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Title: Designing a hybrid inkjet and laser manufacturing system for the digital and non-contact fabrication of emerging nanotechnology based devices
Author: Shams, Yoanna
ISNI:       0000 0004 7962 0332
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2019
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Though many VA-CNT based applications have recently been developed, there is still a research gap in the scalable manufacture of VA-CNT applications in industry. In this research, a hybrid additive and subtractive direct-write digital fabrication platform has been developed to deposit and pattern catalyst for VA-CNT Growth. Inkjet printing has been explored as the additive technology for depositing magnetite nanoparticles as catalyst, and laser ablation has been studied as a subtractive technique to pattern the catalyst for growing VA-CNT structures, using chemical vapour deposition as an assistive growth procedure. The research was conducted in three phases. In the feasibility phase the CVD growth conditions were established and a comparison was made using SEM and AFM analysis. A variation in size between the annealed nano-islands formed from the nanoparticle film and the PVD deposited iron film was identified. The magnetite ink properties were then characterised for inkjet printing. In the specification phase inkjet printing and laser patterning experiments were conducted. It was determined that VA-CNTs can be grown by printing 2.19 \% w/w ink concentration on UV treated 10 nm alumina coated substrates at a droplet spacing of 45 µm. SEM analysis identified that even though the nano-islands formed from the inkjet printed catalyst are larger in size than those formed from the PVD deposited catalyst, VA-CNTs were successfully grown. In the laser patterning experiments a femtosecond laser fluence range between 0.48 J/cm_2 and 0.64 J/cm_2 was found to successfully pattern the nanoparticle catalyst. Varying laser fluence resulted in a change in the annealed catalyst nano-island size, giving varying growth trends. In the conceptualisation phase, an industrially scalable laser system by M-Solv Ltd was successfully demonstrated for patterning the catalyst. Gas sensing experiments were also conducted proving a response of the VA-CNTs to changes in nitrogen dioxide.
Supervisor: Daly, Ronan Sponsor: EPSRC ; M-SOLV Ltd
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Inkjet Printing ; Laser Patterning ; Carbon nanotubes ; Direct-write ; iron oxide nanoparticles ; nano-catalyst ; catalyst nano-islands ; inkjet ; femtosecond laser ; gas sensor ; nanomanufacturing