FIG. 5.

Wearable strain sensors for respiratory rate monitoring. (a) Schematic illustration of the carbonized linen fabric strain sensor deposited with polymer-assisted copper. (b) Photographic image of the strain sensor attached to the throat. (c) Relative resistance changes of the strain sensor over time when the wearer is coughing and when the wearer is breathing with or without tachypnea and tachypnea and cough. [(a)–(c)] Figure adapted from Ref. 24. Reproduced with permission from Liu et al., Chem. Eng. J. 426, 130869 (2021). Copyright 2021 Elsevier B.V. (d) Photographic image of the LIG strain sensor attached to the abdomen. (e) ΔR/R₀ of the strain sensor over time under different conditions. [(d) and (e)] Figure adapted from Ref. 25. Reproduced with permission from Xu et al., Adv. Mater. 33(18), 2008701 (2021). Copyright 2021 Wiley-VCH GmbH.