Nose-dive microrobot

Abstract

The present invention relates to a microrobot (10) configured to move along a propulsion direction within a viscoelastic anatomical environment, the microrobot (10) comprising: a body (12) extending along a body axis (X); a navigation head (14) extending along a head axis (H), the navigation head (14) assuming a given configuration relative to the body; a propulsion element (16) presenting an outer surface (18) having a helical external thread (20) extending along the propulsion axis (A) and assuming a given configuration relative to the body; and a drive means (22) configured to rotationally drive the propulsion element about the propulsion axis (A). The microrobot (10) further comprises an orientation device (24) configured to change at least one of the given configuration of the navigation head and the given configuration of the external thread relative to the body to change the propulsion direction.

Description

[Technical Field]

[0001] The present invention relates to a microrobot configured to navigate within a solid viscoelastic material by the initiation and propagation of cracks within said material. [Background technology]

[0002] The ability to reach deep and functional structures without injury is a major challenge in minimally invasive surgery, especially in neurosurgery.

[0003] Microtechnology makes it possible to send fully autonomous microrobots inside the organs of a subject, such as the brain. However, most existing microrobots in the prior art can only be propelled by propellers in viscous liquids, such as blood or cerebrospinal fluid. On the other hand, the brain is known to be, at least in part, a solid viscoelastic organ.

[0004] In materials science and continuum mechanics, viscoelasticity is the property of a material that exhibits both viscous and elastic properties when subjected to deformation. Viscous materials, such as water, resist shear flow and distort linearly over time when stress is applied. Elastic materials distort when stretched and quickly return to their original state when the stress is removed. Viscoelastic materials have elements of both of these properties and therefore exhibit time-dependent distortion. Viscoelastic materials can sometimes be assimilated to solid materials.

[0005] Therefore, propelling a microrobot with a propeller in a solid, viscoelastic environment like the brain is extremely challenging because the brain is elastic (it can store energy and return it to the environment). Using such a propeller in the brain must meet certain criteria to be able to cross this elastic wall (which is a property of matter) and move into it; otherwise, the propeller and the microrobot will remain in the same place and become blocked within the matter.

[0006] Therefore, effectively penetrating and moving through viscoelastic biological tissue is a challenge.

[0007] In view of the above, the present invention aims to propose a microrobot with an efficient propulsion mechanism in a solid viscoelastic environment such as the brain. The microrobot must first open (or generate) a crack so that it can move inside the solid viscoelastic material, then widen the crack so that it can enter the crack, and finally enter the crack so that it can move inside the environment.

[0008] Another important requirement is that the microrobot must be able to navigate through the organ while causing as little physiological damage as possible to the organ as its passage. Therefore, it is important that the cracks that initiate and propagate are as precisely oriented as possible and as small as possible in size.

[0009] Another important requirement is that the microrobot must be able to move through the organ while at the same time causing as little physiological damage as possible to the organ through its passage.

[0010] To address these technical and biological constraints, an energy-efficient means of propulsion in the solid matter of the brain, the extracellular matrix of the brain parenchyma, and also in other viscoelastic organs such as the pancreas or liver, for medical and surgical purposes, is the propagation of cracks by the skilled insertion of devices, in particular microrobots, inside the organs or organ regions listed above.

[0011] Such microrobots should be technically equipped and configured to at least propagate existing cracks and, in some embodiments, generate cracks that can then be burrowed into in order to navigate the interior of an organ or organ region.

[0012] To propagate such cracks, it is possible to use a rotating end, including (but not limited to) a screw pitch. A rotating screw pitch can thus widen an existing crack (or create a new one) by rotating inside the material, extending its opening further forward, while allowing the microrobot to advance like a screw. The aim of the present invention is to propose a microrobot that is technically capable of navigating biological viscoelastic environments in a controlled manner along a navigation path, as non-invasive and non-damaging as possible. Summary of the Invention

[0013] Accordingly, the present invention provides a microrobot configured to move along a propulsion direction in a viscoelastic anatomical environment, comprising: a body extending along a body axis; a navigation head extending along a head axis between a free distal tip and a proximal base, the navigation head assuming a given configuration relative to the body; a propulsion element extending along the propulsion shaft and presenting an outer surface with a helical external thread, the external thread presenting a predetermined configuration relative to the body; drive means configured to drive the propulsion element in rotation about the propulsion axis relative to the body; The microrobot further comprises an orientation device configured to change at least one of a given configuration of the navigation head and a given configuration of the male thread relative to the body to change a propulsion direction of the microrobot.

[0014] In this way, this solution makes it possible to achieve the above-mentioned objectives, in particular to change the propulsion direction of the microrobot in a controlled manner, thus allowing for precise control of the microrobot's navigation path in a viscoelastic environment.

[0015] The system according to the invention may comprise one or several of the following features, either separately or in combination with one another: the driving means may be further configured to drive the navigation head in rotation; a given form of the external thread may include a given inclination angle of the head axis relative to the body axis, and the orienting device may be configured to change the given inclination angle of the head axis relative to the body axis; the orientation device may include a pivot configured to rotate the navigation head relative to the body along at least one pivot axis; The given form of the external thread of the propulsion element may include a given inclination angle of the propulsion shaft relative to the body axis, and the orientation device may be configured to change the given inclination angle of the propulsion shaft relative to the body axis; The orienting device may comprise a pivot configured to rotate the propulsion element relative to the body along at least one pivot axis; the drive means may comprise a support shaft connecting the proximal base of the navigation head to the body and comprising a pivot connection; the support shaft may be fixed to the engine body by a flexible piece of material; the support shaft may be made of a flexible material; The support shaft may further connect the propulsion element to the body; The external thread morphology may include a pitch of the external thread, and the orienting device may be configured to change the pitch of the external thread; the orienting device may comprise a series of connectors movably mounted inside the propulsion element and coupled to the external threads, the connectors having a relative positioning with respect to one another, the relative positioning varying depending on their angular position with respect to the outer surface of the propulsion element; The series of connectors are arranged such that the relative position of the connectors with respect to the outer surface of the propulsion element is a first relative position in which the outer surface is at a first relative angular position, the connectors at the first relative position being spaced apart from each other by respective first distances, the first distances being a minimum; a second relative position in which the outer surfaces are at a second relative angular position, the connectors at the second relative position being spaced apart from each other by respective second distances, the second distances being a maximum; configured to vary between -A series of connectors an internal central connector positioned inside the propulsion element, the central connector being tiltable relative to the propulsion axis inside the propulsion element; at least two lateral connectors extending between the central connector and the external thread; It may comprise:

[0016] The invention will be better understood and other objects, details, features and advantages will become more apparent on reading the following detailed description of embodiments of the invention, given by way of illustration, purely by way of illustrative and non-limiting example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0017] [Figure 1a] 1 is a schematic diagram of the present invention according to a first embodiment. [Figure 1b] FIG. 1b is the same schematic diagram as FIG. 1a, showing different given configurations. [Figure 2] FIG. 2 is a detailed schematic diagram of a support shaft according to an embodiment of the present invention. [Figure 3a-3b] 5A-5C are schematic diagrams showing two different given configurations of the second embodiment of the present invention. [Figure 4a-4b] 10A-10C are schematic diagrams showing two different given configurations of the third embodiment of the present invention. [Figure 5] FIG. 2 is a detailed schematic diagram of a particular orientation device according to one embodiment of the present invention. [Figure 6a-6b] 10A-10C are schematic diagrams showing two different given configurations of the fourth embodiment of the present invention. [Figure 7a-7b] 10A-10C are schematic diagrams showing two different given configurations of the fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention relates to a microrobot 10 configured to move along a propulsive direction within a viscoelastic anatomical environment, as seen in the different figures.

[0019] This viscoelastic environment can be, for example, the extracellular matrix of the brain.

[0020] According to the present invention, the microrobot 10 comprises: a body 12 extending along a body axis X; a navigation head 14 extending along a head axis H between a free distal tip 14a and a proximal base 14b; a propulsion element 16 extending along a propulsion axis A and presenting an outer surface 18 with an external helical thread 20; drive means 22 configured to drive the propulsion element 16 in rotation relative to the body 12 about the propulsion axis A; Equipped with.

[0021] The drive means 22 comprises a rotor (or moving part) of an actuatable motor (not shown) comprising a stator and a rotor. The motor is located inside the body 12. The stator may be part of the body 12.

[0022] The drive means 22 can be located inside or outside the body 12. The drive means 22 comprises motion transmission means. These motion transmission means are coupled to actuable motors and allow the motion generated by the actuated motors to be transmitted to the elements of the microrobot 10 that need to be actuated. More specifically, the drive means 22 is configured to rotationally drive the propulsion element 16. This is shown in FIGS. 7a and 7b. In these embodiments, the drive means 22 only rotationally drives the propulsion element 16 about the propulsion axis A. In these embodiments, the navigation head 14 is not rotationally driven by the drive means 22. As will become clear from the following description, the navigation head 14 is not rotationally driven by the drive means 22, but can be turned to change the direction of the microrobot 10. In the embodiments of FIGS. 1a, 1b, 3a, 3b, 4a, 4b, 6a, and 6b, the drive means 22 is further configured to rotationally drive the navigation head 14. In these embodiments, the navigation head 14 and the propulsion element 16 are the same technical element.

[0023] The motion transmission means of the drive means 22 can be, for example, a series of threads made of a smart material, such as an electroactive polymer like Nitinol or PEDOT, regularly distributed around the body axis X (see FIGS. 1a, 1b, and 7a, 7b). In the embodiment of FIGS. 3a and 3b, these threads are further coupled to a central string structure that optimizes orientation performance. In a further embodiment not shown, the drive means 22 can comprise a central drive rod. In such an embodiment, the support shaft 24 can be part of the drive means 22. The drive means 22 can further comprise an external drive cylinder directly coupled to the motor and further coupled to the proximal base 14b of the navigation head 14. This external drive cylinder can be coupled to the proximal base 14b of the navigation head by a bellows-like element 23 (see, for example, FIGS. 3a and 3b). This bellows-like element 23 can be a string. Nevertheless, the bellows presents the technical advantage of being a closed element and can therefore function as a kind of shell or envelope, thereby protecting the elements located within the bellows from the viscoelastic environment.If the rotation of the propulsion element 16 occurs from the periphery of the motor of the body 12, it presents the technical advantage of transmitting a stronger torque to the rotating propulsion element 16.

[0024] In some embodiments, the navigation head 14 is coupled to the rotor of the actuatable motor by a support shaft 24, which connects the proximal base 14b of the navigation head 14 to the motor. The support shaft 24 extends along the body axis X. In some embodiments, the propulsion element 16 is also coupled to the rotor of the actuatable motor by the support shaft 24. In these embodiments, the navigation head 14 and the propulsion element 16 are preferably (but not necessarily) the same technical element. In some alternative embodiments, such as the embodiment of FIGS. 7a and 7b, the propulsion element 16 extends around the support shaft 24.

[0025] In some alternative embodiments, navigation head 14 is coupled to the rotor of the actuatable motor by a bellows or string element 25. In the rest position, bellows or string element 25 extends along body axis X. Due to its structure, bellows or string element 25 allows navigation head 14 to easily and smoothly tilt in any possible direction relative to body 12. In some embodiments, propulsion element 16 is also coupled to the rotor of the actuatable motor by a bellows or string element 25. In some embodiments, bellows or string element 25 surrounds support shaft 24.

[0026] The body 12 may carry multiple functional elements, such as electronics, sensors, drug cargo, or other tools or elements. In some cases, the body 12 is formed from successive body sections, each equipped with one or several of the aforementioned functional elements. Two adjacent body sections may be connected to each other by a flexible joint. The body 12 is connected to the stator of an actuatable motor. The orientation of this stator does not move. More precisely, the stator does not rotate itself along the body axis X. Its technical purpose is to serve as an orientation reference.

[0027] The navigation head 14 has a generally conical or spike-like shape. Thus, the free distal tip 14a of the navigation head 14 has a diameter significantly smaller than the diameter of the proximal base 14b of the navigation head 14. This shape may be slightly twisted or curved. More precisely, the free distal tip 14a has a variable length and can bend and / or twist along its length. Its shape may be conical, arrow-shaped, convex, or concave.

[0028] The function of the navigation head 14 is to propagate and, in some embodiments, initiate a crack within the viscoelastic environment through which the microrobot 10 must navigate. The shape of the navigation head 14 influences the general shape of the crack that is generated and therefore must have certain specific technical characteristics. The main technical characteristics of the navigation head 14 are its sharpness and its coefficient of friction with the viscoelastic medium, which should be minimal. Since the microrobot 10 cannot navigate inside solid matter (the elastic part of the viscoelastic environment), it is necessary to initiate a crack within the environment. The microrobot 10 can then navigate inside the crack toward its destination.

[0029] Unlike conventional crack theory, in which crack propagation is linear, the microrobot 10 of the present invention must be able to rotate / steer in all possible directions, right / left and up / down, to change its trajectory. In this way, the microrobot tilts its navigation head 14 in a specific direction to orient the crack. The microrobot 10 then moves forward in this specific direction to propagate the crack in this specific direction.

[0030] In this way, the microrobot 10 according to the present invention: - controlling the crack orientation by controlling the tilt of the navigation head 14 before generating the crack; - Controlling the propulsion of the microrobot 10 inside the crack that has occurred, thereby controlling the propagation of the crack By doing so, it is possible to control the trajectory of the viscoelastic material.

[0031] Regardless of its shape, the navigation head 14 always assumes a given configuration relative to the body 12. The concept of configuration in the context of this application is explained in more detail below.

[0032] In some embodiments, the navigation head 14 and the propulsion element 16 are the same technical element. More specifically, in these embodiments, the navigation head 14 forms the free distal end or forward tip of the propulsion element 16 (see, for example, Figures 1a, 1b or 4a, 4b), and the propulsion element 16 has a generally conical shape.

[0033] As already mentioned above, the propulsion element 16 presents an outer surface 18 having a helical external thread 20 (see, for example, Figures 1a, 1b, 2a, 2b, or 7a, 7b). Depending on the embodiment, the external thread 20 can be formed by a single continuous helical blade 200 (see Figures 1a and 1b) or by a series of small blades 202 (see Figures 6a and 6b) all aligned helically around the outer surface 18 of the propulsion element 16. As with the navigation head 14, the external thread 20 always presents a given form relative to the body 12.

[0034] When a given form of the external thread 20 is defined and the propulsion element 16 is moved (rotated) by the drive means 22, the propulsion element 16 becomes a helix or impeller, allowing the microrobot 10 to move along the propulsion direction. The microrobot 10 according to the present invention can therefore be likened to a system that acts like a screw penetrating a solid material such as a wall or a wooden board.

[0035] In the present invention, the term "form" refers to "the arrangement of a group of things," as defined by the Collins Online Dictionary. Thus, the term "form" includes the relative position of elements relative to one another. Depending on the embodiment, the form of the navigation head 14 relative to the body 12 and the form of the external threads 20 of the propulsion element 16 relative to the body 12 can be either independent of one another (meaning that the form of the navigation head 14 can be changed without affecting the form of the external threads 20 of the propulsion element 16, and vice versa) or interdependent of one another (meaning that a modification of the form of the navigation head 14 induces a modification of the form of the external threads 20, and vice versa).

[0036] Considering the embodiment of FIGS. 7a and 7b, the given configuration of navigation head 14 includes an inclination angle α1 of head axis H relative to body axis X.

[0037] Considering the embodiments of Figures 1a, 1b and 2a, 2b, the given configuration of the external thread 20 of the propulsion element 16 relative to the body 12 includes an inclination angle α2 of the propulsion axis A of the propulsion element 16 relative to the body axis X.

[0038] 1a, 1b, 2a, and 2b, the navigation head 14 is part of the propulsion element 16, and the given tilt angles α1 and α2 are the same. The given configurations of the navigation head 14 and the external thread 20 are interdependent, and one cannot be changed without changing the other.

[0039] 7a and 7b, only the navigation head 14 can be oriented and the tilt angle α1 can be changed, but the propulsion element 16 does not change its configuration relative to the body 12. Thus, a given configuration of the male thread 20 and a given configuration of the navigation head 14 are independent of each other.

[0040] 4a, 4b, 6a, and 6b, the configuration of the external threads 20 of the propulsion element 16 relative to the body 12 includes the pitch of the external threads 20. Thus, the pitch of the external threads 20 is variable along the outer surface 18 of the propulsion element 16.

[0041] A given change in the configuration of one or both of the navigation head 14 and / or the external thread 20 allows the microrobot 10 to change its propulsion direction while moving forward in the viscoelastic environment. This change in configuration can generate new cracks with a desired orientation in the viscoelastic environment, or it can allow the microrobot 10 to smoothly follow a path designed by an existing crack (which may or may not have been previously generated by the microrobot 10).

[0042] To change the given configuration of the external threads 20 of the navigation head 14 and / or the propulsion element 16 relative to the body 12, the microrobot 10 includes an orientation device 26. The orientation device 26 includes a series of elements that interact with each other to change the given configuration of one or both of the external threads 20 and the navigation head 14. Thus, the orientation device 26 is broadly configured to change the propulsion direction of the moving microrobot 10. In other words, the change in propulsion direction is achieved by changing the given configuration of at least one of the external threads 20 or the navigation head 14.

[0043] In some embodiments, the orienting device 26 is configured to change a given inclination angle α2 of the propulsion axis A of the propulsion element 16 relative to the body axis X. The orienting device 26 may also be configured to change a given inclination angle α1 of the head axis H of the navigation head 14 relative to the body axis X.

[0044] In these embodiments, the orienting device 26 may include a pivot connection 28 configured to tilt the navigation head 14 relative to the body 12 along at least one pivot axis. In some other of these embodiments, the orienting device 26 may include a pivot connection 28 (e.g., a ball joint) configured to tilt the propulsion element 16 relative to the body 12 along one or more pivot axes. In these embodiments, the navigation head 14 is preferably part of the propulsion element 16. In some of these embodiments, it is the support shaft 24 that includes the pivot connection 26 that allows the navigation head 14 to be tilted relative to the body 12 (see FIGS. 1a and 1b). In some embodiments, the bellows-like or string-like element 25 is part of the pivot connection 26. In some alternative embodiments, the support shaft 24 is secured to the rotor of the actuable motor by a piece of flexible material (e.g., 3D printed resin, a given polymer, or PEEK).

[0045] In some further alternative embodiments, the support shaft 24 is made of a flexible material (see FIG. 2). In some embodiments, the support shaft 24 includes smart material threads, as described in detail above, that are therefore capable of tilting the navigation head 14 (and sometimes the propulsion element 16) when actuated in a particular direction. In some alternative embodiments shown in FIG. 2, the support shaft 24 includes a series of internal conduits. Each conduit is under pressure, and varying the pressure in one or more of these internal conduits can achieve some tilting of the support shaft 24.

[0046] Typically, the orienting device 26 is part of a compliant mechanism. In mechanical engineering, a compliant mechanism is defined as a flexible mechanism that achieves the transmission of force and motion through elastic deformation. A compliant mechanism derives some or all of its motion from the relative flexibility of its members, rather than solely from rigid joints. The advantage of such a compliant mechanism is that there are no two (or more) parts that move relative to each other. This generally increases the rigidity of the system, but limits the system's ability to move.

[0047] Considering the embodiments of Figures 4a, 4b and 6a, 6b, the orienting device 26 is configured to change the pitch of the external thread 20 of the propulsion element 16. More precisely, for these embodiments, the orienting device 26 comprises a series of connectors 30, 32 movably mounted inside the propulsion element 16 and coupled to the external thread 20. More precisely, the orienting device 26 comprises: a central internal connector 32 positioned inside the propulsion element 16, the central connector 32 being tiltable inside the propulsion element 16 relative to the propulsion axis A; at least two lateral connectors 30 extending between the central connector 32 and the external thread 20; Equipped with.

[0048] Thus, all of the connectors 30 have a relative positioning with respect to one another that changes according to the angular position with respect to the outer surface 18 of the propulsion element 16. In embodiments in which the propulsion element 16 has a single helical blade 200, the connectors 30 function in concert to change the pitch of said single blade 200. In embodiments in which the propulsion element 16 has a series of bladelets 202, each bladelet 202 is coupled to at least one connector 30 and its pitch can be changed independently of the other bladelets 202. This second mechanism is similar to the mechanism for changing blade pitch on a helicopter.

[0049] Regardless of the shape of the male thread 20, the series of connectors 30 are such that the relative positioning of the connectors 30 is a first relative position in which the outer surface 18 is in a first relative angular position; a second relative position in which the outer surface 18 is in a second relative angular position; In the first relative position, the connectors 30 are spaced a first distance from one another, the first distance being a minimum. In the second relative position, the connectors 30 are spaced a second distance from one another, the second distance being a maximum.

[0050] In this particular embodiment, an asymmetric change in the pitch of the male thread 20 can be achieved. The orientation of the propulsion elements 16 and navigation head 14 is not modified, but the given configuration of the male thread 20 is still modified, so that the microrobot 10 exhibits a tighter pitch on one side of the outer surface 18 of the propulsion elements 16, while the pitch is coarser on the other side of the outer surface 18.

Claims

1. A microrobot (10) configured to move along a propulsion direction within a viscoelastic anatomical environment, the microrobot (10) comprising: a body (12) extending along a body axis (X); a navigation head (14) extending along a head axis (H) between a free distal tip (14a) and a proximal base (14b), said navigation head (14) assuming a given configuration relative to said body (12); a propulsion element (16) extending along a propulsion axis (A) and presenting an outer surface (18) with a helical external thread (20), said external thread (20) presenting a given configuration relative to said body (12); - drive means (22) adapted to drive said propulsion element (16) in rotation about said propulsion axis (A) relative to said body (12); Equipped with The microrobot (10) further comprises an orientation device (24) configured to change at least one of a given configuration of the navigation head (14) relative to the body (12) and a given configuration of the male thread (20) to change the propulsion direction of the microrobot (10).

2. The microrobot (10) according to the preceding claim, wherein the driving means (22) is further configured to rotationally drive the navigation head (14).

3. A given configuration of the male thread (20) allows for a given inclination angle (α) of the head axis (H) relative to the body axis (X). １ ), and the orienting device (26) adjusts the head axis (H) to the body axis (X) at a given tilt angle (α １ 10. The microrobot (10) of any one of the preceding claims, configured to change the

4. 10. The microrobot (10) of the preceding claim, wherein the orientation device (26) comprises a pivot connection (28) configured to rotate the navigation head (14) relative to the body (12) along at least one pivot axis.

5. A given configuration of the external thread (20) of the propulsion element (16) allows for a given inclination angle (α) of the propulsion axis (A) relative to the body axis (X). ２ ), and the orienting device (26) adjusts the angle of inclination (α) of the propeller shaft (A) relative to the body axis (X). ２ 10. The microrobot (10) of any one of the preceding claims, configured to change the

6. 10. The microrobot (10) of the preceding claim, wherein the orienting device (26) comprises a pivot connection (28) configured to rotate the propulsion element (16) relative to the body (12) along at least one pivot axis.

7. 10. The microrobot (10) of claim 1, wherein the drive means (22) comprises a support shaft (24) connecting a proximal base (14b) of the navigation head (14) to the body (12) and comprising the pivot connection (28).

8. The microrobot (10) of the preceding claim, wherein the support shaft (24) is fixed to the engine body (12) by a piece of flexible material.

9. 9. A micro-engine according to claim 7 or 8, wherein the support shaft (24) is made of a flexible material.

10. The microrobot (10) of any one of claims 7 to 9, wherein the support shaft (24) further couples the propulsion element (16) to the body (12).

11. 10. The microrobot (10) of any preceding claim, wherein the configuration of the external thread (20) includes a pitch of the external thread (20), and the orienting device (26) is configured to change the pitch of the external thread (20).

12. 10. The microrobot of claim 1, wherein the orienting device comprises a series of connectors movably mounted within the propulsion element and coupled to the external threads, the connectors having a relative positioning with respect to one another, the relative positioning varying depending on the angular position of the propulsion element with respect to the outer surface.

13. The series of connectors (30) are arranged such that the relative position of the connectors (30) with respect to the outer surface (18) of the propulsion element (16) is: a first relative position in which the outer surface (18) is in a first relative angular position, the connectors (30) in the first relative position being spaced apart from each other by respective first distances, the first distances being minimum; a second relative position in which the outer surface (18) is in a second relative angular position, the connectors (30) in the second relative position being spaced apart from each other by respective second distances, the second distances being maximum; 10. The microrobot (10) of the preceding claim, configured to change between

14. The series of connectors (30) an internal central connector (32) positioned inside the propulsion element (16), the central connector (32) being tiltable relative to the propulsion axis (A) inside the propulsion element (16); - at least two lateral connectors (30) extending between said central connector (32) and said external thread (20); The microrobot (10) according to claim 12 or 13, comprising:

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