Ultrasensitive and highly stretchable sensors for human motion monitoring made of graphene reinforced polydimethylsiloxane: Electromechanical and complex impedance sensing performance

• Published in: Carbon (New York) Vol. 192; pp. 234 - 248
• Main Authors: Bosque, Antonio del, Sánchez-Romate, Xoan F., Sánchez, María, Ureña, Alejandro
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-06-2022
• Subjects: EIS; Graphene nanoplatelets; Human motion monitoring; SHM; Wearable sensors; SHM; Graphene nanoplatelets; Human motion monitoring; Wearable sensors; EIS
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2022.02.043

Highly stretchable sensors based on graphene nanoplatelet (GNP) reinforced polydimethylsiloxane (PDMS) are manufactured for human motion monitoring purposes. The strain sensing analysis shows ultra-high gauge factor (GF) values from 40 to 300 at low strain levels up to 106 at high deformations at tensile conditions, and a decreasing sensitivity as GNP content increases. The compressive behavior shows an initial decrease of the electrical resistance, due to the prevalence of in-plane mechanisms, followed by a stable increase, due to the prevalence of out-of-plane mechanisms. In this regard, the Electrical Impedance Spectroscopy (EIS) analysis shows an increase of the complex impedance with increasing compressive strain. The equivalent RC-LRC circuit allows to explain the electrical mechanisms governing the compressive behavior, where the LRC element denotes the contact and intrinsic resistance and the RC element the tunnelling effect. Finally, a proof of concept of human motion monitoring proves the capability of the scalable and easy-manufactured sensors to detect frowning, raising eyebrows, blinking, breathing, blowing and, even, vocal cord motion, where each phoneme follows a unique pattern, with a robust electrical response.
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