Role of chemistry in nature-inspired skin adhesives

Abstract

As an essential component of wearable technology, skin adhesion plays a critical role in a wide range of wearable device applications. To maintain effectiveness and safety in daily use, skin adhesives must exhibit strong wet adhesion and high biocompatibility, particularly for devices that remain in contact with the skin for extended periods under humid and dynamic conditions. A comprehensive understanding of skin adhesion's chemical mechanisms is fundamental to advancing this technology. Nature offers valuable inspiration, as numerous organisms have evolved sophisticated chemical and physical adhesion strategies that enable strong and reversible bonding. This review begins by exploring the historical development of nature-inspired skin adhesives, followed by a detailed examination of their performance in moist environments. Particular emphasis is placed on the covalent and non-covalent interactions between adhesive materials and skin surface functional groups, considering both biocompatibility and wet adhesion properties. Additionally, we discuss strategies to mitigate hydration-related challenges alongside an overview of characterization techniques, including mechanical, chemical, and biological testing methods. The classification of nature-inspired skin adhesives into chemical and physical approaches is presented, highlighting their applications in thermal management, energy harvesting, wound care, and transdermal drug delivery. Finally, we identify current limitations and propose design strategies to guide the development of next-generation skin adhesives, providing a clear trajectory for future research.

Fig. 1. Type, mechanism, and application of nature-inspired skin adhesives.

Fig. 2. The history of nature-inspired skin adhesive.

Fig. 3. (A) Chemical reactions of amino and thiols with various adhesive groups: N-hydroxysuccinimide esters, aldehydes, and catechols. (B) Chemical reactions of amino and hydroxyl with isocyanates. (C) Chemical reactions of amino with cyanoacrylates. (D) The chemical reaction of amino with aryl azides. (E) Carbodiimide cross-linking chemistry.

Fig. 4. Mechanical testing of skin Adhesives. (A) Tensile test. (B) Lap shear test. (C) 90° peeling test. (D) 180° peeling test. (E) Flat punch test.

Fig. 5. Skin adhesives based on hydrogel. (A) Synthetic hydrogel-based skin adhesives. Reproduced with permission. Copyright 2024, Wiley. (B) Protein hydrogel-based skin adhesives. Reproduced with permission. Copyright 2021, AAAS. (C) Polysaccharide hydrogel-based skin adhesives. Reproduced with permission. Copyright 2023, ACS.

Fig. 6. Skin adhesives based on Films and Elastomers. (A) Film-based skin adhesives. Reproduced with permission. Copyright 2020, Springer Nature. (B) Elastomers-based skin adhesives. Reproduced with permission. Copyright 2022, AAAS.

Fig. 7. Skin adhesives based on suction. (A) Octopus-inspired skin adhesives. Reproduced with permission. Copyright 2024, Wiley. (B). Insect-inspired skin adhesives. Reproduced with permission. Copyright 2021, AAAS.

Fig. 8. Skin adhesives based on capillarity force. (A) Tree frog-inspired skin adhesives. Reproduced with permission. Copyright 2024, Wiley-VCH. (B) Chinese cricket-inspired skin adhesives. Reproduced with permission. Copyright 2023, AAAS.

Fig. 9. Skin adhesive for wearable thermal management devices. (A) Photos and device structures of polymer aerogel fibers for passive thermal management. Reproduced with permission. Copyright 2024, Elsevier. (B) Silver nanowire decorated leather with hierarchical structures for integrated visual Joule heating. Reproduced with permission. Copyright 2022, Wiley-VCH. (C) Schematic illustration of textiles based on zylon aerogel fibers for self-powered sensing in harsh environments. Reproduced with permission. Copyright 2024, Wiley-VCH.

Fig. 10. Skin adhesive for wearable power devices. (A) Photos and device structures of silk fibroin hydrogel based wearable stretchable battery. Reproduced with permission. Copyright 2024, Wiley-VCH. (B) Logic diagram of fingerprint-inspired energy-harvesting electronic skin. Reproduced with permission. Copyright 2019, Wiley-VCH. (C) Schematic illustration of a TCNQ/PVA blend film based flexible biomechanical energy harvester. Reproduced with permission. Copyright 2022, Wiley-VCH.

Xiao Yang

Xiaonan Liu

Yeung Yeung Chau

Kannie W. Y. Chan

Zuankai Wang