Air bearings are known for their low friction losses, constant viscosity and cleanliness, making them favourable in numerous high-tech applications. The relatively low aerostatic bearing stiffness is the major topic in state-of-the-art research and some recently proposed concepts are able to create infinite stiffness. This results in a strong coupling between the base and flying mass, enabling unwanted propagation of base vibrations. Why not integrate the vibration-isolation and bearing function? To reduce the out of plane vibrations of a flying mass. A previous study shows the possibility of creating a zero-stiffness bearing with the use of multiple aerostatic pads. However, the effect of the dynamic- thin-film stiffness and damping on the transmission of base vibrations is still unknown. The aim of this research is to optimise and validate the zero-stiffness concept and to study the effect of the static and dynamic pad characteristics on the transmissibility function. It is shown that both the stiffness and damping need to be minimised at equal operating fly height to create a stable system. A stable design is found with the use of a parametric optimisation procedure. The design shows a lower transmissibility when compared to a standard aerostatic bearing, although there are some challenges regarding high design sensitivities and displacement non-linearity. Different manufacturing methods are investigated to build a prototype to validate the concept. The measurements prove the validity of the model, although a clear low-stiffness operating point is not found, due to a combination of manufacturing difficulties and high design sensitivities.

In the high-tech semiconductor industry floating air conveyors are used to transport and position silicon substrates. An interesting point for improvement is to limit the loss of pressurized air as conveyors are only effective at the position of the substrate.
The goal of this research is to develop a local pneumatic valve, that is implemented underneath the surface of a floating air conveyor. Depending on the position of a substrate, the valve is actuated using a pressure signal.

A conceptual design is conceived where a nozzle-flapper system builds up pressure when a wafer is floating nearby. This will actuate a relay with a circular waved membrane that snaps to its inverse shape, to open or close a channel.
The proposed nozzle-wafer concept is modelled to investigate its characteristics. It is found that a desired nozzle back pressure can be achieved by setting the appropriate nozzle restriction and supply pressure. However, at higher pressures the fly-height will be influenced by the nozzles. Therefore, a minimal switching pressure for the relay is key.
The arrangement of nozzles and relays in a conveyor is examined. In this research a black box is used for the valve in order for multiple relay concepts to be applicable. With the current function two inputs are needed to fully operate the relay. It is possible to make a grid where substrates move in one direction and an extra array of outlets are active around it, to make a smoother air film. No arrangement is found that can be used in different directions without leaving a single relay open when the substrate has passed.
Simulations of the snap acting relay showed unreliable membrane behaviour. An adjustment is made in the design for the prototype. A design using a circular single curved membrane is introduced, because the models are consistent in converging to a solution of its snapping behaviour.
A layered design approach is used for the prototype, where laser-cut PMMA plates are glued together. Plastic membranes are created with a vacuum form method. Initial testing of these membranes showed unexpected behaviour (e.g. flipping in other shapes and breaking). Also the pressure required to snap back to the starting position is considerable lower. A prototype is built using the only properly snapping membrane that is found. In a static experiment it proved that the relay functions as it is intended.

This concludes the first iteration of the design process. A working snap acting membrane is fabricated and tested. Because of the behaviour of the other tested membranes it is taken into account that this prototype might not have a lifespan higher than switching a hundred times. Simulations showed that a nozzle-wafer system can provide a back pressure to switch a valve. However, this pressure must be minimal, in order that it does not affect the fly-height of the wafer.
Lastly an alternative design is introduced. Using an elastic membrane with different size surfaces, lower pressures can close off air channels with a higher supply pressure. This combined by a nozzle-wafer conveyor with a resistor network underneath is recommended to investigate in the second iteration of the design process.

Chronic total occlusion (CTO) occurs in approximately a third of all patients with coronary artery disease and is one of the most challenging types of conditions to treat. Minimally invasive methods like percutaneous coronary intervention (PCI) show a high treating potential as well as low costs, short hospital stay and fast recovery. However, their success rate is limited due to their mechanical force transmission, often leading to inability of crossing the hard proximal cap of the CTO. This study focuses on a promising non-mechanical concept for treating CTO using PCI. The proposed idea is based on energy transmission via hydraulic pressure waves in a liquid filled catheter tube. The aim of this project is to conduct a feasibility study for treating CTO by simulating a realistic situation based on the proposed concept. The first stage involved understanding the existing setup and dealing with its flaws and limitations. After the setup was improved and made appropriate for systematic experiments, a realistic scenario was simulated in the lab which led to a drop in force efficiency to one tenth of its original value, a useful result for estimating the required input force to puncture a real CTO. A CTO model was manufactured using gelatin and hydroxyapataite powder. In the final tests, the device was used to puncture effectively the CTO and demonstrate the feasibility of the concept in an ex vivo situation. Only one strike was enough to puncture the soft proximal caps whereas 2 to 4 strikes were needed for the hard caps. The input peak force was set to \SI{36}{N}. Finally, the sensing capabilities of the device were explored with the purpose of getting information on the compliance of the target in contact with the output tip of the catheter.