Research Joris Dirckx

Abstract

The sound of reed musical instruments is strongly influenced by the design of the mouthpiece, and the saxophone is a prime example. To date, mouthpiece playing characteristics are described in qualitative terms, and objective quantitative parameters are lacking. 3D printing techniques bring entirely new design possibilities for mouthpiece shapes, but efficient procedures are needed to test the effects on artistic performance. First, this project will investigate the effect of design alterations on the pressure distribution in the mouthpiece and on the dynamics of the reed. Next, a group of players and listeners will subjectively evaluate performance of existing designs, and advanced sound engineering methods will be used to link subjective evaluation to objective sound parameters. Then, an automated saxophone setup will be used to measure quantitative performance characteristics. These will be linked to the objective and subjective performance parameters obtained with musicians. As a result, the design process of mouthpieces will be strongly accelerated, and mouthpiece characteristics will be defined in objective measurable parameters. As a final test, the shortened design loop will be tested to create a mouthpiece with improved playability, which will accelerate the learning curve of young players. The workflow developed in the project will pave the road towards entirely new mouthpiece designs and sound characteristics, which offer a new range of artistic possibilities.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Ukshini Enis

Research team(s)

Project website

Project type(s)

• Research Project

Abstract

The upper nasal space is a unique drug delivery environment and has long been underutilized. Nose-to-brain delivery of therapeutic agents for neurodegenerative disorders does not have the same limitations as other existing administration methods. However, intranasal drug delivery has its own set of challenges because of the nasal shape's heterogeneous character and dynamics. This large morphological variation demands a person-specific approach that enables live sampling of the nasal structure and subsequently uses it during administration of the therapeutic agent. This project is the first and important step in the creation an efficacious intranasal drug delivery solution: designing and building the portable device able to capture the three-dimensional nasal shape in a non-invasive manner.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Daems Walter
• Co-promoter: Kiekens Filip

Research team(s)

Project type(s)

• Research Project

Abstract

In this project we propose a radically new plasma based-methodology to both characterize as well as treat cancerous tissue (with a focus on melanoma). We will use plasma excitation (in combination with laser vibration measurements) for in-situ characterization of the visco-elastic mechanical properties of biomedical tissue. These mechanical properties will allow us to detect and monitor cancerous tissue. Furthermore, we will develop a novel controlled plasma cancer treatment method which integrates the in-situ material identification method in order to tune the plasma therapy.

Researcher(s)

• Promoter: Vanlanduit Steve
• Co-promoter: Bogaerts Annemie
• Co-promoter: Dirckx Joris
• Co-promoter: Smits Evelien

Research team(s)

• Industrial Vision Lab (InViLab)

Project type(s)

• Research Project

Abstract

In the first step of the process of hearing, the eardrum captures sound vibrations which are passed on by three ossicles to the fluid-filled cochlea. Computer models play an important role to understand this complicated biomechanical system, but current models still do not allow to visualize how sound energy is transferred from the eardrum to the ossicles, mainly because exact anisotropic material parameter distributions are lacking. Understanding this process is essential to further develop surgical procedures for eardrum reconstruction. In this project, I will perform measurements of 3D eardrum motion to characterize its dynamic properties. Additionally, I will develop a new technique, based on the virtual fields method, to determine the material parameters of the eardrum in situ. These data will deliver important input for the further development of artificial eardrum replacements and will improve material choice in clinical grafting techniques to optimize hearing outcome. I will then use these parameters to build a truly realistic computer model of eardrum mechanics and develop a method to calculate energy flow in curved anisotropic structures such as the eardrum. With this new model and method, I will be able to visualize the flow of sound energy. This will finally answer the fundamental biomechanical question of how the eardrum captures and transfers sound energy, and will lead to an evidence-based tool for optimizing clinical procedures to restore eardrum perforations.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Livens Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project website

Project type(s)

• Research Project

Abstract

This core facility integrates top quality infrastructure and unique expertise in X-ray imaging for the reconstruction, processing and analysis of dynamic 3D scenes. It utilizes complementary platforms for 4D X-ray imaging, including an ultra-flexible and multi-modal X-ray CT system (FleXCT) and a stereoscopic high-speed X-ray videography system (3D2YMOX). The facility offers customized services for image acquisition-reconstruction and analysis for both industrial and (in-vivo) biological studies.

Researcher(s)

• Promoter: Sijbers Jan
• Co-promoter: Aerts Peter
• Co-promoter: De Beenhouwer Jan
• Co-promoter: Dirckx Joris
• Co-promoter: Van Wassenbergh Sam

Research team(s)

• Vision lab

Project type(s)

• Research Project

Abstract

The nose performs multiple important functions, including olfaction, humidification and thermal conditioning of the inhaled air and filtration of harmful particles before these reach the lower parts of the air tract. Nasal airway obstruction (NAO) is worldwide one of the most frequent complaints encountered by ear-nose-throat (ENT) physicians. It is a common health condition that affects all age groups and reduces overall quality of life. The functions depend on the airflow through the nasal cavity and will be impacted in case of impaired patency. Within this project the decision support system's proof of concept is further developed to a prototype, and in a second phase into a minimal viable product (MVP). Such a system would allow rhinologists to capture a complete picture of a patient's nasal pathology, e.g. a septum deviation or perforation and enlarged nasal turbinates, which would be in large contrast to current objective measurements, like acoustic rhinometry and rhinomanometry. Unlike the use of audiometry in hearing loss, no gold standard currently exists for assessing nasal function impairment. Clinical examination is mainly used to make treatment decisions but frequently fails to pinpoint the cause of perceived nasal obstruction for a given patient. The system which is envisioned would support physicians (information augmented) while diagnosing and determining the optimal plan of action on patient-specific base, by delivering consistent objective data of nasal airflow and function before surgery (e.g. how the operation will affect other secondary functions of the nose). Physics-based models, like computational fluid dynamic (CFD) models, have the potential to increase the number of successful operations (i.e. without any recurring or new symptoms in a time span of multiple years). Because of large interpatient variability in nose geometry, a patient-specific approach is required. The manual workflow in creating geometric nasal models remains costly and it requires specific technical expertise that is not available to most physicians. The manual editing is not only tedious but it is also prone to the introduction of errors. The dynamic nature of the nasal mucosa can obscure the true cause of a patient's complaint, making support systems that ignore this and only use single snapshot of the nasal geometry less effective. CFD can also be coupled to different physical laws, such as particle deposition and heating loss, giving a much a broader view on all important nasal physiological parameters. The final goal of this project is a decision support system that objectively and quantitatively scores nasal (dys)function based on fluid dynamic simulations, while taking the dynamic nature of the internal nose into account. To this end, a multitude of techniques will be used, for example machine learning to automate the extraction of crucial geometric information out of tomographic data and objective geometry characterization to capture the dynamic nature of the patient-specific internal geometry. An important part of the project is the validation of the different innovations using clinical data.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Keustermans William

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

To efficiently transfer sound from air to the fluid of the inner ear, most species make use of ossicles coupled to an eardrum. Mammals have three ossicles while birds and reptiles only have one ossicle connecting the eardrum directly to the inner ear. Surprisingly they localise and hear sounds as well as similar-sized mammals. An important difference is that roughly half of the terrestrial vertebrates also have an internal connection between both ears. In large animals and in humans, sounds have different travel times and intensities when reaching the ears, and these phase and intensity differences are used to localize sound sources. In small animals such as lizards, the head is too small to deliver significant differences between sounds reaching each ear. I will build on the work of my master thesis to develop accurate computer models for the three main anatomically different lizard-hearing mechanisms. My work will provide the first truly realistic model of the lizard hearing apparatus and it will give an anatomy-based correct model of internally coupled hearing for a broad class of species. To realize this goal, new techniques to determine the material properties of these microstructures will be developed, advanced synchrotron X-ray imaging will be used, and I will push the boundaries of finite-element modelling in highly complicated anatomical structures. My work will reveal the functioning of the lizard ear and the role of the internal connection.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Livens Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

During this sabatical leave I will visit a number of laboratories abroad to strengthen existing collaborations and start new collaborations. Amonst these visits are Oslo University Clinic where we will introduce our new diagnistic technique for testing of middle ear mobility, Harvard medical School in Boston and University of London-Ontario where I will present our new techniques for real-time eardrum measurements, and University of Florianopolis Brazil where I will work with prof. Cordioli on our joint interests in middle ear modelling.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

During this sabatical leave I will focus on three pain topics. I will perform research which will result in clinical applicability of our new techniqes to measure eardrum deformation and middle ear ossicle vibration in patients. I will strengthen my international network and bring our new techniques to the attention of other international research groups and hospitals. Finally, I will visit other Laboratories to learn new techniques and keep informed about the latest developments in our field.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The eardrum and three tiny bones (ossicles) in the middle ear play a vital role in sound perception, as they serve to bridge the gap between air and inner-ear fluid. Flexibility between the ossicles protects the inner ear from large external pressure variations. Several pathologies exist that lead to fixation of the ossicles, but current clinical tools to diagnose such fixations are often inaccurate. I will develop a new optical device to measure 3D eardrum deformations in living patients through the narrow ear canal: structured light patterns are projected and recorded through a newly designed endoscope, which makes it possible to determine quantitative eardrum shape deformation. I will analyze features in the eardrum deformation patterns to distinguish between different types of ossicle fixations, which will lead to an objective diagnostic protocol. When the diagnosis shows that ossicles are fixated or damaged, they are often surgically replaced by a rigid ossicle prosthesis. Due to their lack of flexibility, such reconstructions fail to buffer large external pressure variations, leading to loss of sound conduction and prosthesis dislocation. By using experimentally validated finite-element models of the middle ear I will create and optimize new flexible prosthesis designs that permit pressure buffering while preserving sound conduction. In future work, the custom prostheses will be 3D printed and experimentally tested.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Muyshondt Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The 3D shape of the human eardrum plays a crucial role in the process of sound transmission and any structural change to its topography is an important indicator for existing or impending middle ear pathology and subsequent hearing loss. This POC-project includes the prototyping of a new non-invasive medical device, capable of measuring high-resolution eardrum deformation in 3D and in real-time.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Goethijn Frank
• Co-promoter: Van der Jeught Sam

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The human eardrum is a conically shaped thin membrane which separates the outer ear from the middle ear. It conducts sound vibrations from the external ear canal to the ossicles and protects the middle ear from infections. The 3D shape of the eardrum plays a crucial role in this process and any structural change to its topography is an important indicator for existing or impending pathology or hearing impairment. In previous work, I have demonstrated that 3D shape data of a cadaveric human eardrum can be obtained by using a modified clinical otoscope that simultaneously projects structured light patterns onto the eardrum and records them with a digital camera, placed at a relative angle to the projection axis. By employing a high-speed camera and by using parallel programming techniques, the digital processing pipeline is sufficiently fast to extract full-field surface shape deformations of a dye-coated eardrum in real-time. In the proposed research project, I will redesign both the optical imaging engine and the hardware setup of the otoscopic device to increase its imaging resolution when applied to uncoated eardrums. This way, the non-invasive imaging technique can be employed in the clinical setup and dynamic 3D eardrum shape data of living patients can be gathered for the first time. I will validate tympano-topography as a diagnostic tool in the ENT-office in the detection of early-stage middle ear inflammation, cholesteatoma and Eustachian tube (dys)functioning.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Van Rompaey Vincent
• Fellow: Van der Jeught Sam

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

To efficiently transfer sound from air to the fluid of the inner ear, most species make use of ossicles coupled to an eardrum. Mammals have three ossicles while birds and reptiles only have one ossicle connecting the eardrum directly to the inner ear. Surprisingly they localise and hear sounds as well as similar-sized mammals. An important difference is that roughly half of the terrestrial vertebrates also have an internal connection between both ears. In large animals and in humans, sounds have different travel times and intensities when reaching the ears, and these phase and intensity differences are used to localize sound sources. In small animals such as lizards, the head is too small to deliver significant differences between sounds reaching each ear. I will build on the work of my master thesis to develop accurate computer models for the three main anatomically different lizard-hearing mechanisms. My work will provide the first truly realistic model of the lizard hearing apparatus and it will give an anatomy-based correct model of internally coupled hearing for a broad class of species. To realize this goal, new techniques to determine the material properties of these microstructures will be developed, advanced synchrotron X-ray imaging will be used, and I will push the boundaries of finite-element modelling in highly complicated anatomical structures. My work will reveal the functioning of the lizard ear and the role of the internal connection.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Livens Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The eardrum and the ossicles of the middle ear function as an acoustic impedance transformer which passes sound energy in the air to the fluid of the inner ear. The eardrum is the first part of this chain and conveys sound energy in an extraordinary efficient way on to the middle ear ossicles. Up till now, the process of this energy conversion remains unknown. In recent literature it has been shown that that starting from measurements of the vibration of the surface of a plate it is possible to calculate how energy flows through the plate. With this so-called powerflow method it is possible to determine the location of energy sink and energy drain, but up till now the method has only been developed for application on flat plates of homogenous thickness. In the past two years the research group BIMEF has expanded the method to follow energy flow in a cylindrical curved plate, and now the method will be generalized to arbitrary curved plates and membranes. This requires a very complicated processing of the measured data. The recorded vibration data need to be transferred from the coordinate system of the object to a curvilinear coordinate system in which the powerflow calculations can be performed. Next, the powerflow data need to be back-traced to the coordinate system of the object. The realization of this generalized method will bring an important step forward in the applicability of the powerflow method, with applications is different fields of mechanics and acoustics. Simultaneously, a measurement setup will be developed to measure the shape and vibration of curved plates, using digital image correlation. With this setup vibrations will be measured of cylindrical and arbitrary shaped plates with known position of power source and drain so that the analysis method can be validate. Finally, the method will be expended to inhomogeneous membranes of varying thickness and arbitrary shape. Once this general method is realized, it will be applied to determine the acoustic-mechanical powerflow in the eardrum, so we can finally answer the question: how does sound energy flow in the eardrum?

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Pires Felipe

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Through millions of years of evolution, nature has unfolded an array of armour types in the animal kingdom. The underlying mechanisms of natural body armour have received considerable attention in the field of biomimetics because of their potential role in serving as inspiration for artificial protective materials. Unfortunately, the majority of biomimetic studies often unambiguously assume that nature has selected the most optimal designs. Instead, the response of traits to natural selection is subject to various constrains including functional trade-offs. Hence, the current biomimetics approach might fail to fulfill the requisites of a well-designed biomimetics study and indirectly constrain the development of artificial body armour. The proposed project employs a strong ecological and evolutionary framework to investigate the effect of functional trade-offs on the evolution of body armour. Cordyline lizards are the ideal study system for a comparative and experimental analysis of body armour, because unlike other vertebrates, they display a vast amount of variation in the expression and morphology of osteoderms (i.e. body plates embedded in the skin). The study integrates evolutionary biology and functional morphology with the field of biomechanics while benefiting from state-of-the-art technology such as high-resolution micro-computed tomography scanning, 3D bioprinting and novel simulation software to ultimate put the current approach of biomimetic studies to the test.

Researcher(s)

• Promoter: Van Damme Raoul
• Co-promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Fellow: Broeckhoven Chris

Research team(s)

• Functional Morphology

Project website

Project type(s)

• Research Project

Abstract

In mammals three ossicles transport sound vibrations from the eardrum to the fluid in the inner ear. This system forms an acoustic impedance match, and the mobility between the ossicles protects the cochlea from large quasi-static pressure changes. The middle ear of birds only contains a single ossicle, while hearing functions largely as good as in mammals. In humans with blocked or damaged ossicles, surgeons often replace the entire chain by a rigid prosthesis that directly connects the eardrum to the inner ear. One problem is that this piston can detach from the inner ear due to large quasi-static pressure changes. A good engineering model of the avian ear will lead to a new design of ossicular prostheses for humans. I will build on the results obtained in my master's thesis to develop a detailed finite element model of the eardrum and the ossicle that evolves along its length from rigid bone to soft material. I will measure ossicle vibrations and use my model in inverse analysis to optimize material parameters and find the best match between model and experiment. I will measure 3D motions as the ossicle is proposed to feature a rocking motion rather than a piston-like motion as in humans. The model will show which material parameters and geometric design are essential for the functioning of this ear. I will use these insights to design a virtual ossicular prosthesis that fits the human ear, and test it in human finite element models available in our laboratory.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Muyshondt Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Advances in antenatal medicine and neonatal intensive care have resulted in improved survival of human infants born with a low birth weight and at the limits of viability, but not in the reductions of motor deficits. Locomotor skills are essential for participation in all daily activities and therefore are paradigmatic for insights in motor development in general. Longitudinal experimental designs studying locomotion are needed to elucidate the contributions of intra-uterine growth restricted development of the musculoskeletal and the nervous system onto the motor deficits. Such fundamental longitudinal experiments are ethically controversial in human infants, necessitating appropriate animal models for research. In modern sows, piglets born with a low birth weight and low viability frequently occur. These piglets show characteristics of underdevelopment similar as those seen in human infants with a low birth weight and viability. This, together with their high physiological resemblance, makes the pig an ideal model to study the development of growth-impaired locomotion. This project characterizes and compares the longitudinal development of locomotion in the normal and low birth weight piglet. To this purpose we make use of 4D-morphology, dynamic mechanical modelling and functional morphological analyses (cfr. the concept of neuromechanics). This requires the technological development of rapid 3D dual energy tomography (including soft tissue reconstructions) integrated in the existing 3D²YMOX-platform (biplane X-ray). Differences in both coordination and control will be linked to changes at the level of the musculoskeletal, as well as the neurological components of the locomotor system.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Co-promoter: Sijbers Jan
• Co-promoter: Van Ginneken Chris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

Cardiovascular (CV) diseases are the most common cause of death and their importance only increases. An important factor in the development of CV problems is increased arterial stiffness. Every time the heart contracts a pressure wave propagates through the arterial system with a certain velocity: the pulse wave velocity (PWV). PWV is indicative for arterial stiffness, and increased PWV has a strong predictive value for CV health. One way to measure PWV, is to determine PWV locally in the carotid artery: carotid PWV is hypothesised to be representative for global arterial stiffness, and it is easily accessible. Additionally, carotid stiffness is an important predictor of local plaque formation and stroke. In this proposal, two recent, harmless methods for carotid PWV detection are compared and thoroughly validated: an ultrasound method (pulse wave imaging or PWI) and an optical method (laser doppler vibrometry or LDV). Furthermore, the relation of carotid PWV with global artery stiffness and with CV health is assessed in a large patient population, elucidating the value of carotid PWV as a clinical parameter. These insights will finally lead to a new highly improved prototype of the LDV device. Eventually, this research will show the value of carotid PWV as a CV screening parameter and it will introduce a new LDV-based screening tool for fast, reliable measurement of carotid

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Campo Adriaan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Surgery is often treatment of choice for nasal airway obstruction caused by anatomic abnormalities. Objective measures for nasal patency, such as rhinometry, correlate poorly with patient's symptoms and long-term satisfaction rates are low. In this project we develop a decision support system using patient-specific computational fluid dynamics models as an objective assessment tool in clinics. Model geometry is based on statistical shape models fitted to tomographic data.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Huysmans Toon
• Co-promoter: Sijbers Jan
• Co-promoter: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Surgery is often treatment of choice for nasal airway obstruction caused by anatomic abnormalities. Objective measures for nasal patency, such as rhinometry, correlate poorly with patient's symptoms and long-term satisfaction rates are low. In this project we develop a decision support system using patient-specific computational fluid dynamics models as an objective assessment tool in clinics. Model geometry is based on statistical shape models fitted to tomographic data.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Keustermans William

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Quantitative values for mechanical properties of materials are required in the simulation of the behavior of structures and systems in several engineering domains: civil engineering (buildings, bridges, roads, …), mechanical engineering (aircraft, cars, …), biomedical engineering (implants, scaffolds, etc.) and electronic engineering (semiconductor materials). In addition, the knowledge of these material properties provides a means to follow-up the health of a structure or system during operation and to estimate the remaining lifetime. The proposed novel hybrid material characterization method combines two distinct approaches to estimate mechanical material parameters, which has never been attempted before. By using laser Doppler vibrometry for the optical measurement of both resonating (at low frequencies) and propagating surface waves (at high frequencies), modal parameters and wave propagation characteristics can be derived simultaneously. By comparing these results with Finite Element and analytical models and by using an inverse modelling approach with intelligent optimization algorithms, it will be possible to identify more material parameters with an improved accuracy in a reduced measuring time. This will allow applications on more complex materials (e.g. layered poro-elastic road surface) in an in-situ environment. The proposed method will lead to several innovations, in the fields of measuring, data processing and optimization, and will be validated in three different applications: asphalt pavements (civil engineering), composite materials (mechanical engineering), and a tympanic membrane and bone material (biomedical engineering).

Researcher(s)

• Promoter: Vuye Cedric
• Co-promoter: Dirckx Joris
• Co-promoter: Hasheminejad Navid
• Co-promoter: Vanlanduit Steve

Research team(s)

Project type(s)

• Research Project

Abstract

The human eardrum is a conically shaped thin membrane which separates the outer ear from the middle ear. It conducts sound vibrations from the external ear canal to the ossicles and protects the middle ear from infections. The 3D shape of the eardrum plays a crucial role in this process and any structural change to its topography is an important indicator for existing or impending pathology or hearing impairment. In the proposed research project, I will develop a new technique to measure 3D eardrum deformations in living patients. Using a modified clinical otoscope, structured light patterns will be projected onto the eardrum, after which the patterns are deformed by the eardrum's surface shape. When observed by a digital camera placed at a relative angle to the projection axis, fullfield depth data can be extracted from the deformation of the light patterns. By employing a highspeed camera and state-of-the-art parallel programming techniques, the digital processing pipeline will be sufficiently fast to enable real-time monitoring of eardrum surface shape deformations that are caused by (controlled) pressure changes in the middle ear cavity. Both fundamental properties of eardrum mechanics and practical applicability in the clinical setup will be investigated. The new otological device will be validated in the ENT office as a diagnostic tool in the detection of early-stage middle ear inflammation, retraction pockets, cholesteatoma and Eustachian tube (dys)functioning.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Van der Jeught Sam

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In mammals three ossicles transport sound vibrations from the eardrum to the fluid in the inner ear. This system forms an acoustic impedance match, and the mobility between the ossicles protects the cochlea from large quasi-static pressure changes. The middle ear of birds only contains a single ossicle, while hearing functions largely as good as in mammals. In humans with blocked or damaged ossicles, surgeons often replace the entire chain by a rigid prosthesis that directly connects the eardrum to the inner ear. One problem is that this piston can detach from the inner ear due to large quasi-static pressure changes. A good engineering model of the avian ear will lead to a new design of ossicular prostheses for humans. I will build on the results obtained in my master's thesis to develop a detailed finite element model of the eardrum and the ossicle that evolves along its length from rigid bone to soft material. I will measure ossicle vibrations and use my model in inverse analysis to optimize material parameters and find the best match between model and experiment. I will measure 3D motions as the ossicle is proposed to feature a rocking motion rather than a piston-like motion as in humans. The model will show which material parameters and geometric design are essential for the functioning of this ear. I will use these insights to design a virtual ossicular prosthesis that fits the human ear, and test it in human finite element models available in our laboratory.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Muyshondt Pieter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The eardrum or tympanic membrane (TM) collects energy from incoming sound waves and converts it into vibration energy of the ossicle bones. One of the most remarkable features of the eardrum is that sounds waves are transmitted with high efficiency, regardless of the frequency and without sharp resonances. The importance of possible traveling waves on the TM has been suggested, but fundamental insight on how energy is transferred is lacking. These questions can only be answered through a multidisciplinary approach combining advanced optical measurement techniques and computer modeling to solve biomechanical and physiologic questions. This project aims to examine the mechanical properties of the TM by constructing a finite element model of the middle ear that agrees more with reality than any other model before. This will be achieved by a number of experimental methods and a new elasticity model. I will use data from OCT, μCT and histologic sectioning to enhance the geometry of existing models and a new technique based on stroboscopic holography to determine material parameters. The engineering analysis technique called power flow will be adapted and expanded to be applicable for the TM, which is unprecedented. This will result in unique information about how and where energy is transported on the TM. This analysis will be applied on vibration data from both experiments and the model and will enable me to answer a number of fundamental questions about the mechanics and physiology of the middle ear.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: De Greef Daniël

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

This project represents a formal research agreement between UA and on the other hand the Hercules Foundation. UA provides the Hercules Foundation research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris
• Co-promoter: Van Ginneken Chris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

When life evolved from aquatic to terrestrial animals, a biomechanical system developed which bridges the difference in acoustic impedance between air and fluid: the middle ear (ME). If this structure would not be present, the major part of sound energy in air would reflect at the interface with the fluid-filled inner ear. In mammals, this mechanical system consists of the eardrum and three ossicles, (and two muscles and some ligaments) which act as a lever system to transform sound waves in air to sound waves with higher pressure but smaller amplitude in the fluid of the inner ear (where sound energy is transformed to electric impulses going to the brain). In birds the ME is far simpler, mainly consisting of just an eardrum and one muscle and ossicle (yet partly cartilaginous), the so called columella, directly connecting the eardrum to the oval window in the inner ear. The system is enclosed in a cavity which connects to the outside world with the Eustachian tube. Under normal circumstances this tube is closed so quasi-static pressure differences exist between the ME and the outside world, e.g. due to altitude changes, meteorology circumstances etc. Acoustic information is of primary importance to birds, so it is fascinating to see that such a relatively simple middle ear developed. Moreover, birds are typically subject to sudden height changes and the single ossicle ear does not have the same flexibility to cope with large eardrum deformations as has the mammal three ossicle ear. These fundamental questions have held the attention of many researchers in the past, but up till now no in depth model based quantitative analysis is available. In this project we will measure the necessary input parameters for such a model (elasticity of eardrum and bones, vibration pattern of the eardrum and the ossicle, high resolution anatomical shape model) and use these to develop a highly realistic finite element model of the bird middle ear. We will develop new techniques to investigate how sound energy is transported from the eardrum to the inner ear, based on transfer path and power flow analysis. This will be done for two commercially available species (e.g. pigeon or duck, and chicken), representative for birds who adapted to a life upon the ground or a life facing fast pressure changes. We will measure how pressure change influences the system, and we will investigate how pressure varies in the bird ear, another question which remained unanswered up till now. Then we will use our model to reveal the functional evolution using less common species (e.g. falcons). Finally we will use the model to investigate new designs of an artificial ME ossicle which moves like in birds, and test it in our models of the mammal ear. When in humans the ossicles are blocked or missing, a prosthesis is used to connect the eardrum to the inner ear, but such prosthesis has no flexibility to deal with static pressure changes. We want to learn from nature to see which other single ossicle designs can solve this fundamental problem.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In this project, we will develop a novel procedure to generate distortion corrected endoscope images and combine this technique with graphics card programming to implement a new diagnostic medical tool for measuring eardrum deformations in real-time and in vivo. As my endoscopic profilometry technique is fully non-invasive, it will be very easy to introduce the new technique in the clinical setting once its possibilities have been demonstrated.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Buytaert Jan
• Co-promoter: Sijbers Jan
• Fellow: Van der Jeught Sam

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The eardrum or tympanic membrane (TM) collects energy from incoming sound waves and converts it into vibration energy of the ossicle bones. One of the most remarkable features of the eardrum is that sounds waves are transmitted with high efficiency, regardless of the frequency and without sharp resonances. The importance of possible traveling waves on the TM has been suggested, but fundamental insight on how energy is transferred is lacking. These questions can only be answered through a multidisciplinary approach combining advanced optical measurement techniques and computer modeling to solve biomechanical and physiologic questions. This project aims to examine the mechanical properties of the TM by constructing a finite element model of the middle ear that agrees more with reality than any other model before. This will be achieved by a number of experimental methods and a new elasticity model. I will use data from OCT, μCT and histologic sectioning to enhance the geometry of existing models and a new technique based on stroboscopic holography to determine material parameters. The engineering analysis technique called power flow will be adapted and expanded to be applicable for the TM, which is unprecedented. This will result in unique information about how and where energy is transported on the TM. This analysis will be applied on vibration data from both experiments and the model and will enable me to answer a number of fundamental questions about the mechanics and physiology of the middle ear.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: De Greef Daniël

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In this project J. Buytaert will work on three (related) topics: 1. middle ear muscle physiology; In this field he will develop a setup to measure forces of middle ear muscles and use finite element modeling to clarify the function of these muscles 2. real-time tympanic membrane profilometry: in this topic he will construct an endoscopic moiré profilometer to measure eardrum deformation for clinical applications 3. creating a database of human donor tympano allografts: using his aberration free profilometer which was developed earlier, he will measure dimensions of human allograft eardrums prior to clinical use

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Buytaert Jan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In the proposed project, I will use state-of-the-art imaging techniques to capture the 3D morphological structure of the mouse organ of Corti. Next, I will use this data in a mechanical model, which incorporate active stimulation. The insights gained with this model will give more information about the structure and functioning of the cochlea. Finally, I will couple this cochlear model to a middle ear model, delivering for the first time a complete mechanical model of the hearing organ. Such models are essential to understand this complex biomechanical system and to optimize implantable hearing aids and prosthesis ossicles.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In this project, I will elaborate a new imaging technique, high-power stroboscopic digital holography, which will provide full field as well as time resolved information. The combination of these measurements with vibration calculations on newly constructed finite element (FE) models of the ME will resolve the fundamental questions about the mechanics of the eardrum.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: De Greef Daniël

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In this project, we will develop a novel procedure to generate distortion corrected endoscope images and combine this technique with graphics card programming to implement a new diagnostic medical tool for measuring eardrum deformations in real-time and in vivo. As my endoscopic profilometry technique is fully non-invasive, it will be very easy to introduce the new technique in the clinical setting once its possibilities have been demonstrated.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Buytaert Jan
• Co-promoter: Sijbers Jan
• Fellow: Van der Jeught Sam

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In many animals, sexual selection has produced a conspicuous diversity of morphological structures (like horns, spines, tusks, etc.) used by males in disputes over access to females. Causal insights in relationships between shape, structure and functioning of this armature, as well as in trade-offs with other functions are essential to unravel the evolutionary developmental and ecological aspects of armature. Surprisingly enough, present knowledge is largely void of this basic information. This project precisely aims at filling in this gap in knowledge via the detailed functional morphological and biomechanical analysis of armature in stag beetles. (Lucanidae)

Researcher(s)

• Promoter: Aerts Peter
• Co-promoter: Dirckx Joris

Research team(s)

• Functional Morphology

Project type(s)

• Research Project

Abstract

The key contribution of this research is the development of identification algorithms for the accurate modelling of complex time-varying dynamical systems from noisy input-output observations (= errors-in-variables problem), keeping in mind the intended application (physical interpretation, prediction, or control). The final result is a validated model with reliable error bounds.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Beginning in the early 90's, finite element modeling is used to study the complex behaviour of middle ear mechanics and the action of middle ear prostheses and - implants. Up till now, however, the current models are still restricted to the acoustical regime and the elasticity parameters of the tympanic membrane are determined inaccurately and incompletely. Therefore, we will measure pressure variations in a healthy middle ear and determine tympanic membrane elasticity parameters via inverse finite element modeling of in situ point indentation measurements. In the final stage of this project, our new data will be incorporated in a model that is also valid in the quasi-static pressure regime.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Aernouts Jef

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

This project represents a research agreement between the UA and on the onther hand IWT. UA provides IWT research results mentioned in the title of the project under the conditions as stipulated in this contract.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Aerts Johan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The main objectives of the research project are (i) to turn an existing theoretical automated fitting model into a clinical application by means of various techniques from statistics, machine learning and optimisation; (ii) to develop an evaluation tool to measure functional hearing capacities, in casu the ability to understand speech-in-noise, representative for day-to-day listening situations.

Researcher(s)

• Promoter: Coene Martine
• Promoter: Dirckx Joris
• Co-promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics
• Centre for Computational Linguistics, Psycholinguistics and Sociolinguistics (CLiPS)

Project type(s)

• Research Project

Abstract

Many aspects of the mechanics and physiology of the hearing organ are still to be elucidated. I want to contribute to this field by accurately measuring the shape and behavior of the eardrum, determine its elasticity and mechanical parameters, and measure its thickness distribution over the entire surface for different animal species. Furthermore, the exact shape and location of soft tissue (muscle tendon & ligaments) in the middle ear is not yet known, and the internal hollow structures of hearing bones are not yet mapped. By using, further developing, and even inventing, new dedicated optical measurement techniques, I will obtain the required data which will be incorporated into realistic finite-element models and simulations of the ear (for better understanding of middle ear mechanics and prosthesis development).

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Buytaert Jan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Darwin's finches (Geospizinae) have become a model system for the study of adaptive radiaton. From a single ancestor, thirteen species of Darwin's finches have radiated on the Galápagos Islands, have specialized on different food resources and differ in beak form. Despite the importance of beak size and shape in Darwin's finches ecology, the mechanical link between these aspects of beak morphology and the ability of a bird to crack seeds of different size and hardness remains unknown. Those biological theories can only be validated or refuted by an interdisciplinary approach, based on physical computational modelling. International cooperation supplies us of rare specimens from different species. The in-vivo biting force and place, CT images and histological cuts from different (protected) Darwin's finches and the physiological cuts from which the maximum muscle force could be calculated are important to make a realistic model. The research consists of two parts. First we have the computer modelling part (Finite elements simulations with FEBio), and second, an experimental part for judging the necessary boundary conditions for the simulation, hence validating and optimizing the FE model. Converning the validation, we will use the more common java finches (Padda oryzivora).

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Fellow: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The goals of the current project are: ¿ Development of a new contact less method, based on light interferometry which makes use of the Doppler shift of reflected light, which will allow us to measure PWV between two well defined locations close to one another. ¿ Designing and building a very compact two-channel laser-Doppler heterodyne interferometer which allows to measure blood PWV in realistic circumstances. ¿ Making a physics-based model of the fluid dynamics, and using this model to calculate stiffness of the artery. ¿ Explorative research for miniaturization and integration of the interferometer components, as onset for a fully integrated micro-vibrometer.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Modeling the relation between the electrical parameters of cochlear implants and measurements of auditory performance. To optimize the programming (fitting) of cochlear implants, a model describing the relation between the configuration of the speech processor and a recipient's auditory performance is created. The project aims at estimating the input-output functions of the multiple electrical parameters of the implanted device and their effects on measures of auditory performance which is assessed through a battery of psychoacoustical tests. The I/O relationships are validated case-wise through iterative testing, allowing a progressive adjustment of coefficients in the formulas. Through statistical analysis of gathered data, the model will be described more accurately and multidimensional relationships will be introduced to describe the many complex inter parametric interactions in multi factorial mathematical analyses. The resulting fitting model is the main innovative target of the project and aims at predicting the effects of processor manipulations on auditory performance. In this way the model is capable of supporting applications for automated fitting.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Beginning in the early 90's, finite element modeling is used to study the complex behaviour of middle ear mechanics and the action of middle ear prostheses and - implants. Up till now, however, the current models are still restricted to the acoustical regime and the elasticity parameters of the tympanic membrane are determined inaccurately and incompletely. Therefore, we will measure pressure variations in a healthy middle ear and determine tympanic membrane elasticity parameters via inverse finite element modeling of in situ point indentation measurements. In the final stage of this project, our new data will be incorporated in a model that is also valid in the quasi-static pressure regime.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Aernouts Jef

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

VIRTUAL, FLUORESCENT OPTICAL-SECTIONING TOMOGRAPHY We plan the development of a 3-D standard model from Gerbil, which is of use in the domain of middle ear research: Being the standard laboratory animal species in this field, we need a high-resolution computer model of both bone and soft-tissue in the computer. (ENDOSCOPIC) MOIRE INTERFEROMETRY We continue to build, improve and apply our new Moiré technique and setup, base on liquid crystal TFT matrices for projection and optical demodulation. Data from this will be used to obtain elasticity parameters of the eardrum through backward-engineering, among other. In the end, the goal is to develop an endoscopic moiré setup. A challenge will be the big lens distortions involved in endoscopic imaging. We are developing a moiré method to counter this problem.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Buytaert Jan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Darwin's finches (Geospizinae) have become a model system for the study of adaptive radiaton. From a single ancestor, thirteen species of Darwin's finches have radiated on the Galápagos Islands, have specialized on different food resources and differ in beak form. Despite the importance of beak size and shape in Darwin's finches ecology, the mechanical link between these aspects of beak morphology and the ability of a bird to crack seeds of different size and hardness remains unknown. Those biological theories can only be validated or refuted by an interdisciplinary approach, based on physical computational modelling. International cooperation supplies us of rare specimens from different species. The in-vivo biting force and place, CT images and histological cuts from different (protected) Darwin's finches and the physiological cuts from which the maximum muscle force could be calculated are important to make a realistic model. The research consists of two parts. First we have the computer modelling part (Finite elements simulations with FEBio), and second, an experimental part for judging the necessary boundary conditions for the simulation, hence validating and optimizing the FE model. Converning the validation, we will use the more common java finches (Padda oryzivora).

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony
• Fellow: Soons Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The comparison of direct and indirect methods, both from a theoretical and a practical point of view, is one of the fundamental issues that will be treated in the proposed project. A second fundamental problem is the mathematical modeling of the irreversible behavior (hysteresis) of ferromagnetic materials. One of the essential problems that will be treated in the project is the possible coupling between the magnetic and the magnetostrictive behavior.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In the framework of this project young people are introduced to an aspect of science that is often overlooked, namely to carry out scientific research and work towards a finished product and to study science in preparation of a career in business or industry. Through a step-by-step competition, young people are led to the great role models and finally they will elaborate their own scientific project with an economic goal. They will be directed towards an independent search for the scientists behind some of the world's largest companies (Bayer, Solvay, Kodak, Microsoft, '). Firstly, a quiz will be organized with questions about a number of pre-selected companies, which were set up by scientists. The persons who successfully round off this step will go on to the second phase, namely to submit a proposal for a scientific project which leads to a (imaginary) new product. To collect ideas the participants will go on an educational trip to the science and industry museum 'La Vilette' in Paris, where they will discuss their proposals with the project leader like real entrepreneurs attending a business colloquium. In the last step, a selection is made between the submitted proposals. The selected projects are then fully elaborated (in a theoretical way). This includes all phases of scientific research that are needed to reach the target of a finished product, including a commercial presentation before a jury of possible investors. Laureates will be chosen in different categories: the most inventive product, the greatest scientific challenge, the best commercial perspective, ' In all phases of the competition, the participants are coached by the project collaborator, who puts them in touch with companies that have the know-how for the development of their ideas and who can give them the necessary technical information. In this way, the project is situated between science, economy and management. Young people are supported in their search towards experts in industry. In the initial phase, they gather information through a selective search on the Internet. The project collaborator, as well as the contacted research laboratories, will monitor the scientific foundation of the project proposals.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project website

Project type(s)

• Research Project

Abstract

Measurements of shape and material parameters are measured and incorporated in a finite element model for investigation of the functional characteristics of muscular-sceletal cranial structures of Darwin finches, to gain understanding of phenotypic variation and ecological diversity.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Aerts Peter
• Co-promoter: Herrel Anthony

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In the laboratory of Biomedical Physics, a system was built for Virtual, Fluorescence Optical-Sectioning Tomography (VFOST) or High Resolution Orthogonal Plane Fluorescence Optical Sectioning microscopy (HROPFOS). In this relatively new technique, a plane of laser light is directed through a decalcified, transparent and fluorescent biomedical specimen, and a camera observes the fluorescence image of this virtual section in orthogonal direction. By moving the specimen with a stepper motor and each time registering the virtual section, we can create 3D-reconstructions. In the first phase of the current project, the HROPFOS technique will be further developed, to obtain nearly real-time virtual optical sections in a specimen with high resolution (1 micrometer). This way, the technique will become a valuable addition to confocal microscopy of decalcified biomedical objects and fills a gap between MRI- and CT-tomography, as it images bone and soft tissue simultaneously. Another topic will be the investigation of 3D-vascularisation in the middle ear by use of corrosion-cast techniques in combination with HROPFOS. In our research, HROPFOS will be applied on middle ear ossicles and vascularisation. During the previous activities, a broad knowledge of electro-optics, segmentation and 3D-modelling is obtained, which will be used to create a new method to measure small deformations of small objects, based on endoscopic moiré-interferometry. The big challenge to measure deformation from moiré topograms, is to compensate for the distortion introduced by endoscopy. A specific application of this technique will be to diagnose tympanic membrane disorders, which for the moment can only be done qualitatively by doctors. By measuring deformation of the tympanic membrane caused by small pressure variations, this technique will possibly be able to detect retraction pockets and cholesteatoma in a very early stage. The technique will also be used for fundamental research of the tympanic membrane. After the measuring technique and the image processing are accomplished, the method will be first tested on in-vitro specimen, later on in in-vivo ears of laboratory animals. The method is completely non-invasive. When measuring in-vivo, compensation of movement artifacts will then be necessary. Because moiré is a geometric technique, sub-wavelength stability is not necessary, which is a major advantage over f.i. laser-interferometry. In a next stage, we will increase the resolution by implementing phase-shifting, which is accomplished by moving the projection grating in its own plane. We will try to use an LCD as a moiré grid, which is a new approach. This way, miniaturization will be possible. The technique will be able to measure all kinds of small deformations, but a first application will be to measure the deformation of human tympanic membranes, in cooperation with ENT surgeons, who will establish the diagnostic value of the apparatus. Of course, tests will first be performed on laboratory animals before being applied on humans, although the method is harmless en non-invasive. A last extension of this project can be the combination of laser-vibrometry and endoscopic moiré interferometry. This way, deformation and vibration can be measured at the same time on the same object. In general, this project will produce several new measuring techniques, applicable in different fields of biomedical research, especially for diagnostic purposes and fundamental research of hearing.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Buytaert Jan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

The three middle ear ossicles act as an impedance match bewteen acoustic vibrations in air and in the fluid of the inner ear. Classically, they are seen as a liner mechnaical system. The inner ear itself acts as an active feedback amplifier with non-linear beheviour. These active cochlear processes can only after they have passed the middle ear. Even at normal physiologic sound pressure, the middle ear also introduces weak non-linearity, which up till now has never been quantified. In this project we will use laser-vibrometry to measure the motions of the middle ear ossicles, and we will implement a new signal analysis technique to detect and quantify the non-linear behaviour of the middle ear mechnical system. The results will improve the understanding of cochlear oto-acoustic emissions, as we will be able to separate cochlear non-linearity from middle ear non-linearity.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

We will determine the transfer of quasi-static pressure loads in the middle ear, starting from the eardrum to the cochlea, via the middle ear ossicles. High resolution static displacement measurements of the eardrum and of the ossicles, in combination with pressure monitoring of the middle ear gas, will show how the middle ear deals with high static pressures and how this can influence the mechanics of hearing.

Researcher(s)

• Promoter: Dirckx Joris
• Fellow: Buytaert Jan

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

A new system is developed for measurement of extreme small gas volume changes without changing pressure. The system is based on motion of a droplet in a horizontal capillary. The position of the droplet is measured optically. In the project, the optical setup is developed, and measurement resolution and artefacts are studied.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Commercial heterodyne interferometers are aimed at a broad spectrum of applications. Therefore, a compromise is made between resolution and dynamic range. In this project we will test a number of demodulation techniques to obtain ultra high resolution within limited dynamic range. Our existing heterodyne setup will be optimized f.i. by adding a frequency stabilized laser to obtain minimal noise in the heterodyne signal. Because our heterodyne setup allows the use of a low frequency carrier, we can use filter techniques and demodulation electronics which can not be chosen in existing systems.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

We will measure microfluctuations in atmospheric pressure at different locations, and we will correlate these fluctuations with medical conditions. In test persons changes in hart rithm, bload pressure and attention are measured when fluctations in atmospheric pressure are present. The role of the middle ear as detector of these fluctuations is studied.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

This project is the continuation of the previous experiment kit project, in which 40 kits were developed and distributed amongst high schools, containing fascinating physics experiments. In this next part of the project, the set of experiments is expanded, and thematical kits for specific educations are developed.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

In the framework of this project young people are introduced to an aspect of science that is often overlooked, namely to carry out scientific research and work towards a finished product and to study science in preparation of a career in business or industry. Through a step-by-step competition, young people are led to the great role models and finally they will elaborate their own scientific project with an economic goal. They will be directed towards an independent search for the scientists behind some of the world's largest companies (Bayer, Solvay, Kodak, Microsoft, '). Firstly, a quiz will be organized with questions about a number of pre-selected companies, which were set up by scientists. The persons who successfully round off this step will go on to the second phase, namely to submit a proposal for a scientific project which leads to a (imaginary) new product. To collect ideas the participants will go on an educational trip to the science and industry museum 'La Vilette' in Paris, where they will discuss their proposals with the project leader like real entrepreneurs attending a business colloquium. In the last step, a selection is made between the submitted proposals. The selected projects are then fully elaborated (in a theoretical way). This includes all phases of scientific research that are needed to reach the target of a finished product, including a commercial presentation before a jury of possible investors. Laureates will be chosen in different categories: the most inventive product, the greatest scientific challenge, the best commercial perspective, ' In all phases of the competition, the participants are coached by the project collaborator, who puts them in touch with companies that have the know-how for the development of their ideas and who can give them the necessary technical information. In this way, the project is situated between science, economy and management. Young people are supported in their search towards experts in industry. In the initial phase, they gather information through a selective search on the Internet. The project collaborator, as well as the contacted research laboratories, will monitor the scientific foundation of the project proposals.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

During the last decades, the design of structures and systems has undergone an evolution to miniaturization and usage of lightweight materials. This is the case for mechanical structures (e.g. aircraft components), civil structures (e.g. composite and textile constructions), biomedical structures (e.g. lightweight implants) and for electronic systems (e.g. micro- and nano- electromechanical systems). At the same time more stringent requirements are imposed on the strength and the durability of these structures and systems. In order to be able to fulfill these needs it is very important that the static and dynamic properties of the structures and systems are known with a high reliability and spatial resolution. The classical measurement techniques for measuring (static and dynamic) displacements and strains clearly fail in this purpose. As an attractive alternative, optical measurement techniques can be used. Besides the fact that they give a high amount of spatial information, they also allow measurements to be taken in invasive environments. Recently there has been an important increase in the research on optical measurement techniques, both in Flanders and internationally. One of the major limitations of the development of the research potential in Flanders is the fact that the research activities concerning optical measurement techniques are scattered in many different research groups. Since these groups also cover different application areas (material science, mechanical engineering, civil engineering, biomedical science and electronics) communication is not trivial. However, the past has shown that collaboration between different application groups can result in a breakthrough in optical measurement methods. Indeed, due to the development of the so-called Particle Image Velocimetry (PIV) techniques in fluid mechanics, image correlation techniques for strain fields have emerged rapidly thereafter as the structural counterparts. The aim of the network is to improve communication on scientific developments on optical measurement techniques for the characterization of the static and dynamic behavior of structures and systems. At the same time the scientific research group hopes to consolidate and expand its international contacts. In particular, the following scientific goals are targeted by the FWO (Fund for Scientific Research Flanders) research community: - The extension of optical measurement techniques that have been developed and/or validated by one of the partners to other members of the community (i.e. other application areas) - The optimization of existing measurement techniques by using results of parallel developments within other groups. - Delivering complementary expertise in the individual labs with respect to the different aspects of the measurement problem (design of the measurement set up, signal processing of measurement results and application and validation in the different areas) A number of optical measurement techniques will be investigated (list is not exhaustive): - Electronic Speckle Pattern Interferometry (ESPI) - Image Correlation Techniques - Moiré Techniques - Laser Doppler Vibrometry - Photo-elasticity Information about recent developments on optical measurement techniques on an international level will be monitored and exchanged by the different members of the research community. Therefore cooperation between external research groups will be stimulated. The above goals will be realized by setting up a permanent cooperation between the participating research groups, which extends the currently existing temporary cooperation between some of the groups.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project website

Project type(s)

• Research Project

Abstract

We will develop a new moire technique in which grid lines are projected by means of .an endoscopic imaging system. The projected grid lines are recorded through a second endoscope by a CCD camera. Digital image processing is used to calculate object shape and displacement from the recorded images. The technique will allow us to measure small objects in difficult positions. One of the possible applications may be the development of a new diagnostic technique in otology.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Decraemer Wim

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

We have experimentally shown that de middle ear ossicles do not follow the widespread hypothesis of rotation about a fixed axis. The motion is clearly three-dimensional and strongly frequency dependent en serves most probably to widen the frequency-band of middle ear transmission. We want to study this mechanism by combining kinematical middle ear measurements with pressure measurements in the inner ear.

Researcher(s)

• Promoter: Decraemer Wim
• Co-promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

• Biophysics and Biomedical Physics

Project type(s)

• Research Project

Abstract

A heterodyne-interferometer for measurement of nanometer vibration amplitudes is constructed, using a laser diode. The experiments will deliver the know-how to develop an interferometer for simultaneous multi-point vibration measurements on semi-transparant membranes

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

We developed a high resolution moiré interferometer for use in middle ear research. With this apparatus we will now study shape and deformations of the eardrum. Measurements are first done in-vitro, and later the possibilities will be investigated to use the technique on living subjects. The results will contribute to the fundamental science of the middle ear mechanics, and can contribute to new diagnostic techniques in the ENT clinic.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

A compact pressure registration is developed which will measure middle ear pressure over a period of at least 24 hours at a rate of 10 measurements per second, with a resolution better than 10 Pa, and which can record these data digitally. The new technique will allow us to map the pressure variations in the middle ear, and to better understand the function of the middle ear mechanics in pressure regulation.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Decraemer Wim

Research team(s)

Project type(s)

• Research Project

Abstract

Measurements of vibrations of small amplitude are often made using interferometric techniques such as holographic interferometry or laser-Doppler vibrometrie. Recently new techniques based on digital processing of high-resolution video images have been developed. These techniques demand for high computing power but require less costly equipment and present the advantage of providing full-field measurements,

Researcher(s)

• Promoter: Decraemer Wim
• Co-promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

Sound reaching the ear causes very small vibrations of the middle ear (tympanic membrane, ossicles) and the inner ear structures (hair cells, basilair membrane). In a first study we have used approximate models for the middle ear ossicles. Now we want to include the measurement of the geometry of the experimental preparations with the new micromograph so that high fidelity models can be obtained. With special animation software we will animate the motionof the model.

Researcher(s)

• Promoter: Decraemer Wim
• Co-promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

A study of literature on existing technologies and usable concepts will be made, and a preparatory study will be performed to define a new interferometric technique for hearing research, and to start a joint research project.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

A projection Moiré interferometer will be built, which will allow high resolution 3D shape and deformation measurements in biomedical measuring conditions. Fast, automated calibration procedures are implemented. The technique is used to perform measurements on real middle ear specimens.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Decraemer Wim

Research team(s)

Project type(s)

• Research Project

Abstract

Starting from knowhow developed in the past by our group, this project aims at the realisation of a new technique for fast, non-contacting measurement of three dimensional shapes, with a resolution better than 10 micrometer. The apparatus will offer us a new method for the study of eardrum behavior and middle ear mechanics, but it can also be used for high resolution shape and deformation measurements of small objects in general.

Researcher(s)

• Promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

Middle ear and inner ear structures perform minute virbrations. These vibrations are measured experimentally. This project involves the computer animation of these motions to gain a better insight in the hearing mechanism.

Researcher(s)

• Promoter: Decraemer Wim
• Co-promoter: Dirckx Joris

Research team(s)

Project type(s)

• Research Project

Abstract

The possibility is checked to build a Moiré projection interferometer by means of which the tridimensional form and deformations of objects can be measured with high precision. The final goal is to reach beyond the limit of 1 micrometer depht-precision.

Researcher(s)

• Promoter: Dirckx Joris
• Co-promoter: Decraemer Wim

Research team(s)

Project type(s)

• Research Project