All posts by Paul Breedveld

Octopus-based Instrument used for first time in OR

The ‘mechanical octopus’, a steerable laparoscopic instrument used for minimally invasive surgery in the abdominal cavity, has been used for the first time in an operating room.

Surgeons at the Haags Medisch Centrum are positive about the benefits that the innovative technology in the LaproFlex gave them during a gynaecological operation. The technology behind the instrument was conceived by Paul Breedveld, professor of Medical Instruments & Bio-Inspired Technology. Jules Scheltes, who also obtained his PhD at TU Delft in the field of medical product development and who co-founded the Dutch company DEAM, has been working these past two years to market the product. Following an exciting period, he received CE certification earlier this summer for the LaproFlex and is producing and selling it in Europe.

Paul Breedveld
‘The LaproFlex is an example of research at a university finding its way into industry.’

Jules Scheltes
‘Co-founder Wimold Peters and I are especially proud that we have managed to pull this off with our team. Surgeons have indicated that the instrument is providing them with a better view of the organ they are operating on, and that they can access it from an optimal approach route and are not inconvenienced by intersecting instruments in their field of operation anymore. This is great news. This is exactly what we’ve been working towards.’

What makes this instrument special is that it has a flexible tip. This is made possible by an ingenious steering system based on the anatomy of an octopus’ tentacle, the so-called cable crane mechanism, which ensures that the scissors or grasper can be steered in every direction. Paul Breedveld and the researchers in his Bio-Inspired Technology Group (BITE) have further developed this technology, which has now been globally patented, into a large number of prototypes of steerable surgical instruments. DEAM is a spin-off company of the BITE group that develops steerable precision instruments for minimally invasive interventions. DEAM collaborates with a number of universities of technology and university medical centres. The LaproFlex is the first commercially available instrument using a cable crane mechanism and is considered to be a particularly affordable, disposable alternative for the extremely pricey Da Vinci operation robot.


MemoSlide – Moving like a Mechanical Snake

Developed in 2016-2017, 13 cm wide, 20 cm long, and 10 cm high.

During complex surgical procedures, such as in ENT or skull-base surgery, there is a need to approach difficult-to-reach locations via narrow anatomic pathways. Performing surgery along complex 3D pathways requires a snake-like instrument able to memorize the 3D shape of the followed pathway and shifting the shape backward as the instrument moves forward with its head steering in a new direction. This snake-like method of locomotion is called “follow-the-leader locomotion”, in which the head is the “leader” and the body follows the pathway of the head, see the following animations:

Follow-the-leader locomotion requires a segmented multi-steerable instrument such as our MulfiFlex as well as a memory in which the angles of the segments can be stored and shifted to the neighbouring segments as the instrument moves forward. In robotic follow-the-leader approaches, the actuation usually occurs locally, within the segments, by miniature electric motors controlled by a computer that memorizes the shape. This approach will, however, result in a device too large for surgical applications with a maximum instrument diameter of Ø5 mm. Instead, the actuators can be stored in a handle or console placed outside the patient, so that larger motors can be used in combination with cables or rods that transfer the motion to the snake-like tip. Although feasible, using  electric actuators controlled by a computer will result in a complex and expensive system requiring additional safety measures to ensure reliability during surgery.

In a desire to create a relatively low-cost follow-the-leader system that combines high safety with small dimensions, we explored an alternative follow-the-leader approach by using a mechanical memory inspired by the technology of mechanical calculators such as Charles Babbage’s Difference Engine.

MemoSlide features two mechanical memory registers: a static register (green in the design drawing below) and a moveable register (red) in which the angles of 11 tip segments can be stored, the angles represented by 11 small Ø3 mm ball-bearings that can slide sideways through slots in the brass top plate . The two registers are mutually coupled via a system of ball-bearings and cams underneath the brass top plate. Both registers can be locked and unlocked, and the moveable register can be shifted one segment forward or backward relative to the static register. The position of the first tip segment can be controlled by turning the blue steering wheel. Turning the crank around the steering wheel then results in  a sequence of locking, unlocking and shifting motions, controlled by the four brass cams  at the corners of the device, to memorize and shift the position of the ball bearings backward along the registers. The movie below shows an example in which MemoSlide is programmed with a sinusoidal shape that is shifted backward along the device (and then forward again, as the device works in two directions).

Although in principle suited for controlling the shape of a snake-like surgical device, MemoSlide is in its current configuration still too complex and limited to 2D pathways. Based on our experience with MemoSlide, we are currently developing a new mechanical system suited for memorizing 3D shapes and sufficiently simple for integration in the handle of a snake-like  surgical device. We will keep you posted!


Henselmans P.W.J., Gottenbos S., Smit G., Breedveld P. (2017). The MemoSlide: an explorative study into a novel mechanical follow-the-leader mechanism. Proc. of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine. Vol. 23, No. 12, pp. 1213-1223.


Ovipositor Needle I – Self-Propelling through Tissue

Developed in 2014, thickness 2 mm.

Wasp ovipositors  are thin and flexible needle-like structures used for laying eggs inside wood or larvae.  Wasp ovipositors are composed out of  longitudinal segments, called “valves”, that can be actuated individually and independently of each other with musculature located in the abdomen of the insect. In this way the wasp can steer the ovipositor along curved trajectories inside different substrates without a need for rotatory motion or axial push.

Inspired by the anatomy of wasp ovipositors, we developed an Ovipositor Needle containing a 2 mm thick “needle” composed out of four sharp and polished stainless steel rods, representing four ovipositor valves. The four valves can be individually moved forward and backward by means of  electromechanical actuators mounted in a propulsion unit that is standing on four passive wheels. If the needle is inserted into a gel that represents tissue, and if the four valves are sequentially moved forward and backward, the friction behaviour around the valves in the gel will result in a net pulling motion that drives the needle forward through the gel. The ovipositor needle is therefore self-propelling, meaning that it does not need a net pushing motion for moving forward through tissue like normal needles do.

Ovipositor Needle I is part of the  WASP project that focuses on the development of steerable needles for localized therapeutic drug delivery or tissue sample removal (biopsy). In a new prototype that is currently under development, we aim to extend the self-propelled needle with steering capabilities at an outer diameter of just 1 mm.



Accessible Prosthetics through 3D Printing and a Smartphone App

This research project is part of the Delft Global Initiative program: the portal and booster of Science and Technology for Global Development at TU Delft. Aim of the program is to contribute to sustainable solutions for global societal challenges, through problem-oriented interdisciplinary technical research in close cooperation with partners in the developing world, to meaningfully improve lives of people living in poverty.


Combining modern advances in smartphone technology with the seemingly unlimited possibilities of 3D-printing, in this project we aim to create easy access to prosthetics for amputees in Third World countries. We will develop an advanced, free IOS / Android app that scans the amputee with a smartphone camera and completely automates the complex prosthetic design process ending in design drawings for a 3D-printer that manufactures a well-fitting prostheses. In this project we will not only generate new, fundamental knowledge on automatic designing and manufacturing, we will also collaborate with a number of charity organizations to stimulate local initiatives in 3D printing and to optimize the prosthetic supply chain.

Photo: Example of 3D-printed prostheses from Mich Ebelings “Not Impossible Project” in Sudan.

More information:


DragonFlex Micro – Towards the Limits of 3D-Printing

Developed in 2012-2015, thickness 5 mm, steering range: ±90º in all directions, complex components made by 3D-printing.

The DragonFlex has been developed in close-collaboration with Dr. Filip Jelinek, former PhD from the BITE-Group and currently employed at ACMIT.

In follow-up of the successful DragonFlex Macro, the DragonFlex Micro has been miniaturized to a 5 mm scale, where special attention has been given to the reliability and precision of the mechanism and optimization of the 3D-printing technique for such small scale components. Developing and optimising new design methodologies for 3D-printing,  a number of prototypes have been manufactured from different materials, resulting in world’s first steerable surgical instrument made entirely by 3D printing.



DragonFlex Macro – Smart Steering by 3D-Printing

Developed in 2010-2011, thickness 15 mm, steering range: ±90º in all directions, made entirely by 3D-printing.

Despite its success, e.g. in prostatectomy, da Vinci’s steerable grasper EndoWrist from Intuitive Surgical has a complex design prone to steel cable fatigue, potential sterilization issues and high associated costs, all of which insinuate a need for an alternative. The aim of our DragonFlex project is to demonstrate a design of a structurally simple handheld steerable laparoscopic grasping forceps free from cable fatigue, while attaining sufficient bending stiffness for surgery and improving on EndoWrist’s maneuverability and dimensions.

Having equal joint functionality to EndoWrist, DragonFlex’s instrument tip contains only four parts, driven and bound by two cables mechanically fixed in the handle. Two orthogonal planar joints feature an innovative rolling link mechanism allowing the cables to follow circular arc profiles of a diameter 1.5 times larger than the width of the instrument shaft. Besides maximizing the cable lifespan, the rolling link was designed to equalize the force requirements on both cables throughout joint rotation, making the handling fluid and effortless. The smart stacked joint design enables control of seven Degrees of Freedom (DOF) by only two cables and seven instrument components in tip, shaft and handgrip altogether.

The DragonFlex prototype was developed by means of 3D-printing, allowing grasping and omnidirectional steering over ±90°, exhibiting promisingly high bending stiffness and featuring extreme simplicity. DragonFlex concept sheds new light on the possibilities of additive manufacturing of surgical instruments, allowing for a feature-packed design, simple assembly, suitability for disposable use and potential MRI compatibility.



Multi-Steerable Cardiology Instruments – MULTI

This research project is part of the iMIT program and funded by the Netherlands Organization for Scientific Research NWO. The iMIT Program, executed by a community of Dutch Universities, university medical centers, and companies, aims to develop instruments for minimally invasive interventions. The program will result in the development of interactive Multi-Interventional Tools (iMIT)  that can adapt to their environment and integrate diagnostic and therapeutic functionalities, thus permitting effective single-procedure interventions.

Project MULTI – Design and development of multi-steerable tools for cardiac interventions

Cardiac Catheters  
The field of interventional cardiology is a growing branch of cardiology where minimally invasive instrumentation is of high importance. Catheters are among the most versatile and essential instruments used in interventional cardiology. Where in the past they were designed as flexible tubes, meant for monitoring or drug delivery, today catheters have evolved into more complicated and steerable instruments with additional tip functionality. As such, a large variety of commercially available catheters exist, being adopted in treatments of, for instance, heart rhythm defects and heart valve disease.

Current Difficulties
Despite their frequent and essential use, currently existing catheter designs have limited functionality as a result of several difficulties. Precise positioning of the catheter tip in the heart remains one of the biggest challenges as a result of complex 3D shapes inside heart and the absence of vessel wall support. In addition to that, respiration and heartbeat lead to a constant movement of the heart and changes in blood flow inside the cardiovascular system. Therefore, the use of catheters for complex interventions inside the heart requires a catheter tip that can be positioned accurately at the required location without damaging the heart or other surrounding anatomy. Of specific interest are cardiac biopsies and ablations, where mal-positioning of the catheter due to a lack of steerability can results in severe complications such as ventricular perforation or heart block. This research project at the TU Delft therefore focuses on designing and developing a catheter that is multi-steerable and is able to be directed towards and positioned inside any location in the beating heart.

Multi-Steerable Catheter
The aim of this project is to develop new and multi-steerable catheter technology based on the cable-ring technology and human factor experience at the TU Delft. First catheter concepts will allow left/right and forward/backward motion without rotation of the catheter shaft. More advanced concepts will be included with electro-mechanic controls and multiple steering segments that will allow for complex 3D tip motion. Finally, in-vitro evaluation on an isolated beating heart will take place to enable accurate positioning under physiological circumstances. The project is intended to result in explicitly evaluated multi-steerable catheter prototypes that are ready for commercialization. The realization of such a multi-steerable catheter will offer application in more complex minimally invasive cardiac interventions such as annuloplasty procedures, cardiac tissue resections, precision cardiac biopsies, septal defect closures, and valve implantations. Moreover, our focus is on development of steerable catheters for cardiac biopsies and ablations.

I-Flex – Steering Towards Miniaturization Limits

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

The retina is a light-sensitive layer at the inside of the eye. The macula is the region at the center of the retina with the highest concentration of light-sensitive cells. Macula degeneration – a disease which is a major cause of blindness –  is caused by a disfunctioning choroid layer under the macula. A way to treat macula degeneration is to perform surgery to the choroid layer via a tiny incision in the retina near the macula.  Reaching the choroid layer under the macula is extremely difficult as the surgeon has to operate through the incision under an angle while avoiding damage to the extremely delicate macula layer.  A steerable instrument could potentially solve this issue by making it easier to steer the instrument through the incision.

The largest design and fabrication challenge of such an instrument is the extreme miniaturization of the steerable mechanism in the tip. Down-scaling our patented Cable-Ring mechanism, already applied in the Endo-Periscope III and MicroFlex, to a very small scale, resulted in the  I-Flex – world’s smallest steerable surgical instrument that can be steered in all directions. The compliant tip has a diameter of only  0.9 mm and is constructed from 7 steel cables and a spring. Being equipped with a tiny gripper, the tip can be steered in two Degrees of Freedom (DOF). The instrument contains a novel handle that combines intuitive steering with a fine and precise pincer grip.

Feedback of experienced eye-surgeons from the Eye Hospital in Rotterdam has led to the development of a second prototype which is currently under construction. This instrument incorporates a different handle, allowing further miniaturization of the steerable tip to a diameter of only 0.45 mm – three times the size of a human hair.