nm to avoid increasing roughness.

[0121] Several configurations are possible, in order to connect the electrical tracks and / or electrical wires.

[0122] For example, it is possible to cover part of the lower electrode (the one in contact with the substrate) with one of the electrical tracks.

[0123] The electrical tracks and / or electrical wires can be connected to the lower electrode of an active block by means of an electrically conductive adhesive (of the charged epoxy type for example) or by means of a weld.

[0124] Optionally, an electrically conductive plate (for example made of metal, in particular copper) may be positioned on the substrate, on the one hand glued or welded to the lower electrode and, on the other hand, glued or welded to the electrical wire or electrical track.

[0125] According to another embodiment, mechanical systems such as clips or rivets can be used to connect the electrode of the active block to the wire or track.

[0126] The various connections can be covered by a hood. In particular, it is possible to use an electrically conductive hood. For example, the hood may contain nanoparticles. The hood makes it possible to seal any holes and / or prevent breakdown phenomena.

[0127] It is also possible to increase the stiffness of the central core 2 by locally adding an additional layer to the substrate. For example, this could be a polymer layer. The polymer may be the same as or different from the substrate polymer. It could also be a metallized polymer layer. Polymer layers can be deposited by bonding. Welding can also be used. Alternatively, the additional layer is a dielectric layer, for example, screen-printed. It could also be a metallic foil. The foil can have a thickness of between 10 and 1000 µm, preferably between 10 and 1000 µm. The foil can be made of zinc or aluminum.

[0128] The connection of electrodes 101 to each other and of electrodes 102 to each other can be shared in order to divide the number of electrical traces / wires. This makes it possible to reduce the space required by the connections, and thus reduce the width of the substrate.

[0129] Preferably, the distal end 1 is covered by an encapsulation layer. The encapsulation layer surrounds the different portions of active blocks. The encapsulation layer may be made of a polymer material, for example, an epoxy, polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA), polyvinylidene fluoride (PVDF) or one of its derivatives.

[0130] Even more preferably, the distal end 1, the central core 2 and at least part of the body 3 are covered by the encapsulation layer.

[0131] Encapsulation can be carried out by dipping, by thermal evaporation or by spraying a solution. Advantageously, the encapsulation step is carried out after the electrical connections have been made.

[0132] Radio-opaque elements can be added to the device, for example, to the flexible substrate or to the encapsulation layer, between the portions of active blocks, in order to provide visual tracking of navigation within the target system. The elements are, for example, in the form of crosses, squares, or dots, or even lines or bands.

[0133] The navigation guide has a length that can go, for example, up to 180 cm or even 300 cm.

[0134] The distal part 1 can be made in the following way: a) deposit at least one electrically conductive area on each face of a substrate 10, to form a first electrode 101, b) form an electroactive layer 103 on each electrically conductive area, c) form a second electrode 102 on each electroactive layer 103.

[0135] Alternatively, it is possible to form the active block(s) 11 on one face of the substrate 10, and then to form the active blocks 11 on the other face of the substrate 10.

[0136] In step b), the electroactive material layer can be deposited by spin coating. Other types of localized deposition can be used, such as screen printing, spraying, dispensing, or even inkjet deposition. Preferably, the electroactive layer is deposited by screen printing. In a single pass, the deposited thickness is between 1 and 20 µm. It is possible to superimpose several layers by screen printing until the desired final thickness of the electroactive layer 103 is achieved.

[0137] For the active blocks 11, advantageously, between 1 and 10 layers of composite will be deposited intercalated between the electrodes 101, 102, according to the following sequence: N x (electrode 101 / composite 103 / electrode 102). The number of layers deposited depends on the thickness of the dielectric.

[0138] Steps a), b) and c) are repeated to form the stack, step a) being repeated, not on the substrate, but on the underlying electroactive layer.

[0139] The process also includes a crystallization step of the electroactive layer to improve its performance. This irradiation is carried out, for example, with a UV flash light, with a flash duration, or pulse, of between approximately 500 ps and 2 ms, a fluence (energy delivered per unit area) of between approximately 15 J / cm² and 25 J / cm², and with a light wavelength of between approximately 200 nm and 380 nm. The number of UV flashes, or pulses, produced during this irradiation varies depending on the thickness over which the material is to be crystallized. For example, for a P(VDF-TrFe) thickness of approximately 2 pm, the irradiation can be carried out with a fluence of approximately 17 J / cm², a pulse duration of approximately 2 ms, and 5 pulses.

[0140] The material, possibly having undergone prior crystallization, is then subjected to annealing, for example, at approximately 130°C for approximately 60 minutes, to complete the total crystallization of the material. Annealing can be carried out at ambient pressure or at low pressure.

[0141] The crystallization of the material can therefore be carried out in two stages: first, irradiation by UV light pulses to properly crystallize the second face of the material layer in order to increase its thermal conductivity, then annealing thermal irradiation completing the crystallization of the remaining material not crystallized by the previous irradiation.

[0142] When the material is a P(VDF-TrFe)-based copolymer, a material polarization step is performed before use. This step can be carried out, for example, by applying a direct current voltage across its terminals, via the electrodes, in order to improve the material's coefficient. This polarization is performed only once for the entire lifetime of the material. This polarization by alternating current and / or direct current can be done at room temperature or under heat (up to approximately 100°C). It is, for example, possible to perform alternating current polarization followed by direct current polarization. When the polarization is performed at room temperature, it is possible to apply a direct current voltage of up to approximately 150 V / m or even 200 V / m of the electroactive layer thickness for a duration, for example, of a few seconds to a few minutes.For example, a voltage of 120 V / pm will be applied for 20 seconds. When hot polarization is performed, for example at a temperature of approximately 90°C, a DC voltage, for example, between approximately 50 V / pm and 80 V / pm, can be applied to the dielectric layer for a duration, for example, between approximately 1 and 5 minutes. The temperature is then lowered to ambient temperature, and the electric field applied to the material via the applied DC voltage is then switched off. Such polarizations allow PVDF to achieve remanent polarization values ​​of 8 pC / cm².

[0143] The dipoles within the layer remain oriented in this way, even when the material is no longer subjected to this electric field. The material can thus be polarized by applying an initial polarization voltage across the electrodes. Preferably, a piezoelectric material thickness of between 3 and 4 pm is chosen to promote the polarization of the piezoelectric material by this capacitance, and the level of the electric voltage applied between the electrodes to achieve the initial polarization of the piezoelectric material (when the piezoelectric material must be initially polarized) is also chosen.

[0144] Annealing is advantageously carried out at the end of the process, or between the different steps. Annealing is, for example, at a temperature between 100°C and 150°C, preferably around 100°C to remove residual traces of solvent and / or finalize the crystallization of the piezoelectric material.

[0145] Annealing can be carried out under vacuum. For example, a vacuum on the order of mbar. The annealing time, for Imbar, can be at least 1 minute, preferably 3 minutes.

[0146] At the end of the process, contact is advantageously resumed so as to connect the active blocks 11 of the distal part 1 to the core 2 and to the proximal part 3 of the navigation guide.

[0147] To navigate within a fluidic system, the guide manipulation process may include the following steps: - apply tension on the guide in order to reduce the curvature of the distal part, or even to make it flat ([Fig.lOA]); - advance the guide in a first pipe, for example by pushing it, until it passes an intersection with a target pipe; - decrease the applied tension, stop applying the tension or increase the applied tension to bend the distal part ([Fig.lOB]); - pull on the guide until it reaches the intersection with the target pipe ([Fig.lOC]); - insert the guide into the target pipe; - modify the tension applied to the guide in order to reduce the curvature of the distal part, or even to make it flat ([Fig.lOD]); - advance the guide into the target pipe, for example by pushing it.

[0148] The conduits can be arteries, plumbing ducts, printed air circuits, etc.

[0149] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0150] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Navigation guide for a fluidic circuit comprising successively a distal part (1), a central part (2) and a proximal part (3), the distal part (1) comprising a first end and a second end in contact with the central part, the distal part (1) comprising a substrate (10) of which a first principal face (10a) is covered by a first active block (11) or by a first group of active blocks (11) and of which a second principal face (10b) is covered by a second active block (11) or by a second group of active blocks (11), each active block (11) comprising at least one electroactive layer (103), a first electrode (101) and a second electrode (102),the first active block (11) or the first group of active blocks (11) being disposed at a first distance from the first end of the distal part (1) and the second active block (11) or the second group of active blocks (11) being disposed at a second distance from the first end of the distal part (1), the first distance being different from the second distance, whereby the distal part (1) has a non-zero curvature.

2. Navigation guide according to claim 1, characterized in that the active blocks (11) comprise between 1 and 15 electroactive layers (103), preferably between 1 and 10 electroactive layers (103).

3. Guide according to any one of claims 1 and 2, wherein the electroactive layers (103) of the active blocks (11) are made of polymer, for example a piezoelectric polymer, an electrostrictive polymer or a ferroelectric polymer, of ceramic, for example PZT or SBN, or a composite material comprising a polymer matrix and ceramic particles.

4. Guide according to the preceding claim, wherein the electroactive layers (103) are made of PVDF or one of its copolymers or terpolymers, such as P(VDF-TrFe) or PVDF-TrFE-CFE.

5. Navigation guide according to any one of the preceding claims, characterized in that the electroactive layers (103) have a thickness of between 3 and 50 pm, preferably between 3 and 10 pm.

6. Navigation guide according to any one of the preceding claims, characterized in that the substrate (10) is made of polyimide.

7. Navigation guide according to any one of the preceding claims, characterized in that the first electrodes (101) and the second electrodes (102) are made of an electrically conductive polymer, preferably PEDOT-PSS.

8. Navigation guide according to any one of the preceding claims, wherein the first distance and / or the second distance are between 0 and 15 cm, preferably between 1 mm and 3 cm.

9. Navigation guide according to any one of claims 1 to 8, characterized in that the active blocks (11) of the first group of active blocks (11) are identical or different from the active blocks (11) of the second group of active blocks (11), the active blocks (11) of the first group of active blocks (11) being arranged opposite the active blocks (11) of the second group of active blocks (11).

10. A method of using a navigation guide comprising at least the following steps: - providing a navigation guide as defined in one of the preceding claims, the distal part (1) of the guide having a non-zero curvature, in the absence of applied voltage, - applying a voltage, preferably between 10 and 200 V / pm, even more preferably between 10 V and 60 V / pm, to the organic electroactive layers (103), whereby the curvature of the distal part (1) decreases, for example, until it is zero.

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