Category Archives: Assignments

Flexible Transport System

During percutaneous coronary interventions in the coronaries of the heart, it is often a necessity to remove obstructions from the blood vessels. Obstructions are  removed using specialised instruments, such as atherectomy drills and balloon catheters. During removal, aspiration catheters are used in conjunction with these instruments in order to prevent small particles getting into the blood stream, which can cause a stroke, amongst others. These aspiration catheters use a pressure differential to remove the small particles from the blood stream.

Even though these catheters are successful in removing small particles from the blood stream, they are often plagued by various failure modes. For example, they are prone to clogging and are limited for transport of tissue through long and narrow tubes. Furthermore, the aspiration-force that is created does not only affect the desired tissue but also the surrounding tissue.

Therefore, in this assignment, you will develop a new type of flexible transport system that is not prone to these failure modes.

If you are interested in this assignment, please contact: Aimée Sakes, a.sakes@tudelft.nl

Minimum Assembly Steerable Instrument

Inspired by nature’s hydrostatic skeleton approach, we developed the multi-maneuvrable tip of the HelixFlex, which consists of a single compliant segment, and incorporates three different cable layers: one with parallel cables and two with helically-oriented cables to allow for 4 DOF motion.

Complex steerable devices such as the HelixFlex are difficult to manufacture and can often take up to a few week to assemble. In an effort to improve the manufacturability and assembly, in this assignment it is the aim to develop a new version of the HelixFlex that minimizes assembly.

If you are interested in this assignment, please contact: Aimée Sakes, a.sakes@tudelft.nl

Single-Handed Control of Multiple Functions

In many surgical applications the surgeon needs to control a medical instrument, such as a bronchoscope or steerable grasper, using a specialised handle. This specialised handle often consists of multiple joysticks and buttons and often requires a long learning curve to master. They are also often quite bulky and not very ergonomically designed, causing operator fatigue (amongst others).

In this assignment, you will develop a new kind of handle that can be controlled using one hand and that is ergonomically designed. The handle will be specifically designed for breast biopsy procedures.

Contact: Aimée Sakes, a.sakes@tudelft.nl

Design, fabrication and evaluation of  an adhesion-based medical gripping instrument

Tissue manipulation during surgery is currently done with a grasping forceps. This pinching instrument is prone to errors related to the force that is applied on the gripped tissue. Using too much force may lead to tissue damage, whereas applying too little force may result in tissue slipping out of the forceps.

One way to realize firm yet gentle grip could be by means of an instrument that relies on adhesive forces rather than pinching forces. In this line, we are developing adhesive pads that can generate high friction forces on soft substrates, such as biological tissue.

In this research project you will be designing a medical instrument that integrates such an adhesive pad for tissue manipulation. One of the challenges herein is that such pads are optimized for high friction, which means that the range and type of movements for tissue manipulation may differ from these of a conventional gripper.

You will work towards the design and experimental evaluation of a prototype of an adhesion-based gripping medical instrument. This includes evaluation of the functional requirements of an adhesion-based instrument to be used in minimal invasive surgery, design and fabrication of a prototype thereof, and testing of its performance with phantoms and ex vivo.

Contact: Peter van Assenbergh, s.p.vanassenbergh@tudelft.nl

3D printed wasp-ovipositor replica: reverse engineering approach

In nature, several species of parasitoid wasps have a thin and flexible needle-like structure, called ovipositor, which is used to deposit eggs in a host (e.g., a larva) hidden into tree trunks or fruits. The wasp ovipositor consists of three segments, called valves, longitudinally connected that can slide along each other.  The animals can drill in different substrates by actuating the valves in a reciprocal motion and steer by changing the relative positions of the valves during probing (i.e. protracting and retracting of the valves).

We are currently developing a novel steerable needle for minimally invasive interventions inspired by the wasp-ovipositor. However, the steering mechanisms used by the animal is not yet fully understood.

The project will focus on understanding how the steering mechanism works and which characteristics of the ovipositor play a relevant role.

The student will use detailed 3D images of different ovipositors to design several replicas of the wasp ovipositor in larger scale with 3D printed techniques. The prototypes will be tested with an experimental facility where motion pattern and speed can be controlled. The ovipositors will be inserted in gelatine of different concentration to study the design parameters effecting the steering mechanism.

Contact: Marta Scali, m.scali@tudelft.nl

Picture adapted from “Braconid Wasp Ovipositing” by Katja Schulz is licensed under CC BY 2.0.

Automatic design and manufacturing of upper limb prosthetic sockets for developing countries

Comfort and functionality of upper limb prosthetics is highly dependent on socket performance. Correct anatomical fit is therefore of paramount importance for prosthetic designs. We believe that the complex design process of prosthetic sockets can be achieved automatically using accurate anatomical models of the stump. With the increasing advance in smartphone technology it is possible to reconstruct digital models based on camera information. We plan to explore current technologies for generating 3D digital models from multiple 2D photos and assess such techniques to stablish a framework in which smartphone technology can be used to generate 3D computer models of upper limb stumps. Using precise geometry of the stump and current CAD technologies it is possible to create a socket design that fits accurately into the residual limb. We plan to adopt such process to build fully working prosthetic sockets using 3d printing technology for developing countries.

Contact: Juan Cuellar, J.S.CuellarLopez@tudelft.nl

Design of an endoluminal ovipositor-device

During colonoscopy procedures an endoscopic device is inserted into the patient and pushed through the colon with consequential discomfort to the patient.  Self-propelling devices that are able of moving through a lumen without the need of external push could be beneficial for these applications. Research in this topic is ongoing, but no successful solutions have yet been discovered.

At TU Delft a former master student (Perry Posthoorn) developed a self-propelled device inspired by the mechanism of the ovipositor of the wasp. The ovipositor is a needle-like structure which consists of three elements that can slide along each other. By means of a reciprocal movement of the elements the wasp is able to insert the ovipositor through a substrate. The reciprocal sliding mechanism of multiple elements has inspired the design of our ovipositor-device.

Preliminary tests have shown that the device is able to move through an ex-vivo porcine colon, although at extremely slow speed due to a sub-optimal internal construction of the device.

The aim of this graduation project  is to develop a strongly improved endoluminal device aiming at maximizing propulsion speed at minimal internal complexity with the final aim to make a revolutionary new system suited for disposable use.

For more information contact Marta Scali (m.scali@tudelft.nl).

The Nothern Clingfish, Bio-inspired Suction Cup

The northern clingfish (Gobiesox maeandricus) is able to adhere to slippery, wet, and irregular surfaces in the marine environment. A study by Wainwright et al. (2013) found that the fish can adhere to surfaces with a broad range of surface roughness, from the finest of sandpaper, to highly irregular surfaces such as rocks. The fishes outperform manmade suction cups, which as many of us know, only adhere to smooth surfaces.

Clingfish are able to adhere to these wet and irregular surface due to their highly sophisticated suction disc. This suction disc consists of a cup with at the edge of the cup structured microvilli, similar to those of geckos. When the fish attaches to a surface, water is forced out from under the suction disc by rocking the pelvic girdle and an area of sub-ambient pressure is created. The microvilli at the edge of the disc, subsequently prevent slip of the cup or premature release by creating friction between the cup and the surface.

In this assignment we will focus on the design of a special bio-inspired suction pad for use in medical application to grip and release slippery, wet and soft tissue without damaging the structure.

Shape Shifting in Nature; Creating a Stabile Platform inside the Vasculature

In nature many animals are able to change their appearance to match their surroundings or to mimic other animals. This camouflage protects them from predators and allows for sneaking up on unsuspected prey. Examples of these animals are chameleons and octopi.

A shape shifting/adaptable device could be an asset in the Percutaneous Coronary Interventions (PCI). In PCI, an occlusion of one of the coronaries is crossed using a guidewire (a small metal wire with a diameter of in between 0.36-0.89 mm) and, subsequently compressed against the blood vessel wall using a balloon catheter, also known as balloon angioplasty.

On some occasions, the guidewire buckling can occur during the crossing procedure, which ultimately can result in procedural failure. In order to prevent guidewire buckling, a support structure should be created that can adapt to the blood vessel wall and provide sufficient support.

Inspiration can be drawn from animals that are able to actively change their shape. This knowledge can later be used in the design of the adaptive support structure.

Contact: Aimée Sakes, a.sakes@tudelft.nl

Mechanical Reconstruction of a Chameleon Tongue (Closed)

Chameleons are able to shoot their tongues with accelerations of up to 50g to capture prey. To do this, they use a very specialized mechanism, involving elastic structures and muscle activation. A similar system is currently not seen in any other mechanical product or medical instrument. A shooting mechanism, similar to that of a chameleon can give important insights into new ways to accelerate projectiles.

Therefore, the goal of this research project is to design a mechanical shooting mechanism with similar characteristics using the chameleon’s tongue as inspiration.

Contact: Aimée Sakes, a.sakes@tudelft.nl

Chameleon copy