The FORGUIDE mechanism enables making a shaft-guide out of cheap standard parts that is rigidified by creating a laminate that consists of a spring, cables and expandable tube. The connection between these three layers is obtained by friction. The bench tests showed that the FORGUIDE prototype FGP-01 of only 5.5 mm diameter could provide flexural rigidities up to 1541 Ncm2 , which far exceeds the flexural rigidity of flexible endoscopes. Furthermore, a bending radius of almost 1 cm could be achieved in the compliant state with the FGP-01 without losing the ability to rigidify.

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.





Endo-PaC – Endoscopic Path Controller

Developed in 2011-2012.

In the field of minimally invasive surgery and specifically in pathway surgery – i.e. minimally invasive procedures carried out transluminally or through instrument-created pathways – spatial disorientation is a common experience to surgeons.

Our Endo-PaC (Endoscopic Path Controller) is a simulator designed to investigate human control behavior during path following tasks. Emulating the shaft and handle of a maneuverable surgical instrument, Endo-PaC’s hardware controller consists of a base, an instrument shaft, and a handle with a joystick. The hardware controller contains five position sensors to measure the orientation of the shaft relative to the base, the translational displacement of the shaft, and the orientation of the joystick relative to the shaft. Instead of having a separate joystick, the handle can also be directly connected to the joystick, making the Endo-PaC suitable for comparing thumb control with wrist control.

The hardware controller is combined with custom-developed software animating surgical pathway scenarios. This virtual environment enables the assessment of the user performances based on criteria such as task completion time, motion smoothness, collisions, and the length of the travelled path. This makes the Endo-PaC highly suitable for comparing different control techniques.


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.





Flexible endoscopes are used for diagnostic and therapeutic interventions in the human body for their ability to be advanced through tortuous trajectories. However, this very same property causes difficulties as well. For example, during surgery a rigid shaft would be more beneficial since it provides more stability and allows for better surgical accuracy. In order to keep the flexibility and obtain rigidity when needed, a shaft guide with controllable rigidity could be used. On this page we introduce the PlastoLock shaft-guide concept, which uses thermoplastics (Purasorb PLC 7015) that are reversibly switched from rigid to compliant by changing their temperature from 5 to 43 degrees Celcius. These materials were used to make a shaft that can be rendered flexible to follow the flexible endoscope and rigid to guide it.  A feasibility study shows the great potential of this concept in terms of achievable flexural rigidity, miniaturization, and simplicity.



In order to fully benefit from the functionalities of flexible endoscopes in surgery, a simple shaft-guide that can be used to support the flexible endoscope shaft is required. Such a shaft-guide must be flexible during insertion into the human body and rigidified when properly positioned to support the flexible endoscope shaft. A shaft-guide called ‘Vacu-SL’ was designed.

The Vacu-SL rigidity control mechanism  utilizes the flexural rigidity increase that is achieved by vacuuming foil tubes filled with small particles. In this prototype the influence of particle hardness, size, and shape on the flexural rigidity of vacuumed foil tubes filled with these particles is investigated. Experiments show that the flexural rigidity increases with the hardness and irregularity of the particles and that there may be an optimal particle size in the low particle diameter region.

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.




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.




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.




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.