The demand for nanoparticles in various applications is increasing. These applications can only be realised if nanoparticles can be specifically arranged and patterned on a substrate. This thesis considers a direct write method that uses an aerodynamic focusing nozzle to deposit these particles. A major challenge arises when the nanoparticles are decreased in size. This research studies the control of the deposition resolution of small sized nanoparticles (≤10 nm) in an aerosol flow. A FEM model was developed to describe the particle’s path. These models were made for a converging and converging sheath gas nozzle. Due to the small particle sizes considered, it was found that only the Stokes (drag) force needs to be accounted for during modelling. The effect of different nozzle exit throat, working distance, angle and flow rate configurations are studied. Nozzle designs were evaluated using three performance criteria, namely the contraction factor, focusing ratio and line width. These describe the contraction of the particles within the nozzle system, the focusing after the nozzle system and the width of the line, respectively. It was found that smaller angles, longer converging sections and higher velocities resulted in smaller line widths. Also, the contraction factor hardly depends on the particle size. Smaller nozzle exit throats have significantly higher focusing ratios for particles smaller than 10 nm. The working distance does not effect the contraction factor directly, indicating capabilities of deposition on non-flat surfaces. The converging nozzles can only deposit ≤10 nm particles if the nozzle exits are sufficiently small. This can cause clogging. The focusing ratios, in these nozzles, never exceeds the value of one, indicating always a larger line width than the nozzle exit diameter. In the sheath gas nozzle system, high sheath gas ratios are essential for increasing the contraction factor and particle velocity. This prevents clogging. Introducing the sheath gas earlier in the nozzle system is more effective than at the end. The best modelled contraction factor, focusing ratio and line width achieved, using 10 nm particles, with a converging nozzle are 1.0, 0.4 and 874 microns, respectively. This nozzle has a nozzle exit throat of 400 microns and an angle of 10 degrees. However, a modelled contraction factor of 9.3, focusing ratio of 3.8 and line width of 104 microns are achieved using a converging sheath gas nozzle with a nozzle throat of 400 microns and an angle of 5 degrees. Narrower line widths are expected if the throat diameters are reduced. For the experiments, a setup was used in which nanoparticles are generated using a spark ablation method. During these experiments it was seen that the maximum flow rate is mainly dependent on the nozzle exit throat of the aerosol channel. The line widths, during experimenting, were found to be wider due to inaccuracies in the stage and the differences in settings between the model and setup.

Nanoparticles have unique properties that are sought after for the development and improvement of applications. Prerequisite to achieve these applications, methods are required to put the nanoparticles in different patterns and arrangement on a target substrate. In the course of developing an aerosol-based nanoparticle printing system, this work explores the results of different aerosol deposition configurations. The work is based on a spark ablation process that generates an aerosol of argon and copper nanoparticle agglomerates. The deposition configuration deposits the aerosol on a target substrate. Three configurations are explored, one which deposits at subsonic velocities, and two which deposit at sonic velocities. The aim is to find the most favourable deposition conditions for the direct writing of nanoparticle patterns. It is found that a sonic deposition configuration with a low pressure ratio at small substrate distances has the smallest deposit diameter. The configuration allows for the patterning of narrow lines, that consist of two deposition regions: a micro-aggregate region and a nanoparticle region. It was found that the density of these regions is mainly influenced by the process variables of the spark ablation process, and can thus be used to gain a high consistency and well-defined edges.

Surface-enhanced Raman spectroscopy (SERS) is a powerful non-destructive molecule identification technique. The technique is made viable by the enhancement of the Raman effect which is caused by metallic nanoparticle (MNP) structures. A fabrication method that can manufacture highly consistent SERS substrates is important. Aerosol Direct Write (ADW) is a promising method to achieve consistent SERS substrates. Previous research did not achieve reproducible substrates due to inconsistencies in particle deposition. To improve the quality of SERS substrates fabricated using ADW, key factors within the ADW setup contributing to the substrate quality are identified and analysed. A particle deposition model is created to analyse the impact of those key factors on the substrate quality and to analyse if different operating velocities of the moving stage can minimise the impact of those key factors. The deposition model results are validated by fabricating substrates using a range of operating velocities. It is found that the nozzle diameter has a linear correlation with the spot size. The particle generation is inconsistent and a dominant factor for the SERS substrate quality. The effect of the fluctuating particle generation rate can be minimised by multiple path coverages and higher operation velocities. It is found that the XYZ-stage in the used setup operates optimally between 1000 and 2000 micrometer per second. The deposition model correctly showed that the particle generation rate is the dominant factor for the substrate quality and correctly predicted the ideal operating velocity of the XYZ-stage used in the setup. The model can be used in the future to find an ideal operating velocity and to look at the effects of stage movement characteristics and particle generation fluctuations in ADW setups. SERS measurements show that the SERS substrate fabricated at the ideal operating velocity performed more consistently than substrates fabricated at other velocities.