Three-dimensional inkjet printing of electrically active materials
Additive Manufacturing (AM) for electronics (AME) offers the capability for a new generation of devices, with digitised customisation, remarkable design freedom, and low wastage. To achieve this, AM must enable excellent material properties, high resolution, multi-material processing, and scalabilit...
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| Format: | Thesis (University of Nottingham only) |
| Language: | English English |
| Published: |
2025
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| Online Access: | https://eprints.nottingham.ac.uk/80449/ |
| Summary: | Additive Manufacturing (AM) for electronics (AME) offers the capability for a new generation of devices, with digitised customisation, remarkable design freedom, and low wastage. To achieve this, AM must enable excellent material properties, high resolution, multi-material processing, and scalability to attain industrial relevance. Inkjet printing (IJP) is one of the most mature technologies capable of such material properties and resolution, originating from graphical printing but now with several decades of research into functional materials behind it. IJP excels at multi-material processing and scalability, but major criticisms are the high anisotropy and inability to print truly 3D geometries, generally settling on 2.5D heterostructures instead.
This work reports on a new finding that the anisotropy of conductivity in silver nanoparticle inks has been overestimated, and that it is mostly independent of the ink composition. Further, four polymer inks were investigated to pair with the silver ink as support and for high-quality dielectric contrast. Additionally, a novel method which requires no custom hardware – “Off the Grid” – was developed to remove aliasing which artificially decreases drop placement fidelity. This increases the accuracy of shape outlines and provides methods to control layer topology and negative space.
This work was built upon to create 3D structures with uniquely complex geometries compared to previous IJP efforts, with single-drop-wide micropillars printed ≤ 4 mm high. After investigating the growth mechanism of the pillars, it was shown that they can lean without support, which enables the printing of helices and strut-based lattices. Finally, multimaterial prints are demonstrated with anisotropic silver elements within a dielectric matrix, which allows for easy control of the macro dielectric properties. Overall, this work pushes the boundaries of achievable geometries within AME and opens the potential for a wide range of functional devices to be inkjet-printed. |
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