Ultra-fast self-healable stretchable bio-based elastomer/graphene ink using fluid dynamics process for printed wearable sweat-monitoring sensor

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-02, Vol.454, p.140443, Article 140443
• Main Authors: Gyu Son, Seon, Jun Park, Hong, Kim, Seon-Mi, Jin Kim, Seo, Sik Kil, Min, Jeong, Jae-Min, Lee, Youngeun, Eom, Youngho, Yeon Hwang, Sung, Park, Jeyoung, Gill Choi, Bong
• Format: Article
• Language: English
• Subjects: Graphene; Ink; Real-time monitoring; Self-healing polymer; Sweat sensor
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.140443

•Preparation of self-healable, stretchable, and printable graphene ink based on a fluid dynamic process.•Demonstration of stretchable sweat sensor showing excellent electrochemical performances with high self-healing efficiency (99%).•Demonstration of self-healing ability in real-time monitoring on-body tests of wearable device. The practical application of wearable real-time monitoring systems is currently restricted by the irreversible mechanical damage and fracture of their sensors during physical activity, which has inspired the development of self-healable ink materials. However, progress in this field is limited by the difficulty of combining high mechanical strength with high conductivity and realizing scalable and efficient fabrication. Herein, a fluid dynamics process is used to prepare a self-healable, robust, and conductive ink through the incorporation of graphene into a self-healing polymer, namely poly(1,4-cyclohexanedimethanol succinate-co-citrate). The corresponding screen-printed serpentine-structured electrode exhibits spontaneous conductivity self-healing during 10 cut-heal cycles and at a tensile strain of 200% under ambient conditions. These unique properties are used to fabricate a highly stretchable electrochemical Na+ sensor with a high self-healing efficiency (average sensitivity retention of 99%). On-body tests reveal that this wearable sensor is well suited for the real-time monitoring of sweat during physical exercise and is capable of autonomous repair after mechanical cutting, showing a healing time of ∼12 s. Thus, our work paves the way to the commercialization of devices typically requiring a combination of mechanical resilience and stable electrical performance, e.g., e-skin, sweat sensors, soft robotics, and biofuel cells.