Solvodynamic printed silver nanowire composite films for pressure sensing applications
<p>This thesis examines some of the current issues with the use of non-contact printing techniques for fabricating conductive structures for applications in flexible pressure sensors.</p> <p>Firstly, the concept of solvodynamic printing was introduced as a method to improve printi...
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| Format: | Thesis |
| Language: | English |
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2019
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| _version_ | 1797112802877374464 |
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| author | Liu, W |
| author2 | Watt, A |
| author_facet | Watt, A Liu, W |
| author_sort | Liu, W |
| collection | OXFORD |
| description | <p>This thesis examines some of the current issues with the use of non-contact printing techniques for fabricating conductive structures for applications in flexible pressure sensors.</p>
<p>Firstly, the concept of solvodynamic printing was introduced as a method to improve printing resolution using solvent-solvent interactions. By including an additional carrier solvent into the ink delivery system, both the footprint of the ejected ink and the degree of ink spreading on the substrate could be reduced. The proof-of-concept of this technique was demonstrated by printing lines of silver nanoparticles on polyethylene naphthalate substrates. Silver nanoparticle tracks with widths of 35.2 ± 7.0 m were achieved using a 300 μm nozzle. This is equivalent to 11.7 ± 2.3 % of the nozzle diameter. The result shows great potential in solvodynamic printing as not many modern printing techniques can achieve such nozzle to feature size ratios.</p>
<p>Next, the use of ligand exchange on silver nanowires to formulate a post-treatment free ink which can produce highly conductive printed silver nanowire structures was explored. The use of rigid bidentate linking ligands was studied. Among the ligands used, fumaric acid was shown to be the most effective in improving the film conductivity, reducing the sheet resistance by 70 % of a control sample from 26.5 Ω/□ to 7.66 Ω/□. The decrease in sheet resistance was attributed to the decrease in junction resistance of the nanowire film.</p>
<p>Lastly, a simple fabrication method was used to make piezoresistive composite films consisting of silver nanowires embedded in an ethylene-co-vinyl acetate matrix. The performances of the pressure sensor using compressive and tensile strains were compared. The properties of the pressure sensor were highly tunable based on the composition and design of the film. Overall, the films showed a low detection limit (1.47 ± 0.13 Pa), fast response time (11-22 ± 2.9 ms) and high sensitivity (67.3 ± 5.9 kPa<sup>-1</sup>). We further showed the successful application of the film as a pulse monitoring device.</p>
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| first_indexed | 2024-03-07T08:29:02Z |
| format | Thesis |
| id | oxford-uuid:53a5fea1-488c-41ac-b73c-a1cd43fe94ad |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T08:29:02Z |
| publishDate | 2019 |
| record_format | dspace |
| spelling | oxford-uuid:53a5fea1-488c-41ac-b73c-a1cd43fe94ad2024-03-04T15:15:54ZSolvodynamic printed silver nanowire composite films for pressure sensing applicationsThesishttp://purl.org/coar/resource_type/c_db06uuid:53a5fea1-488c-41ac-b73c-a1cd43fe94adMaterials scienceEnglishHyrax Deposit2019Liu, WWatt, A<p>This thesis examines some of the current issues with the use of non-contact printing techniques for fabricating conductive structures for applications in flexible pressure sensors.</p> <p>Firstly, the concept of solvodynamic printing was introduced as a method to improve printing resolution using solvent-solvent interactions. By including an additional carrier solvent into the ink delivery system, both the footprint of the ejected ink and the degree of ink spreading on the substrate could be reduced. The proof-of-concept of this technique was demonstrated by printing lines of silver nanoparticles on polyethylene naphthalate substrates. Silver nanoparticle tracks with widths of 35.2 ± 7.0 m were achieved using a 300 μm nozzle. This is equivalent to 11.7 ± 2.3 % of the nozzle diameter. The result shows great potential in solvodynamic printing as not many modern printing techniques can achieve such nozzle to feature size ratios.</p> <p>Next, the use of ligand exchange on silver nanowires to formulate a post-treatment free ink which can produce highly conductive printed silver nanowire structures was explored. The use of rigid bidentate linking ligands was studied. Among the ligands used, fumaric acid was shown to be the most effective in improving the film conductivity, reducing the sheet resistance by 70 % of a control sample from 26.5 Ω/□ to 7.66 Ω/□. The decrease in sheet resistance was attributed to the decrease in junction resistance of the nanowire film.</p> <p>Lastly, a simple fabrication method was used to make piezoresistive composite films consisting of silver nanowires embedded in an ethylene-co-vinyl acetate matrix. The performances of the pressure sensor using compressive and tensile strains were compared. The properties of the pressure sensor were highly tunable based on the composition and design of the film. Overall, the films showed a low detection limit (1.47 ± 0.13 Pa), fast response time (11-22 ± 2.9 ms) and high sensitivity (67.3 ± 5.9 kPa<sup>-1</sup>). We further showed the successful application of the film as a pulse monitoring device.</p> |
| spellingShingle | Materials science Liu, W Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title | Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title_full | Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title_fullStr | Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title_full_unstemmed | Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title_short | Solvodynamic printed silver nanowire composite films for pressure sensing applications |
| title_sort | solvodynamic printed silver nanowire composite films for pressure sensing applications |
| topic | Materials science |
| work_keys_str_mv | AT liuw solvodynamicprintedsilvernanowirecompositefilmsforpressuresensingapplications |