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Decoupling Ionic and Electronic Currents in Melanin

Margarita Sheliakina, Bernard Mostert Orcid Logo, Paul Meredith Orcid Logo

Advanced Functional Materials, Volume: 28, Issue: 46, Start page: 1805514

Swansea University Authors: Bernard Mostert Orcid Logo, Paul Meredith Orcid Logo

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DOI (Published version): 10.1002/adfm.201805514

Abstract

Melanin, the human skin pigment, has emerged as a model material for bioelectronic interfaces due to its biocompatibility, ability to be processed into electronic‐device‐grade thin films, and transducing charge transport properties. These charge transport properties have been suggested to be of a mi...

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Published in: Advanced Functional Materials
ISSN: 1616-301X
Published: Wiley 2018
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URI: https://cronfa.swan.ac.uk/Record/cronfa44756
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first_indexed 2018-10-04T13:31:52Z
last_indexed 2020-07-26T19:06:00Z
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spelling 2020-07-26T17:50:23.1686747 v2 44756 2018-10-04 Decoupling Ionic and Electronic Currents in Melanin a353503c976a7338c7708a32e82f451f 0000-0002-9590-2124 Bernard Mostert Bernard Mostert true false 31e8fe57fa180d418afd48c3af280c2e 0000-0002-9049-7414 Paul Meredith Paul Meredith true false 2018-10-04 SPH Melanin, the human skin pigment, has emerged as a model material for bioelectronic interfaces due to its biocompatibility, ability to be processed into electronic‐device‐grade thin films, and transducing charge transport properties. These charge transport properties have been suggested to be of a mixed protonic/electronic nature, regulated by a redox reaction that can be manipulated by changing the material's hydration state. However, to date, there are no detailed reports which clarify, quantify, or disentangle the protonic and electronic contributions to long‐range current conduction in melanin. Described herein, is a systematic hydration controlled electrical study on synthetic melanin thin films utilizing impedance/dielectric spectroscopy, which rationally investigates the protonic and electronic contributions. Through modeling and inspecting the frequency dependent behavior, it is shown that the hydration dependent charge transport is due to proton currents. Results show a real dielectric constant for hydrated melanin of order ≈1 × 103. Surprisingly, this very high value is maintained over a wide frequency range of ≈20–104 Hz. The electronic component appears to have little influence on melanin's hydration dependent conductivity: thus the material should be considered a protonic conductor, and not as previously suggested, a mixed protonic/electronic hybrid. Journal Article Advanced Functional Materials 28 46 1805514 Wiley 1616-301X 12 11 2018 2018-11-12 10.1002/adfm.201805514 COLLEGE NANME Physics COLLEGE CODE SPH Swansea University 2020-07-26T17:50:23.1686747 2018-10-04T08:51:44.7204335 Faculty of Science and Engineering School of Engineering and Applied Sciences - Chemistry Margarita Sheliakina 1 Bernard Mostert 0000-0002-9590-2124 2 Paul Meredith 0000-0002-9049-7414 3 0044756-25102018105119.pdf 44756.pdf 2018-10-25T10:51:19.0570000 Output 531835 application/pdf Accepted Manuscript true 2019-10-01T00:00:00.0000000 true eng
title Decoupling Ionic and Electronic Currents in Melanin
spellingShingle Decoupling Ionic and Electronic Currents in Melanin
Bernard Mostert
Paul Meredith
title_short Decoupling Ionic and Electronic Currents in Melanin
title_full Decoupling Ionic and Electronic Currents in Melanin
title_fullStr Decoupling Ionic and Electronic Currents in Melanin
title_full_unstemmed Decoupling Ionic and Electronic Currents in Melanin
title_sort Decoupling Ionic and Electronic Currents in Melanin
author_id_str_mv a353503c976a7338c7708a32e82f451f
31e8fe57fa180d418afd48c3af280c2e
author_id_fullname_str_mv a353503c976a7338c7708a32e82f451f_***_Bernard Mostert
31e8fe57fa180d418afd48c3af280c2e_***_Paul Meredith
author Bernard Mostert
Paul Meredith
author2 Margarita Sheliakina
Bernard Mostert
Paul Meredith
format Journal article
container_title Advanced Functional Materials
container_volume 28
container_issue 46
container_start_page 1805514
publishDate 2018
institution Swansea University
issn 1616-301X
doi_str_mv 10.1002/adfm.201805514
publisher Wiley
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Chemistry{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Chemistry
document_store_str 1
active_str 0
description Melanin, the human skin pigment, has emerged as a model material for bioelectronic interfaces due to its biocompatibility, ability to be processed into electronic‐device‐grade thin films, and transducing charge transport properties. These charge transport properties have been suggested to be of a mixed protonic/electronic nature, regulated by a redox reaction that can be manipulated by changing the material's hydration state. However, to date, there are no detailed reports which clarify, quantify, or disentangle the protonic and electronic contributions to long‐range current conduction in melanin. Described herein, is a systematic hydration controlled electrical study on synthetic melanin thin films utilizing impedance/dielectric spectroscopy, which rationally investigates the protonic and electronic contributions. Through modeling and inspecting the frequency dependent behavior, it is shown that the hydration dependent charge transport is due to proton currents. Results show a real dielectric constant for hydrated melanin of order ≈1 × 103. Surprisingly, this very high value is maintained over a wide frequency range of ≈20–104 Hz. The electronic component appears to have little influence on melanin's hydration dependent conductivity: thus the material should be considered a protonic conductor, and not as previously suggested, a mixed protonic/electronic hybrid.
published_date 2018-11-12T03:56:08Z
_version_ 1763752823976099840
score 10.998161

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