This study investigates how electrode number and spatial configuration affect electroencephalography (EEG) source localization performance in the context of visual evoked potentials (VEPs). Five healthy participants performed visual stimulation tasks while EEG signals were recorded with a 256-channel cap. Six electrode montages were evaluated: four whole-head configurations (32, 64, 128, and 256 channels) and two targeted layouts (an 84-channel occipital-only montage and a 164-channel montage excluding frontal sensors). Source localization performance was assessed based on VEP neurophysiological expectations using three complementary indices: a Lateralization Index (LI) for hemispheric dominance, a Signal-to-Noise Ratio (SNR) at the source-space level, and a custom Occipital Precision Index (OPI) that quantifies how tightly activation is confined to occipital regions. Higher-density montages (128 and 256 channels) achieved the highest OPI values (≥0.68), yielding the most focal localization and reflecting accurate activity confinement to the visual cortex. Notably, the targeted 84-channel occipital montage performed comparably to both the 128-channel whole-head and the 164-channel targeted configurations in OPI and SNR, demonstrating that dense sampling over the region of interest can rival broader higher-density coverage. In contrast, lower-density whole-head montages (≤64 channels) exhibited inflated LI and SNR values but lower OPI, indicating reduced spatial precision despite seemingly higher signal metrics. The findings suggest that targeted electrode configurations can approach the performance of high-density caps when the region of interest is known in advance, though the small sample size (N=5) warrants caution and further validation.

As the solar industry continues to grow, the accumulation of photovoltaic (PV) module waste highlights the pressing need for more circular and repairable designs. Conventional laminated modules are difficult to disassemble and recycle, which limits both material recovery and component reuse. While avoiding the lamination improves disassembly, it also compromises the module’s mechanical integrity. This trade-off demands a careful redesign to maintain structural requirements without sacrificing key criteria such as repairability, weight, and cost. This study presents a reliability based optimization approach to redesign the PV module while balancing repairability, weight, and cost constraints. A semi-quantitative relative repairability assessment method, tailored specifically for PV modules, was developed to quantify repairability impacts of design changes. Using Robustimzer software, reliability-base optimization was incoporated to account for uncertain scenarios during the life cycle of the product. Finite Element Analysis and prototype verification ensured compliance with IEC61215 mechanical load standards, achieving an optimized design for mass, repairability and costs simultaneously. As a case study, this methodology was applied to a laminate-free module developed by Biosphere Solar, demonstrating how repairability-focused design can be effectively balanced with structural and economic requirements. The proposed approach offers a scalable framework for advancing sustainable design practices in the PV industry.

With the growing popularity of virtual and augmented reality, there is an increasing demand for haptic devices that can replicate naturally occurring tactile sensations. Specifically, multimodal devices capable of delivering multiple types of haptic feedback simultaneously are crucial for enhancing realism and immersion. In this paper, we introduce a novel, entirely soft, multimodal haptic ring designed to provide vibratory, pressure, and thermal stimuli. Our ring, targeted for texture rendering applications, integrates pneumatic and hydraulic circuits to accurately simulate the roughness, temperature, and compliance cues experienced when freely exploring surfaces with the fingertip. We validated the performance of our system through a psychophysical experiment, which demonstrated that participants could match virtual textures displayed by the ring with real textures with up to 90 % accuracy for several surfaces. Participant’s adjectives ratings indicated that the ring can provide distinctly different stimuli in all of the rendered perceptual dimensions, closely matching those of real textures. This study shows that by relocating tactile feedback from the fingertip, our ring offers maximum wearability, enabling free exploration of surrounding environments and full range of motion, highlighting its potential in mixed reality applications.

Trans-catheter aortic valve replacement (TAVR) has been widely used for treating Aortic stenosis (AoS). Numerical simulation of TAVR process is valuable in terms of reducing surgical risk for patients and cost for valve design. Finite element simulations are performed in this thesis to investigate the risk of coronary obstruction for patients who went through Aortic Valve Neo-cuspitization (AVNeo or Ozaki) procedure. The Expected Leaflet-to-ostium Distance was used as a criterion for assessing coronary obstruction risk. This value in 3 different deployment configurations is compared to determine the optimal deployment strategy. It is found that there is a large risk of coronary obstruction after TAVR for such patients under distal and midplane configuration but no risk under proximal configuration.

Brachytherapy (BT) is an essential component in the curative treatment of cervical cancer. With commercial BT implant devices, called applicators, the radioactive sources can only be positioned in fixed intracavitary channels or in a fixed array of interstitial needles. Patient-tailored BT applicators containing individualised needle channels have the potential to enhance the delivered dose to the tumour while minimising tissue damage of the organs-at-risk (OARs). During the optimisation process of the needle channels, several constraints must be considered. The needle paths in the applicator are curvature-constrained, and the needles should not collide with each other or potentially perforate OARs. Furthermore, clinicians can impose additional constraints based on their preferences.

Existing approaches in literature for optimising needle placement in patient-tailored BT applicators for cervical cancer treatment have employed various algorithms. However, these approaches often rely on significant approximations. For instance, some assume that all needles are inserted in parallel or focus solely on optimising geometric coverage as opposed to optimising the dose distribution. Moreover, the few methods in literature incorporating needle path planning in the optimisation process require manually pre-specified dwell positions. To improve dose conformity and minimise the dependence on the clinician’s expertise and time, there is a need for the development of software that optimises the needle placement and paths without resorting to these severe assumptions.
This work proposes and validates a novel three-stage approach to generate a patient-tailored applicator configuration without resorting to fully geometric optimisation. First, a high-potential set of dwell positions is obtained by running a modified version of the dwell time optimisation software BiCycle (Erasmus Medical Centre, Rotterdam, the Netherlands) on a grid of possible dwell positions. This results in a resolution optimal treatment plan when not considering geometry and applicator constraints. The positions with the highest dwell times according to the resolution optimal treatment plan are selected in the high-potential set. Next, a weighted set cover problem is used iteratively to find a combination of feasible needle segments to cover all dwell points in the high-potential set at a minimum distance. Lastly, needle channels to steer the needle to these segments are simultaneously optimised to be of minimum curvature and mutually collision-free.

To evaluate our approach, a virtual configuration and planning study was performed in a cohort of 22 locally advanced cervical cancer patients previously treated with the Venezia (Elekta AB, Stockholm, Sweden). The resulting treatment plans of the clinically used configuration were compared with the resulting treatment plans of the proposed patient-tailored and grid configurations on clinically relevant dose-volume histogram parameters, dwell times, conformity index and number of interstitial needles. Statistical significance is assessed with Wilcoxon signed-rank tests.

The proposed workflow was demonstrated to be feasible, and for every patient, a configuration could be generated in clinically acceptable time. All treatment plans generated for the grid configuration, the patient-tailored configuration and the clinical configuration were acceptable following the EMBRACE ll aims. Planning aims, however, were met more frequently with both the grid configurations (145/151 instances) and the patient-tailored configurations (137/151 instances) in comparison with the clinically used configurations (119/151 instances). The treatment plans generated with the grid configurations obtained significantly better (p < 0.01) median normalised CTVIR D98 dose with respect to the clinical configurations. Moreover, with the grid configurations, there was a significant improvement in median normalised D2cm3 dose for the bladder (p < 0.001), rectum (p < 0.001), sigmoid (p < 0.01) and bowel (p < 0.001) compared to treatment plans obtained with the clinical configurations. The treatment plans generated with the patient-tailored configurations obtained comparable target doses, but median normalised D2cm3 doses for the bladder (p < 0.001), rectum (p < 0.01) and bowel (p < 0.01) were significantly better for the patient-tailored configurations compared to the clinical configurations.

The proposed automated patient-tailored BT source channel configuration planning method was demonstrated to be clinically feasible. The resulting treatment plans have dosimetric advantages over the treatment plans generated with the clinical applicator configuration. Improvements to the intracavitary dwell position placement are expected to further increase dose conformity.

Slipped Capital Femoral Epiphysis (SCFE) is the most common hip disorder in adolescents characterised by the displacement of the femoral head relative to the femoral neck through the growth plate [3]. In-situ fixation, the current standard type of treatment, stabilises the epiphysis to prevent further slippage. Although it prevents further slippage of the femoral head, the altered morphology of the proximal femur remains [4], leading to long-term complications. Recent studies have, however, revealed that bone growth can continue after fixation, suggesting potential for guided bone growth through strategic screw placement. The aim of this study is to find the optimal screw position for in-situ fixation to stimulate longitudinal bone growth in desired areas, thereby potentially improving the femur morphology and reducing SCFE severity. The study is divided into two parts: the first part focuses on modeling healthy bone growth to validate the computational approach against results from a prior study and clinical data, while the second part concentrates on SCFE analysis to explore the optimal screw position for in-situ fixation to stimulate longitudinal bone growth in desired areas. A finite element (FE) model of a femur with a mild slip was developed to predict bone growth under various screw positions. The Osteogenic Index (OI), which quantifies the expected amount of bone growth, was used to predict growth patterns. The findings indicate that the conventional center-center screw position, commonly used in surgical practice, results in minimal bone growth. Conversely, anteriorly positioned screws, particularly in the anteromedial (AM) and anterolateral (AL) regions, were associated with the most significant and beneficial growth on the posterior side of the growth plate. The expected amount of growth in the AM and AL positions was approximately 211% and 138% greater, respectively, than in the conventional center-center position. These results suggest that anterior screw placement could enhance bone growth in desired areas, potentially mitigating the severity of SCFE and improving long-term functional outcomes. These results reinforce similar findings of a prior retrospective clinical study by [2]. This study contributes to a growing body of evidence supporting the reconsideration of traditional screw placement strategies in SCFE treatment. The insights gained could inform surgical practices aimed at optimising growth modulation and improving patient outcomes. Recommendations have been given to improve the FE analysis and validation. The largest uncertainty lies in the hip contact force in SCFE patients. Further research is needed to investigate this loading for different patients and slip severities and test the influence of the loading conditions on the growth pattern. In addition, clinical trials are necessary to fully validate these findings and assess their practical implications in the treatment of SCFE.

Congenital heart disease (CHD) affects almost 1% of newborns. Right ventricular outflow tract (RVOT) CHD affects 20% of newborns and includes anomalies such as tetralogy of Fallot (TOF) with or without pulmonary atresia, transposition of the great vessels, and truncus arteriosus. All these anomalies require RVOT reconstruction. Prosthetic heart valves are needed to improve the quality of life of patients suffering from CHD. One such prosthetic device is the pulmonary valved Conduit developed by XeltisTM. This study aimed to investigate the difference in the mechanical response of the XeltisTM pulmonary valved Conduit sizes 16, 18, and 20 (XPV16, XPV18, and XPV20) using mechanical experiments and a predictive finite element model.
Experiments of two load cases, Leaflet opening behavior (LC1) and parallel compression (LC2) have been done where measurements were taken for input parameters used for uncertainty quantification (UQ) in the FE model. Furthermore, the reaction force and displacement were measured to calculate the force values and stiffness values of the device during each experiment. The experiments were replicated with a developed FE model. From the results of the FE model, a metamodel (MM) was developed and a Monte Carlo simulation was performed to retrieve a distribution of the force values and stiffness values obtained in the simulation. Furthermore, UQ was performed and the sensitivity of the input parameters on the force values and stiffness values were quantified. Finally, with an area metric the accuracy of computational finite element (FE) models in simulating the mechanical response observed in the experiments of the XeltisTM pulmonary valved Conduit size 16, 18, and 20 mm was quantified.
For the Leaflet opening behavior, the reaction force increases when the device size increases while the stiffness doesn’t change with device size. As for the accuracy of the predictive FE model, the predictive FE model can simulate the mechanical response of the stiffness with an accuracy of at least 70.7% for the reaction force and at least 50.3% for the stiffness.
For the parallel plate compression, the reaction force and the stiffness increase when the XPV size decreases from size 18 to size 16. Furthermore, the difference between the XPV18 and the XPV20 is smaller for both the reaction force and the stiffness. As for the accuracy of the predictive FE model, the predictive FE model can simulate the mechanical response of the stiffness with an accuracy of at least 37.3% for the reaction force and at least 38.1% for the stiffness.
As for the important variables influencing the mechanical response, the reaction force and the stiffness are influenced mostly by the fiber stiffness of the component that is subjected to the load. Furthermore, the reaction force and stiffness are also influenced by the direction of the fibers. If the fibers are in the same direction as the load, the reaction force and stiffness increase. Although specifically for the Leaflet the amount of material has more influence on the reaction force and stiffness for larger XPV sizes with the Leaflet opening behavior load case. This indicates that for larger XPV sizes the material properties of the Leaflet have a smaller influence and the Leaflet geometry has a higher influence on the stiffness of the Leaflet opening.
Improvements are possible for a better agreement between the simulation and the experiment. These include performing more experiments with different samples from different production batches, and better estimation of input parameters with a high sensitivity to the output parameters.
This study provides a step in the direction of predictive computational device modeling that will help shorten the development time of new pulmonary heart valve devices. As the devices in this study are designed for pediatrics, this will help improve the quality of life of pediatrics suffering from congenital heart disease.