Advanced electrospinning apparatus for control, alignment and coating

Abstract

The work contained within this thesis is concerned with the further innovation and the development of apparatus for the electrospinning method which in its most basic form is used to produce and deposit small diameter fibres of many polymers and other materials in a mat structure with random orientation of the deposited fibres. The focus of the innovation is concerned with expanding the ways of collecting these fibres by implementing newly developed techniques, building upon the conventional electrospinning technique and literature to create an advanced electrospinning system. The innovation can be split into the following areas of study: Development of apparatus for the control of the electrospinning process, apparatus for the control of the deposition of the fibres and the development of apparatus for coating conductive wires and other materials with electrospun polymer fibres. Each of the apparatus designed and tested within this work build upon previous examples of experimental apparatus created by other groups as discussed in the following chapters. The apparatus developed and described is a combination of incremental improvement and previously untried combinations of the work that as gone before. All the apparatus developed for use as part of the ectrospinning process were designed to be easily improved incrementally and the development cycles to achieve the final apparatus shown have also been included. The novelty within this work is concerned the development of apparatus for use with the electrospinning process and with the overall supporting systems that have been developed alongside them. The novelty of the apparatus used in conjunction with the electrospinning process includes a remotely controlled fibre printer that can print tracks of electrospun fibres creating shapes and patterns. The development of the apparatus is discussed in detail covering all mechanical and electronic considerations and design decisions. The final apparatus is shown to operate as desired with polymer tracks thicknesses of 20mm in width achieved. A novel apparatus was developed using multiple ground electrodes that were digitally controlled in conjunction with the electrospinning method to achieve a new method of layering aligned fibres in layers with alternating orientations. Also the apparatus can be used in an alternate mode which allows the selective electrospinning of aligned bundles of fibres between multiple electrodes in user defined patterns. The apparatus is shown to achieve good polymer fibre alignment between electrodes and also is shown to work as deigned in regard to the layering of the aligned fibres. An alternate way of using the apparatus is successfully demonstrated allowing the selective patterning of deposited fibre bundles between multiple electrodes. A polymer coating apparatus was also developed to extend the electrospinning method to create core-shell fibres as part of a larger system developed for creating smart textiles and fibrous sensors. The novel electrospinning apparatus is shown to be able to uniformly coat both the circumference and along the length over a comparatively long length of core-shell fibre. A deposition thickness of polymer between 36 μm and 242 μm was achieved by changing the coating speed. An alignment of the electrospun fibres along the length on the core wires is also shown and discussed. The core-shell fibres developed are used in conjunction with another developed apparatus piece that weaves a series of wires around the outer shell to create a three layer device consisting of an outer electrically conductive layer, an electrospun polymer layer and an electrically conductive core. The system is shown to successfully create these three layer devices.