Patent ID: 12213649

FIG.2ashows a side view of a non-limiting embodiment of a rigid invasive instrument240andFIG.2bshows a non-limiting embodiment of a steerable invasive instrument10.FIG.1shows a non-limiting embodiment of an invasive instrument assembly1having an introducer with two such steerable invasive instruments10. Details of the non-limiting embodiment of the steerable invasive instruments10are explained in relation toFIGS.2cto2k.

The rigid invasive instrument240as shown inFIG.2acomprises an elongated shaft242having a proximal end part241and a distal end part243. At the distal end part243a tool2, for example a forceps, is arranged. At the proximal end part241a handle3is arranged that is adapted for manipulating the tool2, i.e. opening and closing the jaw of the forceps. To that effect, a control rod (not shown) is present within the elongated shaft242, which rod connects the handle3with the tool2. The rod can be moved by the handle3and the movement of the rod is translated into a predetermined movement of the tool2, as is known to persons skilled in the art and need no further explanation here. Also, the shaft242may comprise conducting wires to allow a current to flow to a tool, e.g. to heat said tool in order to perform a heat treatment within a human or animal body.

FIG.2bshows a side view of a steerable invasive instrument10. The steerable instrument10comprises an elongated tubular body18having a proximal end part11including two actuation flexible zones14,15, a distal end part13including two distal flexible zones16,17, and a rigid intermediate part12. The actuation flexible zones14,15in the present embodiment are configured as flexible proximal zones, and will further be referred to as flexible proximal zones. At the distal end part13a tool, like a forceps2is arranged. At the proximal end part11a handle3is arranged that is adapted for opening and closing the jaw of the forceps2.

FIG.2cprovides a detailed perspective view of the distal portion of the elongated tubular body18of the steerable instrument10and shows that the elongated tubular body18comprises of a number of co-axially arranged layers or cylindrical elements including an outer cylindrical element104that ends after the first distal flexible zone16at the distal end portion13. The distal end portion13of the outer cylindrical element104is fixedly attached to the cylindrical element103located within and adjacent to the outer cylindrical element104, e.g. by means of spot welding at welding spots100. However, any other suitable attachment method can be used, including any mechanical snap fit connection or gluing by a suitable glue.

FIG.2dprovides a more detailed view of the distal end part13and shows that it includes three co-axially arranged layers or cylindrical elements being an inner cylindrical element101, a first intermediate cylindrical element102and a second intermediate cylindrical element103. The distal ends of inner cylindrical element101, first intermediate cylindrical element102and second intermediate cylindrical element103are all three fixedly attached to one another. This may be done by means of spot welding at welding spots100. However, any other suitable attachment method can be used, including any mechanical snap fit connection or gluing by a suitable glue. The points of attachment may be at the end edges of inner cylindrical element101, first intermediate cylindrical element102and second intermediate cylindrical element103, as shown in the figures. However, these points of attachment may also be located some distance away from these edges, be it, preferably, between the end edges and the locations of the flexible zone17.

It will be clear to the skilled person that the elongated tubular body18as shown inFIG.2ccomprises four cylindrical elements in total. The elongated tubular body18according to the embodiment shown inFIG.2ccomprises two intermediate cylindrical elements102and103in which the steering members of the steering arrangement are arranged. The steering arrangement in the exemplary embodiment of the elongated tubular body18as shown inFIG.2ccomprises the two flexible zones14,15at the proximal end part11of the elongated tubular body18, the two flexible zones16,17at the distal end part13of the elongated tubular body18and the steering members that are arranged between related flexible zones at the proximal11and distal13end parts. An exemplary actual arrangement of the steering members is shown inFIG.2e, which provides a schematic longitudinal cross-sectional view of the exemplary embodiment of the elongated tubular body18as shown inFIG.2c.

FIG.2eshows the four layers or cylindrical elements mentioned above, i.e. the inner cylindrical element101, the first intermediate cylindrical element102, the second intermediate cylindrical element103, and the outer cylindrical element104.

The inner cylindrical element101, as seen along its length from the distal end to the proximal end of the instrument, comprises a rigid ring111, which is arranged at the distal end part13of the steerable instrument10, a first flexible portion112, a first intermediate rigid portion113, a second flexible portion114, a second intermediate rigid portion115, a third flexible portion116, a third intermediate rigid portion117, a fourth flexible portion118, and a rigid end portion119, which is arranged at the proximal end portion11of the steerable instrument10.

The first intermediate cylindrical element102, as seen along its length from the distal end to the proximal end of the instrument, comprises a rigid ring121, a first flexible portion122, a first intermediate rigid portion123, a second flexible portion124, a second intermediate rigid portion125, a third flexible portion126, a third intermediate rigid portion127, a fourth flexible portion128, and a rigid end portion129. The longitudinal dimensions of the rigid ring121, the first flexible portion122, the first intermediate rigid portion123, the second flexible portion124, the second intermediate rigid portion125, the third flexible portion126, the third intermediate rigid portion127, the fourth flexible portion128, and the rigid end portion129of the first intermediate element102, respectively, are aligned with, and preferably approximately equal to the longitudinal dimensions of the rigid ring111, the first flexible portion112, the first intermediate rigid portion113, the second flexible portion114, the second intermediate rigid portion115, the third flexible portion116, the third intermediate rigid portion117, the fourth flexible portion118, and the rigid end portion119of the inner cylindrical element101, respectively, and are coinciding with these portions as well. In this description “approximately equal” means that respective same dimensions are equal within a margin of less than 10%, preferably less than 5%.

The second intermediate cylindrical element103, as seen along its length from the distal end to the proximal end of the instrument, comprises a first rigid ring131, a first flexible portion132, a second rigid ring133, a second flexible portion134, a first intermediate rigid portion135, a first intermediate flexible portion136, a second intermediate rigid portion137, a second intermediate flexible portion138, and a rigid end portion139. The longitudinal dimensions of the first rigid ring131, the first flexible portion132together with the second rigid ring133and the second flexible portion134, the first intermediate rigid portion135, the first intermediate flexible portion136, the second intermediate rigid portion137, the second intermediate flexible portion138, and the rigid end portion139of the second intermediate cylinder103, respectively, are aligned with, and preferably approximately equal to the longitudinal dimensions of the rigid ring111, the first flexible portion112, the first intermediate rigid portion113, the second flexible portion114, the second intermediate rigid portion115, the third flexible portion116, the third intermediate rigid portion117, the fourth flexible portion118, and the rigid end portion119of the first intermediate element102, respectively, and are coinciding with these portions as well.

The outer cylindrical element104, as seen along its length from the distal end to the proximal end of the instrument, comprises a first rigid ring141, a first flexible portion142, a first intermediate rigid portion143, a second flexible portion144, and a second rigid ring145. The longitudinal dimensions of the first flexible portion142, the first intermediate rigid portion143and the second flexible portion144of the outer cylindrical element104, respectively, are aligned with, and preferably approximately equal to the longitudinal dimension of the second flexible portion134, the first intermediate rigid portion135and the first intermediate flexible portion136of the second intermediate element103, respectively, and are coinciding with these portions as well. The rigid ring141has approximately the same length as the rigid ring133and is fixedly attached thereto, e.g. by spot welding or gluing. Preferably, the rigid ring145overlaps with the second intermediate rigid portion137only over a length that is required to make an adequate fixed attachment between the rigid ring145and the second intermediate rigid portion137, respectively, e.g. by spot welding or gluing. The rigid rings111,121and131are attached to each other, e.g., by spot welding or gluing. This may be done at the end edges thereof but also at a distance of these end edges.

In an embodiment, the same may apply to the rigid end portions119,129and139, which can be attached together as well in a comparable manner. However, as will be explained hereinafter, the construction may be such that the diameter of the cylindrical elements at the proximal portion is larger, or smaller, with respect to the diameter at the distal portion. In such embodiment the construction at the proximal portion differs from the one shown inFIG.2e. As a result of the increase or decrease in diameter an amplification or attenuation is achieved, i.e., the bending angle of a flexible zone at the distal portion will be larger or smaller than the bending angle of a corresponding flexible portion at the proximal portion. This will be further described below with reference toFIG.4.

The inner and outer diameters of the cylindrical elements101,102,103, and104are chosen in such a way at a same location along the elongated tubular body18that the outer diameter of inner cylindrical element101is slightly less than the inner diameter of the first intermediate cylindrical element102, the outer diameter of the first intermediate cylindrical element102is slightly less than the inner diameter of the second intermediate cylindrical element103and the outer diameter of the second intermediate cylindrical element103is slightly less than the inner diameter of the outer cylindrical element104, in such a way that a sliding movement of the adjacent cylindrical elements with respect to each other is possible. The dimensioning should be such that a sliding fit is provided between adjacent elements. A clearance between adjacent elements may generally be in the order of 0.02 to 0.1 mm, but depends on the specific application and material used. The clearance preferably is smaller than a wall thickness of the longitudinal elements to prevent an overlapping configuration thereof. Restricting the clearance to about 30% to 40% of the wall thickness of the longitudinal elements is generally sufficient.

As can be seen inFIG.2e, flexible zone14of the proximal end part11is connected to the flexible zone16of the distal end part13by portions134,135and136, of the second intermediate cylindrical element103, which form a first set of longitudinal steering members of the steering arrangement of the steerable instrument10. Furthermore, flexible zone15of the proximal end part11is connected to the flexible zone17of the distal end part13by portions122,123,124,125,126,127, and128of the first intermediate cylindrical element102, which form a second set of longitudinal steering members of the steering arrangement. The use of the construction as described above allows the steerable instrument10to be used for double bending. The working principle of this construction will be explained with respect to the examples shown inFIGS.2fand2g.

For the sake of convenience, as shown inFIGS.2e,2fand2g, the different portions of the cylindrical elements101,102,103, and104have been grouped into zones151-160that are defined as follows. Zone151comprises the rigid rings111,121, and131. Zone152comprises the portions112,122, and132. Zone153comprises the rigid rings133and141and the portions113and123. Zone154comprises the portions114,124,134and142. Zone155comprises the portions115,125,135and143. Zone156comprises the portions116,126,136and144. Zone157comprises the rigid ring145and the parts of the portions117,127, and137coinciding therewith. Zone158comprises the parts of the portions117,127, and137outside zone157. Zone159comprises the portions118,128and138. Finally, zone160comprises the rigid end portions119,129and139.

In order to deflect at least a part of the distal end part13of the steerable instrument10, it is possible to apply a bending force, in any radial direction, to zone158. According to the examples shown inFIGS.2fand2g, zone158is bent downwards with respect to zone155. Consequently, zone156is bent downwards. Because of the first set of steering members comprising portions134,135, and136of the second intermediate cylindrical element103that are arranged between the second intermediate rigid portion137and the second rigid ring133, the downward bending of zone156is transferred by a longitudinal displacement of the first set of steering members into an upward bending of zone154with respect to zone155. This is shown in bothFIGS.2fand2g.

It is to be noted that the exemplary downward bending of zone156, only results in the upward bending of zone154at the distal end of the instrument as shown inFIG.2f. Bending of zone152as a result of the bending of zone156is prevented by zone153that is arranged between zones152and154. When subsequently a bending force, in any radial direction, is applied to the zone160, zone159is also bent. As shown inFIG.2g, zone160is bent in an upward direction with respect to its position shown inFIG.2f. Consequently, zone159is bent in an upward direction. Because of the second set of steering members comprising portions122,123,124,125,126,127and128of the first intermediate cylindrical element102that are arranged between the rigid ring121and the rigid end portion129, the upward bending of zone159is transferred by a longitudinal displacement of the second set of steering members into a downward bending of zone152with respect to its position shown inFIG.2f.

FIG.2gfurther shows that the initial bending of the instrument in zone154as shown inFIG.2fwill be maintained because this bending is only governed by the bending of zone156, whereas the bending of zone152is only governed by the bending of zone159as described above. Due to the fact that zones152and154are bendable independently with respect to each other, it is possible to give the distal end part13of the steerable instrument10a position and longitudinal axis direction that are independent from each other. In particular the distal end part13can assume an advantageous S-like shape. The skilled person will appreciate that the capability to independently bend zones152and154with respect to each other, significantly enhances the maneuverability of the distal end part13and therefore of the steerable instrument10as a whole.

Obviously, it is possible to vary the lengths of the flexible portions shown inFIGS.2eto2gas to accommodate specific requirements with regard to bending radii and total lengths of the distal end part13and the proximal end part11of the steerable instrument10or to accommodate amplification or attenuation ratios between bending of at least a part of the proximal end part11and at least a part of the distal end part13.

The steering members comprise one or more sets of longitudinal elements that form integral parts of the one or more intermediate cylindrical elements102,103. Preferably, the longitudinal elements comprise remaining parts of the wall of an intermediate cylindrical element102,103after the wall of the intermediate cylindrical element102,103has been provided with longitudinal slits that define the remaining longitudinal steering elements.

Further details regarding the fabrication of the latter longitudinal steering elements are provided with reference toFIGS.2ito2kregarding an exemplary embodiment of a steerable instrument that comprises only one flexible zone at both its proximal11and distal end13parts.

FIG.2ishows a longitudinal cross-section of a steerable instrument2201comprising three co-axially arranged cylindrical elements, i.e. inner cylindrical element2202, intermediate cylindrical element2203and outer cylindrical element2204. Suitable materials to be used for making the cylindrical elements2202,2203, and2204include stainless steel, cobalt-chromium, shape memory alloy such as Nitinol®, plastic, polymer, composites or other cuttable material. Alternatively, the cylindrical elements can be made by a 3D printing process.

The inner cylindrical element2202comprises a first rigid end part2221, which is located at the distal end part13of the instrument2201, a first flexible part2222, an intermediate rigid part2223, a second flexible part2224and a second rigid end part2225, which is located at the proximal end part11of the instrument2201.

The outer cylindrical element2204also comprises a first rigid end part2241, a first flexible part2242, an intermediate rigid part2243, a second flexible part2244and a second rigid end part2245. The lengths of the different parts of the cylindrical elements2202and2204are substantially the same so that when the inner cylindrical element2202is inserted into the outer cylindrical element2204, the different parts are positioned against each other.

The intermediate cylindrical element2203also has a first rigid end part2331and a second rigid end part2335which in the assembled condition are located between the corresponding rigid parts2221,2241and2225,2245respectively of the two other cylindrical elements2202,2204. The intermediate part2333of the intermediate cylindrical element2203comprises three or more separate longitudinal elements which can have different forms and shapes as will be explained below. After assembly of the three cylindrical elements2202,2203and2204whereby the element2202is inserted in the element2203and the two combined elements2202,2203are inserted into the element2204, at least the first rigid end part2221of the inner cylindrical element2202, the first rigid end part2331of the intermediate cylindrical element2203and the first rigid end part2241of the outer cylindrical element2204at the distal end of the instrument are attached to each other. In the embodiment shown inFIGS.2iand2j, also the second rigid end part2225of the inner cylindrical element2202, the second rigid end part2335of the intermediate cylindrical element2203and the second rigid end part2245of the outer cylindrical element2204at the proximal end of the instrument are attached to each other such that the three cylindrical elements2202,2203,2204form one integral unit.

In the embodiment shown inFIG.2jthe intermediate part2333of intermediate cylindrical element2203comprises a number of longitudinal elements2338with a uniform cross-section so that the intermediate part2333has the general shape and form as shown in the unrolled condition of the intermediate cylindrical element2203inFIG.2k. FromFIG.2kit also becomes clear that the intermediate part2333is formed by a number of over the circumference of the intermediate cylindrical part2203equally spaced parallel longitudinal elements2338. Advantageously, the number of longitudinal elements2338is at least three, so that the instrument2201becomes fully controllable in any direction, but any higher number is possible as well. Preferably, the number of longitudinal elements2338is 6 or 8.

The production of such an intermediate part is most conveniently done by injection moulding or plating techniques or starting from a cylindrical tube with the desired inner and outer diameters and removing parts of the wall of the cylindrical tube required to end up with the desired shape of the intermediate cylindrical element2203. However, alternatively, any 3D printing method can be used.

The removal of material can be done by means of different techniques such as laser cutting, photochemical etching, deep pressing, conventional chipping techniques such as drilling or milling, high pressure water jet cutting systems or any suitable material removing process available. Preferably, laser cutting is used as this allows for a very accurate and clean removal of material under reasonable economic conditions. The above mentioned processes are convenient ways as the member2203can be made so to say in one process, without requiring additional steps for connecting the different parts of the intermediate cylindrical element as required in the conventional instruments, where conventional steering cables must be connected in some way to the end parts. The same type of technology can be used for producing the inner and outer cylindrical elements2202and2204with their respective flexible parts2222,2224,2242and2244.

FIG.2hshows an exemplary embodiment of longitudinal (steering) elements4that have been obtained after providing longitudinal slits5to the wall of the second intermediate cylindrical element103that interconnects proximal flexible zone14and distal flexible zone16as described above. I.e., longitudinal steering elements4are, at least in part, spiraling about a longitudinal axis of the instrument such that an end portion of a respective steering element4at the proximal portion of the instrument is arranged at another angular orientation about the longitudinal axis than an end portion of the same longitudinal steering element4at the distal portion of the instrument. Were the longitudinal steering elements4arranged in a linear orientation, than a bending of the instrument at the proximal portion in a certain plane would result in a bending of the instrument at the distal portion in the same plane but in a 180 degrees opposite direction. This spiral construction of the longitudinal steering elements4allows for the effect that bending of the instrument at the proximal portion in a certain plane may result in a bending of the instrument at the distal portion in another plane, or in the same plane in the same direction. A preferred spiral construction is such that the end portion of a respective steering element4at the proximal portion of the instrument is arranged at an angularly shifted orientation of 180 degrees about the longitudinal axis relative to the end portion of the same longitudinal steering element4at the distal portion of the instrument. However, e.g. any other angularly shifted orientation, e.g. 90 degrees, is within the scope of this document. The slits are dimensioned such that movement of a longitudinal element is guided by adjacent longitudinal elements when provided in place in a steerable instrument.

The flexible portions112,132,114,142,116,144,118, and138as shown inFIG.2e, as well as the flexible parts2222,2224,2242, and2244shown inFIGS.2iand2jcan be obtained by the methods described in European patent application 08 004 373.0 filed on 10 Mar. 2008, page 5, lines 15-26, but any other suitable process can be used to make flexible portions.

Such flexible parts may have a structure as shown inFIGS.2cand2d. I.e., the flexibility may be obtained by a plurality of slits14a,15a,16a,17a. E.g., two circumferential slits may be provided in a cylindrical element along a same circumferential line where both slits are located at a certain distance from one another. A plurality of identical sets of circumferential slits14a,15a,16a,17ais provided at a plurality of distances in the longitudinal direction of the instrument, where consecutive sets are arranged at an angularly rotated position, e.g. each time 90 degrees rotated. In such an arrangement, all parts of the cylindrical element are still connected to each other.

FIGS.3a,3band3cshow alternative manners of how such flexibility in part can be obtained.FIG.3ashows a schematic representation of a flat rolled-out flexible proximal or distal cylindrical zone. The intermediate cylindrical elements are then made by rolling-up the flat element and attaching the side edges together in any suitable fashion that is known as such, such as by a welding technique. In the embodiment shown inFIG.3a, the part of the cylindrical tube to become flexible has been provided with slits14a,15a,16a,17aextending in a helical manner over the length of the flexible zone. The flexibility can be controlled by the number of slits and/or the angle of the slits with respect to the axial direction of the cylindrical element. In the embodiment ofFIG.3bthe part of the cylindrical tube to become flexible has been provided with a number of short slits14a,15a,16a,17a. The slits can be divided into groups, the slits in each group being located in the same line extending perpendicular to the axis of the cylindrical element. The slits of two neighboring groups are offset. In the embodiment ofFIG.3cthe part of the cylindrical tube to become flexible has been provided by making slits14a,15a,16a,17aproducing a number of swallow's tails between the slits, which fit into each other as shown. It will be obvious that other systems of providing a flexible zone in a cylindrical tube wall may be used as well. More specifically it is possible to use combinations of the systems shown above. However, any other suitable flexible construction may be used instead. For instance, any of the flexible constructions shown and described in EP 0 764 423 A and EP 0 782 836 A may be used as well.

Furthermore, if the portions122,123,124,125,126,127, and128of the first intermediate cylindrical element102and the portions134,135, and136of the second intermediate cylindrical element103that respectively form the first and second set of longitudinal steering members, as shown inFIG.2e, are implemented as longitudinal steering elements4as shown inFIG.2h, the fabrication methods described above can be used. The same applies to the longitudinal elements2338ofFIGS.2jand2k. Moreover, any embodiment described in EP 2 762 058 A can be used.

Otherwise, the longitudinal elements4,2338can also be obtained by any other technique known in the art such as for example described in EP 1 708 609 A. The only restriction with respect to the construction of the longitudinal elements used in these portions is that the total flexibility of the instrument in these locations where the flexible portions coincide must be maintained.

The different co-axially arranged layers or cylindrical elements101,102,103,104,2202,2203and2204as described above in relation to the exemplary embodiments of the steerable instruments shown inFIGS.2eand2i, respectively, may be produced by any of the known methods, provided that they are suitable to make a multilayer system. A multilayer system is to be understood as being a steerable instrument that comprises at least two separate sets of longitudinal elements4,2338for transferring the movement of the proximal end part to the distal end part. The assembly of the different cylindrical elements can be realized in the same way as well. Preferred methods of producing the different cylindrical elements have been described in the above mentioned EP 2 762 058 A which is hereby incorporated by reference in its entirety.

In the above embodiments, the proximal portions and distal portions are constructed in a similar way. However, that need not be the case always as will be explained now.

E.g., the proximal portion may have a wider diameter as shown inFIG.4, which shows a special embodiment of an instrument. The inner cylindrical element2202is composed of a first rigid end part2225, a first flexible part2224, an intermediate rigid part2223, a second flexible part2222and a second rigid end part2221which is normally used as the operating part of the instrument in that it serves to steer the other end of the unit. The outer cylindrical element2204is in the same way composed of a first rigid part2245, a first flexible part2244, an intermediate rigid part2243, a second flexible part2242and a second rigid part2241. The intermediate cylindrical element2203also has a first rigid end part2335and a second rigid end part2331which in the assembled condition are located between the corresponding rigid parts2225,2245and2221,2241, respectively, of the two other cylindrical elements2202,2204. In the embodiment shown the longitudinal elements2338are of the type shown inFIG.2j, but it will be obvious that any other type described above may be used as well. So far the construction is comparable to the instruments described above. The main difference with respect to the above embodiments is the use of a different set of diameters for some parts of the instrument. In the embodiment shown inFIG.4the parts2222,2221,2331,2242and2241have a larger diameter than the other parts. In the parts2223,2333and2243frusto-conical portions2212,2213,2214have been made in order to connect the small diameter parts with the large diameter parts. As shown inFIG.4the different parts can easily be assembled by inserting one into the other. The main reason, however, to have such an instrument with different diameters is that by using an operating part with a larger diameter, the movement of the other end is amplified, whereas if a smaller diameter is used the movement of the other end is attenuated. Dependent of the application and its requirements larger diameters can be used to have the amplified movement or smaller diameters can be used to attenuate the movement and increase maneuverability accuracy of the handling head.

Such widening of the instrument with increasing diameter towards the proximal portions can also be applied in an instrument with more than two bendable portions, as shown inFIGS.5aand5b.

InFIG.5athere is shown a first exemplary embodiment of a steerable instrument having four layers and as such the instrument is comparable to the instrument ofFIG.2ebut the distal actuation flexible zone156and the proximal actuation flexible zone159of the proximal end part of the instrument have a larger diameter compared to the respective corresponding distal flexible zones154and152of the distal end part of the instrument. In the zone155a frusto-conical part has been incorporated that schematically represents a cylindrical diameter adaptation section162of a steerable instrument. The cylindrical diameter adaptation section162occupies at least a distance in an axial or longitudinal direction of the elongated tubular body over which the longitudinal elements change from a second diameter at a first side of the cylindrical diameter adaptation section to a third diameter at a second side of the cylindrical diameter adaptation section. As a result of the larger diameter of the proximal actuation flexible zone156and the proximal actuation flexible zone159of the proximal end part, the flexion of the respective corresponding distal flexible zones154and152will be amplified upon bending, thereby amplifying the flexion of the handling head. It is also possible to work in the opposite direction with distal flexible zones154and152having a larger diameter than the proximal actuation flexible zones156and159, whereby the degree of flexion is attenuated, thereby improving accuracy of movement of the handling head.

FIG.5bshows a schematic cross-section of a second exemplary embodiment of a steerable instrument in which a proximal actuation flexible zone159of the actuating portion of the cylindrical elements as well as an intermediate rigid zone158, that is arranged between said proximal actuation flexible zone159and a proximal actuation flexible zone156, have a larger diameter than the other parts of the elongated tubular body. A frusto-conical part schematically representing a cylindrical diameter adaptation section164of a steerable instrument has been incorporated in zone158. The cylindrical diameter adaptation section164extends at least along distance in an axial or longitudinal direction of the elongated tubular body over which the longitudinal elements change from a second diameter at a first side of the cylindrical diameter adaptation section to a third diameter at a second side of the cylindrical diameter adaptation section. It will be clear to the skilled person that only the flexion of the corresponding distal flexible zone152will be amplified upon bending of the corresponding proximal actuation flexible zone159of the proximal end part. The degree of flexion of the distal flexible zone154will in principle be the same as the degree of flexion of the corresponding proximal actuation flexible zone156, because of the fact that the intermediate cylindrical element, which comprises the longitudinal elements that are configured and arranged to transfer the flexion of the proximal actuation flexible zone156to the corresponding distal flexible zone154, has the same diameter in these zones. In practice there may be slight differences between these degrees of flexion due to stretching of the longitudinal elements.

FIGS.6-13bshow how an increasing or decreasing diameter of a radius of a flexible actuation zone can be implemented and manufactured. I.e.,FIGS.6-10show consecutive manufacturing actions performed to make a diameter adaptation section of a steerable instrument having five cylindrical elements inserted into one another (any other suitable number than five can, of course be used).

FIG.6shows an inner protective cylindrical element600having two opposing ends601,603. End601will be called the distal end, here, whereas end603will be called the proximal end. However, that could in practice be the other way around. The inner protective cylindrical element600is, preferably, a single cylindrical tube of any suitable material like stainless steel, cobalt-chromium, shape memory alloy such as Nitinol®, plastic, polymer, composites or other cuttable material. Alternatively, the inner protective cylindrical element600can be made by a 3D printing process. The thickness of that tube depends on its application. For medical applications the thickness may be in a range of 0.1-2.0 mm, preferably 0.1-1.0 mm, more preferably 0.1-0.5 mm, and most preferably 0.2-0.4 mm. The diameter of the inner protective cylindrical element600depends on its application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably 0.5-10 mm, more preferably 0.5-6 mm.

FIG.7shows the inner protective cylindrical element600inserted into an intermediate cylindrical element619. The intermediate cylindrical element619is provided with slits605which define adjacent longitudinal elements602. As will become clear hereinafter, those longitudinal elements602can be used as pushing/pulling wires in the assembled state of the steerable instrument. The slits605can be made by laser cutting and have a width, preferably, in a range of 5-50 μm, more preferably 15-30 μm.

At end615, i.e. the proximal end of the steerable instrument, the intermediate cylindrical element619comprises a rigid, ring-shaped element610. The rigid, ring-shaped element610is attached to a set of finger-shaped elements608. Preferably, the number of finger-shaped elements608equals the number of longitudinal elements602.

Preferably, each longitudinal element602, at the same end as rigid, ring-shaped element610is provided with one or more finger-shaped elements611, each one being located between two adjacent finger-shaped elements608.

Preferably, the intermediate cylindrical element619is made from a single cylindrical tube of any suitable material that may be the same material as the one from inner protective cylindrical element600. The thickness of that tube depends on its application. For medical applications the thickness may be in a range of 0.1-2.0 mm, preferably 0.1-1.0 mm, more preferably 0.1-0.5 mm, and most preferably 0.2-0.4 mm. Intermediate cylindrical element619has a slightly larger diameter than inner protective cylindrical element600, such that when inner protective cylindrical element600is inserted into intermediate cylindrical element619, there is a clearance between them in a range of e.g. 0.02 to 0.1 mm. The diameter of the intermediate cylindrical element619depends on its application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably 0.5-10 mm, more preferably 0.5-6 mm.

As explained above, the longitudinal elements605can then be made by laser cutting the cylindrical tube such as to render the slits605, and thus, the longitudinal elements602. If the slits605would be present along the entire length of the intermediate cylindrical elements602directly after the cutting process, it would be difficult to keep them together during the manufacturing process of the steerable instrument. Therefore, the cutting process is arranged such that after the cutting process is finished, at the end of the intermediate cylindrical element619opposing end615(or at any other desired location) adjacent longitudinal elements602are connected by so-called “break islands”604.

These break islands604are, at two opposing ends, attached to two adjacent longitudinal elements602. The break islands604are shown to have a circular shape and to be attached to adjacent longitudinal elements602by means of thin flexible bridges. In use, when the longitudinal elements602are used to control deflection of flexible portions of the steerable instrument, adjacent longitudinal elements602move relative to one another in the longitudinal direction of the steerable instrument. By this movement, at least one of the attachments of the break islands604to the adjacent longitudinal elements602will break such that the adjacent longitudinal elements602can move freely in the longitudinal direction. Such movement can be postponed until the steerable instrument has reached its assembled state. This greatly facilitates the manufacturing process of the steerable instrument since all adjacent longitudinal elements602can be kept together in a position such that, together, they still form their original cylindrical shape as long as possible.

Manufacturing of a steerable instrument while using break islands604can be summarized as follows. Such a steerable instrument comprises at least an elongated tubular body having a proximal end part, a distal end part and an intermediate part between the proximal and distal end parts, the proximal end part having at least one actuation proximal zone, the distal end part having at least one flexible distal zone, and the elongated tubular body being configured such that a movement of an actuation proximal zone is transferred to a corresponding flexible distal zone for a corresponding movement thereof. The elongated tubular body comprises an inner cylindrical element, an outer cylindrical element and at least one intermediate cylindrical element having longitudinal elements and provided between the inner and outer cylindrical elements, the inner, outer and intermediate cylindrical elements being coupled such that movement of an actuation proximal zone is transferred by the longitudinal elements of one of the intermediate cylindrical elements to a corresponding flexible distal zone.

The manufacturing actions can be summarized as follows:providing the inner and outer cylindrical elements;providing an intermediate cylindrical element such that adjacent longitudinal elements are attached to one another at one or more positions by one or more attachments distributed along a length of the longitudinal elements arranged to allow relative movement of the longitudinal elements with respect to one another in a longitudinal direction of the longitudinal elements, and so as to restrict movement of longitudinal elements in a radial direction of the intermediate cylindrical element; andincorporating the intermediate cylindrical element between the inner and outer cylindrical elements,

wherein the one or more attachments are releasable attachments and the method comprises releasing said releasable attachments during said manufacturing.

Preferably, the steerable instrument is manufactured at to such a state that the intermediate cylinder with the longitudinal elements is inserted between a protective inner cylindrical element and a protective outer cylindrical element before the longitudinal elements are moved relative to one another such that the break islands will break off. Then, after these break islands have been broken off adjacent longitudinal elements keep their respective locations on a virtual cylinder between the protective inner and outer cylindrical elements.

A break island604is a fracture element which can be defined as follows. Each fracture element is configured and arranged to fracture when adjacent longitudinal elements602to which each such fracture element is attached are moved in a longitudinal direction relative to one another such as to develop an actual fracture element stress, σact,fe, in each such fracture element which is larger than or equal to an ultimate tensile stress, σUTS,fe, of each individual fracture element, while, at the same time, the actual longitudinal element stress, σact,le, as developed in each one of these adjacent longitudinal elements602remains lower than their own respective yield stresses, σy,le, which can be stated in the equation:
σact,le≤σy,leand σact,fe≥σUTS,fe.

Such break islands604have been described in detail and claimed in PCT application PCT/NL/2014/050837 of the present applicant, which is only published after the priority date of the present application. Its content is incorporated in the present application by reference in its entirety. PCT/NL/2014/050837 shows and explains break island604as shown in the present application in more detail. It is to be understood that the term “break island” is not meant to be limited to the embodiment shown in the present application but may be implemented in any suitable form, including any one of the examples shown in PCT/NL/2014/050837.

The cylindrical tube used to manufacture the intermediate cylindrical element619is cut such as to render finger-shaped elements608attached to rigid, ring-shaped element610, as well as finger-shaped elements611of the longitudinal elements602. Moreover, the cutting process is arranged such that, at the end of the cutting process, adjacent finger-shaped elements608and finger-shaped elements611have an interleaved position relative to one another.

The cutting process is also arranged such that it renders an open space627between each end face of finger-shaped element611and rigid, ring-shaped element610, such that, in use of the steerable instrument, the finger-shaped elements611can freely move in a longitudinal direction between adjacent finger-shaped elements608. However, when the cutting process is finished, preferably, each finger-shaped element611is still attached to an adjacent finger-shaped element608by one or more break islands606. As explained above, such break islands608are designed such that, when in use of the steerable instrument finger-shaped elements611move in a longitudinal direction relative to adjacent finger-shaped elements608, each break island608will break off from at least one of the adjacent finger-shaped elements608,611. This breaking apart will result in a situation where finger-shaped elements608can move freely relative to finger-shaped elements611, and vice versa. Again, this breaking apart can be postponed until the steerable instrument is in its assembled state. This facilitates the manufacturing process seriously. These break islands606may have a circular shaped portion attached to adjacent finger-shaped elements608,611by thin flexible bridges like the break islands604. If desired, the break islands606may have any other suitable design including any one described in PCT/NL/2014/050837.

It is observed that, once break islands606are broken off, intermediate cylindrical element619falls apart into two independently moveable sections at either side of dotted line613.

FIG.8shows how the set of cylindrical elements comprising cylindrical element600inserted in intermediate cylindrical element619is inserted in a cylindrical element621. In the shown embodiment, cylindrical element621does not have longitudinal elements itself. Cylindrical element621is, preferably, made from a single cylindrical tube which may be made from the same material and may have the same thickness as inner protective cylindrical element600and intermediate cylindrical element619.

The outer diameter of intermediate cylindrical element619and the inner diameter of intermediate cylindrical element621are chosen such that the clearance between the two is so small that they can easily move relative to one another in the longitudinal direction but that mutual radial play is kept at a minimum. The clearance may be in a range of 0.02 to 0.1 mm. Preferably, the intermediate cylindrical element621is made from a single cylindrical tube of any suitable material that may be the same material as the one from inner protective cylindrical element600. The thickness of that tube depends on its application. For medical applications the thickness may be in a range of 0.1-2.0 mm, preferably 0.1-1.0 mm, more preferably 0.1-0.5 mm, and most preferably 0.2-0.4 mm. The diameter of the intermediate cylindrical element621depends on its application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably 0.5-10 mm, more preferably 0.5-6 mm.

At the right-hand side ofFIG.8, i.e. the proximal side, intermediate cylindrical element621comprises a rigid, ring-shaped element626having an end628. The rigid, ring-shaped element626is connected to a flexible portion624which extends along a predetermined distance of intermediate cylindrical element621. Flexible portion624comprises one or more hinges such that flexible portion624can be deflected to a certain, predetermined angle relative to a central axis of the steerable instrument (i.e. the central axis of inner protective cylindrical element600). Any suitable hinge known from the prior art can be used, e.g. the hinges shown inFIGS.2c,2d,3a,3b, and3cof the present document. However, other hinges can be used including any suitable future one.

Towards the distal side of the intermediate cylindrical element621, flexible portion624is connected to a rigid portion622. The rigid portion622comprises rigid, cylindrical portions612a,612bwhich are attached to one another by means of longitudinally arranged connection elements617. Preferably, these connection elements617have the form of straight strips with a constant width and thickness. Rigid, cylindrical portion612bis connected to flexible portion624.

As can better be seen in the enlarged view ofFIG.11, the rigid, cylindrical portions612a,612band the connection elements617are arranged to define open spaces631, one associated with one longitudinal element602. Again, these open spaces631result from a cutting process, such as laser cutting. The cutting process is arranged such it also renders a sliding island618in each open space631. When the cutting process is finished, preferably, each sliding island618is still attached to at least one of an adjacent connection element617and rigid, cylindrical portion612a,612bby means of one or more break islands616,620. Such break islands616have the same function as break islands604and606and may have the same form.

However, since break islands616,620are connected to a connection element617and not to a longitudinal element, their definition is slightly different. I.e., here break islands616,620are fracture elements which can be defined as follows. Each fracture element is configured and arranged to fracture when adjacent connection elements617to which each such fracture element is attached are moved in a longitudinal direction relative to one another such as to develop an actual fracture element stress, σact,fe, in each such fracture element which is larger than or equal to an ultimate tensile stress, σUTS,fe, of each individual fracture element, while, at the same time, the actual connection element stress, σact,ce, as developed in each one of these adjacent connection elements617remains lower than their own respective yield stresses, σy,ce, which can be stated in the equation:
σact,ce≤σy,ceand σact,fe≥σUTS,fe.

For example, as shown inFIGS.8and11, at the end of the cutting process sliding island618is attached to one of the adjacent connection elements617by means of a break island616,620at either longitudinal end. The length of sliding island618, as measured in the longitudinal direction, is shorter than the longitudinal length of open space631in which it is located. Thus, when in the assembled state of the steerable instrument break islands616,620are broken off sliding island618can freely move in open space631along a predetermined distance. To provide the sliding islands618with a guiding function as will become apparent hereinafter, their width, as measured in a tangential direction, is, preferably at least along a predetermined portion of e.g. more than 50% of their total length, only slightly smaller than the width of open space631, as measured in the tangential direction. In an embodiment, the difference between these two widths is less than 60 μm, preferably less than 40 μm.

During inserting intermediate cylindrical element619into intermediate cylindrical element621, every sliding island618is aligned with one longitudinal element602now located at its inside. After the sliding islands618have been properly aligned with the longitudinal elements602each sliding island618is connected or attached to one longitudinal element602. The connection/attachment may be to finger-shaped island611as is schematically indicated with dotted arrow634betweenFIGS.8and7.

Such a connection/attachment can be made by welding, like laser welding. However, also a mechanical connection/attachment can be made, e.g., by means of a snap fit connection. Alternatively, glue can be used. The connection/attachment is preferably made when the longitudinal elements602are still attached to each other by means of break islands604at the distal end, the finger-shaped elements611are still attached to the finger-shaped elements608by means of the break islands606and the sliding islands618are still attached to at least one of the connection elements617and the rigid cylindrical portions612a,612bby means of break islands616,620. Moreover, the connection/attachment should be such that each sliding island618moves together with the longitudinal element602to which it is connected/attached with as little play as possible. This common movement of longitudinal elements602and respective sliding island618causes the break islands616and620to break off during the first time the longitudinal elements602, after being connected/attached to the respective sliding islands618, move relative to intermediate cylindrical element621.

In order to provide stability to the steerable instrument, rigid ring-shaped element610of intermediate cylindrical element619is, preferably, connected/attached to rigid portion612bof intermediate cylindrical element621, as shown by dotted arrow636betweenFIGS.8and7. This connection/attachment can be done by welding, like laser welding, or any suitable mechanical connection, like a snap fit connection. Alternatively, glue can be used. This connection/attachment is preferably such that rigid, ring-shaped element610and rigid portion612bcannot move independently from each other.

Thus, when longitudinal elements602are connected/attached to sliding islands618, they are guided in a longitudinal direction both by their finger-shaped elements611between finger-shaped elements608and by the sliding islands618in open spaces631. Their possible tangential movement is limited by the width of the slits between their finger-shaped elements611and finger-shaped elements608and between the sliding islands618and adjacent connection elements617.

As shown inFIG.9, the set of cylindrical elements inserted into each other as shown inFIG.8and comprising inner cylindrical element600, intermediate cylindrical element619and intermediate cylindrical element621, is inserted in an intermediate cylindrical element623.

The outer diameter of intermediate cylindrical element621and the inner diameter of intermediate cylindrical element623are chosen such that the clearance between the two is so small that they can easily move relative to one another in the longitudinal direction but that mutual radial play is kept at a minimum. The clearance may be in a range of 0.02 to 0.1 mm.

Preferably, the intermediate cylindrical element623is made from a single cylindrical tube of any suitable material that may be the same material as the one from inner protective cylindrical element600. The thickness of that tube depends on its application. For medical applications the thickness may be in a range of 0.1-2.0 mm, preferably 0.1-1.0 mm, more preferably 0.1-0.5 mm, and most preferably 0.2-0.4 mm. The diameter of the intermediate cylindrical element623depends on its application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably 0.5-10 mm, more preferably 0.5-6 mm.

At the left hand, distal, side, in the embodiment ofFIG.9, intermediate cylindrical element623comprises a rigid, ring-shaped element642. The rigid, ring-shaped element642is provided with a set of finger-shaped elements627.

At the right hand, proximal, side, in the embodiment ofFIG.9, intermediate cylindrical element623comprises a rigid, cylindrical portion656. Towards the distal side, the rigid, cylindrical portion656is attached to one or more flexible longitudinal elements633. In a portion of the intermediate cylindrical element623that should be aligned with flexible portion624of intermediate cylindrical element621, the flexible longitudinal elements633should be flexible enough to allow deflection of the steerable instrument. To that end, in the embodiment as shown, the flexible longitudinal elements633have a relative small width measured in the tangential direction. Their width is, preferably, constant along their length. In order to ensure that the flexible longitudinal elements633are secured in the tangential direction in this flexible portion, flexible spacers654are provided between them. Any suitable design of spacers may be used, e.g. the ones described in not yet published application PCT/NL2015/050798 of the present applicant.

At the distal side of the flexible portion, each flexible longitudinal element633is attached to a longitudinal element635which may have a larger width to provide them with a certain desired strength. E.g., adjacent longitudinal elements635may substantially touch one another. Here, the term “substantially” indicates that adjacent longitudinal elements635can be as close as possible along at least part of their length, the mutual distance only being determined by the cutting process used to make slits650between them.

At their distal ends, the longitudinal elements635are provided with finger-shaped elements646that are each located between two adjacent finger-shaped elements627.

Again, all the shown slits, open spaces and spacers are preferably made by cutting, like laser cutting, a cylindrical tube. At the end of the cutting process, the finger-shaped elements646are still attached to the finger-shaped elements627by means of break islands644. Such break islands644have the same function as explained with reference to break islands604,606,616,620. Therefore, break islands644may have the same design as break islands604,606,616,620. Break islands644, preferably, remain intact and attached to both finger-shaped elements627and646during the assembling process of the steerable instrument and will only be broken off by, e.g., a user after finishing the assembling process.

As indicated by a dotted arrow638, each longitudinal element635is connected/attached to one sliding island618, after proper tangential and longitudinal alignment of the intermediate cylindrical element621and intermediate cylindrical element623such that each longitudinal element635is aligned with one sliding island618. Thus, in this embodiment, the number of longitudinal elements635equals the number of sliding islands618, and equals the number of longitudinal elements602in intermediate cylindrical element619. The connection/attachment can be made by welding, e.g. laser welding, or any suitable mechanical connection like a snap fit connection. Alternatively, glue can be used. Again any play in such a connection should be kept to a minimum.

As an alternative, one or more of the longitudinal elements635are provided with a flexible lip648. Such a lip648, can then, again after proper alignment, be connected/attached to one sliding island618, e.g. by laser welding. The advantage of using such a lip648is that it is flexible in a radial direction and, thus, can cope with tolerances in internal/external diameters of the intermediate cylindrical elements621,623.

FIG.9shows that also intermediate cylindrical element623will be separated into two independently moveable sections, as indicated with dotted line652, once the break islands644have been broken off. Then, the longitudinal elements635will be guided in their longitudinal direction both by their finger-shaped elements646each located between two adjacent finger-shaped elements627and by the respective sliding islands618to which they are connected/attached.

In order to provide enough stability to the steerable device and align all cylindrical elements properly to one another, preferably, proximal end658is connected/attached to proximal end628of intermediate cylindrical element621, as indicated with dotted arrow640betweenFIGS.9and8.

FIG.10shows how a last, outer protective cylindrical element625is shifted over the set of cylindrical elements shown inFIG.9, including inner cylindrical element600and three intermediate cylindrical elements619,621and623. Of course, a plastic sleeve or the like may be shifted over at least one or more portions of the steerable instrument as is clear to persons skilled in the art.

Outer protective cylindrical element625has a flexible portion666that should be longitudinally aligned with flexible longitudinal elements633of intermediate cylindrical element623and with flexible portion624of intermediate cylindrical element621. At opposite sides of the flexible portion666, outer protective cylindrical element625is provided with bend-resistive portions664and668. Preferably, all flexible portions of the steerable instrument are at least 5 times, but more preferably at least 10 times more flexible than the bend-resistive or rigid portions of the steerable instrument.

The outer diameter of intermediate cylindrical element623and the inner diameter of outer cylindrical element625are chosen such that the clearance between the two is so small that they can easily move relative to one another in the longitudinal direction but that mutual radial play is kept at a minimum. The clearance may be in a range of 0.02 to 0.1 mm. Preferably, the outer cylindrical element625is made from a single cylindrical tube of any suitable material that may be the same material as the one from inner protective cylindrical element600. The thickness of that tube depends on its application. For medical applications the thickness may be in a range of 0.1-2.0 mm, preferably 0.1-1.0 mm, more preferably 0.1-0.5 mm, and most preferably 0.2-0.4 mm. The diameter of the outer cylindrical element625depends on its application. For medical applications the diameter may be in a range of 0.5-20 mm, preferably 0.5-10 mm, more preferably 0.5-6 mm.

In order to provide enough stability to the steerable device and align all cylindrical elements properly to one another, preferably, proximal end670is connected/attached to proximal end658of intermediate cylindrical element623, as indicated with dotted arrow662betweenFIGS.10and9. For the same reason, distal end663of outer cylindrical element625is connected/attached to intermediate cylindrical element623, as indicated with dotted arrow660betweenFIGS.10and9. Such connection/attachment may be made by (laser) welding or by mechanical means including a snap-fit connection. Alternatively, glue can be used.

FIG.12shows a cross section view of a steerable instrument in accordance with an embodiment in its assembled state, comprising a diameter adaptation section164as described with reference toFIGS.6-11. The same reference numbers refer to the same elements/components as in earlier figures.

In the example ofFIG.12, inner cylindrical element600, intermediate cylindrical elements619,621,623and outer cylindrical element625are all coaxially arranged about a common axis of symmetry692. The diameter of inner cylindrical element600is smaller than the diameter of intermediate cylindrical element619, which is smaller than the diameter of intermediate cylindrical element621, which is smaller than the diameter of intermediate cylindrical element623, which is smaller than the diameter of outer cylindrical element625.

FIG.12shows how different sections of inner cylindrical element600, intermediate cylindrical elements619,621,623, and outer cylindrical element625are longitudinally aligned in order to form the cylindrical diameter adaptation section164.

I.e. bend-resistive portion668of outer cylindrical element625is aligned with and connected/attached to rigid, cylindrical portion656of intermediate cylindrical element623, whereas rigid, cylindrical portion656itself is aligned with and connected/attached to rigid, ring-shaped626of intermediate cylindrical element621.

Similarly, flexible portion666of outer cylindrical element625is aligned with flexible longitudinal elements633, as well as with flexible portion624of intermediate cylindrical element621.

Longitudinal elements635of intermediate cylindrical element623are aligned with rigid, cylindrical portion612bof intermediate cylindrical element621, as well as with rigid, ring-shaped element610of intermediate cylindrical element619.

Each longitudinal element635of intermediate cylindrical element623is, at its inside, connected/attached to the outside of one of the sliding islands618of intermediate cylindrical element621. Moreover, each sliding island618is, at its inside, connected/attached to one of the longitudinal elements602, possibly via finger-shaped element611, of intermediate cylindrical element619.

As best shown inFIG.11, each sliding island618is located in an open space631allowing the sliding island618to be moved back and forth in the longitudinal direction in space631once break islands616,620have been broken off from connection element617. Such breaking off will happen once the sliding island618is connected/attached to longitudinal element635and to longitudinal element602, and the distal end of the steerable instrument is deflected about the flexible part of the steerable instrument defined by flexible portion666, flexible longitudinal elements633and flexible portion624. I.e., such a deflection causes, for instance, the longitudinal element635at the upper side ofFIG.12to be shifted to the right. Consequently, because this longitudinal element635is connected/attached to one sliding island618and to one longitudinal element602, also that sliding island618and that longitudinal element602will shift to the right, effectively developing a force on the attachments of the break islands616,620to the adjacent connection elements617and breaking them off from the connection elements617. However, the longitudinal elements635remain connected/attached to a respective one of the longitudinal elements602via a respective sliding island618.

Towards the distal side of the steerable instrument, the steerable instrument is, in an embodiment, similarly designed as the steerable instrument shown inFIG.5b. Therefore, the same reference numbers inFIG.12brefer to the same elements as inFIG.5b. One difference between the embodiments ofFIGS.5band12is that the device ofFIG.5bonly shows 3 cylindrical elements inserted into one another, because the inner protective cylindrical element600and outer protective cylindrical element625are not shown.

In the arrangement ofFIG.12, inner protective cylindrical element600comprises a rigid portion as shown inFIG.6which is located at the proximal side of the steerable instrument. This rigid portion is, at its distal end, connected to a flexible portion680which may be made of one or more hinges like flexible portion666. At its distal end, flexible portion680is connected to a rigid portion681which, at its distal end, is connected to a flexible portion682. This flexible portion682is, at its distal end, connected to a rigid portion683which itself, at its distal end, connected to a flexible portion684. Flexible portion684is, at its distal end, connected to a rigid portion685which may be a rigid ring. As will be evident to a person skilled in the art, inner protective cylindrical element600with all its rigid and flexible portions may be made from a single cylindrical tube, e.g. by laser cutting.

In the arrangement ofFIG.12, longitudinal elements602of intermediate cylindrical element619have a flexible portion670at the longitudinal location of flexible portion680of inner protective cylindrical element600. At its distal end, each flexible portion670may be attached to a less flexible portion671which itself, at its distal end, may be connected to a flexible portion672. Flexible portions672are located at the same longitudinal location as flexible portion682of inner protective cylindrical element600. At its distal end, each flexible portion672may be attached to a less flexible portion673which itself, at its distal end, is attached to a flexible portion674. Finally, all flexible portions674, at their distal ends, are connected to a single rigid ring675. Rigid ring675is attached to rigid portion685of inner protective cylindrical element600, e.g. by laser welding or by any suitable mechanical connection including a snap-fit connection. Alternatively, glue can be used. As will be evident to a person skilled in the art, intermediate cylindrical element619with all its rigid portions, longitudinal elements, flexible portions, and less flexible portions may be made from a single cylindrical tube, e.g. by laser cutting.

In the arrangement ofFIG.12, rigid, cylindrical portion612aof intermediate cylindrical element621, at its distal end, is attached to a plurality of longitudinal elements. Each such longitudinal element is provided with a flexible portion676at the longitudinal location of flexible portion680of inner protective cylindrical element600. At its distal end, each flexible portion676may be attached to a less flexible portion677of the longitudinal element which itself, at its distal end, may be connected to a flexible portion678. Flexible portions678are located at the same longitudinal location as flexible portion682of inner protective cylindrical element600. At its distal end, each flexible portion678is attached to a rigid portion689which has the form of a rigid ring. The rigid portion689is, at its distal end, attached to a flexible portion690. The flexible portion690may be implemented by hinges like flexible portion666. Finally, flexible portion690, at its distal end, is connected to a single rigid ring691. Rigid ring691may be attached to rigid ring675of inner intermediate cylindrical element619, e.g. by laser welding or by any suitable mechanical connection including a snap-fit connection. Alternatively, glue can be used. As will be evident to a person skilled in the art, intermediate cylindrical element621with all its rigid portions, longitudinal elements, flexible portions, and less flexible portions may be made from a single cylindrical tube, e.g. by laser cutting.

In the arrangement ofFIG.12, intermediate cylindrical element623has different functions. As explained above, at its proximal side the intermediate cylindrical element623is provided with a plurality of longitudinal elements635which, at their distal ends, have finger-shaped elements646. These finger-shaped elements646are interleaved with finger-shaped elements627(cf.FIG.9). These finger-shaped elements627are, at their distal ends, attached to rigid, ring-shaped element642. At its distal end, the rigid, ring-shaped element642is connected to a flexible portion686which is located at the same longitudinal location as flexible portion680of inner protective cylindrical element600. Flexible portion686may be designed in the same way as flexible portion666of outer protective cylindrical element625. At its distal end, flexible portion686is connected to a rigid, bend-resistive portion687, preferably, designed such as to completely cover longitudinal elements677and, thus, protect them against dust, liquids, moisture, and other contaminations. At its distal end, the rigid, bend-resistive portion687is connected to a flexible portion688which may be designed in a similar way as flexible portion666. Finally, at its distal end, flexible portion688is connected to a rigid, ring-shaped portion691. Rigid, ring-shaped portion691is attached to rigid portion689of intermediate cylindrical element621, e.g. by laser welding or by any suitable mechanical connection including a snap-fit connection. Alternatively, glue can be used. As will be evident to a person skilled in the art, intermediate cylindrical element623with all its rigid portions, longitudinal elements, flexible portions, and less flexible portions may be made from a single cylindrical tube, e.g. by laser cutting.

First actuation zone15at the proximal side of the steerable instrument is formed by flexible portion666, flexible longitudinal elements633, and flexible portion624, respectively, which are connected/attached to rigid, ring-shaped elements668,656, and626, respectively. By deflecting the first actuation zone15longitudinal elements635will move in a longitudinal direction of the steerable instrument.

As explained above, any longitudinal movement of one or more of the longitudinal elements635translates into a longitudinal movement of respective ones of the longitudinal elements602because each one of the longitudinal elements635is connected/attached to a respective one of the longitudinal elements602via a sliding island618. Consequently bendable zone152, which forms first deflectable zone17, at the distal side will be deflected. Because longitudinal elements635are located at a greater distance from the axis of symmetry692of the steerable instrument than the longitudinal elements602, a certain deflection angle of the first actuation zone15results in a larger deflection of deflectable zone17at the distal side. Thus, an amplification effect is obtained. Some of the amplification may be lost due to elasticity of the longitudinal elements635,602.

Similarly, flexible zone156forms second actuation zone14comprising flexible portion686, flexible portions676of the longitudinal elements in the intermediate cylindrical element623, flexible portions670of longitudinal elements602, and flexible portion680. By deflecting the steerable instrument about the second actuation zone14bendable zone154, which forms deflectable zone16, will be deflected too due to longitudinal movement of the longitudinal elements678,677,676. Deflectable zone16comprises flexible portion688, flexible portions678of the longitudinal elements in the intermediate cylindrical element623, flexible portions672of longitudinal elements602, and flexible portion682.

As will be evident to persons skilled in the art, the longitudinal elements in the different cylindrical elements may be oriented in a spiral form such that a bending of the first and/or second actuation zone14,15in a certain surface results in a deflection of the deflectable zones16,17in a different surface with a different orientation. One preferred orientation change is in a range of 170-190°, more preferably in a range of 175-185°. Reference is made toFIG.2h.

Diameter adaptation zone164is shown between actuation zones14,15. However, as shown inFIG.5a, diameter adaptation zone164can, alternatively, equally well be located at the distal side of actuation zone14.

Now, some alternative embodiments are briefly explained.

First of all, it is observed that in the above explanation ofFIGS.6-12the increase of the distance to the axis of symmetry of longitudinal elements602to the longitudinal elements635equals the sum of the thickness of intermediate cylindrical element619and the thickness of intermediate cylindrical element621. Alternatively, a longitudinal element in first cylindrical element can simply be attached, e.g. by laser welding or any desired mechanical connection, to a longitudinal element in a second cylindrical element that is adjacent to the first cylindrical element. As a further alternative, sliding island618may itself be attached to another sliding island in another cylindrical element adjacent to cylindrical element621in which sliding island618is located, such that there are two (or even more) sliding islands located between longitudinal elements602and635. This would increase the amplification factor.

Sliding islands can be also used in an embodiment where they are attached to longitudinal elements arranged in a spiral form (cf.FIG.2h). Such sliding islands can prevent out-of-plane reactions of the tip, support a linear load of flexible longitudinal elements and cause less fatigue.

As a further alternative, no sliding island618is used in space631but lip648of longitudinal element635is folded inwardly through space631such that it engages and is welded to longitudinal element602.

A still further alternative embodiment of a cylindrical diameter adaptation section164is shown inFIGS.13aand13b. These figures show a mechanical connection between longitudinal element635and longitudinal element602. Such a mechanical connection can be made by providing longitudinal element635with an inwardly (i.e. towards the axis of symmetry) extending lip700. This lip700may result from a T-shaped longitudinal element635of which the upper two small branches are folded inwardly, as shown inFIG.13a. Of course, if desired there may only be one such lip700, or more than two such lips700. Lip700is arranged such that, in the assembled state, the most extending portion of lip700is located in a hole702in longitudinal element602. Preferably, that most extending portion of lip700has a tight fit into hole702such that play of lip700in hole702is kept to an absolute minimum.

FIG.13bshows how such a lip extends through space631in cylindrical element621. Thus, again longitudinal elements635are located at a distance from axis of symmetry692equal to the distance of longitudinal elements602from axis of symmetry692plus the thickness of cylindrical element619and of cylindrical element621. Of course, such a lip700can be made smaller or larger. This lip700can be used to connect adjacent longitudinal elements in adjacent cylindrical elements or longitudinal elements divided by more than one cylindrical element.

Even though the instrument has been mainly explained with reference to the embodiment ofFIGS.6-12in which the steerable instrument has two actuation zones at a proximal side of the instrument and two bendable zones at a distal side, each one being controlled by one actuation zone, it should be understood that the invention is not restricted to two such actuation zones and two such controlled bendable zones. It can be applied in an instrument having one or more actuation zones and one or more controlled bendable zones. Moreover, even though the embodiment ofFIG.5bhas been used as a starting point for explaining the invention with reference to cylindrical diameter adaptation section164inFIGS.6-12, the invention can also be applied in the embodiment ofFIG.5awith reference to cylindrical diameter adaptation section162.

To summarize, in the above examples a steerable instrument has been described and explained with at least the following features.

The steerable instrument10is designed for endoscopic and/or invasive type of applications, such as in surgery, and comprises an elongated tubular body18having at least one actuation zone14,15at a proximal side of the steerable instrument and at least one bendable zone16,17at a distal side of the steerable instrument. The at least one actuation zone14,15is arranged to control bending of the at least one flexible zone16,17by means of a plurality of longitudinal elements. The steerable instrument has a cylindrical diameter adaptation section164comprising a first side and a second side. The longitudinal elements are located at a first distance from an axis of symmetry692of the steerable instrument at the first side and at a second distance from the axis of symmetry692at the second side, where the first distance is different from the second distance.

The longitudinal elements comprise at least a first set of one or more longitudinal elements602and a second set of one or more longitudinal elements635.

The one or more longitudinal elements602of the first set of longitudinal elements are located at the first distance from the axis of symmetry692at the first side as well as within the cylindrical diameter adaptation section164.

The one or more longitudinal elements635of the second set of longitudinal elements are located at the second distance from the axis of symmetry692at the second side as well as within the cylindrical diameter adaptation section164.

Each one of the one or more longitudinal elements602of the first set of longitudinal elements overlaps with one of the one or more longitudinal elements635of the second set of longitudinal elements within the cylindrical diameter adaptation section164as seen in a radial direction from the axis of symmetry692, and is at least one of connected and attached to the one of the one or more longitudinal elements635of the second set of longitudinal elements, such that a movement of the one of the one or more longitudinal elements602of the first set of longitudinal elements in a longitudinal direction of the steerable instrument results in a same movement of the one of the one or more longitudinal elements635of the second set of longitudinal elements in the longitudinal direction.

Advantages of the presented design may be as follows.

The proximal side of the steerable instrument can made from a rigid intact portion of a tube.

No longitudinal elements need to be guided to another diameter layer of the instrument during manufacturing, thus simplifying the manufacturing process.

The longitudinal elements undergo less stress and compression.

All flexible portions are cut in the same way resulting in less play between spacers and longitudinal elements.

A cylindrical element with sliding islands forms a mask during (laser) welding of the sliding islands to innerly located longitudinal elements. This prevents welding of adjacent longitudinal elements to one another or to other tube portions.

Sliding islands are guiding longitudinal elements when they move in a longitudinal direction and prevent tangential movement of them which also compensates torque.

The presented design can be used to implement more than one diameter adaptation section easily.

By using break islands, a tube can be separated into different independent sections (as indicated with dotted lines613,652) which can be used for different functions.

Spacers

A second aspect relates to using sliding islands as spacers and guiding elements between adjacent longitudinal elements in the same cylindrical element. This second aspect elaborates upon prior art disclosed in WO2009112060A of the present applicant. To illustrate this second aspect, firstFIG.8and its related description from WO2009112060A will be repeated here. WO2009112060AFIG.8is copied here asFIG.14a.

FIG.14ashows an unrolled version of a part of an intermediate cylindrical element810. The figure shows two end portions831,835which are mutually connected by means of a plurality of longitudinal elements800of which two are shown. In this figure, the two adjacent longitudinal elements802are shown as having a first flexible portion801attached to end portion831and a second flexible portion803attached to end portion835. The first flexible portion801is attached to the second flexible portion803by means of an intermediate portion802which may be more rigid than the first flexible portion801and the second flexible portion802e.g., at least twice as rigid. The end portions831,835and the longitudinal elements800can be made by laser cutting from a single cylindrical tube.

The first flexible portions801and the second flexible portions803, respectively, have a circumferential width such that there is a circumferential gap804and805, respectively, between each pair of adjacent first flexible portions801and second flexible portions803, respectively. The intermediate portions802have a circumferential width such that two adjacent intermediate portions802are substantially in contact with each other, meaning that they are only separated from one another by a slit remaining after laser cutting the single cylindrical tube to render the end portions X31, X35and the longitudinal elements800connecting them.

In each gap804and805, respectively, sliding islands806and807, respectively, have been placed which sliding islands806and807, respectively, have a circumferential width filling the width of the gap804and805, respectively. Thus, sliding islands806and807provide guiding elements for the adjacent first flexible portions801and adjacent second flexible portions803, respectively, such that they prevent substantial tangential movement of adjacent first flexible portions801relative to one another and of adjacent second flexible portions803relative to one another.

The sliding islands806,807may be made by laser cutting them from the same single cylindrical tube from which the end portions831,835and the longitudinal elements800have been made. Then, the sum of the separations at either sides between sliding island806and the first flexible portions801and between sliding island807and the second flexible portions803may be two times the width of a slit remaining after such laser cutting.

Free movement of the longitudinal elements800in the longitudinal direction is achieved in that in the longitudinal direction the sliding islands806and807, respectively, do not completely fill up the entire space of the gaps804and805, respectively, but leave a predetermined free space.

For the production of such a system as shown inFIG.14a, as explained in WO2009112060A, it is possible to first make the intermediate cylindrical elements by means of, e.g., laser cutting from a single cylindrical tube, which results in an intermediate cylindrical element in which each sliding islands806and807are still connected either to an adjacent longitudinal element800or to end portions831or835. In this form, the connection point between the sliding island element806and807and the remaining of the intermediate cylindrical element810remains intact when the intermediate cylindrical element810is shifted into another cylindrical element external to the intermediate cylindrical element810, which is provided with holes coinciding with the connection points. Once the assembly is finished, the connection points can then be destroyed.

As also explained in WO2009112060A, the sliding islands806and807are not completely free from the remaining of the instrument, but each sliding island806and807is connected either to another cylindrical element either internal to or external to the intermediate cylindrical element810. In the embodiment shown this has been achieved by welding at one point808and809, respectively, the sliding islands806and807to an intermediate rigid portion of the other cylindrical element external or internal to the intermediate cylindrical element810. In this way the longitudinal elements800are accurately guided by the sliding island806and807in the flexible portions of the instrument, but the sliding island element806and807themselves are not free to move whereby the control of movement has been improved.

FIG.14bshows how sliding islands can be used as spacers between adjacent longitudinal elements which sliding islands are first connected to adjacent longitudinal elements by means of break islands which are later in in the manufacturing process broken off such that the sliding islands can freely move in an open space between adjacent longitudinal elements. This breaking off process can be performed without needing any holes in other cylindrical elements to destroy connection points as disclosed in WO2009112060A.

FIG.14bis based onFIG.4described above and the same reference numbers refer to the same components. So, second aspect is explained with reference to a steerable instrument with one actuation zone at a first, e.g. proximal, side and arranged to control deflection of a single bendable zone at a second other, e.g. distal, side of the instrument. The shown steerable instrument comprises a diameter adaptation zone at the first side. However, the steerable instrument according to the second aspect may have no or more than one diameter adaptation zone at any desired location. Moreover, the steerable instrument according to the second aspect may also have more than one actuation zone and more than one bendable zone, wherein a deflection of each one is controlled by one actuation zone by means of its own set of longitudinal elements and wherein the sets are arranged in one or more intermediate cylindrical elements.

During the manufacturing process, the following actions are performed.

Inner cylindrical element2202is provided with its flexible parts2222and2224, and intermediate rigid part2223. Inner cylindrical element2202is preferably produced from a single tube, e.g. by laser cutting. Its material and dimensions, respectively, are selected from the same materials and dimensions, respectively, as indicated above with reference to inner cylindrical element600.

Intermediate cylindrical element2203is provided. It comprises rigid ring2331at the proximal side and rigid ring2335at its distal side. Rigid ring2331and rigid ring2335are attached to one another by means of a plurality of longitudinal elements2338. Intermediate cylindrical element2203is preferably produced from a single tube, e.g. by laser cutting. Its material, diameter and thickness, respectively, are selected from the same materials, diameter and thickness, respectively, as indicated above with reference to intermediate cylindrical elements619,621,623. Between adjacent longitudinal elements2338, the intermediate cylindrical element2203comprises one or more sliding islands618a,618b,618c. Each sliding island618a,618b,618cis still attached to at least one adjacent longitudinal element2338by means of at least one break island616a/620a,616b/620b,616c/620c. Each one of these break islands616a/620a,616b/620b,616c/620cmeet the requirements of the definition given above with reference to break islands604,606,616,620,644.

At predetermined portions, sliding islands618a,618b,618care separated from adjacent longitudinal elements2338by means of a small slit which is not wider than as caused by the manufacturing process to cut into the cylindrical tube. Smallest widths of these slits may be between 5-50 μm, preferably between 15-30 μm, as resulting from e.g. laser cutting.

Inner cylindrical element2202is inserted into intermediate cylindrical element2203such that flexible parts222and2224are longitudinally aligned with flexible portions of longitudinal elements2338.

In the shown example, after such alignment, sliding islands618a,618band618c, respectively, are longitudinally aligned with flexible part2224, intermediate rigid part2223, and flexible part2222of inner cylindrical element2202, respectively. A portion of sliding island618ais arranged such that it extends beyond flexible part2224as seen in the longitudinal direction. The other portion, which is longitudinally aligned with flexible part2224should be flexible in a longitudinal direction because, if not, the steerable instrument cannot be deflected about flexible part2224. This can be done by making suitable transverse slits in that other portion of sliding island618a, as persons skilled in the art will understand.

Similarly, a portion of sliding island618cis arranged such that it extends beyond flexible part2222as seen in the longitudinal direction. The other portion, which is longitudinally aligned with flexible part2222should be flexible in a longitudinal direction because, if not, the steerable instrument cannot be deflected about flexible part2222. This can be done by making suitable transverse slits in that other portion of sliding island618c, as persons skilled in the art will understand.

Since sliding island618bis entirely aligned with intermediate rigid part2223it need not be flexible in its longitudinal direction.

Now, sliding islands618a,618b,618ccan be attached to inner cylindrical element2202. To that effect, each one of said sliding islands618a,618b,618cis attached, preferably, to a location on a rigid part of inner cylindrical element2202. The attachment is made on one or more locations on each sliding island618a,618b,618c. Instead of these attachments, or in addition to them, the sliding islands618a,618b,618cmay be attached at one or more locations to outside cylindrical element2204, as will be explained below.

The set of inner cylindrical element2202and intermediate cylindrical element2203is inserted into outer cylindrical element2204. Flexible parts2242and2244, respectively, are aligned with flexible parts2222and2224, respectively.

Sliding island618bis now aligned with intermediate rigid part2243. Portions of sliding islands618aand618care aligned with rigid parts of outer cylindrical element2204too.

As indicated with respective arrows840,841,842,843,844,845,846, and847sliding islands618a,618b,618cmay be attached at one or more suitable locations to a rigid part of outer cylindrical element2204.

It is observed that inner cylindrical element2202and outer cylindrical element2204need not be provided both. One of them is sufficient. Moreover, if they are both present, sliding islands618a,618b,618cmay be attached at one or more suitable locations to rigid parts of only one of inner cylindrical element2202and outer cylindrical element2204.

After the inner cylindrical element2202, intermediate cylindrical element2203and outer cylindrical element2204have been inserted into one another the flexible zone as defined by flexible parts2222,2242and/or the flexible zone as defined by flexible parts2224and2244is deflected. By doing so, a longitudinal force in longitudinal elements2338is applied resulting in a counter-force in respective break islands616a,620a,616b,620b,616c,620csuch that they break off from the respective longitudinal elements2338to which they are attached. However, they remain attached to said inner and/or outer cylindrical element2202,2204and will function as longitudinal guides between adjacent longitudinal elements2338which prevent tangential movement.

It is observed that exerting a longitudinal force in the longitudinal elements2338to let the break islands616a,620a,616b,620b,616c,620cbreak off may be generated in any desired way.

It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The present invention is not limited to the disclosed embodiments but comprises any combination of the disclosed embodiments that can come to an advantage.

Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the description and claims, the word “comprising” does not exclude other elements, and the indefinite article “a” or “an” does not exclude a plurality. In fact it is to be construed as meaning “at least one”. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention. Features of the above described embodiments and aspects can be combined unless their combining results in evident technical conflicts.