Spinal bone anchor fixation by molding to the pedicle

During spinal fusion surgery, multiple vertebrae are fused by fixating them together. The fixation of the vertebrae is achieved by placing screws through the pedicles of the vertebrae that are connected to rods. The fixation strength of the screw mainly relies on the contact area between the screw and the outer bone layer of the vertebra. This contact can only be achieved within the pedicle of the vertebra. However, even in the pedicle, this contact is limited due to the hourglass shape and oval cross-section of the pedicle.

In this graduation project, you will design a bone anchor that can adapt its shape in 3D to the pedicle of the vertebra to fixate to increase the contact area between the anchor and the cortical outer layer of the pedicle.

Interested? Contact Esther de Kater, E.P.dekater@tudelft.nl

Design of an internal fixation system for spinal fusion surgery

During spinal fusion surgery multiple vertebrae are fused by fixating them together. The fixation of the vertebrae is achieved by placing screws through the pedicles of the vertebrae that are connected to rods. The rods run along the vertebrae and are embedded in the surrounding soft tissue. This can result in pain and irritation for the patient.

The vertebra grow together and form one bony mass in the first six months after surgery. During this period the forces acting on the fixation are substantial during daily activities. If the screw loosen during this period, the desired fusion cannot be achieved.

In this graduation project we will set the first steps in the direction of a new fixation method that is mainly located within the vertebra. The graduation projects focuses on the development of a drilling and/or anchoring system that can be used to create the desired fixation.

Interested? Contact Esther de Kater, E.P.dekater@tudelft.nl

Neural network for tissue classification

The spine is the central support structure of the body that helps us humans sit, stand up and walk around, twist and bend. Age-related degeneration, but also congenital deformities can cause back pain and spinal instability, requiring surgical fixation of the spine. To guide the surgeon’s drill during spine surgery, the tissue in front of its tip is assessed with a fiber-optic sensing system, but we currently don’t know how to evaluate the recorded data.

The focus of this graduation project in collaboration with Philips Research will be to train a neural network with data from different tissues found in/around the spine to develop a classifier that will guide surgeons during spine surgery. This project does not require preliminary AI knowledge or programming skills, although knowing some python basics will be of use.

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

TU DELFT – Ultrasonic Friction Modulation of Catheters

This Project is funded by TU Delft as part of the cohesion projects grants

In cardiovascular interventions, in order to safely reach the heart,  catheters  (and guidewires) need to easily follow the curves in the  vascular  system,  while  creating  as  little  friction  as  possible to avoid damaging the blood vessel 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 procedure (thus, limiting the force transmission capability and the stability). The aim of this project is to develop a novel class of catheters whose frictional properties are controllable and can be adjusted depending on the phase of the catheterization procedure using the ultrasonic friction modulation technique which has been widely adopted in surface haptics applications.

Design of an Octopus-Inspired Device for Stable Needle Insertion (CLOSED)

Octopuses have eight arms that are perfect for gripping rocks, catching prey, and walking along different surfaces. They do this with the suction cups that underline their arms. We are currently developing soft suction cups for stable needle insertion in flexible tissue inspired by these octopus suction cups.

Tissue motion and deformation leads to needle positioning errors. Hence, clinicians typically needle multiple attempts to position the needle at the target location. To achieve accurate needle positioning, clinicians can stabilize the tissue by gripping it. However, gripping and handling of slippery and flexible tissues during minimally invasive surgery is often challenging. Current grippers commonly use a force grip to manipulate tissue, which makes it prone to damage. Octopus-inspired suction cups integrated with a needle could be the solution that stabilizes tissue during needle insertion without damaging the tissue.

This MSc-graduation project involves designing, developing, and testing a novel stable-needle insertion device that allows for accurate needle positioning. We are searching for a student that is interested in a design-oriented project. For this project, SolidWorks, 3D-printing, and creative-problem-solving skills are useful.

Interested? Please contact Vera Kortman (v.g.kortman@tudelft.nl) or Jette Bloemberg (j.bloemberg@tudelft.nl)

3D-GriP – A minimal assembly fully 3D printed instrument

Developed in 2020-2021, diameter Ø8 mm, bending angle ±60˚, consists of 5 separate parts.

In minimally invasive surgery, small incision sizes limit the manoeuvrability of surgical instruments. The number of degrees of freedom (DOF) of the instrument shaft can be increased by making the instrument tip steerable. Such instruments are controlled by the surgeon on the side of the handle. Steerable instruments offer many advantages in terms of DOF and functionality, however they have high mechanical complexity, and the steerable shaft can be difficult to operate for the surgeon.

Additive manufacturing (AM) can aid in the development of these instruments by reducing the mechanical complexity in the form of minimal assembly designs. The freedom of complexity offered by AM allows parts to be merged together into larger, more complex parts, that can be 3D printed in a single step. In addition, AM allows the production of one-off, personalized designs.

The 3D-GriP is a 3D printed steerable instrument that consists of only 5 separate parts. The handle part is designed based on ergonomic principles for handheld instruments, and can be adjusted to the size of the surgeon’s hands for a perfect fit. The joystick steers the instrument and works with a passive lock, which is automatically engaged when no pressure is applied. The grasper can be closed with the trigger, designed with two perpendicular flexures, which can be operated by one or two fingers, as the surgeon prefers.

Culmone C., Lussenburg K., Alkemade J., Smit G., Sakes A., Breedveld P. (2021). A fully 3D-printed steerable instrument for minimally invasive surgery. Materials, Vol. 14, No. 24, 18 p. 

Design of a steerable device for spine surgery

Spinal fusion is one of the most common surgical procedures in the world. 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.

For this graduation project, inspiration will be drawn from nature to design a steerable device for spine surgery. A 3D-printed model will be built, and its usability for steering through the vertebra will be assessed.

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



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.)


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

Solving medical problems through nature’s ingenuity