Abstract

This thesis presents an investigation into the fabrication and characterisation of microstructured Ultra Thin Layer Chromatography (UTLC) systems and their application towards chemical separation. These systems were fabricated using laser direct-write processing of polymer substrates. ULTC systems, which are becoming a topic of increasing interest in the fields of nanomaterials and chromatography, employ substrates with porous functional layers for chemical separation which are typically on the order of 10 μm thick. Techniques for fabrication of the sorbent layer include atomic layer deposition, polymer electrospinning and sol-gel deposition. Though these processes are capable of both deposition of materials with the required functionality, and creation of feature sizes on the scales needed for UTLC, they are high cost and have low-throughput. Contrastingly, laser direct-write processing offers an adaptable, scalable, environmentally-friendly and cost-effective method for rapid fabrication of micronscale features on various substrates. Cyclic Olefin Polymer (COP), was chosen as the substrate material based on its superior optical properties and chemical resistance compared to other polymers commonly used in analytical applications. Microchannels were fabricated on COP substrates via laser ablation utilising a 1064 nm Nd:YAG solid-state laser. The ability to create microchannels ranging from 20 to 120 μm deep and 60 to 160 μm wide was demonstrated. An investigation into modelling of this ablation process was also presented. A route towards the single-step functionalisation of COP via a novel atmospheric pulsed laser deposition process was also examined. Towards the development of a UTLC platform, the flow behaviour of different microstructured surfaces was examined. A 45° crosshatched microchannel design was chosen and the effectiveness of this platform when compared with commercially available platforms examined. The separation on the COP’s native functionality is also compared with that of the COP after two surface modifications: an oxygen plasma treatment and silanisation via (3-Aminopropyl)triethoxysilane (APTES) exposure.