WO2019068137A1

WO2019068137A1 - A device and method for immobilising a robotic capsule within a body lumen

Info

Publication number: WO2019068137A1
Application number: PCT/AU2018/051034
Authority: WO
Inventors: Gursel ALICI; Hao Zhou
Original assignee: University Of Wollongong
Priority date: 2017-10-03
Filing date: 2018-09-21
Publication date: 2019-04-11

Abstract

A device and method for immobilising a robotic capsule within a body lumen is disclosed. The device comprises a magnetic actuator, and at least one retractable member operably coupled to the magnetic actuator, wherein the magnetic actuator is responsive to an external magnetic field to cause the at least one retractable member to move between a retracted position, in which the at least one retractable member is substantially disengaged from an intraluminal wall of a body lumen, and a deployed position, in which the at least one retractable member is substantially engaged with the intraluminal wall of the body lumen to immobilise the device, and a robotic capsule coupled thereto, at a site specific location therewithin.

Description

A DEVICE AND METHOD FOR IMMOBILISING A ROBOTIC CAPSULE WITHIN A

BODY LUMEN

Technical Field

[0001 ] The present invention relates to a device and method for using said device for immobilising a robotic capsule within a body lumen at a site specific location.

[0002] The invention has been developed primarily for use in body lumen such as the gastrointestinal tract and will be described hereinafter with reference to this application.

[0003] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge in Australia or any other country as at the priority date of any one of the claims of this specification.

Background of Invention

[0004] Wireless capsule endoscopy (WCE) has revolutionised the world of minimally invasive medicine for diagnosing suspected diseases in body lumen such as the small bowel in vivo. Indeed, over the last few years, technologies associated with this technology have been greatly developed, making WCE a promising alternative to conventional fibre-scope based endoscopy for application in vivo, particularly in the gastrointestinal (Gl) tract and the small intestine.

[0005] However, the robotic capsules used in WCE applications to date are incapable of monitoring a site specific location in vivo at a desired point in time, which poses constraints on the diagnostic functions of such robotic capsules. This inability stems from the fact that robotic capsules, whether configured for active or passive locomotion within a body lumen, are invariably at the mercy of the natural peristalsis forces that occur in such lumen. This means that when a robotic capsule reaches a site specific location in vivo, it is unable to stop, and therefore has only a fleeting moment to capture images or obtain a pH or conductivity reading at this location, before it is whisked off along the lumen under the influence of the natural peristalsis. [0006] This inability to actively monitor a site of interest for any meaningful length of time would make a follow-on surgical or endoscopic intervention necessary, which really undermines the purpose of employing a robotic capsule in the first place.

[0007] The ability to stop a robotic capsule at a site specific location in vivo clearly represents a significant challenge.

[0008] To the best of our knowledge, most reported immobilising mechanisms simply use an on-board micromotor to open/close arms, without even considering the space consumption and energy consumption associated with such a mechanism.

[0009] The ability to immobilise a robotic capsule at a site specific location in vivo is not simply a matter of employing a mechanical actuation mechanism to engage the intraluminal walls of a body lumen to anchor the robotic capsule in place. For instance, where such robotic capsules are intended to operate in the gastrointestinal (Gl) tract, the irregular and slippery nature of the intestinal wall of this lumen renders it difficult to establish a firm anchoring point without running the risk of damaging the lining of the intestinal wall. In this respect, it is necessary to consider factors such as adhesion.

[0010] The present invention seeks to provide a device and method for using said device for immobilising a robotic capsule within a body lumen, which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.

Summary of Invention

[001 1 ] According to a first aspect of the present invention there is provided a device for immobilising a robotic capsule within a body lumen, the device comprising:

[0012] a magnetic actuator; and

[0013] at least one retractable member operably coupled to the magnetic actuator, wherein the magnetic actuator is responsive to an external magnetic field to cause the at least one retractable member to move between a retracted position, in which the at least one retractable member is substantially disengaged from an intraluminal wall of a body lumen, and a deployed position, in which the at least one retractable member is substantially engaged with the intraluminal wall of the body lumen to immobilise the device, and a robotic capsule coupled thereto, at a site specific location therewithin. [0014] In one embodiment, the at least one retractable member comprises a pair of retractable members operably coupled to the magnetic actuator at laterally opposing sides thereof.

[0015] In one embodiment, the magnetic actuator is a magnetic spring comprising two coaxially aligned magnets, each magnetized in a diametric direction of opposing polarity to the other.

[0016] In one embodiment, the at least one retractable member is operably coupled to each of the two coaxially aligned magnets.

[0017] In one embodiment, the two coaxially aligned magnets are magnetically coupled in the absence of the external magnetic field, and magnetically opposed when the external magnetic field has a magnetic field strength that is of sufficient magnitude to induce a magnetic force in the two magnetically coupled and coaxially aligned magnets which is greater than the attractive force therebetween.

[0018] In one embodiment, at least one of the two coaxially aligned magnets is caused to rotate about a longitudinal axis of the device in response to the external magnetic field applied in a plane of rotation of the coaxially aligned magnets that is perpendicular to a longitudinal axis of the device.

[0019] In one embodiment, a degree of said rotation of the at least one of the two coaxially aligned magnets is constrained by the at least one retractable member operably coupled between the two coaxially aligned magnets.

[0020] In one embodiment, the at least one retractable member comprises two arms, and wherein a first of the two arms is pivotably coupled at a first end thereof to an uppermost one of the two coaxially aligned magnets and a second of the two arms is pivotably coupled at a first end thereof to a lowermost one of the two coaxially aligned magnets.

[0021 ] In one embodiment, the two pivotably coupled arms are pivotably journaled together at a common pivot point distanced from their respective first ends to define a scissor-like opening and closing mechanism when at least one of the two coaxially aligned magnets is caused to rotate about the longitudinal axis relative to the other of the two coaxially aligned magnets in response to the external magnetic field. [0022] In one embodiment, each of the two coaxially aligned magnets is a ring magnet with an aperture extending substantially therethrough.

[0023] In one embodiment, the device further comprises an elongate central core, wherein each of the two coaxially aligned ring magnets is configured to receive the central core when said apertures are coaxially aligned to align with the longitudinal axis of the device.

[0024] In one embodiment, the central core comprises at least one groove disposed along a length of the central core, and a first of the two coaxially aligned ring magnets comprises an engaging portion arranged to locate at least partially within the groove to preclude the first coaxially aligned ring magnet from rotating about the central core.

[0025] In one embodiment, a second of the two coaxially aligned ring magnets is free to rotate about the central core relative to the first coaxially aligned ring magnet in response to the external magnetic field.

[0026] In one embodiment, the engaging portion of the first of the two coaxially aligned ring magnets being received within the groove portion facilitates sliding translation of the two coaxially aligned ring magnets relative to the longitudinal axis of the device.

[0027] In one embodiment, the device further comprises a lock configured to transition between a locked configuration in which the at least one retractable member is in the deployed position in response to the external magnetic field, and a released configuration in which the at least one retractable member is in the retracted position.

[0028] In one embodiment, the lock comprises a locking plate mounted to the central core that is configured to lock an uppermost one of the two coaxially aligned ring magnets relative to the central core when the lock is in the locked configuration.

[0029] In one embodiment, the uppermost one of the two coaxially aligned ring magnets comprises at least one lock portion and the locking plate comprises at least one complementary lock aperture configured to receive the at least one lock portion in the locked configuration by virtue of the sliding translation of the two coaxially aligned ring magnets relative to the longitudinal axis of the central core.

[0030] In one embodiment, each of the two arms is pivotably coupled at the respective first end thereof to an inner surface of a corresponding one of the two coaxially aligned magnets.

[0031 ] In one embodiment, each of the two arms is pivotably coupled at the respective first end thereof to an outer surface of a corresponding one of the two coaxially aligned magnets.

[0032] In one embodiment, each of the two arms comprises an end effector located at a terminal end thereof to engage with the intraluminal wall of the body lumen when the at least one retractable member is in the deployed position.

[0033] In one embodiment, the end effector is positioned proximal to the central core when the at least one retractable member is in the retracted position, and positioned distal to the central core when the at least one retractable member is in the deployed position.

[0034] In one embodiment, the end effector comprises a pad having a micro- and/or nano-patterned surface to increase the coefficient of friction (COF).

[0035] In one embodiment, the pad is manufactured from polydimethylsiloxane (PDMS).

[0036] According to a second aspect of the present invention there is provided an immobilisable assembly comprising:

[0037] a device according to the first aspect; and

[0038] a robotic capsule configured for operably coupling to the device.

[0039] In one embodiment, the device comprises an elongate central core, and wherein the robotic capsule comprises an elongate housing configured at an end portion thereof for coupling to the central core. [0040] In one embodiment, the elongate housing comprises diagnostic and/or therapeutic means located at an opposing end portion thereof.

[0041 ] In one embodiment, the magnetic actuator of the device is a magnetic spring comprising two coaxially aligned ring magnets magnetized in a diametric direction of opposing polarity, and each ring magnet is configured with an aperture extending substantially therethrough, and wherein the robotic capsule comprises an elongate housing configured to be received by the apertures of the two coaxially aligned ring magnets.

[0042] In one embodiment, the elongate housing comprises diagnostic and/or therapeutic means located at at least one end portion thereof,

[0043] In one embodiment, the diagnostic means is a camera.

[0044] In one embodiment, the immobilisable assembly further comprises an additional ring magnet magnetized in a diametric direction and operably coupled to the elongate housing of the robotic capsule at a location that is distanced from the magnetic actuator of the device part of the immobilisable assembly to reduce magnetic interference between the additional ring magnet and the magnetic actuator.

[0045] In one embodiment, the device comprises a locking plate slidable relative to the central core and configured to engage and lock an uppermost one of the two coaxially aligned ring magnets relative to the central core when an external magnetic field gradient is applied in proximity to the additional ring magnet to cause the at least one retractable member to be locked in the deployed position according to a locked configuration.

[0046] According to a third aspect of the present invention there is provided a system for immobilising a robotic capsule at a site specific location within a body lumen, the system comprising:

[0047] an immobilisable assembly according to the second aspect; and

[0048] a magnetic field generator configured to generate a magnetic field external of a body lumen, and in proximity to the magnetic actuator of the device part of the immobilisable assembly to cause the at least one retractable member to engage with an intraluminal wall of the body lumen to immobilise the immobilisable assembly, and thus the robotic capsule part thereof, at a site specific location therewithin.

[0049] According to a fourth aspect of the present invention there is provided a method for immobilising a robotic capsule at a site specific location within a body lumen, the method comprising:

[0050] coupling a robotic capsule to an immobilising means of a device according to the first aspect to provide an immobilisable assembly according to the second aspect;

[0051 ] positioning the immobilisable assembly within a body lumen; and

[0052] applying a magnetic field external of the body lumen, but in proximity to the magnetic actuator of the device, which is responsive to the external magnetic field to cause the at least one retractable member to engage with an intraluminal wall of a body lumen to immobilise the immobilisable assembly and thus the robotic capsule thereof, at a site specific location therewithin.

[0053] Suitably, movement of the immobilisable assembly toward the site specific location within the body lumen occurs by natural peristalsis.

[0054] Other aspects of the invention are also disclosed. Brief Description of Drawings

[0055] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0056] Fig. 1 shows schematic perspective views of a device according to a preferred embodiment of the present invention for use in immobilising a robotic capsule within a body lumen, in which two pairs of laterally opposed scissor-type extendable arms of the device are shown in (a) a retracted position, and (b) an extended position, and (c) a schematic representation of a magnetic spring element that forms the basis of a magnetic actuator for actuating movement of the two pairs of scissor-type extendable arms between the retracted and extended positions in response to an external magnetic field (B); [0057] Fig. 2 shows a schematic plan view of a device comprising a pair of coaxially aligned and rotatable discs, and two pairs of scissor-type extendable arms, each pair being pivotably coupled to each of the two discs at laterally opposed sides thereof, wherein the arms are configured for moving from a retracted (closed) position (a) through (b) to a fully extended or deployed (open) position (c) in response to rotation of one disc relative to the other disc (not visible);

[0058] Fig. 3 shows (a) a schematic plan view of the device of Fig. 2 with the laterally opposed scissor-type extendable arms in the fully extended (open) position when located within a body lumen, and (b) a schematic plan view of the device of Fig. 2 with the laterally opposed scissor-type extendable arms in the fully extended position and the forces associated with the laterally opposed scissor-type extendable arms acting on the intraluminal wall of the body lumen;

[0059] Fig. 4 shows a plot of torque (imNm) versus distance (mm) to compare experimental maximum internal torque values (diamonds) of a magnetic spring element comprised of two coaxially aligned ring magnets, each with an internal diameter of 2 mm, an outer diameter of 9 mm, a height of 10 mm, and a residual magnetic flux density (magnetic remanence) of about 1 tesla, with theoretical data (continuous line) obtained by finite elemental analysis (FEA);

[0060] Fig. 5 shows a plot of torque (imNm) versus distance (mm) to determine a maximum internal torque of three (3) differently configured magnetic spring elements using theoretical data obtained by finite elemental analysis (FEA), wherein each magnetic spring element is defined by two coaxially aligned ring magnets, each with an internal diameter of 2 mm, an outer diameter of 9 mm, and a residual magnetic flux density (magnetic remanence) of about 1 tesla, but with different heights: height = 1 .5 mm (squares), 2 mm (diamonds), 2.5 mm (triangles);

[0061 ] Fig. 6 shows schematic perspective views of the device of Fig. 1 coupled to an end portion of a housing of a robotic capsule to provide an immobilisable assembly with diagnostic and/or therapeutic means, wherein the magnetic actuator for actuating movement of the two pairs of scissor-type extendable arms of the device between (a) the retracted (closed) position and (b) the extended (open) position in response to an external magnetic field (B) is defined by two coaxially aligned magnets; [0062] Fig. 7 shows a plot of friction (imN) versus time (seconds) to determine a sliding friction value (imN) for the immobilisable assembly of Fig. 6 within a first sample of porcine small intestine mounted on a platform positioned within a Helmholtz coil system, wherein the external magnetic field (B) is 0 tesla;

[0063] Fig. 8 shows a plot of friction (imN) versus time (seconds) to determine a sliding friction value (imN) for the immobilisable assembly of Fig. 6 arranged to slide within the same first sample of porcine small intestine, in which the external magnetic field (B) applied by the Helmholtz coil system is 0.01 tesla, causing the laterally opposed scissor-type extendable arms to move from the retracted (closed) position (OFF, from 0 to 2 seconds) to the extended (open) position (ON, after 2 seconds) within the porcine small intestine sample (measurement repeated twice to obtain an average reading);

[0064] Fig. 9 shows a plot of friction (imN) versus time (seconds) to determine a sliding friction value (imN) for the immobilisable assembly of Fig. 6 arranged to slide within a second sample of porcine small intestine from the same animal, wherein the external magnetic field (B) is 0 tesla (measurement repeated);

[0065] Fig. 10 shows a plot of friction (imN) versus time (seconds) to determine a sliding friction value (imN) for the immobilisable assembly of Fig. 6 arranged to slide within the same second sample of porcine small intestine, in which the external magnetic field (B) applied by the Helmholtz coil system is 0.01 tesla, causing the laterally opposed scissor-type extendable arms to move from the retracted (closed) position (OFF, from 0 to 8 seconds) to the extended (open) position (ON, after 8 seconds) within the porcine small intestine sample (measurement repeated three times);

[0066] Fig. 11 shows a series of photographs (a) to (e) taken of the immobilisable assembly of Fig. 6, sliding within a third sample of porcine small intestine from the same animal, in which the laterally opposed scissor-type extendable arms are caused to move from the retracted (closed) position (OFF) to the extended (open) position (ON) in (c) in response to an external magnetic field (B) applied by the Helmholtz coil system is 0.01 tesla, and subsequently caused to transition back to the retracted position in (d) when the external magnetic field is switched OFF; [0067] Fig. 12 shows schematic perspective views of another device according to a preferred embodiment of the present invention, in which a pair of laterally opposed scissor-type extendable arms of the device are shown in (a) a retracted (closed) position, and (b) an extended or deployed (open) position, and (c) a schematic representation of a magnetic spring element that forms the basis of a magnetic actuator for actuating the laterally opposed scissor-type extendable arms to move between the retracted and extended positions in response to an external magnetic field (B);

[0068] Fig. 13 shows schematic perspective views of yet another device according to a preferred embodiment of the present invention, in which two pairs of laterally opposed scissor-type extendable arms for anchoring said device in a body lumen are shown in (a) a retracted (closed) position, and (b) an extended or deployed (open) position, and (c) a schematic representation of a magnetic spring element that forms the basis of a magnetic actuator for actuating the laterally opposed scissor-type extendable arms to move between the retracted and extended positions in response to an external magnetic field (B);

[0069] Fig. 14 shows schematic perspective views of still yet another device according to a preferred embodiment of the present invention coupled to a generally mid-portion of a housing of a robotic capsule to provide an immobilisable assembly with diagnostic and/or therapeutic means, wherein the device comprises a magnetic spring element that forms the basis of a magnetic actuator comprising of two coaxially aligned ring magnets configured for actuating movement of two pairs of scissor-type extendable arms of the device between (a) a retracted (closed) position and (b) an extended or fully deployed (open) position in response to an external magnetic field (B);

[0070] Fig. 15 shows schematic perspective views of still yet another device according to a preferred embodiment of the present invention for use in immobilising a robotic capsule within a body lumen, in which two pairs of laterally opposed scissor- type extendable arms of the device are shown in (a) a retracted (closed) position, (b) an extended or fully deployed (open) position in response to an external magnetic field (B), and (c) a locked position in response to an external magnetic field which has a magnetic field gradient (B_g); and [0071 ] Fig. 16 shows schematic perspective views of the device of Fig. 15 coupled to an end portion of a housing of a robotic capsule to provide an immobilisable assembly with diagnostic and/or therapeutic means, wherein the magnetic actuator for actuating movement of the two pairs of scissor-type extendable arms of the device between (a) the retracted (closed) position and (b) the locked position.

Detailed Description

[0072] It is to be understood that the following description is for the purpose of describing particular embodiments only and is not intended to be limiting with respect to the above description.

[0073] The present invention is predicated on the finding of a compact and effective device for coupling to a commercial robotic capsule with diagnostic and/or therapeutic function for use in selectively immobilising the robotic capsule at a site specific location within a body lumen such as the gastrointestinal (Gl) tract.

[0074] More specifically, the device is configured with immobilising means that is responsive to an externally applied magnetic field to cause laterally opposing extending scissor-type arms, each modified with an end effector at a terminal end thereof, to move from a retracted position (closed) to a deployed (open) position to impart a sufficient force against the intraluminal walls of the body lumen to overcome the natural peristalsis and other forces associated within the body lumen to selectively arrest movement of the robotic capsule at the desired location in order to allow the corresponding diagnostic and/or therapeutic task to take place. By removing the external magnetic field, the scissor-type arms simply revert back to their respective retracted positions to release the robotic capsule to allow it to continue movement along the body lumen under natural peristalsis.

[0075] Device 10

[0076] In a particularly preferred form, and as shown schematically in Fig. 1 , the device 10 comprises immobilising means in the form of a magnetic spring element that forms the basis of a magnetic actuator 30 configured for actuating movement of a pair of retractable members operably coupled to the magnetic actuator 30 at laterally opposite sides thereof in response to an external magnetic field (B). [0077] Magnetic Actuator

[0078] Specifically, and as shown in Fig. 1 (a) and Fig. 1 (b), the magnetic actuator 30 includes two magnetically responsive members 40, 50, mounted about a generally cylindrical elongate central core 20 in a coaxial arrangement relative to each other. The two magnetically responsive members 40, 50 take the form of a generally circular magnet with an aperture extending substantially through a central portion of each magnet 40, 50 that is configured to receive the generally cylindrical central core 20 when said apertures are coaxially aligned.

[0079] In a preferred form, one of these two coaxially aligned ring magnets 40, 50 is fixed to the central core 20, while the other is free to rotate about a longitudinal axis, c-c' that is coaxial with a longitudinal axis of the central core 20 (see Fig. 1 (c)) of the device 10.

[0080] Alternatively, both of the two coaxially aligned ring magnets 40, 50 are free to rotate about the longitudinal axis. In this arrangement, however, it will be appreciated by those skilled in the relevant art that the central core 20 includes a base portion (not shown) that is suitably configured with, for example, a larger diameter than the remaining portion of the central core 20, so as to prevent the two coaxially aligned ring magnets 40, 50 from sliding off and becoming separated from the central core 20.

[0081 ] In either form, the two coaxially aligned ring magnets 40, 50 are each magnetized in a diametric direction. That is, each ring magnet 40, 50 is magnetized across its respective diameter such that half of the ring magnet 40, 50 is of one polarity ((N)orth) and the other half is of the opposite polarity ((S)outh).

[0082] Retractable Members

[0083] As shown in Fig. 1 (a) and Fig. 1 (b), each of the two laterally opposed retractable members includes a pair of elongate arms 60, 65 and 70, 75, configured with a curvature that conforms to the curvature of the coaxially aligned ring magnets 40, 50. One arm 60 of the first pair of arms 60, 65 is pivotably coupled at a first end thereof to an inner facing surface of the uppermost ring magnet 40 at pivot point 90 while the other arm 65 is pivotably coupled at a first end thereof to an inner facing surface of the lowermost ring magnet 50 at a pivot point (not shown). Similarly, one arm 70 of the second pair of arms 70, 75, is pivotably coupled at a first end thereof to the uppermost ring magnet 40 at pivot point 80 and the other arm 75 is pivotably coupled at a first end thereof to the lowermost ring magnet 50 at a pivot point (not shown). The first pair of pivotably coupled arms 60, 65 is pivotably journaled together at a common pivot point 62 distanced from their respective first ends, while the second pair of pivotably coupled arms 70, 75 is pivotably journaled together at a common pivot point 72 distanced from their respective first ends. The degree of rotation of said one of the two coaxially aligned ring magnets 40, 50 relative to the other magnet is constrained by the pair of elongate arms 60, 65 and 70, 75.

[0084] By virtue of this arrangement, each of the two pairs of arms 60, 65 and 70, 75 defines a scissor-type extending mechanism, whereby the two pairs of scissor extendable arms 60, 65 and 70, 75 can be moved between a retracted position (closed) and an extended or deployed position (open) simply by rotating one of the two coaxially aligned ring magnets 40, 50 relative to the other about the longitudinal axis of the central core 20, or by rotating both of the two coaxially aligned ring magnets 40, 50 in opposite directions about the same longitudinal axis.

[0085] For instance, the uppermost ring magnet 40 in Fig. 1 (b) is shown as having been rotated 180° about the longitudinal axis of the central core 20 in an anticlockwise direction relative to the lowermost ring magnet 50, as indicated by the difference in the light and dark shading of the two magnetic rings 40, 50 in this figure when compared to Fig. 1 (a). This rotation causes the two pairs of scissor extendable arms 60, 65 and 70, 75 to transition from the retracted (closed) position (see Fig. 1 (a)) to the fully extended or deployed (open) positon (see Fig. 1 (b)).

[0086] To illustrate the scissor extending mechanism, Fig. 2 shows a schematic plan view of a device comprising a pair of coaxially aligned discs, of which only one disc is visible, and two pairs of scissor-type extendable arms, wherein each pair is pivotably coupled to the two discs at laterally opposed sides thereof. Referring specifically to one pair of arms, for description purposes, the arm denoted as AC is free to rotate around Point A, while the arm denoted as BC is free to rotate around Point B. Both arms AC and BC are constrained by their common joint, Point C.

[0087] As shown schematically in Fig. 2, when one or both of the two coaxially discs is caused to rotate in an opposite direction to the other, Point A and Point B move together causing the scissor extendable arms AC and BC to move from Fig. 2(a) the retracted position (closed) through Fig. 2(b) to Fig. 2(c) the fully extended or deployed position (open).

[0088] Indeed, by rotating Points A and B together, the length of the whole device increases by (2 + V2)r in y-axis and 2(V2 - l)r in x-axis.

[0089] As shown schematically in Fig. 2, when the two coaxially aligned discs are rotated back again, the two arms AC and BC are caused to retract back to the retracted position shown in Fig. 2(a).

[0090] The inventors conclude that the relative torsional displacement between these two discs is 180°, which is perfectly in accordance to the torsional displacement of a magnetic spring (MS) element, which will be discussed in more detail below.

[0091 ] Magnetic Spring Element

[0092] In simple terms, a basic magnetic spring (MS) element consists of two coaxially aligned permanent magnets, each magnetized in a diametric or diametral sense, with their magnetization directions parallel to each other. The coaxial magnets are allowed to rotate freely about the longitudinal axis but not to have linear movement perpendicular to this axis. To this end, the two magnets attract each other due to magnetic dipole-dipole coupling, and this same internal magnetic coupling restricts rotation and linear motion (along the longitudinal axis).

[0093] However, when the MS element is placed in a uniform magnetic field, both magnets tend to align to the external field, making one magnet rotate clockwise and the other magnet rotate anticlockwise. If the linear movements of the two magnets are restricted in the axial direction, only torsional elastic energy is stored in the MS element, making it a magnetic torsion spring, and its maximum torsional 'strain' is 180°. Otherwise, the attractive force between the two magnets turns into a repulsive magnetic force after the torsional 'strain' of 90° and the stretching of the MS element in the axial direction, which is similar to the loading process of a tensile magnetic spring. Hence, the MS element can be regarded as not only a torsional spring but also a tensile spring in this situation. When the external field is removed, both the torsional and linear elastic energy is released and the MS element comes back to the initial state. [0094] With this in mind, the inventors purposely devised the magnetic actuator 30 of the device 10 to exploit this capability. Specifically, and as schematically represented in Fig. 1 (c), the two ring magnets 40, 50 of the magnetic actuator 30, which are each magnetized in a diametric or diametral sense, are coaxially aligned about the longitudinal axis ((c - c'), where linear movement perpendicular to this axis is restricted by virtue of the two pairs of scissor-type extendable arms 60, 65 and 70 being pivotably coupled thereto. Thus, the two coaxially aligned ring magnets 40, 50 are magnetically coupled in the absence of an external magnetic field (B), but magnetically opposed when an external magnetic field (B) having a magnetic field strength that is of sufficient magnitude to induce a magnetic force in the two magnetically coupled and coaxially aligned ring magnets 40, 50 which is greater than the attractive force between the two coaxially aligned ring magnets 40, 50, is applied in a plane of rotation of the two coaxially aligned ring magnets 40, 50 that is perpendicular to the longitudinal axis of the central core 20. In this respect, the two pairs of arms 60, 65 and 70 are caused to move from the retracted position (closed) to the extended or deployed position (open) in response to an external magnetic field (B) of sufficient strength being switched ON in proximity to the device 10. The arms 60, 65 and 70, 75 in their fully extended or deployed positions are configured to engage with the intraluminal wall of the body lumen for use in immobilising a robotic capsule coupled to the central core 20 of the device 10 at a site specific location therewithin. As soon as the external magnetic field (B) is switched OFF, the two pairs of arms 60, 65 and 70 are caused to move back to the retracted position (closed), thereby disengaging from the intraluminal wall of the body lumen, thus releasing the robotic capsule.

[0095] End Effectors

[0096] As briefly described above, each of the four elongate arms 60, 65 and 70, 75 of the device 10 comprises a terminal end portion located distal to their respective first end, that acts as an end effector to engage with the intraluminal wall of the body lumen when the arms 60, 65 and 70, 75 are in their respective extended or deployed positions (open), distal to the central core 20.

[0097] In one embodiment, the end effector is simply the terminal end portion of the scissor-type extendable arm 60, 65 and 70, 75 itself. As shown in Fig. 1 , the scissor-type extendable arms 60, 65 and 70, 75 are outwardly curved when they are in their respective deployed (open) positions. In this respect, and as schematically represented in Fig. 3, each terminal end portion presents a significant amount of surface area for engaging with the intraluminal wall of a body lumen when the scissor- type extendable arms 60, 65 and 70, 75 are deployed. A large surface area amounts to a greater degree of contact with the intraluminal wall and thus a greater degree of friction. The outward curvature of the scissor-type extendable arms 60, 65 and 70, 75 at the terminal end portion also ensures that damage of the intraluminal wall is kept to a minimum.

[0098] In a preferred embodiment, the terminal end portions of the scissor-type extendable arms 60, 65 and 70, 75 are modified with bio-inspired adhesives to increase the coefficient of friction (COF). For instance, the bio-inspired adhesives may take the form of polymer pads with micro-sized patterns formed on the surface of the pad.

[0099] Results and Discussion

[0100] Force Analysis

[0101 ] To deploy a robotic capsule inside the Gl tract for a desired period of time, the force required to arrest the movement of the robotic capsule must be strong enough to overcome the natural peristalsis associated with the Gl tract. Since the Gl tract is viscoelastic and deformable, the hoop stress resulted from the stretched body lumen causes more compression and consequently more friction on the device 10, thereby enabling it to overcome the natural peristalsis within the Gl tract.

[0102] From the literature'²¹, it has been reported that the amplitude of the peristaltic forces is estimated to be 17.2 g/cm in the axial direction and 26.9 g/cm in the radial direction. For a commercial robotic capsule with a length of 2.6 cm, the corresponding estimation of the peristaltic forces is approximately 450 mN in the axial direction and 700 mN in the radial direction. It is the axial force that pushes the robotic capsule forward. Therefore, in this study, only the axial peristaltic force (450 mN) is considered for understanding the force required to arrest the movement of a robotic capsule within a body lumen such as the Gl tract.

[0103] Fig. 3(a) shows a schematic plan view of the device of Fig. 2 when located within a body lumen such as the Gl tract, in which the laterally opposed scissor-type extendable arms AC and BC are deployed in the fully extended or deployed position and the associated deformation of the intraluminal wall of the Gl tract that this mechanism causes. The reaction force exerted by the intraluminal wall of the Gl tract on the extended arms AC and BC of the device is indicated (by arrows) in both normal direction and tangential direction (in the form of friction) when natural peristalsis occurs.

[01 04] Fig. 3(b) shows the normal force (F-i) from the intraluminal wall of the Gl tract acting on one of the extended arms AC and BC.

[01 05] To understand the amount of torque required to keep the scissor-type extendable arms in a fully extended state when in their respective deployed (open) positions, the inventors have performed a series of calculations which will now be described.

[01 06] From Fig. 3(b), the requirement of torque T,_n on one permanent magnet to hold a scissor-type extendable arm at extension can be calculated by:

[01 07] F₂ = F₁L₁/L₂ (1 )

[01 08] T_in = 2F₂L₃ (2)

[01 09] in which,

[01 1 0] L_x = rcos(67.5° - £) (3)

[01 1 1 ] L₂ = V2r (4)

[01 1 2] L₃ = rcos(a + ) (5)

[01 1 3] since =

(6)

[01 14] The magnitude of T reaches a maximum when the arm is fully extended, in

5°

which a = β = 0° and L-_L/I^ =—=— = 0.27 and T_in = 0.54^Γ consequently.

[01 1 5] From the literature'³¹, it has been reported that the coefficient of friction (COF) for a maximum static friction can reach 0.35 when an adhesive is employed as an end effector at the terminal end portion of an extended arm. In addition, a robotic capsule itself can cause approximately 70 imN friction when its size is 1 1 .0 mm in diameter and 26.0 mm in length. Hence, for each extended arm, the required frictional force is / = (450 - 70)/4 = 95 imN and the normal force from the intraluminal wall of the Gl tract is calculated to be F₁ = f/μ = 271 mN. Assuming r = 5.5 mm, T,_n is calculated to be 0.81 imNm when a = β = 0°. As a and β increase, the requirement of magnetic torque for holding the extension decreases.

[01 16] Defining Θ as the torsional 'strain' of a MS element, we have Θ = 2(90° - a) = 0° before activation and Θ = 2(90° - a) = 180° when the arms are fully extended. In the latter situation, both the magnets have aligned to the external field, which produces no torque for the magnets. Hence, the full extension of the mechanism can only be reached when it is not under a load. With any forces from the intestine, there must be deflection between the external field and the magnet's magnetization so that magnetic torque can be induced by the external field to balance the load from the interaction with the intraluminal wall of the Gl tract. This actuation torque is T_E = T_Epsina for each magnet and TE_p is the maximum torque, which occurs when the external field is perpendicular to the magnet's direction of magnetization.

[01 17] However, once the magnetization directions of these two magnets do not align, another torsional load is produced by the MS' internal magnetic coupling, which needs to be overcome as well. This load can be determined by T_m = T_mpsin2a , in which T_mp is the maximum internal torque of the MS element.

[01 18] Thus, the actuation torque TE needs to overcome the combination of T,_n and T_m together to hold the arms in their fully extended state when in the deployed position for use in immobilising the robotic capsule at a site specific location within the Gl tract.

[01 19] Magnetic Spring Element

[0120] Here, the inventors used two ring-shape neodymium permanent magnets, both radially magnetized with the magnitude of ~ 1 T, as the components of a MS element. To suit the size of a typical commercial robotic capsule, the magnets were selected with the following dimensions: 9.0 mm in outer diameter and 2.0 mm in inner diameter. The height of the magnets can be altered by employing an automatic precision cut-off machine (Model No. Accutom 5; Struers Australia) to reduce the original height (10.0 mm). After cutting, the magnets do not show a noticeable degradation in magnetic strength. From the point of space-saving, it is certainly better to use magnets with a smaller height. However, as the height of the magnet is decreased, so too is the volume, which puts a higher requirement on the intensity of the external magnetic field if the same magnitude of magnetic actuation is needed. Moreover, if the size of the magnet becomes too small, the internal magnetic coupling of the MS element may not be strong enough to retract the extended arms. Hence, the height of the magnets is a compromise for the space-saving for the device 10 and the power consumption of the external electromagnetic system.

[0121 ] Besides the height of the magnets, the gap between them is another factor affecting the size and maximum internal torque of the MS element and its remote loading ability.

[0122] To this end, a finite element analysis (FEA) was conducted to investigate the magnetic interaction within a single MS element, which can be used as a guide for selecting a suitable MS element.

[0123] In a magnetostatic simulation, the time varying effects are neglected.

[0124] From Ampere's Law, it can be obtained that:

[0125] V x H = J , (7)

[0126] where Η is the magnetic field intensity and J is the current density.

[0127] Eq. (7) can be further deducted to:

[0129] The magnetic vector potential A has the relationship with the magnetic flux density B,

[0130] B = V x A . (9) [0131 ] Together with Gauss's Law,

[0132] V » B = 0. (10)

[0133] The governing equation for the magnetostatic solver can be derived as follows,

[0134] J(x, y, z) = V (11 )

[0135] Once J(x,y,z) is given as an excitation, the magnetic vector potential at all points in the domain can be solved. Consequently, the magnetic flux density and magnetic field intensity can be computed from Eq. (11 ).

[0136] To investigate the accuracy of the magnetic FEA simulation results, a testing apparatus (not shown) is assembled to measure the internal torque of a MS element.

[0137] The MS element consists of two neodymium magnets with the following specification: inner diameter (ID) = 2.0 mm, outer diameter (OD) = 9.0 mm, height = 10.0 mm, remanence (Br) ~ 1 T, magnetized radially. One magnet is fixed to a torque meter (Model No. HTG2; Imada, Inc.) and the other is mounted on a rotatable bench. The magnets are kept coaxial and the gap between them is adjustable. By rotating one magnet, the maximum torque between the coaxially aligned magnets can be found for different gaps between them.

[0138] The maximum internal torque of the MS element is measured as the gap between the coaxially aligned magnets is gradually raised. The magnetic FEA is also performed by using commercial software (COMSOL Multiphasics™ Modeling Software, ver. 5.2, COMSOL, Inc., USA) and the parameters are set to correspond to the experiments.

[0139] Both the simulation and experimental results are shown in Fig. 4. The torque drops when the gap distance starts to increase. The slope becomes flatter as the gap is enlarged further. From the graph, it is seen that the results are reasonably consistent with each other, which validates the feasibility of the FEA simulation results (by COMSOL) as a tool to estimate the magnetic torque with an acceptable level of accuracy for the design and optimization of a MS element employed in the proposed device 10.

[0140] Simulation Results

[0141 ] Additional FEA simulations were conducted to investigate the effect of the height of the MS element on the magnetic torque of the MS element, which is affected by the height of the two coaxially aligned magnets and the corresponding gap between them.

[0142] Specifically, three sets of simulations have been performed using two coaxially aligned permanent magnets with different heights (1 .5 mm, 2.0 mm, and 2.5 mm). The maximum magnetic torque between the two coaxially aligned magnets is calculated and plotted as the gap between the two coaxially aligned magnets was set in the range of 0 ~ 4.0 mm.

[0143] Fig. 5 shows the results of the magnetic simulations. When the gap between the two coaxially aligned magnets is widened, the maximum internal torque of the MS element decreases because the magnetic dipole-dipole coupling between the two coaxially aligned magnets is weakened. But this reduction becomes less as the gap increases further. All the values of T_mp in the simulation results are larger than the maximum torque (T_in = 0.81 imNm, presented above) by the action of the intraluminal wall of the Gl tract on the extended arms for overcoming an average value of the peristaltic force within the Gl tract. This indicates that T_mp is a more important factor than T,_n until the deflection of the MS element increases (at least Θ≥ 90°). Therefore, to ensure that the proposed immobilising mechanism works effectively, it is necessary for T_Em > 2r_mp (T_m reaches a maximum when a = 45°).

[0144] As the gap increases, TE does not change while T_m decreases, which suggests that it becomes easier to load the MS element remotely. However, the widened gap means that the MS element must be larger, resulting in an undesirable increase in overall size, which is likely to impact on patient compliance.

[0145] As for the height of the two coaxially aligned magnets, this is more complicated to consider because the height of the magnets not only affects the overall size of the device 10, it also affects the remote loading ability of the MS element since both T_E and T_m are related to the volumes of the two coaxially aligned magnets. To assess the effect of magnet height on the loading ability of the MS element, the inventors introduced a dimensionless factor E.H.T (effect of height on torques) that compares its contribution to the external torque (by the external field) with its contribution to the internal coupling torque. As is known, the magnetic torque produced by an external field is proportional to the volume of a magnet if the other parameters remain unchanged. Therefore, the contribution of the height of the magnet to this torque is proportional, too. Regarding the effect of magnet height on the internal coupling torque, it can be directly reflected by using the simulation results.

[0146] Dividing the external torque (height multiplied by a certain common value to all the cases) by the simulation results shown in Fig 5, a dimensionless factor to compare the effects of height can be acquired. Divided by a reference value, the factor is made to be unity for H=1 .5mm without a gap, for the sake of simplicity. The values in all other cases are adjusted according to the same point of reference.

[0147] Feasibility Study

[0148] To investigate the performance of the proposed mechanism for immobilising a robotic capsule 100 at a site specific location within a body lumen, a proof-of-concept prototype of the device 10 has been designed and tested, and coupled to a robotic capsule 100 according to the steps of a method described below, to realise an immobilisable assembly 150 that, in combination with a magnetic field generator, provides a system whereby the scissor-type extendable arms 60, 65 and 70, 75 can be activated by an external magnetic field generated by the magnetic field generator to engage with an intraluminal wall of the body lumen to immobilise the immobilisable assembly 150, and thus the robotic capsule 100 part thereof, at a site specific location within the body lumen..

[0149] Specifically, and according to a first step of the method, a commercial robotic capsule 100 (1 1 mm in diameter and 26 mm in length) was coupled to an upper end portion of the central core 20 of the device 10 described above, and as shown schematically in Fig. 1 , to provide an immobilisable assembly 150 (see Fig. 6). A commercial robotic capsule 100 typically comprises an elongate housing and diagnostic and/or therapeutic means such as, for example, an image sensor or camera or biopsy forceps, located at one end portion of the elongate housing. In this respect, it would makes sense for the device 10 to be coupled to the opposite end portion of the elongate housing so that the camera is facing away from the device 10, such that the image taking capability of the camera is not impeded by the device 10 part of the immobilisable assembly 150.

[0150] The device 10 part of the immobilisable assembly 150 is configured with an MS element comprised of two permanent ring magnets 40, 50 (internal diameter of 2.0 mm, outer diameter of 9.0 mm, height of 1 .5 mm, radially magnetized with a magnitude of ~1 Tesla), in which each ring magnet 40, 50 is mounted to an acrylic disc with the same internal diameter of 2.00 mm and outer diameter of 9.0 mm, but with a height of 1 .0 mm. The two ring magnets 40, 50 are then mounted in coaxial alignment to the central core 20 provided in the form of a thin aluminium pin (1 .5 mm in diameter), with the two discs facing one another. For test purposes, and due specifically to constraints on the magnetic intensity of the external field, the two coaxially aligned ring magnets 40, 50 are separated by a relatively large gap (4.0 mm) at the cost of space consumption.

[0151 ] The laterally opposed scissor-type extendable arms 60, 65 and 70, 75 are also made of acrylic and cut into shapes from a 1 .0 mm thick sheet by a laser cutting machine. The laterally opposed scissor-type extendable arms 60, 65 and 70, 75 are pivotably coupled to each of the two disc portions of the MS element by way of several aluminium pins with a diameter of 0.8, which mm were used as the pivot joints (62, 72 and 80, 90) to enable the scissor-type extender arms 60, 65 and 70, 75 to extend and retract according to the proposed scissor-type extending mechanism. Before activation, the device 10 part of the immobilisable assembly 150 has a diameter of 1 1 .0 mm and a height of 9.0 mm.

[0152] According to a second step, the inventors conducted a series of in-vitro tests in which the immobilisable assembly 150 shown in Fig. 6 was positioned inside a length of porcine small intestine. The intestinal specimens were stored in a refrigerator below 0°C until required. The frozen intestinal specimens were defrosted a few hours before each experiment and subsequently immersed in a jar of physiological saline prior to use to prevent tissue rupture.

[0153] Each intestine sample was mounted on a platform and positioned within a Helmholtz coil system, which serves as a magnetic field generator capable of generating a uniform magnetic field external of the intestine sample, but in proximity thereto, and thus in proximity to the immobilising means of the device 10.

[0154] According to a third step, and as described above, a magnetic field can be generated by simply switching the coil system ON, which is then applied external of the intestinal sample, but in proximity to the magnetic actuator 30 of the device 10 to activate the magnetic actuator 30, so as to cause each of the two laterally opposed pairs of scissor-type extendable arms 60, 65 and 70, 75 to be moved from the retracted positon (closed) to the deployed position (open) for use in engaging/disengaging the intraluminal wall of the intestinal sample. That is, the terminal end portion of each of the scissor-type extendable arms 60, 65 and 70, 75 that acts either as an end effector, or is modified with an end effector, is positioned distal to the central core 20 of the device 10 part of the immobilisable assembly 150 when the arms 60, 65 and 70, 75 are in the deployed position.

[0155] According to a fourth step, and as described above, the external magnetic field can be removed simply by switching the coil system OFF, thereby causing the scissor-type extendable arms 60, 65 and 70, 75 to revert back to their original retracted (closed) positions, such that the end effector at the terminal end portion of each arm 60, 65 and 70, 75 is positioned proximal to the central core 20 of the device 10 part of the assembly 150.

[0156] The front end portion of the robotic capsule 100 portion of the immobilisable assembly 150 was connected to a linear force sensor (not shown) to acquire the measurements of the friction caused by the immobilisable assembly 150 acting on the intraluminal wall of the intestine sample. To mimic the natural peristalsis of the Gl tract, the inventors employed a stepper motor (not shown) to provide an axial force and a linear movement to the immobilisable assembly 150 through the intestine sample.

[0157] In order to evaluate the performance of the immobilising mechanism separately, all of the force measurements were taken with the two laterally opposed pairs of scissor-type extendable arms 60, 65 and 70, 75 of the device 10 part of the immobilisable assembly 150 in their respective: (i) retracted positions (closed), and (ii) deployed positons (open), as triggered by the external magnetic field being switched ON or OFF as required.

[0158] Fig. 7 shows a plot of friction (mN) versus time (seconds) to determine a sliding friction value (mN) for the immobilisable assembly 150 with the device 10 part of the immobilisable assembly 150 of Fig. 6 in the inactivated state (namely, with the arms 60, 65 and 70, 75 in their respective retracted (closed) positions). It will be understood by those skilled in the relevant art that the sliding friction on tissue is velocity-dependent. Since the immobilisable assembly 150 moves at a constant speed inside the intestinal tract, it can be seen from Fig. 7 that the sliding friction is relatively uniform over the movement, with the magnitude of ~95 mN, which is close to that caused by the immobilisable assembly 150 itself and is still much smaller than the average value of the peristaltic force (450 mN). Without activation, the device 10 part of the immobilisable assembly 150 produces only a negligible amount of friction compared to that produced by the immobilisable assembly 150 as a whole. Hence, coupling the device 10 to a robotic capsule 100 is unlikely to impact on the overall moving capability of the immobilisable assembly 150. The break in the immobility of the immobilisable assembly 150 is also indicated in Fig. 7 and the static friction is measured to be approximately 120 mN.

[0159] Fig. 8 shows a plot of friction (mN) versus time (seconds) to determine a sliding friction value (mN) for the immobilisable assembly 150 of Fig. 6 with the device 10 part of the immobilisable assembly 150 in the activated state (namely, with the scissor-type extendable arms 60, 65 and 70, 75 in their respective deployed (open) positions). As shown in the plot, the external magnetic field was switched ON midway through the linear movement along the platform, as confirmed by the jump in the friction (mN) after around 2 seconds. Before activation, the average sliding friction is approximately 1 10 mN. While in the activated state, with the scissor-type extendable arms 60, 65 and 70, 75 opened, the immobilising mechanism causes the deformation of the Gl tract and subsequently receives more compressive force from the intraluminal wall, which consequently gives rise to an increase in the friction, as confirmed by the large increase to approximately 550 mN, corresponding to an increase ratio (compared to that before activation) of about 5.

[0160] Fig. 9 and Fig. 10 show plots of friction (mN) versus time (seconds) to determine a sliding friction value (mN) for the immobilisable assembly 150 of Fig. 6 arranged to move linearly within a second sample of porcine small intestine from the same animal. The plot in Fig. 9 corresponds to the linear movement of the immobilisable assembly 150 with the device 10 part of the assembly 150 in the inactivated state (external magnetic field is OFF), and the plot in Fig. 10 corresponds to the linear movement of the immobilisable assembly 150 of Fig. 6 with the device 10 part of the assembly 150 in the activated state (external magnetic field is ON).

[0161 ] As is apparent from a comparison of the plots in Fig. 9 and Fig. 10 with the corresponding plots in Fig. 7 and Fig. 8, the sliding friction measurements are of generally the same magnitude. The one noticeable difference, however is that a slightly higher static friction is observed in Fig. 9 (compared to that in Fig. 7), which is possibly a result of the two intestine samples having different local topologies.

[0162] Referring specifically to Fig. 10, the increase in sliding friction from approximately 100 mN (before actuation) to approximately 474 mN (after actuation) implies an increase ratio of about 4.74, which is largely consistent with the ratio calculated from Fig. 8.

[0163] Fig. 11 presents a series of photographs (a) to (e) recording the linear movement of the immobilisable assembly 150 of Fig. 6 within a third sample of porcine small intestine taken from the same animal, under a constant pulling force of 450 mN, applied using a pulley-weight system (not shown).

[0164] Fig. 11 (a) shows the immobilisable assembly 150 as it begins to move from a stationary state, and Fig. 11 (b) shows the apparatus 150 during linear movement.

[0165] In Fig. 11 (c), the Helmholtz coil system is switched ON, thereby producing an external magnetic field (B) in proximity to the immobilisable assembly 150 during linear movement, As a result of the external magnetic field (B), the device 10 part of the assembly 150 is activated, causing the scissor-type extendable arms 60, 65 and 70, 75 to move from their respective retracted (closed) positions to their respective deployed (open) positions. The inventors observed that the scissor-type extendable arms 60, 65 and 70, 75 in their fully extended positions caused the immobilisable assembly 150 to stop moving. Moreover, the combined force imparted by the scissor- type extendable arms 60, 65 and 70, 75 against the intraluminal wall of the intestine sample was sufficient to hold the immobilisable assembly 150 in place at this location. This result confirms the capability of the immobilising mechanism to overcome the simulated peristaltic force (450 mN).

[0166] As shown in Fig. 11 (d), when the external magnetic field (B) was removed (by switching the Helmholtz coil system OFF), the scissor-type extendable arms 60, 65 and 70, 75 returned to their respective retracted (closed) positions, the immobilisable assembly 150 was subsequently released and linear movement through the intestine sample as a result of the pulling force was resumed (see Fig. 11 (e)).

[0167] The whole process validates the feasibility and functional integrity of the immobilising mechanism of the device 10 as an anchoring module for coupling to a commercial robotic capsule 100. [0168] Conclusion

[0169] In this work, the inventors have successfully designed and fabricated a novel and compact device 10 configured with immobilising means that can be coupled to a commercial robotic capsule 100 with diagnostic and/or therapeutic function to provide an immobilisable assembly 150 capable of being selectively immobilised at a site specific location within a body lumen such as the gastrointestinal tract simply by applying an external magnetic field, and selectively released from its immobilised position by removing the external magnetic field. In-vitro tests using this immobilisable assembly 150 inside a length of porcine small intestine have successfully demonstrated that movement of the robotic capsule 100 part of this immobilisable assembly 150 can be selectively arrested at a site specific location within the intestine sample and as easily released from this location simply by switching an external magnetic field on and off in proximity to the immobilising means of the device 10 part of the immobilisable assembly 150.

[0170] Friction measurements (imN) taken during testing of the immobilisable assembly 150 within a porcine small intestine, show that when the immobilising means of the device 10 part of the immobilisable assembly 150 is triggered by an external magnetic field (B) of appropriate magnetic strength and the scissor-type extendable arms 60, 65 and 70, 75 extended to their respective deployed (open) positions, the combined frictional force produced by the end effectors at the terminal end of each of these arms 60, 65 and 70, 75 acting on the intraluminal wall of the intestine sample is approximately five times greater than the frictional force produced by the immobilisable assembly 150 when the arms 60, 65 and 70, 75 are in their respective retracted (closed) positions. The inventors have performed calculations to determine that this approximate five-fold increase in frictional force is capable of providing the immobilisable assembly 150 with a sufficient and reliable anchoring force to overcome the natural peristalsis (450 imN) within a body lumen in vivo.

[0171 ] In essence, when the device l Oaccording to the preferred embodiments of the present invention is coupled with a robotic capsule 100, the length of the entire immobilisable assembly 150 will be less than 30 mm and it will immediately transform a passive robotic capsule to an active tool capable of freely stopping and immobilising at any position in vivo without the need for an onboard motor and associated power source, which paves the way towards some very attractive diagnostic and/or therapeutic applications, such as biopsy and drug delivery.

[0172] Other Configurations

[0173] It will be appreciated by those skilled in the relevant art that the device 10 is not limited to the configuration described above, and that other configurations may be possible.

[0174] For instance, Fig. 12 shows schematic perspective views of a device 200 according to another embodiment of the present invention, in which two pairs of laterally opposed scissor-type extendable arms 260, 265 and 270, 275 are pivotably coupled at their respective first ends thereof, to a corresponding one of an uppermost 240 and a lowermost 250 ring magnet of a magnetic actuator 230, each with a central aperture to allow the ring magnets 240, 250 to be mounted at a central core 220 of the device 200 in coaxial alignment.

[0175] Specifically, and as shown in Fig. 12(a) and Fig. 12(b), the two arms 260 and 270 are each pivotably coupled to an outer surface of the uppermost ring magnet 240 at laterally opposing pivot points 280 and 290, respectively, thereof, while the other two arms 265 and 275 are each pivotably coupled to an outer surface of the lowermost ring magnet 250 at laterally opposing pivot points (not shown). This allows the two coaxially aligned magnets 240, 250 to be mounted to the central core 220 adjacent one another.

[0176] It will be appreciated by persons skilled in the relevant art that the immobilising mechanism is the same as that described for the device 10 above in that the two coaxially aligned ring magnets 240, 250 mounted at the central core 220 of the device 200 are magnetically coupled in the absence of an external magnetic field, but magnetically opposed when the strength of the external magnetic field is greater than the attractive force caused by the magnetic dipole-dipole interaction between the two coaxially aligned magnets 240, 250 (see Fig. 12(c)). The corresponding rotation of one or both of the two coaxially aligned magnets 240, 250 in opposite directions in response to the external magnetic field causes the first ends of each pair of laterally opposed scissor-type extendable arms 260, 265 and 270, 275 to move towards each other, which in combination with the corresponding journaled pivot points 262, 272, causes the two pairs of arms 260, 265 and 270, 275 to move from their respective retracted positions (a) to an extended position when deployed (b) in response to the external magnetic field (B).

[0177] For instance, and with reference to Fig. 12(a) and Fig. 12(b), the lowermost ring magnet 250 has been rotated about 180° in an anticlockwise direction relative to the uppermost ring magnet 240, as indicated by the light and dark shading of the two magnetic rings 240, 250, to cause the two pairs of scissor extendable arms 260, 265 and 270, 275 to transition from the retracted (closed) position (see Fig. 12(a)) to the fully extended or deployed (open) positon (see Fig. 12(b)).

[0178] According to another embodiment, and as shown in Fig. 13, a further device 300 is configured with two pairs of laterally opposed scissor-type extendable arms 360, 365 and 370, 375 that are again pivotably coupled at their respective first ends thereof, to a corresponding one of an uppermost 340 and a lowermost 350 ring magnet of a magnetic actuator 330, each having a central aperture to allow the ring magnets 340, 350 to be mounted at a central core 320 of the device 300 in coaxial alignment.

[0179] Specifically, and as shown in Fig. 13(a) and Fig. 13(b), the two arms 360 and 370 are each pivotably coupled to the uppermost ring magnet 340 at laterally opposing pivot points 380 and 390, respectively, thereof, while the other two arms 365 and 375 are each pivotably coupled to the lowermost ring magnet 350 at laterally opposing pivot points (not shown). In this embodiment, the four pivot points 380, 390 (and the two not shown) each comprise an elongate bracket portion with the pivot point located at one end thereof. In this respect, the bracket portion is mounted at an opposing end thereof to an outer surface of the corresponding coaxially aligned ring magnet 340, 350, at a periphery thereof such that the actual pivot point 380, 390 is distanced slightly away from the periphery of the corresponding ring magnet 340, 350. This allows the two coaxially aligned magnets 340, 350 to be mounted to the central core 320 adjacent one another. Thus, when the two pairs of laterally opposed scissor- type extendable arms 360, 365 and 370, 375 are in their respective retracted positions, as shown in Fig. 13(a), the curvature of the retracted arms 360, 365 and 370, 375 conforms to the curvature of the coaxially aligned ring magnets 340, 350 such that the retracted arms 360, 365 and 370, 375 wrap part way around the periphery of the corresponding ring magnet 340, 350. [0180] Again, when an external magnetic field (B) of sufficient strength is applied in proximity to the device 300, one or both of the two coaxially aligned ring magnets 340, 350 mounted at a central core 320 of the device 300 are caused to rotate in opposite directions, subsequently causing the first ends of each pair of laterally opposed scissor-type extendable arms 360, 365 and 370, 375 to move towards each other. This, in combination with the corresponding journaled pivot points 362, 372, causes the two pairs of arms 360, 365 and 370, 375 to move from their respective retracted (closed) positions (Fig. 13(a)), in which the coaxially aligned ring magnets 340, 350 are magnetically coupled (Fig. 13(c)), to an extended (open) position when deployed (Fig. 13(b)) as a result of the repulsive magnetic dipole-dipole force between the magnetically opposed coaxially aligned ring magnets 340, 350.

[0181 ] Fig. 14 shows schematic perspective views of a device 400 according to another embodiment of the present invention.

[0182] The device 400 comprises a magnetic actuator 430 that takes the form of a pair of coaxially aligned ring magnets 440, 450, each having an aperture that extends substantially through a central portion thereof, and which is of a diameter that is sized to receive the housing of the robotic capsule 100. Laterally opposed scissor-type extendable arms 460, 465 and 470, 475 are pivotably coupled at their respective first ends to a corresponding one of the uppermost 440 and lowermost 450 coaxially aligned ring magnet via a corresponding pivot point (of which only 490 is shown in respect of arm 470). Each pair of arms 460, 465 and 470, 475 is pivotably journaled together at a common pivot point (of which only pivot point 472 is shown in respect of arms 470, 475) distanced from their respective first ends.

[0183] One of the two coaxially aligned ring magnets 440, 450 is fixed to the housing of the robotic capsule 100, while the other ring magnet is free to rotate about the longitudinal axis relative to the fixed ring magnet, where the degree of rotation is constrained only by the laterally opposed scissor-type extendable arms 460, 465 and 470, 475 coupled between the two ring magnets 440, 450.

[0184] For the purpose of describing the actuating mechanism, ring magnet 440 is taken as being fixed to the housing, while ring magnet 450 is free to rotate about the longitudinal axis. Thus, when an external magnetic field (B) of sufficient strength is applied in proximity to the device 400, the free coaxially aligned ring magnet 450 is caused to rotate, causing the first ends of each pair of laterally opposed scissor-type extendable arms 460, 465 and 470, 475 to move towards each other. This, in combination with the corresponding journaled pivot points (not shown, 472) causes the two pairs of arms 460, 465 and 470, 475 to move from their respective retracted positions (Fig. 14(a)), in which the coaxially aligned ring magnets 440, 450 are magnetically coupled, to an extended position when deployed (Fig. 14(b)) as a result of the repulsive magnetic dipole-dipole force between the magnetically opposed coaxially aligned ring magnets 440, 450.

[0185] From a practical sense, the device 400 can be mounted at any point along the length of the housing of the robotic capsule 100. In this respect, the resulting immobilisable assembly 150A as shown in Fig. 14 is mounted at a generally mid- portion of the housing. This is advantageous in situations in which the robotic capsule 100 comprises, for example, a camera at both ends of the housing, such that the device 400 does not impede the view of each camera.

[0186] Fig. 15 shows schematic perspective views of a device 500 according to another embodiment of the present invention.

[0187] The device 500 is configured similarly to device 10 in that device 500 comprises a magnetic actuator 530 in the form of a pair of ring magnets 540, 550 each with a central aperture to allow the ring magnets 540, 550 to be mounted at a central core 520 of the device 500 in coaxial alignment, and two pairs of laterally opposed scissor-type extendable arms 560, 565 and 570, 575, that are each pivotably coupled at their respective first ends thereof, to a periphery of the two coaxially aligned ring magnets 540, 550. Specifically, and as shown in, for example, Fig. 15(a) and Fig. 15(b), the two arms 560 and 570 are each pivotably coupled to an inner surface of the uppermost ring magnet 540 at laterally opposing pivot points 580 and 590, respectively, thereof, while the other two arms 565 and 575 are each pivotably coupled to an inner surface of the lowermost ring magnet 550 at laterally opposing pivot points (not shown). Like device 10, the arms 560, 565 and 570, 575 are curved, such that when the arms 560, 565 and 570, 575 are in their respective retracted positions (see Fig. 15(a)), the curvature of the retracted arms 560, 565 and 570, 575 conforms to the curvature of the coaxially aligned ring magnets 540, 550. Again, each pair of arms 560, 565 and 570, 575 is pivotably journaled together at a common pivot point 562, 572 to provide the desired scissor action. [0188] In this embodiment, the central core 520 comprises a pair of opposing translational grooves (of which only one 525 is visible in Fig. 15(a), Fig. 15(b), Fig. 15(c)) that extend longitudinally along the length of the central core 520. Additionally, one of the two coaxial ring magnets 540, 550 comprises a pair of laterally opposing portions (not shown) that are located at the central aperture of the ring magnet. Each portion extends inwardly towards a corresponding one of the two grooves 525 to be received at least partially therein.

[0189] This arrangement not only prevents this particular ring magnet from rotating about the central core 520, it also facilitates sliding translational movement of this ring magnet, and the other ring magnet by virtue of the two ring magnets 540, 550 being operably coupled together by the arms 560, 565 and 570, 575, relative to the length of the central core 520. It will be appreciated by those skilled in the relevant art that the other of the two coaxial ring magnets is still free to rotate relative to the central core 520 such that the scissor-type extending mechanism of the arms 560, 565 and 570, 575 is not impeded in use.

[0190] In this particular embodiment, the device 500 is configured with a locking mechanism in the form of a lock configured to transition between a locked configuration, in which the two laterally opposing scissor extendable arms 560, 565 and 570, 575 are in their respective extended or deployed (open) positions in response to the external magnetic field (B), and a released configuration, in which the two laterally opposing scissor extendable arms 560, 565 and 570, 575 are in their respective retracted positions upon removal or in the absence of the external magnetic field (B).

[0191 ] Specifically, and as shown in Fig. 15(a) to Fig. 15(c), the locking mechanism is provided by way of a generally circular locking plate 600 that comprises a central aperture sized to receive and mount an upper end of the central core 520. Additionally, the locking plate 600 comprises a pair of laterally opposing portions that are located at the central aperture and extend inwardly towards a corresponding one of the two grooves 525 to be received substantially therein to prevent the locking plate 600 rotating relative to the central core 520. The locking plate 600 is mounted to the upper end of the central core 520 by way of this arrangement, and fixed substantially thereto so as to prevent sliding translation of the locking plate 600 along the central core 520. The locking plate 600 comprises three lock apertures 642, 644, 646 that extend substantially through the locking plate 600. The three lock apertures 642, 644, 646 are radially disposed in spaced apart arrangement around the locking plate 600, generally midway between the periphery and the central aperture thereof. The uppermost ring magnet 540 comprises three lock portions 542, 544, 546 that extend upwardly from an outer surface of the ring magnet 540. The three lock portions 542, 544, 546 are also radially disposed in spaced apart arrangement around the ring magnet 540, generally midway between the periphery and the central aperture thereof, and are each of complementary size to a corresponding one of the three lock apertures 642, 644, 646 of the locking plate 600.

[0192] For the purpose of describing the actuating mechanism, only the lowermost ring magnet 550 of the device 500 comprises inwardly extending portions (not shown) for engaging the corresponding longitudinal translational grooves of the central core 520 to not only preclude rotation of this ring magnet 550 relative to the central core 520, but also to facilitate sliding translation of the lowermost ring magnet 550 relative to the longitudinal axis of the central core 520. The uppermost ring magnet 540 is thus free to rotate about the longitudinal axis of the central core 520 and free to slide, together with the lowermost ring magnet 550 and the two laterally opposing scissor extendable arms 560, 565 and 570, 575 pivotably coupled therebetween, along the length of the central core 520.

[0193] Thus, when an external magnetic field (B) of sufficient magnetic strength is applied in proximity to the device 500, the uppermost coaxially aligned ring magnet 540 is caused to rotate relative to the 'fixed' lowermost ring magnet 550, causing the first ends of each pair of laterally opposed scissor-type extendable arms 560, 465 and 570, 575 to move towards each other. This, in combination with the corresponding journaled pivot points 562, 572 causes the two pairs of arms 560, 565 and 570,575 to move from their respective retracted (closed) positions (Fig. 15(a)), in which the coaxially aligned ring magnets 540, 550 are magnetically coupled, to an extended (open) position when deployed (Fig. 15(b)) as a result of the alignment of the magnetization of ring magnets 540, 550 to the external magnetic field.

[0194] By virtue of this rotation, the three lock portions 542, 544, 546 at the outer surface of the uppermost ring magnet 540 are now each in substantial alignment with a corresponding one of the three lock apertures 642, 644, 646 of the locking plate 600, as shown in Fig. 15(b). [0195] To induce the locking mechanism, a magnetic field (with a field direction substantially in the same direction as the external magnetic field (B) to avoid undue torque on the device 500, and a magnetic field gradient (as indicated by B_g) of sufficient variation of field strength) is then applied such that the strength of the field varies in the direction of the arrow shown in Fig. 15(c), which is a direction that is perpendicular to the two diametrically magnetized coaxially aligned ring magnets 540, 550. This causes the two coaxially aligned ring magnets 540, 550, and the two laterally opposing scissor extendable arms 560, 565 and 570, 575 in their respective deployed (open) positions, to slide relative to the central core 520 in the direction of the arrow towards the locking plate 600. The lock of the device 500 attains the locked configuration once the three lock portions 542, 544, 546 of the uppermost ring magnet 540 are received within the corresponding lock apertures 642, 644, 646 of the locking plate 600 by virtue of the sliding translation of the two coaxially aligned ring magnets 540, 550 relative to the longitudinal axis of the central core 520 in response to the external magnetic field gradient (B_g).

[0196] It will be appreciated by those persons of ordinary skill in the relevant art that the sliding translation of these elements relative to the central core 520 and the locking plate 600 occurs on the basis that the deployed arms 560, 565 and 570, 575 are not engaged with an intraluminal wall of a body lumen, and thus restricted from moving in response to the magnetic field with a magnetic field gradient (B_g).

[0197] Fig. 16 shows schematic perspective views of the device 500 of Fig. 15 coupled to an end portion of a housing of a robotic capsule 100 to provide an immobilisable assembly 150B with diagnostic and/or therapeutic means. The immobilisable assembly 150B comprises an additional ring magnet 700 having an aperture that extends substantially through a central portion thereof, and which is of a diameter that is sized to receive the housing of the robotic capsule 100. The ring magnet 700 is also magnetized in a diametric direction. That is, ring magnet 700 is magnetized across its diameter such that half of the ring magnet 700 is of one polarity ((N)orth) and the other half is of the opposite polarity ((S)outh). The magnetization of the ring magnet 700 is oriented to the same direction as that of the ring magnet 550.

[0198] The following will now be described in terms of the immobilisable assembly 150B being located within a body lumen (not shown) such as an intestine. [0199] Referring firstly to Fig. 16(a), the two pairs of scissor-type extendable arms 560, 565 and 570,575 of the device 500 are shown in their respective retracted (closed) positions, in which the two coaxially aligned ring magnets 540, 550 are magnetically coupled. With the arms 560, 565 and 570,575 in their respective retracted (closed) positions, the immobilisable assembly 150B is free to move within the body lumen under natural peristalsis.

[0200] Referring next to Fig. 16(b), when an external magnetic field (B) is applied in proximity to the device 500, the uppermost ring magnet 540 is caused to rotate relative to the lowermost ring magnet 550 as a result of the alignment of the magnetization to the external magnetic field (B). As a result, the two pairs of scissor- type extendable arms 560, 565 and 570,575 of the device 500 are caused to transition to their respective extended or deployed (open) positions such that end effectors at the terminal ends of arms 560, 565 and 570,575 engage with an intraluminal wall of the body lumen, thereby causing the immobilisable assembly 150B to stop moving.

[0201 ] As described above, and with reference to Fig. 15(b), the uppermost ring magnet 540 in Fig. 16(b) is now sufficiently rotated relative to the locking plate 600 such that each of the three lock portions 542, 544, 546 is substantially aligned with a corresponding one of the three lock apertures 642, 644, 646 of the locking plate 600. As the external magnetic field (B) is maintained, a magnetic field gradient (B_g) is produced such that the strength of the magnetic field gradient (B_g) varies in the direction of the arrow shown in Fig. 16(b).

[0202] Referring to both Fig. 15 and Fig. 16, by virtue of the ring magnet 700 being mounted to the robotic capsule 100, and the robotic capsule 100 being coupled to the central core 520, the magnetic force induced in the ring magnet 700 by the magnetic field gradient (B_g) is of sufficient magnitude to cause this whole subassembly, together with the locking plate 600 which is mounted to the central core 520, to slide in the direction of the magnetic field gradient (B_g) relative to the two coaxially ring magnets 540, 550, which are anchored in place within the body lumen as a result of the two pairs of scissor-type extendable arms 560, 565 and 570,575 of the device 500 being in their respective deployed positions. The device 500 attains a locked position once the lock apertures 642, 644, 646 of the locking plate 600 receive the corresponding lock portions 542, 544, 546 of the uppermost ring magnet 540. [0203] Once in the locked position, it is possible to remove the external magnetic field (B) and yet still maintain the locked position, due to friction between the lock portions 542, 544, 546 of the uppermost ring magnet 540 and the inner walls of the corresponding lock apertures 642, 644, 646 of the locking plate 600.

[0204] To unlock the device 500, the direction of the magnetic field gradient (B_g) is simply reversed, thereby causing this subassembly of the robotic capsule 100, the central core 520 and the locking plate 600, to slide in this reversed direction relative to the two coaxially ring magnets 540, 550 anchored in place within the body lumen by the deployed arms 560, 565 and 570,575, thereby freeing the lock portions 542, 544, 546 of the uppermost ring magnet 540 from the corresponding lock apertures 642, 644, 646 of the locking plate 600.

[0205] Advantages

[0206] The devices 10, 200, 300, 400, 500 according to the preferred embodiments of the present invention described above provide a number of benefits, including, but not limited to:

[0207] 1. An externally triggered mechanism to cause the arms of said devices 10, 200, 300, 400, 500 to move from their respective retracted (closed) positions to extended or deployed (open) positions, thus dispenses with the need to use an onboard micro-motor and power source, thereby realising a significant reduction in weight, size, complexity and cost. To this end, devices 10, 200, 300, 500 are only fractionally longer than the robotic capsule 100 to which they are coupled to in the corresponding immobilisable assembly, thereby ensuring patient compliance is maintained. Device 400 adds nothing to the length of the robotic capsule 100, thereby increasing only marginally the width of the robotic capsule 100.

[0208] 2. By changing the direction of the external magnetic field, it is possible to cause the devices 10, 200, 300, and thus the corresponding immobilisable assembly 150, 150A, 150B to tilt according to the direction of the external magnetic field. This means that when the immobilising means of the immobilisable assembly 150, 150A, 150B is activated within a body lumen to immobilise the robotic capsule 100 at a site specific location, it becomes possible to alter the orientation of the immobilised robotic capsule 100 simply by changing the direction of the external magnetic field, thereby actively changing the viewing direction of an onboard camera embedded on the robotic capsule 100 to capture a wider view of the site specific location.

[0209] Other Embodiments

[0210] It will be appreciated by those skilled in the relevant art that the embodiments of the present invention are not limited to what has been described above.

[021 1 ] In other embodiments, it will be appreciated that the end effector at the terminal end portion of each of the scissor-extending arms of these devices 10, 200, 300, 400, 500 can be modified to better engage the intraluminal wall of the body lumen. In one example, the end effectors include a pad or pads configured with micro- or nano patterned surface to increase the coefficient of friction (COF). Such pads may be manufactured from, for example, a natural or synthetic elastomer or silicon elastomer such as polydimethylsiloxane (PDMS).

[0212] In other embodiments, it will be appreciated that the devices 10, 200, 300, 400, 500 described herein are not limited to comprising two pairs of laterally opposing retractable members as described above, but may comprise just one retractable member or more than two pairs of retractable members, as required.

[0213] In other embodiments, it will be appreciated that the magnetic actuator of the device is not limited to comprising two coaxially aligned ring magnets as described above. For instance, the magnetic actuator may comprise two coaxially aligned magnetically responsive members without a central aperture extending substantially therethrough. The two coaxially aligned magnetically responsive members are thus operably coupled together by virtue of the one or more pairs of retractable members, and the robotic capsule 100 is coupled to an upper surface of one of the two coaxially aligned magnetically responsive members.

[0214] References

[0215] [1] P.R. Slawinski, K.L. Obstein and P. Valdastri, "Emerging issues and future developments in capsule endoscopy," Techniques in Gastrointestinal Endoscopy, vol. 17, pp. 40-46, 2015.

[0216] [2] R.N. Miftahof, "The wave phenomena in smooth muscle syncytia," In Silico Biology, vol. 5, pp. 479-498, 2005. [0217] [3] J. Song, Y. Mengug and M. Sitti, "Enhanced fabrication and characterization of gecko-inspired mushroom-tipped microfiber adhesives, " Journal of Adhesion Science and Technology, vol. 27, pp. 1921- 1932, 2013.

[0218] Definitions

[0219] Whenever a range is given in the specification, for example, a temperature range, a time range, or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

[0220] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

[0221 ] Throughout this application, the term "about' is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.

[0222] The indefinite articles "a" and "an," as used herein in the specification, unless clearly indicated to the contrary, should be understood to mean "at least one."

[0223] The phrase "and/or," as used herein in the specification, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and/or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and/or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. [0224] Spatially relative terms, such as "inner" "outer" "beneath " "below " "lower" "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the Figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the Figures.

[0225] While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternatives, modifications and variations in light of the foregoing description are possible. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the invention as disclosed.

[0226] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

Claims

Claims The claims defining this invention are as follows:

1 . A device for immobilising a robotic capsule within a body lumen, the device comprising:

- a magnetic actuator; and

- at least one retractable member operably coupled to the magnetic actuator, wherein the magnetic actuator is responsive to an external magnetic field to cause the at least one retractable member to move between a retracted position, in which the at least one retractable member is substantially disengaged from an intraluminal wall of a body lumen, and a deployed position, in which the at least one retractable member is substantially engaged with the intraluminal wall of the body lumen to immobilise the device, and a robotic capsule coupled thereto, at a site specific location therewithin.

2. A device according to claim 1 , wherein the at least one retractable member comprises a pair of retractable members operably coupled to the magnetic actuator at laterally opposing sides thereof.

3. A device according to claim 1 , wherein the magnetic actuator is a magnetic spring comprising two coaxially aligned magnets, each magnetized in a diametric direction of opposing polarity to the other.

4. A device according to claim 3, wherein the at least one retractable member is operably coupled to each of the two coaxially aligned magnets.

5. A device according to claim 3, wherein the two coaxially aligned magnets are magnetically coupled in the absence of the external magnetic field, and magnetically opposed when the external magnetic field has a magnetic field strength that is of sufficient magnitude to induce a magnetic force in the two magnetically coupled and coaxially aligned magnets which is greater than the attractive force therebetween.

6. A device according to claim 3, wherein at least one of the two coaxially aligned magnets is caused to rotate about a longitudinal axis of the device in response to the external magnetic field applied in a plane of rotation of the coaxially aligned magnets that is perpendicular to a longitudinal axis of the device.

7. A device according to claim 6, wherein a degree of said rotation of the at least one of the two coaxially aligned magnets is constrained by the at least one retractable member operably coupled between the two coaxially aligned magnets.

8. A device according to claim 4, wherein the at least one retractable member comprises two arms, and wherein a first of the two arms is pivotably coupled at a first end thereof to an uppermost one of the two coaxially aligned magnets and a second of the two arms is pivotably coupled at a first end thereof to a lowermost one of the two coaxially aligned magnets.

9. A device according to claim 8, wherein the two pivotably coupled arms are pivotably journaled together at a common pivot point distanced from their respective first ends to define a scissor-like opening and closing mechanism when at least one of the two coaxially aligned magnets is caused to rotate about the longitudinal axis relative to the other of the two coaxially aligned magnets in response to the external magnetic field.

10. A device according to claim 4, wherein each of the two coaxially aligned magnets is a ring magnet with an aperture extending substantially therethrough.

1 1 . A device according to claim 10, further comprising an elongate central core, wherein each of the two coaxially aligned ring magnets is configured to receive the central core when said apertures are coaxially aligned to align with the longitudinal axis of the device.

12. A device according to claim 1 1 , wherein the central core comprises at least one groove disposed along a length of the central core, and a first of the two coaxially aligned ring magnets comprises an engaging portion arranged to locate at least partially within the groove to preclude the first coaxially aligned ring magnet from rotating about the central core.

13. A device according to claim 12, wherein a second of the two coaxially aligned ring magnets is free to rotate about the central core relative to the first coaxially aligned ring magnet in response to the external magnetic field.

14. A device according to claim 12, wherein the engaging portion of the first of the two coaxially aligned ring magnets being received within the groove portion facilitates sliding translation of the two coaxially aligned ring magnets relative to the longitudinal axis of the device.

15. A device according to claim 12, further comprising a lock configured to transition between a locked configuration in which the at least one retractable member is in the deployed position in response to the external magnetic field, and a released configuration in which the at least one retractable member is in the retracted position.

16. A device according to claim 15, wherein the lock comprises a locking plate mounted to the central core that is configured to lock an uppermost one of the two coaxially aligned ring magnets relative to the central core when the lock is in the locked configuration.

17. A device according to claim 16 wherein the uppermost one of the two coaxially aligned ring magnets comprises at least one lock portion and the locking plate comprises at least one complementary lock aperture configured to receive the at least one lock portion in the locked configuration by virtue of the sliding translation of the two coaxially aligned ring magnets relative to the longitudinal axis of the central core.

18. A device according to claim 8, wherein each of the two arms is pivotably coupled at the respective first end thereof to an inner surface of a corresponding one of the two coaxially aligned magnets.

19. A device according to claim 8, wherein each of the two arms is pivotably coupled at the respective first end thereof to an outer surface of a corresponding one of the two coaxially aligned magnets.

20. A device according to claim 8, wherein each of the two arms comprises an end effector located at a terminal end thereof to engage with the intraluminal wall of the body lumen when the at least one retractable member is in the deployed position.

21 . A device according to claim 20, wherein the end effector is positioned proximal to the central core when the at least one retractable member is in the retracted position, and positioned distal to the central core when the at least one retractable member is in the deployed position.

22. A device according to claim 20, wherein the end effector comprises a pad having a micro- and/or nano-patterned surface to increase the coefficient of friction (COF).

23. A device according to claim 22, wherein the pad is manufactured from polydimethylsiloxane (PDMS).

24. An immobilisable assembly comprising:

- a device according to any one of claims 1 to 23; and

- a robotic capsule configured for operably coupling to the device.

25. An immobilisable assembly according to claim 24, wherein the device comprises an elongate central core, and wherein the robotic capsule comprises an elongate housing configured at an end portion thereof for coupling to the central core.

26. An immobilisable assembly according to claim 25, wherein the elongate housing comprises diagnostic and/or therapeutic means located at an opposing end portion thereof.

27. An immobilisable assembly according to claim 23, wherein the magnetic actuator of the device is a magnetic spring comprising two coaxially aligned ring magnets magnetized in a diametric direction of opposing polarity, and each ring magnet is configured with an aperture extending substantially therethrough, and wherein the robotic capsule comprises an elongate housing configured to be received by the apertures of the two coaxially aligned ring magnets.

28. An immobilisable assembly according to claim 25, wherein the elongate housing comprises diagnostic and/or therapeutic means located at at least one end portion thereof,

29. An immobilisable assembly according to claim 26 or 28, wherein the diagnostic means is a camera.

30. An immobilisable assembly according to claim 27, further comprising an additional ring magnet magnetized in a diametric direction and operably coupled to the elongate housing of the robotic capsule at a location that is distanced from the magnetic actuator of the device part of the immobilisable assembly to reduce magnetic interference between the additional ring magnet and the magnetic actuator.

31 . An immobilisable assembly according to claim 30, wherein the device comprises a locking plate slidable relative to the central core and configured to engage and lock an uppermost one of the two coaxially aligned ring magnets relative to the central core when an external magnetic field gradient is applied in proximity to the additional ring magnet to cause the at least one retractable member to be locked in the deployed position according to a locked configuration.

32. A system for immobilising a robotic capsule at a site specific location within a body lumen, the system comprising:

- an immobilisable assembly according to any one of claims 24 to 31 ; and

- a magnetic field generator configured to generate a magnetic field external of a body lumen, and in proximity to the magnetic actuator of the device part of the immobilisable assembly to cause the at least one retractable member to engage with an intraluminal wall of the body lumen to immobilise the immobilisable assembly, and thus the robotic capsule part thereof, at a site specific location therewithin.

33. A method for immobilising a robotic capsule at a site specific location within a body lumen, the method comprising: - coupling a robotic capsule to an immobilising means of a device according to any one of claims 1 to 23 to provide an immobilisable assembly;

- positioning the immobilisable assembly within a body lumen; and

- applying a magnetic field external of the body lumen, but in proximity to the magnetic actuator of the device, which is responsive to the external magnetic field to cause the at least one retractable member to engage with an intraluminal wall of a body lumen to immobilise the immobilisable assembly and thus the robotic capsule thereof, at a site specific location therewithin.

34. A method according to claim 33, wherein movement of the immobilisable assembly toward the site specific location within the body lumen occurs by natural peristalsis.