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Recyclable near-body temperature eutectic system with double positive temperature coefficient effect for personalised thermal regulation

Recyclable near-body temperature eutectic system with double positive temperature coefficient effect for personalised thermal regulation
Recyclable near-body temperature eutectic system with double positive temperature coefficient effect for personalised thermal regulation

Wearable temperature sensors are essential for medical and personal thermal management applications but often face challenges in achieving accuracy, flexibility and multifunctionality. To address these limitations, we developed a biodegradable polymer-based quaternary composite that leverages a binary eutectic fatty acid system and graphene nanoplatelets (GNPs) to deliver self-regulating heating and temperature sensing capabilities. The incorporation of polycaprolactone (PCL), lauric acid (LA) and myristic acid (MA) facilitates precise thermal control by enabling a tuneable phase transition range of 30 to 60 °C, while GNPs enhance electrical conductivity and thermal response. Notably, the material exhibits a distinct double positive temperature coefficient (PTC) effect, maintaining PTC behaviour up to 80 °C without transitioning to a negative temperature coefficient (NTC) effect. This double PTC behaviour enables precise thermal regulation, with self-regulating heating at ∼36 °C under low-power operation (∼100-250 mW), demonstrating stable power consumption and effective heat absorption through its phase change properties. The composite also supports operation under practical voltages, 5 V (standard power bank), making it well-suited for wearable systems. Additionally, the material demonstrates excellent recyclability through a simple dissolution and recasting process, retaining its stable thermal response even after recycling. These attributes make the composite highly suitable for electronic skins, smart thermal regulation and overcurrent protection fuses. The integration of PCL and fatty acids (FAs) enhances recyclability, promoting sustainable and long-term applications in personal thermal management systems.

2051-6355
1517-1531
Guo, Hongxu
e065a74f-5791-4d0e-9db5-5c7c8bb499bc
Lu, Lichang
6fb794d4-e20e-4b3b-bd77-89dee25f8534
Zhao, Kairen
9234dab9-36f8-4963-aacf-27f94bfdf17c
Yang, Huaiyu
fd4e56e0-c9cb-4e5d-82e9-a819a486ae5b
Willcock, Helen
d999980e-8c74-4a81-8b3f-ab648e9332d0
Mele, Elisa
cb22ed24-3d8c-4ad0-bf47-0d998761d0de
Bao, Xujin
de77ecef-9fd0-4329-b08d-9d66b098c18b
Yu, Eileen
28e47863-4b50-4821-b80b-71fb5a2edef2
Zhang, Han
be995ae3-ca78-4f48-a3cf-02ed7ed20710
Liu, Yi
c2a184fe-ad55-4ffb-9b08-df1fcb518e1e
Guo, Hongxu
e065a74f-5791-4d0e-9db5-5c7c8bb499bc
Lu, Lichang
6fb794d4-e20e-4b3b-bd77-89dee25f8534
Zhao, Kairen
9234dab9-36f8-4963-aacf-27f94bfdf17c
Yang, Huaiyu
fd4e56e0-c9cb-4e5d-82e9-a819a486ae5b
Willcock, Helen
d999980e-8c74-4a81-8b3f-ab648e9332d0
Mele, Elisa
cb22ed24-3d8c-4ad0-bf47-0d998761d0de
Bao, Xujin
de77ecef-9fd0-4329-b08d-9d66b098c18b
Yu, Eileen
28e47863-4b50-4821-b80b-71fb5a2edef2
Zhang, Han
be995ae3-ca78-4f48-a3cf-02ed7ed20710
Liu, Yi
c2a184fe-ad55-4ffb-9b08-df1fcb518e1e

Guo, Hongxu, Lu, Lichang, Zhao, Kairen, Yang, Huaiyu, Willcock, Helen, Mele, Elisa, Bao, Xujin, Yu, Eileen, Zhang, Han and Liu, Yi (2025) Recyclable near-body temperature eutectic system with double positive temperature coefficient effect for personalised thermal regulation. Materials Horizons, 13 (3), 1517-1531. (doi:10.1039/d5mh01491c).

Record type: Article

Abstract

Wearable temperature sensors are essential for medical and personal thermal management applications but often face challenges in achieving accuracy, flexibility and multifunctionality. To address these limitations, we developed a biodegradable polymer-based quaternary composite that leverages a binary eutectic fatty acid system and graphene nanoplatelets (GNPs) to deliver self-regulating heating and temperature sensing capabilities. The incorporation of polycaprolactone (PCL), lauric acid (LA) and myristic acid (MA) facilitates precise thermal control by enabling a tuneable phase transition range of 30 to 60 °C, while GNPs enhance electrical conductivity and thermal response. Notably, the material exhibits a distinct double positive temperature coefficient (PTC) effect, maintaining PTC behaviour up to 80 °C without transitioning to a negative temperature coefficient (NTC) effect. This double PTC behaviour enables precise thermal regulation, with self-regulating heating at ∼36 °C under low-power operation (∼100-250 mW), demonstrating stable power consumption and effective heat absorption through its phase change properties. The composite also supports operation under practical voltages, 5 V (standard power bank), making it well-suited for wearable systems. Additionally, the material demonstrates excellent recyclability through a simple dissolution and recasting process, retaining its stable thermal response even after recycling. These attributes make the composite highly suitable for electronic skins, smart thermal regulation and overcurrent protection fuses. The integration of PCL and fatty acids (FAs) enhances recyclability, promoting sustainable and long-term applications in personal thermal management systems.

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Accepted/In Press date: 27 October 2025
Published date: 29 October 2025

Identifiers

Local EPrints ID: 510441
URI: http://eprints.soton.ac.uk/id/eprint/510441
ISSN: 2051-6355
PURE UUID: 50a72362-92bb-4c88-921c-f99a143bc10b
ORCID for Eileen Yu: ORCID iD orcid.org/0000-0002-6872-975X

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Date deposited: 31 Mar 2026 16:49
Last modified: 01 Apr 2026 02:13

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Contributors

Author: Hongxu Guo
Author: Lichang Lu
Author: Kairen Zhao
Author: Huaiyu Yang
Author: Helen Willcock
Author: Elisa Mele
Author: Xujin Bao
Author: Eileen Yu ORCID iD
Author: Han Zhang
Author: Yi Liu

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