WO2024256885A1

WO2024256885A1 - Continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery

Info

Publication number: WO2024256885A1
Application number: PCT/IB2024/053849
Authority: WO
Inventors: Alessio Merola; Donatella DRAGONE; Carlo Cosentino; Francesca Federica DONADIO; Paolo Zaffino; Domenico LA TORRE; Maria Francesca Spadea
Original assignee: Universita degli Studi "Magna Graecia" di Catanzaro
Current assignee: Universita degli Studi "Magna Graecia" di Catanzaro
Priority date: 2023-06-13
Filing date: 2024-04-19
Publication date: 2024-12-19
Anticipated expiration: 2025-12-13
Also published as: IT202300012135A1

Abstract

Continuous robot (100) with auxetic lattice modular structure for minimally invasive neurosurgery, comprising: - an element (101), flexible and comprising a plurality of modules connected in series by means of a sequence of rolling joints; - a plurality of tie rods (102) crossing the element (101) by means of through holes made on external portions of each module; - an actuation module (103) of the plurality of tie rods (102), connected to each tie rod; - an electronic control unit (104), connected to the actuation module (103); - a computer program product executed by the electronic control unit (104) and configured to manage the actuation module (103). In particular, the element (101) is an elastic element, each module has a reticular structure and is made of an auxetic metamaterial, and the actuation module (103) is a pneumatic actuation module.

Description

DESCRIPTION

Continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery"

The present invention relates to a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery .

In particular, the present invention relates to a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, comprising modular components actuated on the basis of a speci fic control algorithm executed by processing units .

The reference technical field is the electromedical sector, speci fically the field of electronically controlled robotic hardware designed to assist neurosurgeons in targeted interventions on the brain parenchyma .

Cranial neurosurgical procedures generally aim at removing tumors or blood clots in the brain tissues , trying to make the interventions safer and little or nothing invasive . To this end, currently, elongated and tubular instruments are used, inside which auxiliary instruments and devices , possibly provided with an adj ustable and prehensile end, are inserted . The use of such systems allows to reach brain areas , even deep, through a single hole of a few centimeters made on the skull of a patient , according to a minimally invasive approach . In this way a neurosurgeon is able to operate from outside the skull by inserting the various instruments inside the rigid tubular structures , reaching the region of interest while minimi zing the risk of damaging delicate and functional structures of the brain . Furthermore , neurosurgical procedures , particularly those aimed at removing tumors , can benefit from continuous imaging techniques , such as magnetic resonance imaging, MRI , which can provide excellent contrast , as well as high resolution, of the soft tissues . Imaging techniques , in this sense , help the neurosurgeon to avoid critical structures of the brain not af fected by the surgical task .

The advantages provided by continuous imaging, however, can be nulli fied by the use of the aforementioned instruments , such as neuroendoscopes and stereotaxic guides , which are straight and rigid, with possible risks for the safety of a patient , due to the reduced maneuverability o f the surgical devices . The l imitations of surgical instruments are particularly relevant when important brain structures are in line with the desired surgical traj ectory, making it difficult to avoid unwanted contact, or when deep areas of the brain have to be reached.

In order to overcome these problems, caused by reduced maneuverability and reduced control of the curvature of the instruments, a possible solution is offered by the adoption of robotic devices, with the function of flexible manipulators, integrated with MRI imaging systems, that allow a control accuracy of the robot configuration and of the operating trajectories. The so-called continuous robots, having characteristics of manipulators with multiple degrees of freedom and compatible MRI, allow for example to remove tumors with high dexterity, thanks to the accurate control of the kinematics of the robot and the trajectories of the end-effector, i.e., the terminal actuated in the operating field in a distal position, the farthest position from the neurosurgeon. The aforementioned continuous robots, classifiable as flexible and hyper-redundant manipulators, ensure flexibility, safety, dexterity, construction simplicity and miniaturization.

One of the most effective solutions in favor of the safety of neurosurgical intervention and tissue integrity is the adoption of a continuous manipulator having a flexible mechanical structure with basic modules connected in series. This structure, tubular in shape, is able to offer a passage section for intracerebral aspiration and irrigation, as well as speci fic channels for wiring sensors , tie rods for cable actuation and microsurgical instruments for the removal o f tumors . Such a continuous robot , inserted by means of an intracranial access through the aforementioned hole made in the skull , allows the surgeon to reach the target site and manipulate a set of miniaturi zed instruments in correspondence with the distal end of the manipulator, to perform a set of surgical tasks .

Even these robotic instruments , however, suf fer from some limitations , as will be better clari fied hereafter, primarily the reduced possibi lity of combining the mouldability of the rigidity of the structure with a high dexterity of the distal portion .

Several robotic systems , useful to assist neurosurgical tasks , are available in the patent literature .

A first example of a known technical solution is cited in the patent application US2020323599A1 , whose obj ect is an articulated structure , guided by the relative movement of a plurality of segments connected in series , which includes a first segment and a second segment arranged in contact with each other, wherein the contact surfaces of the first segment and second segment are rolling surfaces in line of contact along a first direction . The first segment has a pin on one side , the second segment has a mating hole in which the aforementioned pin is inserted, with the first segment and the second segment performing a relative rolling movement for the translation of the contact line along the first direction, maintaining the contact line . The mating hole is manufactured with an area larger than the area of the pin, to allow the latter to move within the hole during the rolling motion .

Furthermore , the patent application US2021095700A1 describes a fluidic actuator having a surface configured to be deformed in response to a pressure gradient . One or more auxetic elements are arranged and engage the surface of the actuator in the form of a network of bundle elements , and regulate the deformation of the fluidic chambers of the actuator . The auxetic element has a negative Poisson ' s ratio which involves a kinematic chain such that upon application of the pressure of the internal fluid, the surface of the actuator is induced to undergo a speci fic kinematics which allows planar and three-dimensional movements .

The subj ect of the patent application US2015202013A1 is a medical instrument comprising a stem which includes at least two sections , adj acent and movable with respect to each other . The same sections are engaged so as to roll over each other and lock by friction, or mesh with each other through teeth .

The patent application US2023158692A1 discloses an external cladding, made using a metamaterial , which includes a tessellation of folded structures . Such an external cladding integrates the mechanical needs of mobile structures through a single process , which replicates engineering models available in nature . The tessellation can be assembled discretely and can include a staggered arrangement of corrugations . In some embodiments , the metamaterial may consist of a portion of a continuous robotic structure .

The patent application US2022370162A1 , instead, cites a set of tools for minimally invasive surgery which comprises a wrist assembly including a first j aw, a first drive hub and a cable redirection hub operatively coupled to the aforementioned first drive hub . The tools also include a second j aw, a second drive hub, a housing for the first and second j aw, three cables , rotational position sensors and a control system .

Finally, the patent application EP3380180B1 discloses a pneumatic device for holding and moving an elongated obj ect , comprising an annular hollow body, crossed by the obj ect and constituted by two end parts forming j aws and by a median segment connecting the two j aws between them, with the ability to move relative to one another under the ef fect of a controlled deformation of at least a portion of said median segment . The device is characteri zed by the various parts of the hollow body defining respective chambers , and by the aws including elastically deformable internal membranes . The chambers of the two end portions are in fluid communication with the chamber of the median segment , each by means of at least one respective calibrated flow medium, while the inj ection of a pressuri zed gaseous fluid occurs through a single supply line .

Several limitations af fect robotic systems such as those mentioned, such as the aforementioned inability to guarantee the modulability of the flexural sti f fness coupled with the dexterity of the distal portion required in delicate neurosurgical interventions , in which continuous robots are used, with the frequent use , in such known systems , of rolling j oints which do not provide a structure having a controllable compliance .

A possible resolution of this constraint , only partially adopted in some of the patent texts previously described, is provided by the use of robotic modules whose structure is created entirely or at least partially using auxetic metamaterials , and which contemplates segments of such modules comprising rolling j oints . Auxetic metamaterials , i . e . , metamaterials having a negative Poisson ' s ratio , understood as the ratio between a transversal deformation and a longitudinal deformation, thanks to the possibility of calibrating their mechanical sti f fness allow to modi fy their curvature in order to adapt to the profile of various obj ects .

The purpose of the present invention is to provide a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery which, thanks to the control of the structural compliance of the same robot , allows to achieve a gradient of flexural sti f fness along the extension of the robot itsel f by calibrating the mechanical behavior of the individual modules , having, therefore , characteristics such as to overcome the limits that still af fect the known technical solutions .

Another purpose of the present invention is to provide a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery which ensures the functions of an endosurgical/endocranial manipulator characteri zed by a kinematic chain useful for insertion into the narrow and/or deep spaces of the operating field, without the risk of damaging primary functional structures of the brain . A further purpose of the present invention is to provide a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery which allows the use of electronic instrumentation for MRI imaging during an intracranial surgery .

Finally, another purpose of the present invention is to provide a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery characteri zed by construction simplicity, by means of additive manufacturing techniques , cost-ef fectiveness and the possibility of disposable use .

According to the present invention, a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery is provided, as defined in claim 1 .

For a better understanding of the present invention, a preferred embodiment is now described, purely by way of nonlimiting example , with reference to the attached drawings , in which :

- figures la and lb show two di f ferent schemati zations of the di f ferent mechanical responses , to stresses , of elastic solids , in the respective portions ( a ) , and of auxetic elastic solids , in the respective portions (b ) ;

- figure 2 shows a first overall view of a component of a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, according to the invention;

- figure 3 shows a second overall view of the component , showed in figure 2 , of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, according to the invention;

- figure 4 shows a sagittal view representative of an application of the component showed in figure 2 of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, according to the invention ; figure 5 shows an overall schematic view of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, according to the invention .

With reference to these figures and, in particular, to figure 5 , a continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery is shown, according to the invention .

In particular, the continuous robot 100 with auxetic lattice modular structure for minimally invasive neurosurgery comprises : an element 101 , elastic, flexible and having a substantially tubular shape , comprising a plurality of modules connected in series by means of a sequence of rolling j oints and made of an auxetic metamaterial ; - a plurality of tie rods 102 cros sing the element 101 , for the overall extension of the element 101 itsel f , by means of through holes made on external portions of each module comprised in the plurality of modules ;

- an actuation module 103 of the plurality of tie rods 102 , connected to each tie rod comprised in the plurality of tie rods 102 ;

- an electronic control unit 104 , based preferably on a microcontroller unit and provided with non-volatile integrated memory modules , connected to the actuation module 103 ;

- an automatic control algorithm or control unit module , i . e . , a computer program product , executed by the electronic control unit 104 and configured to manage the actuation module 103 .

According to one aspect of the invention, each module comprised in the plurality of modules , made of an auxetic metamaterial , has a reticular structure .

According to one aspect of the invention, the actuation module 103 is a pneumatic actuation module , powered, preferably, by an electrical compressor .

According to one aspect of the invention, the plurality of reticular modules consists of a first proximal segment 101a, of a second central segment 101b and of a third distal segment 101c .

According to one aspect of the invention, the element 101 performs the functions of an endocranial manipulator actuated by a neurosurgeon by means of an external console connected to the electronic control unit 104 .

According to one aspect of the invention, the plurality of tie rods 102 is made by means of Bowden cables .

Figure 1 schemati zes the di fferent behavior to mechanical stresses , in particular traction and compression, of auxetic materials , which among others include Gore-Tex , and non-auxetic materials . Auxetic metamaterials are particularly used in the production of personal protective equipment , or PPE , armor and other devices where impact resistance properties are important . Unlike non-auxetic elastic solids , schemati zed in portion ( a ) of figure la by a honeycomb lattice , in which a compressive force causes a transversal expansion visible in the same figure , the same stress applied to an auxetic metamaterial , schemati zed in portion (b ) of figure la, involves , by virtue of the characteristics of these materials , a contraction or " reclosure" of the structure of the auxetic materials/ solids . It follows that a compressive force applied to an auxetic metamaterial , due to the contraction of the structural lattice of the same metamaterial , increases its level of sti f fness . The same considerations can be replicated about figure lb, schemati zing the mechanical response to a compressive force applied to a non-auxetic ( a ) and auxetic solid (b ) .

According to one aspect of the invention, the plurality of tie rods 102 preferably comprises a number of such actuation means equal to four .

According to another aspect of the invention, in particular, the plurality of tie rods 102 includes a first tie rod 102a and a second tie rod 102b subj ected in use to an antagonistic simultaneous actuation, operated by means of the actuation module 103 .

Furthermore , according to another aspect of the invention, such an antagonistic simultaneous actuation, according to two forces ' F ' applied respectively to the first tie rod 102a and to the second tie rod 102b, having the same module but in the opposite direction, as visible in figure 2 , is able to modulate the curvature of the element 101 along substantially its entire extension and to vary the bend o f the third distal segment 101c, i . e . , the segment directly applied to the intracranial surgical field, better shown in figure 4 . In fact , advantageously according to the invention, the application of these forces ' F ' , opposite in direction, leveraging the mechanical response of the reticular modules of the elastic element 101 , in detail the first proximal segment 101a, the second central segment 101b and the third distal segment 101c, as a consequence of the antagonistic action of the tie rods 102a, 102b crossing the through holes of the aforementioned three segments , allows the shape/curvature of the structure of the element 101 to be locally modulated .

Furthermore , advantageously according to the invention, the variation of the local shape/curvature of the structure of the endocranial manipulator 101 , consequence of the antagonistic action of the tie rods 102a, 102b exerted by the actuation module 103 , is particularly useful for exerting a curvilinear traj ectory when inserting the element 101 into the skull , avoiding sensitive areas of the brain and avoiding potential inj uries until reaching the surgical field, often located in depth . Such an advantage , which guarantees dexterity and compliance of the elastic element 101 to reduce the risk of damage in delicate situations such as the aspiration of a cerebral hemorrhage , is once again ensured by the auxetic nature of the metamaterial with which the structural lattice of the manipulator is made , and by the external convex profiles of each mesh of the lattice , which implements the sequence of rolling j oints that ensures the flexibility of the same endocranial manipulator 101 .

According to one aspect of the invention, the plurality of tie rods 102 comprises also a third tie rod 102c and a fourth tie rod 102d subj ected in use to a concordant simultaneous actuation, operated by means of the actuation module 103 .

According to one aspect of the invention, the aforementioned concordant simultaneous operation, according to two forces ' F ' applied respectively to the third tie rod 102c and to the fourth tie rod 102d, having the same modules and directions , as shown in figure 3 , is suitable for modulating the flexural sti f fness of the element 101 along substantially its entire extension .

In fact , advantageously according to the invention, the application of such forces ' F ' , acting as a co-contraction stress applied to the tie rods 102c and 102d to simulate a similar activation of biological muscles , stressing the rolling j oints of the element 101 , and in detail of the three proximal , central and distal segments 101a, 101b, 101c crossed in correspondence with the respective through holes by such cables 102c, 102d, acts as a compressive force on the auxetic cells of the element 101 , locally increasing the flexural stiffness of the structure of the same element 101 and/or reducing the cross section of such an endocranial manipulator 101.

Furthermore, advantageously according to the invention, such an increase in the flexural stiffness of the element 101, and in particular of the third distal segment 101c, is useful, during a neurosurgical intervention, where high strength and stiffness of the manipulator are needed, understood as the ability to transfer the actuation forces through the tie rods 102, for example for the resection/removal of tumors.

Advantageously according to the invention, differently from the conventional kinematic chains of known continuous robots, the reticular modular structure, made of an auxetic metamaterial, of the continuous robot 100, allows to robustly control the curvature of the element 101 of the same robot.

Advantageously according to the invention, the continuous robot 100 implements a so-called variable neutral line mechanism, i.e., a mechanism whose flexural stiffness can be efficiently controlled thanks to the adoption of rolling joints; through the regulation of the tension of some tie-rods, the rolling contact between curvilinear and convex profiles of such joints is modulated in order to enhance the controllability of the flexural stiffness with enhanced robustness against external interaction forces perturbing the desired bending of the robot body . Furthermore , for optimi zing the control of the flexural sti f fness , the speci fic elastic properties of materials and structures having negative Poisson' s ratio are advantageously exploited, according to the invention, to extend the range of controllability of the sti f fness . On the contrary, in known technical solutions , such a range is constrained by the limited extens ion of the contact arc o f the j oint profiles , during a relative rolling, which are rigid and, therefore , lacking of elastic structures with controllable compliance .

According to one aspect of the invention, the continuous robot 100 comprises a set of microsurgical instruments , each in use removably connected, for example interchangeably with one of the other instruments , to the element 101 , in correspondence with the third distal segment 101c to be used directly in the operatory field by the neurosurgeon, and to the electronic control unit 104 by means of cables 105 housed inside the same element 101 . The neurosurgeon, through the aforementioned external console , by means of the control performed by the electronic control unit 104 which activates the actuation module 103 and, consequently, the tie rods 102 , actuates the endocranial manipulator 101 and, more speci fically, the microsurgical instruments fixed to the third distal segment 101c or other devices , connected and managed by the electronic control unit 104 and crossing the entire element 101 within suitable sheaths , for example suction probes for the reduction of hematomas , or irrigation probes of the surgical field .

According to another aspect of the invention, the continuous robot 100 comprises also a plurality of sensors , with each of such sensors being, in use , positioned in correspondence with the third distal segment 101c and connected to the electronic control unit 104 by means of further cables , in turn housed and passing through the overall element 101 .

According to one aspect of the invention, among the aforementioned sensors there is , preferably, a fiber optic probe useful for imaging the intracranial operatory field .

According to one aspect of the invention, the computer program product , i . e . , the speci fic management logic, stored and executed by the electronic control unit 104 , is configured to process electrical signals generated by each sensor .

According to one aspect of the invention, the element 101 and the plurality of tie rods 102 are compliant with electronic instrumentation for MRI imaging . Advantageously according to the invention, the compatibility with the use of electromedical equipment for MRI is achievable thanks to the use of cable actuators , the tie rods 102 , which allow the robotic endocranial manipulator 101 to be adequately distanced from the actuation module 103 and from the electronic control unit 104 , so as to be able to perform one or more magnetic resonance imaging .

Advantageously according to the invention, the separation and distance between the tie rods 102 and the actuation module 103 allows the element 101 to be miniaturi zed .

Therefore , the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention allows , thanks to the control of the structural compliance , to obtain a bending sti f fness gradient along the extension of a robotic endocranial manipulator which combines high maneuverability in the surgical field and reduced ris k of causing damage to functional structures of the brain .

Another advantage of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is that it allows the use of MRI electromedical instrumentation during an intracranial operation . Furthermore , the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is suitable for being produced by means of additive manufacturing techniques , including for example 3D printing .

A further advantage of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is that its use i s safe for the patient .

A further advantage of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is that it is inexpensive .

A further advantage of the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is that it is suitable for a disposable use .

Furthermore , the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is easy to apply .

Finally, the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery according to the invention is characteri zed by reduced complexity related to the prototyping and industriali zation steps .

It is finally clear that the continuous robot with auxetic lattice modular structure for minimally invasive neurosurgery, described and illustrated herein, may be subj ect to modi fications and variations without departing from the protective scope of the present invention, as defined in the appended claims .

Claims

1. Continuous robot (100) with auxetic lattice modular structure for minimally invasive neurosurgery, comprising :

- an element (101) , flexible and having a substantially tubular shape, comprising a plurality of modules connected in series by means of a sequence of rolling joints;

- a plurality of tie rods (102) crossing the element (101) , for the overall extension of said element (101) , by means of through holes made on external portions of each module comprised in the plurality of modules;

- an actuation module (103) of the plurality of tie rods (102) , connected to each tie rod comprised in the plurality of tie rods (102) ; characterized in that:

- the element (101) is an elastic element;

- each module comprised in the plurality of modules has a reticular structure and is made of an auxetic metamaterial;

- the actuation module (103) is a pneumatic actuation module, and in comprising:

- an electronic control unit (104) , connected to the actuation module (103) ; - a computer program product executed by the electronic control unit (104) and configured to manage the actuation module (103) .

2. Continuous robot (100) according to claim 1, characterized in that the plurality of modules consists of a first proximal segment (101a) , of a second central segment (101b) and of a third distal segment (101c) .

3. Continuous robot (100) according to claim 1, characterized in that the plurality of tie rods (102) is made by means of Bowden cables.

4. Continuous robot (100) according to claim 2, characterized in that the plurality of tie rods (102) comprises a first tie rod (102a) and a second tie rod (102b) subjected in use to an antagonistic simultaneous actuation, operated by means of the actuation module (103) and able to modulate the curvature of the element (101) along the overall extension of said element (101) and to vary the bend of the third distal segment (101c) .

5. Continuous robot (100) according to claim 1, characterized in that the plurality of tie rods (102) comprises a third tie rod (102c) and a fourth tie rod (102d) subjected in use to a concordant simultaneous actuation, operated by means of the actuation module (103) and able to modulate the flexural stiffness of the element (101) along the overall extension of said element (101) .

6. Continuous robot (100) according to claim 1, characterized in that the element (101) performs the functions of an endocranial manipulator actuated by a neurosurgeon by means of an external console connected to the electronic control unit (104) .

7. Continuous robot (100) according to claim 2, characterized in comprising a set of microsurgical instruments, each of said microsurgical instruments being removably connected to the element (101) , in correspondence with the third distal segment (101c) , and to the electronic control unit (104) by means of cables (105) housed and passing through said element (101) .

8. Continuous robot (100) according to claim 2, characterized in comprising a plurality of sensors, each of said sensors being placed in correspondence with the third distal segment (101c) and connected to the electronic control unit (104) by means of further cables housed and passing through said element (101) .

9. Continuous robot (100) according to claim 8, characterized in that the computer program product is configured for processing electrical signals generated by each sensor comprised in said plurality of sensors.

10. Continuous robot (100) according to claim 1, characterized in that the element (101) and the plurality of tie rods (102) are compliant with electronic instrumentation for MRI imaging.