Fungi and oomycetes, which can grow invasively, can lead to some of the most devastating die-offs and extinctions of both animals and plants. In their natural environment, such as soil, and during the infection, they may be confronted with low levels of atmospheric oxygen, which may alter their growth behaviour.

The aim of this research was to develop a lab-on-a-chip device, which can control the oxygen levels around fungi or oomycetes. The chip designed in this work has one main channel for the growth of hyphae and flow of the media, feeding into this are two gas channels, which enable manipulation of oxygen concentrations in the main channel.

To demonstrate the applicability of this device, the oomycete Achlya bisexualis was inoculated on the chip for a preliminary investigation of the growth behaviour of hyphae at different oxygen levels. Hyphal growth rate and diameter were measured at different flow rates and shown they could not be affected by the flow rates.

The response of the hyphae to the oxygen gradient in the channel was characterised by light microscopy. A change of hyphal behaviour was found due to the oxygen gradient. Some hyphae, which were growing in a high oxygen concentration area, changed their growth directions towards to hypoxic area, suggesting that A. bisexualis hyphae were more likely to grow towards hypoxic conditions. Similar to their ability to avoid barriers in their growth path, they might also have the ability to sense the surrounding oxygen concentrations.

The work presented in this thesis provides a device that could lead to a better understanding of fungal and oomycete growth behaviour at different oxygen levels and may open the way to the improvement of existing antifungal therapies or new approaches to tackling their invasive capabilities.