Surgical instruments used in eye surgery are very small, which makes it difficult to produce instruments with high functionality. The bottleneck in the production of eye surgical instruments is the assembly step. Assembly has to be done by hand, because of the small size of the parts. Automation is difficult to implement, due to the relatively small number of specific instruments. As a solution to this problem, the complexity offered by 3D printing can be used. A way to do this is to 3D print entire functioning products or mechanism in one single step, without the need of assembling them afterwards, called non-assembly 3D printing.

A vitrectome is a specific instrument used in eye surgery to remove the vitreous from the eye. It consists of two thin, hollow needles that are inserted into the eye, and a handle containing a vibrating mechanism. In this assignment, you will be working on the design of a non-assembly 3D printed vitrectome mechanism, which should have the same specifications as current vitrectomes.

This assignment will be available from January/February 2021. Interested? Contact Kirsten Lussenburg, k.m.lussenburg@tudelft.nl.

During spinal fusion surgery multiple vertebrae are fused by fixating them together with an internal brace. The brace is connected to a vertebra with pedicle screws. The inside of the bone (cancellous bone) is too weak to achieve sufficient grip. Therefore, screw fixation mainly relies on locations where the screw is in direct contact with the surrounding  layer of the much harder cortical bone. We are developing a steerable bone drill in order to increase the contact area of screws and cortical bone by drilling along the cortical bone layer. An optical sensing system that can differentiate the two types of bone tissue will help the surgeon find and maintain the right drilling trajectory. Furthermore, a novel anchoring device that is flexible during insertion, but becomes rigid once in place will replace straight pedicle screws.

There are multiple graduation projects available related to optical sensing, bone drilling and anchoring.

• Development of a bone phantom for testing of a steerable drill or screw
  Contact: Merle Losch, m.s.losch@tudelft.nl
  
• Design of a drill prototype to provide directional feedback
  Contact: Merle Losch, m.s.losch@tudelft.nl

• Design of  flexible screw that can become incredibly stiff in order to transfer the forces acting of the screw
  Contact: Esther de Kater, e.p.dekater@tudelft.nl
  
  
• Design of a flexible screw that adheres to the bone surface in order to transfer the forces acting on the screw
  Contact: Esther de Kater, e.p.dekater@tudelft.nl

If you are looking for a challenging assignment that combines bio-inspiration with actual animals, I have currently multiple projects available directed towards veterinary research. The projects are in collaboration with the Rotterdam Zoo and Faculty of Veterinary Medicine of the University Utrecht. Projects are aimed at surgical interventions of different types of animals, including elephants, rhinos, birds, and horses. A selection of the projects is illustrated below:

• Suturing abdomen of larger animals

Suturing of the abdomen of larger animals is difficult and often results in ripping along the suture line due to the large force on the stitches. This ripping will in most cases lead to death of the animal. Since operations, such as caesarean sections, can be necessary at time to safe both the mother as well as the offspring, a solution should be found for this problem.

• Design of an stand-up aid for horses after surgery

When horses suffer a bone fracture, the bone needs to be surgically stabilised using screws and plates. In many cases this is done successfully. However, after the horse wakes up after surgery, they are often very tense and tend to panic, which can result in refracture of the bone. The goal of this project is to design a device that can help the horse to stand up safely after the surgery.

• Design of a bullet removal device in Elephants and Rhinos

In Africa, elephants and rhinos are often hunted for their tusks. Luckily, on some occasions, the elephants and rhinos are able to get away. However, they often sustain severe damage due to bullet wounds. The main challenge the veterinarians face is the removal of these bullets. These bullets are often very deep inside the animal and, therefore, difficult to reach. Furthermore, they often migrate through the body to deeper locations, potentially becoming life threatening. In this assignment, you will develop a bullet removal device for elephants and rhinos that can be used in the field.

• Design of a tusk extraction device for Elephants

When an elephant’s tusk breaks off, the living tissue inside the tusk will become exposed. If it is not possible to safe the tusk, the best option is to extract it to prevent further harm to the elephant. However, current methods for removing tusks are difficult to perform. Therefore, in this assignment you will develop a new type of instrument that allows for easy and fast task extraction.

• Design of a smart hatch for animals in Rotterdam Zoo (internship)

In Rotterdam Zoo, they would like to build a smart hatch system for their Wallabies. This system will allow them to keep track of which animal is where and also allows them to capture specific animals with minimal stress.

• Design of a tusk protection device for Elephants in Rotterdam Zoo (internship)

On some occasions, an elephant tusk might get damaged and a crack may form. On these occasions, veterinarians often place a metal ring around the tusk to protect the living tissue inside the tusk and prevent further damage. However, these rings are heavy and do not offer full protection. Therefore, in this assignment you will design a new type of tusk “ring”.

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

Tree roots are able to find their way through the soil towards a water source. They do this by growing their roots in a special way. First, they extend the middle part of the root into the soil. Second, they thicken the roots.

In this assignment, you will develop a soft tree-root inspired needle that is able to propel itself through the body in a minimally invasive way. The challenge will mainly lie in how you can propagate yourself through the body.

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

The tree-frog is able to adhere to multiple surfaces. It does this by employing several strategies, one of which is the use of special “suction-cup” feet.

Based on this principle, in this assignment, you will develop a robotic foot inspired by the tree-frog. This robotic-foot can be used for many different applications. Think, for example, on medical applications, where you need to attach and detach quickly, but also on a wall-climbing robot!

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

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.

Inspired by tree frogs, here, we will investigate whether firm but gentle grip on slippery tissue can be generated with grippers containing soft pads. With such a grasper, grip is still friction-based, but does no longer depend on the applied normal load. This probably

In this project, we will implement soft pads into 3D-printed graspers. The grasper design has to be adapted in order to generate load-independent grip. The project includes characterization of a prototype on biological tissues.

Start: January-February 2019

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

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.

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

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

Complex medical devices, such as the EndoWrist, 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 medical instrument that minimizes assembly.

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

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.