Atrial fibrillation is a cardiac arrhythmia resulting from abnormal electrical conduction and impulse formation within the atria. To address this condition, a minimally invasive procedure called cardiac ablation is performed. Real-time visual feedback during this procedure plays a critical role in determining its success.

Photoacoustic imaging is a technique capable of providing real-time visual feedback. Integrating photoacoustic capabilities into existing Radiofrequency ablation catheters poses a significant challenge, which this thesis addresses. The proposed integrated solution employs optical fibers for light delivery and an ultrasound transducer for signal reception.

This work investigates the design of two light delivery systems for integrated photoacoustic-guided surgery. Monte Carlo simulations are employed to study three-dimensional light propagation in tissue, informing the catheter design specifications. Optimal fiber distances and orientations within the catheter are determined based on normalized fluence values and illumination spot size—critical parameters for assessing the amount of delivered light, its area of coverage, and depth of penetration. The methodology presented applies to various photoacoustic applications.

The simulation study was able to successfully inform design specifications and it was able to establish a relation between design variables and the evaluation criteria such that it can be referred to for future designs. The comparative study yielded a better-performing design configuration and its optimal specifications were found out. This proves the use of a simulation-based evaluation to design a photoacoustic intracardiac catheter. In the final phase of this research, an experiment is set up to validate the light delivery of the design, which provides a clear outlook for the future of these designs into fabricated products.

The work presented in this report is an attempt to allow density-based topology optimization algorithms to take into account machining costs when optimizing. To this end, and estimation model for the cost of 2.5-axis CNC milling was developed based on the principles of Design for Manufacturing.
This estimation model was implemented in a generic topology optimization algorithm in five steps of complexity. The behaviour of the model was evaluated at each step by means of a set of experiments, showing how the addition of the cost estimation influences the optimization results.
The most promising results from the experiments are validated with Autodesk Fusion 360, with which the designs were programmed to be machined on a CNC mill. The machining times from this software were used to calculate the actual machining costs and these were compared to the machining costs estimated by the optimizer.
Two formulations of the method were found to be useful for estimating the machining cost of designs. A simple formulation that uses the shape factor and the differentiation between internal and external pockets to estimate the cost resulted in a cost saving of 13% at the expensive of a compliance increase of 9%. The more complex formulation uses multiple pocket domains to evaluate pocket-specific properties. This allowed a more accurate estimation of the costs, but did not result in a better performing optimization. The cost saving was comparable at 12%, but the compliance increased by 16%.
It was concluded that there is a use for both methods. The simple formulation allows to find cheaper designs, but does not allow much control in the cost estimation. The complex formulation however can be used to fine-tune the method for a specific situation, which could enable it to perform better that the simple formulation.

Multi­-material 3D inkjet printing has great potential for rapid prototyping and manufacturing of functional mesoscale structures when novel inks are combined into a fully integrated AM-process. This process can be faster and cheaper than conventional methods to produce functional structures. Research is conducted on a large range of potentially inkjet­-printable materials to extend current possibilities with 3D inkjet printing. Material incompatibility together with strict fluid properties limit the range of multifunctional inks available for an integrated print process. This raises challenges such as printing with three or more materials, and finding inkjet printable materials that can be cured simultaneously using the same curing method. The aim of this research is to print functional structures using at least three materials consisting of a structural, support, and conductive material, requiring only one curing technique involving UV light exposure. An experimental setup of PiXDRO LP50 inkjet printers and various printhead assemblies are used to conduct experiments. Suitable off the shelf available inks are selected after a state of the art literature review. Stratasys Vero­series and Stratasys SUP706B are industry standard, compatible materials and cure using UV induced photopolymerisation. They are chosen as structural and support material, respectively. Novacentrix Metalon JS­B25P and Mitsubishi NBSIJ­MU01 silver nanoparticle inks are chosen as conductive inks. First, multi­material printing is set up and extended to 3D printing using the structural and support material inks only. Afterwards, conductive inks are tested for resistivity and behaviour on different substrates before integrating with the structural and support material ink into a multi­material 3D print. Conductive nanoparticle inks show good conductivity on photopaper substrate, but not when printed on top of structural material. Several experiments are performed to document ink behaviour and optimise performance. A workflow is designed allowing the conversion of complex CAD models to inkjet ­printable files. Custom support material density for stronger supports can be generated using an in-­house developed conversion application. Proof­ of ­concept multi­-material functional structures are printed showcasing success of the proposed methodology.

In this thesis, a methodology is developed that allows for both reliable and computational efficient robustness analysis of aircraft component distortion. This research applies to dis- tortion caused by reductive manufacturing processes that are used to obtain monolithic components from pre-stressed stock material. With the developed methodology, orienta- tions of any component within rolled plate stock material can be found where distortion is most robust. Part distortion is defined as a deviation in shape of an aircraft component from original intent as a result of the component’s reductive manufacturing process. As extreme precision is required in aircraft component assembly, the distortion phenomenon is highly undesired. The developed methodology in this thesis contributes to AIRBUS’ objectives to minimize part distortion related issues. In this thesis, the fundamentals of part distortion are studied. It is found that aircraft com- ponents distort as a result of residual stresses that are present in stock material from which the components are manufactured. As residual stress in rolled plate is subjected to substan- tial variation, part distortion is stochastic in nature. Positions of the components in rolled plate are searched for where distortion is most robust. The robustness of distortion refers to the insensitivity of distortion to uncertainty in residual stress. A mathematical stochastic representation of residual stress in rolled plate is developed showing high coherence with experimental measurement data provided by AIRBUS. For elementary geometries, the rela- tionship between distortion robustness and residual stress is derived analytically. The developed method for predicting distortion robustness is more than one hundred times more efficient in terms of computation cost compared to state-of-the-art methods and al- lows for reliable robustness predictions. In the developed method, three-dimensional po- sitioning of a component in rolled plate can be simulated where state-of-the-art distortion modeling tools usually stick to one dimension. The developed methodology is put to the test in a case study concerning an aircraft stiffener component. The case study emphasizes the significance of robustness predictions; distor- tion dispersion is found to be relatively large compared to the distortion magnitude and significant correlation is found between the component’s orientation in rolled plate and the level of robustness. Positions of components in rolled plate can be found where distortion is extremely robust. Moreover, a relationship is found between the component’s degree of symmetry and the level of robustness.

In the industry motion systems with electric motors are used for transporting and positioning thin flexible substrates at high throughput rates. A possible alternative actuation solution could be to apply contactless air film actuators which make use of air bearing principles. The air film actuators use a thin film of air to levitate and propel a substrate. The main advantage of such a technique is that it actuates directly on the substrate and therefore eliminates the moving mass of a carrier. This drastically reduces the actuation force required to accelerate the substrate, which reduces unwanted deformations and excitations of the machine frame. Because the substrate is not in direct contact with the bearing surface, the substrate does not experience any wear, stiction or backlash effects. In this project a demonstrator with opposed air film actuators is designed and manufactured to actuate a flexible substrate in one degree of freedom. To predict the performance of the motion system, the air film actuators are modelled with the use of the Reynolds equation for compressible air, determined both analytically and numerically. The demonstrator consists of two manifolds with their bearing surfaces facing each other and where a substrate is placed between the two bearing surfaces. By using pressurized air, the substrate can be levitated between the two bearing surfaces. By controlling proportional valves, the substrate can be moved in negative or positive x-direction. The theoretical models show good resemblance with the measurement results. However, the substrate vibrated and did not float fully contactless between the two bearing surfaces. Based on these results, improvements can be made on the bearing function of the system, but the demonstrator shows promising results for actuating substrates with large accelerations and fast responses.

Organ on a Chip (OoC) systems are of high interest through its use for medicine testing in a small time scale without the need for animal testing. Membranes used in OoCs form a base to grow cells on and need to be suitable for cell-attachment and porous. Fouling is the 'Achilles heel' in membrane performance. Research shows that as a result of fouling the viability of the skin cells grown in the chip decreased to zero after 3 weeks. If research on organs is to extend and research on cell- or tissue growth will include longer time spans, the influence of membrane fouling with conditions similar to the OoC is an important factor to understand.
In this research a microfluidic flow cell is produced and used to explore fouling within the OoC. Static and dynamic fouling experiments are executed on membranes having pore sizes ranging from 0.4 to 5 μm.
Scanning electron microscope (SEM) images indicate that standard blocking and cake layer formation are dominating fouling mechanisms.
Membranes with 1 μm pore size are the most susceptible to standard blocking. Further a decrease in pore area of 0%, 11% and 20% and a decrease in uncovered amount of pores of 27%, 34% and 80% for Glycine, BSA and λ-DNA respectively are measured after one week of fouling.
Cake layer formation is seen after fouling for a shorter duration for BSA (one day) than for Glycine (one hour) and a higher concentration of BSA particles is permitted through all tested membranes than Glycine, therefore the conclusion is drawn that BSA causes less fouling than Glycine.