Category Archives: Maneuverable Devices

MultiFlex – Tentacle from Steel

 

 

Developed in 2008-2009, diameter 5 mm, steering range: ±200º in all directions.

The MultiFlex is what we call a multi-steerable instrument. Based on the Cable-Ring mechanism applied in the Endo-Periscope III, the MultiFlex does not contain just one, but five steering segments serially stacked on top of each other. Each of these segments can be actuated in two Degrees of Freedom (DOF) by its own set of four steering cables, resulting in a total of 20 steering cables and a 10-DOF maneuverable tip capable of making a wide range of 3D shapes and curves. This level of maneuverability gives the instrument the ability to steer around anatomic strucures, making it world’s first instrument of this kind developed at 5 mm dimensions.

By using the Cable-Ring mechanism, all actuation cables could be positioned at the same diameter. Consequently, the increase in maneuverability does not affect the outer diameter of the instrument, which is still equal to Ø5 mm with a complexity similar to the Endo-Periscope III. The control handle of the MultiFlex has a  structure similar to the tip, yet its dimensions are scaled-up for a better fit to the surgeon’s hand.

 

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Steerable Guidewire – Maneuvering without Twisting

Developed in 2007-2008, diameter 0.9 mm, length 1 m, steering range: ±90º in all directions.

The Steerable Guidewire has been developed by spin-off DEAM in a very close collaboration with the BITE-group, using our patented Cable-Ring technology. Intended for easy steering through a network of blood vessels during catheter interventions, the guidewire contains a flexible shaft ending in a steerable tip with two Degrees of Freedom (DOF). The mechanism is novel as compared to existing guidewire designs in that it requires no need for twisting the guidewire body for re-directing the tip, which results in a much more stable and fluent 3D steering motion. The tip-mechanism is similar to the I-Fex and composed out of seven steering cables surrounded by a spring. The handle contains two joysticks, one at the proximal handle side and one at the distal handle side, that can both be used to control the 2-DOF tip. The Steerable Guidewire forms the basis for a series of new multi-steerable catheters designs currently being developed in the BITE-group.

 

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MicroFlex – Steering at a Micro-Scale

Developed in 2005-2006, diameter 1.3 mm, steering range: ±90º in all directions.

The MicroFlex is a steerable instrument for micro-surgery with a miniature Cable-Ring mechanism consisting of a ring of six steel cables (Ø0.2 mm) surrounded by a spring. The six cables are used for steering the tip, whereas the inner spring is replaced by a central cable that can be used to drive a miniature gripper on the tip (not yet incorporated in this prototype). The result is an instrument that realizes 3D-steering with only seven cables and a spring – smaller and at the same time simpler than existing steerable instruments.

 

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Endo-Periscope III – Revolution from a Squid

Developed in 2003-2004, diameter 5 mm, steering range: ±110º in all directions.

Construction equivalent to Endo-Periscope II, however with Ring-Springs replaced by novel patented “Cable-Ring” mechanism based on tentacles of squid. The Cable-Ring mechanism consists of a ring of 22 steel cables (Ø0.45 mm) enclosed by two conventional coil springs, allowing only axial cable displacements to control the motion of the steerable tip. The Cable-Ring mechanism is entirely constructed out of standard parts and therefore very suitable for low cost mass production. The Cable-Ring mechanism is being commercialized worldwide by spin-off company DEAM.

 

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Endo-Periscope II – Smart Ring-Spring Steering

Developed in 2001-2002, diameter 12 mm, steering range: ±125º in all directions.

The Endo-Periscope II has been developed in cooperation with Prof. Shigeo Hirose of the Hirose & Fukushima Laboratory, Tokyo Institute of Technology.

Endo-Periscope II is a simplified, patented version of Endo-Periscope I containing two enhanced compliant Ring Springs to control both left/right and up/down tip rotations. Endo-Periscope II contains an improved spatial parallelogram-mechanism that minimizes bending radius in all positions of the tip. A prominent part of the mechanism is a compression spring in the handgrip that compensates the spring force of the two Ring-Springs.

 

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Endo-Periscope I – Compliant yet Torsion Stiff

Developed in 1999-2000, diameter 15 mm, steering range: up/down 0º-180º, left/right ±60º

The Endo-Periscope I has been developed in cooperation with Prof. Shigeo Hirose of the Hirose & Fukushima Laboratory, Tokyo Institute of Technology.

Endo-Periscope I is a patented steerable endoscope for laparoscopic surgery containing a novel, torsion-stiff “Ring-Spring”. The compliant Ring-Spring consists of a number of spring-metal rings that are bent and welded to each other in pairs. The rings contain holes for guiding steering cables. The Ring-Spring is controlled by a novel spatial parallelogram-mechanism that unfolds the spring from a compressed position to minimize bending radius of the steerable tip. The tip has always the same orientation as the hand grip, offering intuitive control to the surgeon showing how the tip is oriented in the abdominal cavity. The Ring-Spring is only used to control up/down tip rotations. Left/right tip rotations are controlled by a conventional hinge-mechanism.

 

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Steerability – How it all started…

During Minimally Invasive Surgery (MIS) surgical instruments and an endoscopic camera are inserted  through tiny  incisions into the human body. This approach reduces the patient’s recovery time, the size of the scars and the risk of complications. Unfortunately, MIS also has its drawbacks since the intervention becomes more difficult for the surgeon:

  • There is limited visual 3D information (and thus no proper depth perception) of the surgical area.
  • The surgeon’s eye-hand coordination is distorted because the camera looks at the organ from a different angle than the surgeon would normally do.
  • The motion of rigid instruments is strongly limited by the fixed position of the incisions.
  • The surgeon’s ergonomic position deteriorates due to the use of  long and rigid instruments in combination with fixed incision points.

One way to obtain more depth information is to enable motion parallax – obtaining depth information by mutual displacements of objects in the field of view when moving the eye while keeping the viewpoint in focus. With conventional rigid endoscopes, however, moving the endoscope results in the viewpoint to shift away as the endoscope rotates around its incision point.

During his stay in the Hirose & Fukushima Laboratory, Tokyo Institute of Technology, Paul Breedveld and Shigeo Hirose developed an endoscope with a steerable parallelogram mechanism, enabling motion parallax and facilitating eye-hand coordination. This resulted in the first steerable endoscope of the BITE-Group – the Endo-Periscope I.

 

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