Layer-by-Layer Deposition

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Background: Layer-by-Layer film deposition has gained a high level of interest over the past few decades as a technique to develop thin film layers on the micro- and nano- scale. The technique has shown promise for applications such as optics, catalysis and tissues engineering. Layer-by-Layer has risen as an exciting technique with a multitude of methodologies at its disposal: dip, spray, spin, electromagnetic and fluidic have become five distinct methodologies that have provided commercial outcomes. However, each method has specific advantages and disadvantages within the processing procedure, e.g. layering speed, efficiency, manufacturing cost and applications. It is therefore essential to identify and create a system able to produce thin films layers with a whole range of properties. Currently, commercial Layer-by-Layer technology is limited to the use of dip coating due to its simplicity. However, it is a time-consuming process that can take, for example, two days to form 400 layers (a not uncommon amount required for optical filters). To promote the wider adoption of the Layer-by-Layer fabrication process there is a need to speed-up the whole process while maintaining the unique properties of the coated substrates in a cost-effective manner. Technology Overview: To account for this unmet need researchers at Newcastle University have developed a hybrid thin coating manufacturing system that integrates dip and spray technologies to produce films on the nano- and micro- scale for a wide range of industrial applications. By combining these two techniques into one apparatus the researchers have been able to greatly reduce the time required to build up multiple layers while maintaining the same film properties achievable with the dip coating process. The system consists of three core elements: a spray coating apparatus with atomizing nozzles for spraying the substrate with charged polymeric solutions for thinner layers; a dip coating apparatus for thicker and more stable layers; the simultaneous combination of spray and dip apparatus for creating alternate polymeric layers with different features. The system combines the advantages of both Layer-by-Layer methods, spray technology – speed, wide material selection, and large surface area - and those of dip technology - high coating stability, thicker layers, and full 3D-coated capability. The Layer-by-Layer hybrid system allow to reduce the overall time of coating growth compared to standard methods, as a single apparatus can house multiple polymeric solutions enabling to build-up for thin layer deposition by varying the coating polymers.