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. Author manuscript; available in PMC: 2021 Apr 1.
Published in final edited form as: Matter. 2020 Feb 26;2(4):921–937. doi: 10.1016/j.matt.2020.01.021

Figure 1. An integrated wireless graphene-based sweat stress sensing system (GS4) for dynamic and non-invasive stress hormone analysis.

Figure 1.

(A) Schematic illustration of the origin of cortisol in sweat and saliva and the use of the GS4 to track the circulating cortisol level. CRH, corticotrophin-releasing hormone; ACTH, adrenocorticotropic hormone.

(B and C) Conceptual illustration of cortisol dynamics regulated by circadian rhythm (B) and triggered by physiological and psychological stress (C).

(D) Illustration of the laser engraving process of a graphene platform.

(E) Graphene sensor arrays mass-produced on a polyimide (PI) substrate.

(F) Image of a disposable flexible graphene sensor array.

(G) Transmission electron microscopy (TEM) image of the graphene electrode surface.