Fig. 4

Impact reduction ability of hydrogel yarns. a Snapshots of a free falling 20-g object connected to a hydrogel yarn. The falling height was 15 cm. Scale bar: 2 cm. b, c Acceleration and impact force of the object buffered by (b) a hydrogel yarn and (c) a cotton yarn as a function of time. The hydrogel yarns were made of 100-plied, 10-cm-long, 20-μm-diameter hydrogel fibres and the hydrogel fibre contained 0.1 wt% VSNPs and 20 mM ZnCl₂ with an inserted twist of 3 turns mm⁻¹. The cotton yarn was 200 μm in diameter and 25 cm in length