Design of a steerable fiber-optic device

Various diseases can require patients to undergo spine surgery. At the BITE group, we are developing a novel drill that allows for the surgeon to steer through the vertebra along a secure drilling trajectory, avoiding nerves and blood vessels that run along the spinal column. To help the surgeon find and maintain the right trajectory, a fiber-optic sensing system will be integrated into the drill to provide the surgeon with positional feedback in real time.

In the scope of the proposed graduation project, inspiration will be drawn from nature to design a steerable fiber-optic device. A scale model will be fabricated by rapid prototyping, and its usability for steering through the vertebra will be assessed.

Interested? Contact Merle Losch, m.s.losch@tudelft.nl.

navigation for steerable bone drill

Multiple diseases can require patients to undergo spine surgery. At the BITE group, we are developing a novel drill that allows for the surgeon to steer through the bone along a secure drilling trajectory, avoiding nerves and blood vessels that run along the spinal column. To help the surgeon find and maintain the right trajectory, an optical sensing system based on Diffuse Reflectance Spectroscopy (DRS) will be integrated into the drill to differentiate the tissue ahead of the tool tip, thereby providing positional feedback for the surgeon in real time.

In the scope of the proposed graduation project, a surgical navigation concept for the steerable bone drill will be developed, and its usability for guidance will be assessed.

Interested? Contact Merle Losch, m.s.losch@tudelft.nl.

Novel “Tattoo”-based instrumentation for Dupuytren’s contracture surgery (CLOSED)

The hand is one of the most complex structures of the human body, allowing an advanced spectrum of motion. Dupuytren’s contracture, or Dupuytren’s disease, is an abnormal thickening of the palmar fascia, just below the skin of the palm of the hand, which impairs the motion of the finger tendons, leading to loss of finger function and causing the fingers to curl.

Surgical treatment of Dupuytren’s contracture involves making an incision through the thickened palmar tissue which is then partially removed. As the hand anatomy is very delicate, with a fine network of blood vessels and small nerves leading to the fingers, there is a risk of severe complications, especially when fragile nerves under the palmar fascia are accidentally cut.

This MSc-graduation project involves the development of novel high-tech “tattoo”-based instrumentation for Dupuytren’s contracture surgery by which the risk of damaging delicate palmar structures can be totally avoided. The project will be carried out in a very close collaboration with hand surgeons from the Reinier Haga Orthopedic Center (RHOC). We are searching for a student that can start at a short term with this challenging and very interesting graduation project.

Interested? Please contact Paul Breedveld, p.breedveld@tudelft.nl

Wasp-Inspired Tissue Transportation Device

Developed in 2017-2018, diameter 6 mm. 

A wasp ovipositor is a needle-like structure composed out of three elements, called valves. A female wasp uses this structure to drill into wood or fruit and deposit eggs inside a living host. The propagation of eggs through the ovipositor is achieved by a smart push-pull mechanism, in which some valves are pushed while other valves are pulled, using surface- and direction-dependent friction with the egg to make it move forward. Inspired by the ovipositor of parasitoid wasps, we developed a novel tissue transportation device that can transport tissue samples at a precisely controlled speed without any risk of clogging.

The developed mechanism consists of an outer tube surrounding six semi-cylindrical blades that make a reciprocal forward/backward motion, driven by a miniature electric motor with a cam, similar to our Self-Propelling Ovipositor Device. Tissue samples are transported using a friction differential between the tissue and the blades, at a speed which is set by the surgeon. We tested the device with various tissue-mimicking gels as well as with compacted minced meat, using different motion sequences of the blades. In all cases the substance was transported reliably, showing that the ovipositor principle is well-suited for tissue transportation and a useful alternative to conventional aspiration (suction)-based devices that are prone to clogging.

The BBC made a nice animation showing the working principle of the device. In a new research project within Dutch Soft Robotics we are currently equipping the device with a flexible steering section to facilitate tissue transport from difficult-to-reach locations in the human body.

Publications

Media

SIGMA Catheter – steering inside the Heart

Developed in 2016-2017, diameter Ø3 mm, lumen Ø1 mm

In recent years, steerable catheters have been developed to combat the effects of the dynamic cardiac environment. However, current solutions are bound to a number of limitations: (1) low torsion, (2) shaft shortening, (3) high unpredictable friction, and (4) coupled tip-shaft movements. These effects make it very hard to steer in tortuous blood vessel and inside the heart.

In order to tackle these limitations we developed a novel multi-steerable catheter prototype with four degrees of freedom. The tip has two steering segments that can be steered in all directions, controlled by two joysticks on the handle: one for the thumb and one for the index finger. The prototype features automatic lock of the steering angle once the joystick is released.

To solve the four limitations mentioned above we used eight miniature Bowden-cables inside of the flexible shaft for independent omnidirectional steering of each tip segment. As each segment can steer in all directions, twisting the shaft is not needy for directing the catheter tip, which solves the issue with low torsion (1). The issue with shaft shortening (2) is solved with the Bowden-cables which are axially incompressible. The Bowden cables generate very low predictable friction (3) and coupled tip-shaft movements (4) are absent as the Bowden-cables transfer the joystick motions directly to the tip without influencing the shaft.

The ability to steer inside the heart with a variety of complex shapes and curves opens great possibilities for complex catheter interventions. We evaluated our SIGMA catheter in a transparent 3D printed heart, based on MRI-images and created by the company Materialize, as well as ex-vivo in a beating porcine heart at the LifeTec Group. Both evaluations show very promising results and superior behaviour as compared to conventional steerable catheters.

Publications:

Ali A., Sakes A., Arkenbout E.A., Henselmans P., Starkenburg R. van, Szili-Torok T., Breedveld P. (2019). Catheter steering in interventional cardiology: mechanical analysis and novel solution. Proc. Inst. Mech. Eng. Part H: Journal of Engineering in Medicine, 12 p.

Media

https://www.materialise.com/en/blog/how-a-modular-testbed-helps-medical-device-developers

Design of a Bone Marrow Harvesting Device

Bone marrow is a soft and fatty tissue located within the porous bone structure at the centre of the larger bones. During bone marrow biopsies, also called trephine biopsies, a 1-2 cm long sample of the bone and bone marrow is taken to check, amongst others, for blood cell abnormalities. A Jamshidi needle is used to collect the bone marrow by pushing the needle through the rigid cortical outer layer of the bone such that it will be located within the softer cancellous bone. During retrieval of the needle, the biopsy sample sometimes remains inside the incision. This requires manual removal of the sample using forceps, and possibly a second biopsy has to be taken.

During this project, you would first look into current instruments used to perform a bone marrow biopsy after which you will design a novel device that could be used for harvesting bone marrow samples.

Interested? Contact Esther de Kater, e.p.dekater@tudelft.nl

MemoFlex 2 – Mechanical Cam-Following Snake

Developed in 2018-2020, diameter Ø8 mm

During complex surgical procedures such as in skull-base surgery, there is a need to reach difficult-to-reach locations via narrow anatomic corridors. Performing surgery along complex 3D pathways requires a snake-like instrument that memorizes the 3D shape of the followed pathway and shifts the shape backward as the instrument moves forward. 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 as well as a memory in which the angles of the segments can be stored and shifted. In robotic approaches, the actuation occurs by a range of electric motors controlled by a computer. Although feasible, this will result in a very complex system requiring additional safety measures to ensure reliability during surgery.

In a desire to create a simpler system, we explored an alternative follow-the-leader approach by using a mechanical memoryFollowing our  HelicoFlex design, the MemoFlex II contains an Ø8 mm multi-steerable tip with 14 segments controlled by 56 steering cables in 28 Degrees of Freedom. The novel compliant frame of the tip is entirely non-assembly 3D printed out of one single part, creating an easy-to-make construction with a large range of snake-like motion possibilities.

The mechanical shape memory consists of four 3D printed plates (two for the horizontal plane and two for the vertical plane) containing curved grooves representing the required pathway of the tip. The four plates are mounted in a rotatable blue cylinder that is surrounded by a static exoskeleton. When the instrument is moved forward, the cylinder turns around, driven by a cam in the exoskeleton, and the curved grooves move along a set of ball bearings, each bearing connected to one of the steering cables, causing the tip to move along the shape of the curved grooves. The pre-programmed groove-shape can be derived preoperatively from CT or MRI-images.

Publications:

Variable Friction Catheter

In cardiovascular interventions, Catheters are typically inserted in the radial or femoral artery and are navigated through the arteries to the heart, where the interventions are performed.  In order to safely reach the heart,  catheters  (and guidewires) used during these procedures need to be able to easily follow the curves in the  vascular  system,  while  creating  as  little  friction  as  possible to avoid damaging the blood vessel inner wall.  While low friction is beneficial during navigation, it makes holding the catheter at a specific location in open spaces, such as inside the heart, difficult during the execution of the surgical procedure. Thus, it limits the force transmission capability of the catheter. In this project, we look forward to developing a new variable friction catheter which can be modulated to have low friction while navigating and high friction while performing the surgical task to ensure optimal performance and outcomes in both cases.

The assignment is currently available with compatible literature review assignments. Interested? Contact Mostafa Atalla: m.a.a.atalla@tudelft.nl  

Self-Propelling Ovipositor Device

Developed in 2016 by MSc. student Perry Posthoorn

A wasp ovipositor is a needle-like structure composed out of three elements, called valves. A female wasp uses this structure to drill into wood or fruit and deposit eggs inside a living host. The propagation of the ovipositor through the substrate is achieved by a smart push-pull mechanism, in which one of the valves is pushed while the other two are pulled, using the surface-dependent friction properties with the soft substrate to move forward.

Inspired by the ovipositor of parasitoid wasps, we developed a novel self-propelling Ovipositor Device designed for locomotion through the large intestine (colon). The device contains a miniature electric motor connected to a cylindrical cam. Six sliders are placed around the cam and move forward and backward following the path defined by the cam. Designed for motion through soft environments, the working principle of the propulsion mechanism is that multiple stationary sliders create sufficient friction to allow for a single slider to shuffle forward. In each step, one slider moves forward whereas the others remain stationary relative to the environment, generating a smooth and continuous motion at approximately 1/6 of the speed of a moving slider. The ovipositor mechanism allows a simple and robost construction that can be easily miniaturised to very small dimensions, see our research on self-propelled ovipositor needles.

Experiments were carried out with various flexible 3D-printed structures attached to the outer surface of each slider to generate direction-dependent friction for further enhancement of grip. Tests in plastic tubes showed fast and fluent self-propelled motion. Locomotion in a colon was succesfully achieved with an improved 3D-printed outer surface in which the tangential spacing between the sliding structures was decreased so that the colonic wall does not flex between them. The improved prototype was able to self-propel ex-vivo through a porcine colon without any visual damage to the colonic wall.

(Featured image adapted from “Braconid Wasp Ovipositing” by Katja Schulz is licensed under CC BY 2.0.)

Publications

Solving medical problems through nature’s ingenuity