WO2010044053A2

WO2010044053A2 - Hybrid active locomotion teleoperated endoscopic capsule

Info

Publication number: WO2010044053A2
Application number: PCT/IB2009/054491
Authority: WO
Inventors: Arianna Menciassi; Paolo Dario; Pietro Valdastri; Claudio Quaglia; Elisa Buselli; Massimiliano Simi
Original assignee: Scuola Superiore Di Studi Universitari E Di Perfezionamento Sant'anna
Priority date: 2008-10-13
Filing date: 2009-10-13
Publication date: 2010-04-22
Also published as: WO2010044053A3; ITFI20080195A1

Abstract

A teleoperated endoscopic capsule for performing diagnostic and therapeutic activities in the gastro-intestinal tract of a patient, comprising a capsule body (1) extending longitudinally with a forward end (1a) and a rear end (1b), locomotion/orientation means (5) responsive to the action of a magnetic field controlled from the outside of the patient, image acquisition means (4) for acquiring images of at least predefined portions of the gastro-intestinal tract arranged at least at the forward end (1a) of the body (1), a power source (18), microprocessor means (16) for controlling the operation of the capsule, and means for receiving/transmitting signals(16, 17) from and towards an outside operator for transferring the acquired images and for sending control signals. Auxiliary locomotion means (6, 13, 15) are houseable inside the capsule in a rest condition and extendable from it to modify the external profile of the capsule. Sensors (23, 24) detect a stopped locomotion condition of the capsule and send a signal to the microprocessor means (16) to generate an actuation signal of the auxiliary locomotion means (6,13,15).

Description

TITLE

HYBRID ACTIVE LOCOMOTION TELEOPERATED ENDOSCOPIC CAPSULE

DESCRIPTION

Field of the Invention The present invention generally relates to the field of endoscopic devices and more specifically refers to an endoscopic capsule for diagnostic and/or therapeutic purposes, which is teleoperated and is able to move in the gastro-intestinal tract, in particular capable of actively moving back and forth in the colon. Background art Wireless endoscopic procedures for pain-free exploration of the gastro-intestinal tract, for diagnostic purposes, are known. These procedures require that the patient swallows a capsule sized roughly like a vitamin tablet that is transported by peristalsis along the digestive tract. During its transit the capsule acquires images that are transmitted to an array of antennae arranged outside at the patient's abdomen and recorded in a portable unit attached to a belt arranged around the patient's waist. The acquisition of the images takes about eight hours and during this time patients can freely perform their normal activities. The device is ejected naturally after about twenty-four hours, if there are no complications. After this, the patient takes the instruments back to the doctor or to the analysis laboratory to download the images into a workstation for their examination.

An endoscopic capsule for a wireless endoscopic procedure of the aforementioned type is described in US 5604531 and comprises a capsule body, a window on the capsule body and a light source, in particular an LED system, to light up the inner portion of the digestive system passed through, a sensor for acquiring the images and a focusing system, a transmitter, an energy source and a data processing unit that generates the video sequence from a single data flow. A commercial capsule developed based on this patent is the capsule known as PillCam^® put onto the market in the USA by InScope, a division of Ethicon Endo-Surgery, a company controlled by Johnson & Johnson, for displaying the mucous membrane of the small intestine, colon and oesophagus. A similar device for examining the small intestine is produced by Olympus Corporation and placed on the market with the name EndoCapsule. Endoscopic capsules currently on the market move passively in the gastrointestinal tract, pushed by peristalsis. In this way, the doctor cannot stop the capsule and position it in the points of greatest clinical interest for a more detailed analysis, thus preventing accurate diagnoses of mucous membrane requiring repeated observations from being completed. Moreover, the passive devices currently in use cannot be used for surgical purposes, also in view of the fact that it is difficult to position externally operated instruments on-board.

In the field of research there are at least two distinct approaches for controlling the locomotion and the orientation of endoscopic capsules: external locomotion and internal locomotion.

Capsules with external locomotion are generally actuated through magnetic fields: there are numerous patents relating to wireless capsules guided from the outside through magnetic forces interacting with forces generated by permanent magnets on-board the capsule. Examples of these are the systems patented by Olympus (US20070265496; EP1591057), Siemens (US20070265496) and KIST (WO2005122866), which disclose endoscopic capsules equipped exclusively with magnetic locomotion. The systems are made up of two parts: an external device equipped with a magnet and directly or indirectly actuated by an operator, who carries out the function of directing and guiding the capsule and of acquiring data; and the capsule, equipped with suitably shaped magnets, which moves according to the interaction with the external magnetic field.

Endoscopic capsules equipped with an active locomotion system of this type have the advantage of having just the permanent magnets or the induction coils that take up space on-board the capsule. On the other hand, however, external locomotion systems require bulky instruments outside of the patient's body and they have obvious problems of locomotion in Gl tracts with obstructions or in portions in which the tissue has collapsed.

With regard to internal locomotion, the actuators are placed on-board the capsule bringing advantages in terms of precision and reliability of the motion. The greatest disadvantage is given by the energy needs of the actuators, as well as by the size of the actuators themselves, which cannot always be miniaturised. For example, US2006030754 describes an active control system for an endoscopic capsule comprising a motor consisting of an electromagnetic stator unit and a permanently magnetized rotor unit, in particular in the form of blades fixed to a rotary shaft. The energy can be supplied by external ultrasound energy sources, electromagnetic waves or magnetic fields. EP1715789 describes an active locomotion system for an endoscopic capsule obtained by means of a group of legs made from superelastic shape memory alloys that can be retractably housed in axial seats formed on the body of the capsule. Each leg has one active degree of freedom, to allow the rotation of the entire leg around a pin to open and close the leg itself radially, and one passive degree of freedom, to fold the leg around an intermediate portion thereof so as to adapt it to the deformability of the tissue of the gastro-intestinal tract. Patent application PCT no. PCT/IT2007/000259 describes an endoscopic capsule in which the locomotion and orientation are performed by two sets of retractable legs that extend radially from the body of the capsule. The capsule houses two motors, parallel to its axis, and connected linkages for the controlled movement of the two sets of legs. In this case, in spite of the greater controllability of the position and orientation of the capsule during its locomotion in the gastro-intestinal tract compared to all of the solutions proposed previously, there is a greater need for power and less internal space is available for diagnostic and surgical instruments with relative actuators.

Basically, both of the active locomotion systems of endoscopic capsules according to the prior art have specific drawbacks that limit their use, particularly in the case in which the capsule must perform not only exploratory functions for diagnostic purposes, but also therapeutic or surgical endoscopic functions.

EP1932462A1 describes an endoscopic capsule equipped with a propulsion mechanism that converts a rotary movement around a longitudinal axis of the capsule into a propulsive movement according to such a longitudinal axis. The propulsion mechanism is a spiral-shaped mechanism arranged on the external surface of the capsule. In particular, the capsule comprises a spiral structured portion that can change its diameter ensuring an appropriate shape of the spiral to obtain a stable thrust force. Summary of the inventiom

The object of the present invention is to provide a teleoperated endoscopic capsule equipped with better locomotion capability in the gastro-intestinal tract compared to endoscopic capsules with external magnetic propulsion of the known type, especially in collapsed intestinal tracts or tracts that have blockages that prevent normal movement.

A particular object of the present invention is to provide an endoscopic capsule of the aforementioned type that is able to restore normal locomotion conditions in the presence of tissue collapsed on the capsule that hinders its movement.

Another particular object of the present invention is to provide an endoscopic capsule of the aforementioned type that is also able to vary its own external profile so as to work in synergy with the external magnetic propulsion system to supply a temporary additional propulsive force adapted to allow obstacles preventing normal movement to be passed.

A further object of the present invention is to provide an endoscopic capsule of the aforementioned type equipped with auxiliary locomotion means and capable to autonomously detect when these auxiliary locomotion means need to be actuated to restore normal locomotion conditions.

Another particular object of the present invention is to provide an endoscopic capsule of the aforementioned type that, whilst keeping the same size as known endoscopic capsules, has sufficient on-board space to house devices for therapeutic and/or surgical activities and relative actuators. Yet another particular object of the present invention is to provide an endoscopic capsule of the aforementioned type that can be stopped, when needed, in a desired area and in a proper operating position.

These objects are accomplished with the endoscopic capsule according to the present invention the essential characteristics of which are set forth in claim 1. Further important characteristics are outlined in the dependent claims.

According to one aspect of the invention, the endoscopic capsule is characterised by a hybrid active locomotion system, i.e. made by magnetic locomotion means actuated from the outside and auxiliary mechanical locomotion means with relative on-board actuators of the capsule capable of intervening autonomously to modify the lateral profile of the capsule whenever its forward motion is made difficult or is blocked. The auxiliary locomotion means can be formed from an array or set of legs extendable radially from a rest position, in which they are housed in corresponding seats formed longitudinally on the body of the capsule, or else from wings coming out from the capsule body laterally or axially on the front part and going back into rest position inside the capsule in suitable housings. In order to control the autonomous operation of the auxiliary locomotion means whenever the need arises, sensor means are foreseen that are adapted to detect the occasional ineffectiveness of magnetic locomotion. In particular, the sensor means can be contact sensors, for example force, pressure or bioimpedence sensors, adapted to detect when a preset threshold value has been exceeded, or magnetic coupling sensors, adapted to detect a reduction of the intensity of the external magnetic field below a preset threshold value.

In this way, the change in external profile of the capsule body produced by the opening of the legs or wings, makes the movement of the capsule itself more efficient. Indeed, near to areas in which the intestine has collapsed, the protrusions allow the diameter of the available lumen to be widened to allow the capsule to pass. In this situation, magnetic locomotion by itself is insufficient, since there are no internal movements available as an alternative to the external dragging; however, at the same time internal locomotion with legs alone is not adequate from the energy point of view. The solution proposed with the present invention solves the problem, since the magnetic locomotion is helped by a dynamic change in shape of the device. Such a change of the external profile is intended both to unblock the capsule from the stalled conditions thanks to the propulsive thrust of the legs, and to aid the external magnetic locomotion thanks to a change in the shape factor of the capsule, which will interact with the surrounding tissue in a more efficient manner for locomotion (for example, by expanding the contact points between the capsule and the tissue the lever effect that can be obtained through external magnetic locomotion is increased). Indeed, a static configuration is unable to move the capsule if it is blocked at one point. The synergic action of magnetic dragging and of opening/closing of the on-board mechanism manages to overcome any kind of obstacle.

According to another aspect of the invention, the capsule is equipped with a stop device so as to be able to be stopped in a desired point of the intestinal tract to complete a more accurate inspection of the area of greatest clinical interest. Brief description of the drawings Further characteristics and advantages of the hybrid endoscopic capsule according to the present invention will be apparent from the following description of an embodiment thereof given as an example and not for limiting purposes with reference to the attached drawings, in which: figure 1 is a schematic view of the hybrid endoscopic capsule according to the present invention; figure 2 is a perspective view of an embodiment of the endoscopic capsule according to the invention; figure 3 is a longitudinal sectional view of the endoscopic capsule of figure 2; figure 4 is a front sectional view of the endoscopic capsule of figure 2; figures 5a and 5b, 6 and 7 are schematic views of other possible embodiments of the endoscopic capsule according to the invention;

Figure 8 is a representation of the platform for magnetic locomotion in the specific case of control with a robotic arm; figure 9 illustrates a control loop when either force sensors or magnetic sensors are used; fig. 10 illustrates a control loop when both force sensors and magnetic sensors in parallel are used.

Detailed description of the invention With reference to figure 1 , the endoscopic capsule according to the invention comprises a capsule body 1 , extending longitudinally and in particular substantially cylinder shaped, closed at its forward and rear ends 1a and 1 b by respective caps 2 and 3. The cap 2 at the forward end is at least partially transparent since it houses image sensor means and relative lighting means inside it, generically indicated with 4. A plurality of permanent magnets 5 is longitudinally housed inside the capsule body 1. Alternatively, electromagnets can be foreseen, instead of the permanent magnets. The permanent magnets, or electromagnets, allow the capsule to move in response to control signals coming from an external magnet and allow the device to be rotated and oriented towards the points of clinical interest. An array of legs 6 is provided near the forward end 1a. Legs 6 are capable of taking up positions extending radially from the body of the capsule 1 , as also shown in figure 1 , and two different rest positions, in which the legs are enclosed within longitudinal seats 7 formed along the body of the capsule 1 and visible in figure 2. The two different rest positions are angularly spaced apart by an angle of over 90°, i.e. the legs can be arranged in the respective longitudinal seats 7 pointing its free end towards the forward end 1a or towards the rear end 1b of the capsule 1. In particular and purely as an example, there can be three legs 6 that can be housed in as many longitudinal seats 7.

The movement allowing the legs 6 to displace from the rest positions to the extended positions and vice versa is controlled by a motor 8 through a motion transmission mechanism made up of a pinion 21, a driven wheel 22, a worm screw 9 and gear wheels 10 to which the legs 6 are connected at an end thereof.

The array of legs 6, or other functionally equivalent mechanical structure, allows interaction with the surrounding tissue, for example, to increase the visual field of the video camera or to increase the probability of getting through blocked areas, acting as a magnetic locomotion aid. The legs, or equivalent structures, not only push from inside the capsule in one direction, but also increase the interaction surface with the surrounding tissue so as to make the magnetic locomotion controlled from the outside more efficient.

Moreover, the presence of auxiliary locomotion means, in the form of legs, as illustrated, or another equivalent structure, makes it easier to stop the capsule in a desired position and orientation. Indeed, both the opening of the legs and the magnetic coupling between the internal magnets and the external magnet can advantageously interact to stop the capsule so that it can be stopped in a desired point of the intestinal tract for more accurate inspection of the area of greatest clinical interest. Other parts of the system are an electronic control circuit 16 of the various electric and electromechanical devices, comprising a microcontroller and a driver for the motor, a wireless transceiver system 17 for control data and for the images coming from the video camera and a power supply system 18, such as a battery (for example a lithium battery with wireless recharging module) or an electromagnetic energy transfer module (wireless power supply).

Figures 2, 3 and 4 illustrate, in particular, an embodiment of the endoscopic capsule shown schematically in figure 1. The legs 6 can consist of rods 6a having an enlarged end 6b, whereas the other end is fixedly connected to the respective gear wheel 10. The device for moving the legs 6 is housed in the body of the capsule 1 , which has slits 7a in the longitudinal seats 7, which allow the legs to protrude by passing from the inside towards the outside of the body.

The device for actuating the legs 6 comprises the motor 8 connected to a pinion 21 engaging on a driven wheel 22. Wheel 22 is coaxial and fixedly connected to the worm screw 9 with which gear wheels 10, kinematically connected to the legs 6, are engaged. In particular, the worm screw 9 is coaxial to the capsule body 1 and the motor 8 is arranged with its power shaft parallel to the longitudinal axis of the body 1. The motor 8 is connected to the corresponding worm screw 9 through an ordinary gear train, consisting of the pinion 21 and the driven wheel 22, with a transmission ratio of less than 1.

The motor 8 can, for example, be a brushless DC motor produced by Namiki Precision Jewel Co., Ltd., or equivalent, which has an outer diameter of 4 mm and a total length of 17.4 mm; such a motor has an integrated reducer and has a maximum torque value delivered to the shaft of the reducer equal to 5.7 mNm (the same motor, without reducer has a maximum torque value delivered to the shaft equal to 0.058 mNm); such an electric motor is powered by a battery 18. Each leg 6 has a constraint consisting of a rotating hinge to the system of gears that allows a rotation around an axis perpendicular to the main axis of the body of the capsule 1.

In practice, from a first initial position in which the corresponding legs 6 are in a minimum bulk or rest set-up, laying along the body 1 , a final position is reached in which the legs 6 are in a maximum bulk set-up, projecting towards the outside of the body 1 up to a second rest position.

The movement of the legs 6 is controlled by the electronic control circuit 16 that receives signals from sensors 23, 24 and is thus able to manage, either autonomously or based on the commands of the outside operator, the movements of the legs 6,

The sensors 23, 24 are dedicated to autonomously controlling the device both in magnetic locomotion and in the activation of the legs to provide sufficient information to identify the occasional ineffectiveness of magnetic locomotion. The sensors foreseen can be of the type that monitors the coupling between internal magnets and the external magnetic field or else that evaluates characteristics of the contact of the tissue on the surface of the capsule. More specifically, the sensors integrated on-board the capsule 1 can be of the following types: a. contact sensors 24: for example force, pressure or bioimpedence sensors arranged on the outer surface of the capsule. Whenever the magnitude detected by the sensors shows that purely magnetic locomotion is impossible, the legs are actuated autonomously by the control system until the conditions suitable for locomotion are restored, identified by a value detected by the sensor within a functionality range defined experimentally or analytically. b. location and magnetic coupling sensors 23, visible in figure 1 : the sensor (for example magnetic field sensor or an accelerometer) inside the capsule is able to provide precise indication data about the location of the device with respect to the external field source for example mounted on a robotic arm. A disadvantageous positioning between the two systems, which defines a loss of sufficient magnetic coupling for magnetic locomotion, can be constantly and autonomously compensated by a looped control set between the measurements extracted by the sensors and the position of the robot and therefore of the field source.

The capsule 1 can be equipped with just the contact sensors 24 or with just the location sensors 23 or else with both. In the latter case the legs are activated whenever even just one of the control conditions is not satisfied.

The external magnetic device for controlling locomotion comprises at least one external magnet 25, permanent or of the electromagnet type that can also be mounted for easier movement on a possibly hydraulic articulated support or on a robotic arm 26, as represented in figure 8, and as substantially described for example in WO 2005/122866.

A dedicated interface can be used to control the arm in real time in the workspace (for example a joystick with 6 degrees of freedom, not shown),

Thanks to the control loop (see figures 9 and 10) between sensors, robotic arm and on-board actuators, it is possible not only to autonomously reposition the robotic arm in order to restore the better magnetic coupling, but also to automatically activate the leg system until the conditions sufficient for a purely magnetic locomotion are restored.

According to another embodiment of the invention, schematically shown in figures 5a and 5b, the auxiliary locomotion mechanical structure is again formed by a set of legs 6 as a mechanism for modifying the lateral profile of the capsule. The aforementioned legs are moved by a shape memory alloy (SMA) wired actuator 11 , placed inside the capsule body, which transmits the motion to the legs. The mechanism for moving the legs is similar to the previous solution, the main difference being the actuation system that consists of SMA wires. They open (figure 5a) or close (figure 5b) the mechanism according to the current that is circulated.

According to another embodiment of the invention, schematically shown in figure 6, the auxiliary locomotion mechanical structure is formed, instead of a set of legs, by a mechanism for modifying the lateral profile of the capsule comprising three wings 13 made from superelastic material that, once released, protrude from the capsule body at the side. In the case in which one wishes to close the wings up to go back to the initial profile, an internal motor 8, through a wired mechanism 12 wound on an intermediate pulley 20, recovers the wings and arrange them on the outer body of the capsule. According to another embodiment of the invention, schematically shown in figure 7, the auxiliary locomotion mechanical structure is formed, instead, by a mechanism for modifying the axial profile of the capsule comprising two arms 15 made from superelastic material, i.e. capable of recovering the previously memorised shape after a deformation. Such arms are memorised in a shape suitable for the function performed. Initially, such arms are retracted inside the capsule body. By actuating the mechanism 14 with a motor 8, they come out axially from the front dome 2 of the capsule symmetrically with respect to the video camera 4. The arms, whilst they come out by axial translation, spread apart since they recover the originally memorised shape. This shape, in a possible embodiment thereof, is similar to that of pincers. Its main functions are the action on the surrounding tissue in order to unblock the capsule from a stalled situation and the modification of the geometry of the capsule to make magnetic locomotion easier. When the arms have performed their function they can be retracted inside the capsule body thanks to the action of a motor 8 and of a gear wheel mechanism 14.

The endoscopic capsule according to the invention can advantageously be coated by a biocompatible and biodegradable layer that avoids the accidental eversion of the legs during ingestion making the swallowing process simpler and safer. When the capsule reaches the stomach the coating is then destroyed by the acidity of the environment making it possible for the legs to move.

The endoscopic capsule according to the present invention allows wireless and pain-free endoscopic examinations to be carried out, both for diagnostic and therapeutic purposes.

As compared to the classical endoscopes, the advantage in the use of the endoscopic capsule of the present invention consists of a significantly less painful examination, and therefore a greater acceptability of the proposed procedure by the patient. The advantage compared to passive capsules currently on the market

(moved by just peristalsis) is given by the presence of an active locomotion mechanism that allows the doctor, through a dedicated interface, to direct the movements of the device. In this way the capsule can also be used for therapeutic as well as diagnostic purposes. The advantage compared to capsules with an internal locomotion device, and in particular compared to the capsule of the prior art in which the locomotion is carried out through a legged device, concerns not only the power consumption and the consequent greater free space for additional therapeutic and diagnostic modules, but also the definition of an autonomous control over the opening of the legs thanks to the device being equipped with sensors. With the hybrid solution according to the present invention the legs act as locomotion aid only, and therefore a single motor is necessary that is actuated autonomously in stalled situations in the gastro-intestinal tract. This solution thus allows the size and the power consumption to be reduced, because a single motor and a less bulky battery is required with respect to the case of locomotion performed entirely with legs.

The advantage compared to capsules equipped with an exclusively magnetic movement system concerns the ease with which the capsule according to the present invention gets past areas of the intestine with blockages or with very tight curves thanks to the synergy with an internal active system. This type of operation is, indeed, very problematic and is not always possible using exclusively the magnetic solution.

Finally, an important advantage is represented by the autonomous control both of the opening of the aforementioned legs and of the robotic arm in the case of jamming or loss of the correct magnetic coupling, defined based on the integrated sensors.

Variations and modifications can be brought to the endoscopic capsule with hybrid active locomotion according to the present invention without departing from the scope of the invention as defined by the following claims.

Claims

1. Teleoperated endoscopic capsule for performing diagnostic and therapeutic activities in the gastro-intestinal tract of a patient, comprising a capsule body (1) extending longitudinally with a forward end (1a) and a rear end (1 b), locomotion/orientation means (5) responsive to the action of a magnetic field controlled from the outside of said patient, image acquisition means (4) for acquiring images of at least predefined portions of the gastro-intestinal tract arranged at least at the forward end (1a) of said body (1), a power source (18), microprocessor means (16) for controlling the operation of the capsule, and means for receiving/transmitting signals (16, 17) from and towards an outside operator for transferring the acquired images and for sending control signals, characterised in that it comprises auxiliary locomotion means (6, 13, 15) houseable inside the capsule in a rest condition and extendable from it to modify the external profile of the capsule, and sensor means (23, 24) adapted to detect a stopped locomotion condition of the capsule and to send a signal to said microprocessor means (16) to generate an actuation signal of said auxiliary locomotion means (6,13,15).

2. Endoscopic capsule according to claim 1 , wherein said sensor means comprise contact sensors (24), situated on the surface of the capsule body (1), adapted to generate a signal correlated to the contact with the tissue around the capsule, said microprocessor means (16) generating said actuation signals for said auxiliary locomotion means (6,13,15) when the signal transmitted by said contact sensors exceeds a preset threshold value.

3. Endoscopic capsule according to claim 1 , wherein said sensor means comprise magnetic sensors (23) adapted to measure the intensity of the magnetic field to which it is subjected, said microprocessor means (16) generating said actuation signal for said auxiliary locomotion means (6,13,15) when the signal transmitted by said magnetic sensors falls below a preset threshold value.

4. Endoscopic capsule according to any one of the previous claims, wherein said auxiliary locomotion means comprise an array of legs (6), able to extend radially from the capsule body (1) from a rest position in which said legs are housed in seats (7) formed longitudinally on said capsule body (1), and motor means (8) connected to means (9, 10) for transmitting motion to said legs, placed inside said capsule body (1).

5. Endoscopic capsule according to any one of claims 1 to 3, wherein said auxiliary locomotion means comprise legs (6) extendable radially from the capsule body (1) and an actuation system based on shape memory metals (11).

6. Endoscopic capsule according to any one of claims 1 to 3, wherein said auxiliary locomotion means comprise wings (13) that come out from the side of the capsule body, and motor means (8) connected to wired means (12) for transmitting motion to said wings.

7. Endoscopic capsule according to any one of claims 1 to 3, wherein said auxiliary locomotion means comprise two arms made from superelastic material axially projectable at the sides of the forward end cap (2), a motor (8) and means (14) for transmitting motion to said arms.

8. Endoscopic capsule according to any one of the previous claims, wherein said locomotion/orientation means comprise a plurality of permanent magnets (5) or of electromagnets arranged longitudinally in said capsule body.