Micro ElectroMechanical Systems (MEMS) is a term that describes a wide range of miniaturised systems, including Biofactory-on-a-chip devices that are currently under development at Bangor. Traditionally, silicon fabrication processes have been used to allow micro-structuring of components needed to create such MEMS, although polymer based fabrication technologies are gaining popularity. Polymer based MEMS are well suited to rapid development and mass manufacture, so allowing low-cost, disposable devices. However, alternative methods have to be developed to allow high-resolution patterning of such materials. One such method is excimer laser ablation. This process is ideally s uited to fabricating small, micron sized features in a wide variety of materials. This work investigates utilising an excimer laser micromachining system to fabricate micron-resolution structures. Conventional laser ablation was used to create planar structures in thin films between lμm and 200μm thick. This allowed the fabrication of miniaturised polymer-based on-chip optical sensors, both optical fibre and planar waveguide based, compatible with existing Biofactory fabrication processes. Laser patterning of thin films combined with optical reduction-projection was used to produce high-resolution contact masks. This enabled the in-house fabrication of a circular AC electroosmotic chromatography device, with electrode sizes as small as 4.2μm. The unwanted side-effect of excimer laser machining, where laser ablation generated debris is re-cast onto the sample, was also investigated and it was found that the debris could be prevented using an electrostatic collection system. Laser machining was also used to create greyscale masks, suitable for use in a contact exposure photolithographic process, allowing the fab1ication of a fluidic manifold system. Greyscale masks were then applied to laser machining. Implementing such masks allowed arbitrary surface profiles to be machined in a wide vaiiety of materials. The complex structures that were defined were machined to depths in excess of lOOμm, without mask degradation. This is not known to have been previously reported. The excimer laser system was also used as a stereolithography exposure source, in a preliminary investigation. The results obtained suggest that sub-micron patterning is possible using such an approach.