Ongoing research projects
Ongoing research projects in iMMC (January 2022)
This a short description of research projects which are presently under progress in iMMC.
Hereunder, you may select one research direction or choose to apply another filter:
List of projects related to: medical device
|ELSA, an ankle-foot prosthesis to restore amputees locomotion |
Researcher: François Heremans
Supervisor(s): Renaud Ronsse
Over the last decade, active lower-limb prostheses demonstrated their ability to restore a physiological gait for lower-limb amputees by supplying the required positive energy balance during daily life locomotion activities.
However, the added-value of such devices is significantly impacted by their limited energetic autonomy, excessive weight and cost preventing their full appropriation by the users. There is thus a strong incentive to produce active yet affordable, lightweight and energy efficient devices.
To address these issues, we are developing the ELSA (Efficient Lockable Spring Ankle) prosthesis embedding both a lockable parallel spring and a series elastic actuator, tailored to the walking dynamics of a sound ankle. The first contribution concerns the developement of a bio-inspired, lightweight and stiffness adjustable parallel spring, comprising an energy efficient ratchet and pawl mechanism with servo actuation. The second contribution is the addition of a complementary rope-driven series elastic actuator to generate the active push-off.
Our new system produces a sound ankle torque pattern during flat ground walking. Up to 50% of the peak torque is generated passively at a negligible energetic cost (0.1 J/stride). By design, the total system is lightweight (1.2 kg) and low cost.
Researcher: Xavier Bollen
Supervisor(s): Benoît Raucent
obtained his master's degree in electromechanical engineering, with specialization in mechatronics in 2011 from the Université catholique de Louvain (UCL), Belgium. In 2016, he obtained his PhD degree from the UCL.
During his thesis, under the supervision of Pr. Benoît Raucent and Pr. Parla Astarci (Cliniques universitaires Saint Luc, Brussels), he developed a new device for minimally aortic valve resection. The device was used on patients undergoing open heart surgery in order to validate its design and its functional principle.
Now he still works on the design of the device and he also works on additive manufacturing inside the IMAP department. Since September 2015, he is invited lecturer at the Polytechnic School of Louvain where he teaches technical drawing to the first year bachelor's students in engineering.
|Influence of defects on the life of biomedical implants|
Researcher: Maïté Croonenborghs
Supervisor(s): Pascal Jacques, Thomas Pardoen
Implants are devices aiming to support, help, or even correct biological structures. However, with time, some of these implants show aging problems. The roots of these problems can have numerous explanations. In some cases, the body reacts to the presence of a foreign body, and this can lead to health risks. Sometimes, the material can show, with time, signs of weakness. Later on, these defects can lead to the failure of the implant.
In the case of permanent stent implants, the presence of a foreign body in the blood vessels can lead to restenosis or late thrombosis. This is why bioresorbable stents are nowadays developed. These stents should support the vessels during their healing period and dissolve in an inoffensive way afterward. Iron-based alloys are investigated for their appropriate mechanical properties but their degradation rate is too low. One investigated solution is to increase surface roughness to dissolve faster the implant. The effect of this roughness on the expansion process has not been analyzed for now.
The case of growth rods shows that the material itself can lead to implant failure. These rods are placed, during surgery, along the spine of scoliotic children. They aim to support the spine and help it to straighten back. However, fracture events occur in 36% of the patients. During the surgery, the rods are bent to fit the natural shape of the spine. The tools employed for this process can introduce some indentation marks on the surface of the rods and decrease their fatigue lifetime.
From these case studies, it is observed that the completion of an implant (i.e. stent implantation process) or its lifetime (i.e. growth rod failure) can be affected by its surface state. This research will therefore focus on the imperfection sensitiveness of such devices. Various kinds of defects are introduced at the sample surface. To understand the influence of these defects on the mechanical properties, these samples are tested and compared.
|A microCT-based approach for high-resolution characterization of biodegradable metallic intravascular stent materials|
Researcher: Lisa Leyssens
Supervisor(s): Greet Kerckhofs, Pascal Jacques
The goal of my research project is to assess different potential biodegradable metallic intravascular stent materials using high-resolution 3D microfocus X-ray computed tomography (microCT). In a first step, the optimization of microCT and contrast-enhanced microCT (CECT) for the characterization of the 3D microstructure of different blood vessels is performed (aorta, femoral artery, vena cava). Then, this technique is applied to study the degradation behaviour of potential materials for biodegradable metallic intravascular stents. Structural properties are investigated. They are critical because they will influence the mechanical and in vivo behaviour of the stents. The materials (in the shape of wires) are screened to analyze the corrosion and surface changes, before and after immersion tests (in vitro part) and before and after implantation in rat arteries to additionally study interactions between the tissue (artery) and the metal (in vivo part).
|Locomotion assistance through active motor primitives|
Researcher: Henri Laloyaux
Supervisor(s): Renaud Ronsse
This project is about the development and validation of a new method for assisting human locomotion with robotic devices. It will be based on so-called “motor primitives”, i.e. fundamental units of action which have been identified in the human locomotor apparatus. These primitives will be constrained to be mathematical functions with a limited number of open parameters, therefore optimizing the computational efficiency. Next, the assistance will be designed to be adaptive to the user’s particular gait and status. Finally, some primitives will be specifically developed to support the user’s balance, on top of delivering energy for assisting locomotion. These three objectives will require first theoretical developments, and then experimental validation.