Fig. 2: Mitigation of mechanical artefact by the metahydrogel platform.
a, Schematic nucleation and periodic pattern growth model based on supersaturation theory. As the ion concentration (cab) exceeds the critical supersaturation (Ksp), nucleation and pattern growth are initiated to form the first precipitation region. Back-diffusion of electrolyte within the matrix creates a depleted zone, followed by iterative reactions and ionic diffusion. b,c, Photographs of cross-sectional morphology of CuCl2/K2CrO4 periodic pattern (b) and the large-scale fabrication via stamp method (c). Scale bars, 2 mm (b) and 3 cm (c). Experiments were independently repeated at least three times (n = 3) with consistent results. d, Simulated mechanical wave propagation in hydrogel matrix and metahydrogel. Right curves present the amplitude as marked by the dashed white line. e, Ashby plot of loss factor (η) and modulus (E) of metahydrogel and other damping materials. The dashed lines represent the materials with different ηE products. f, Damping frequency versus structural factor of metahydrogel. The inset shows the definition of structural factor P = xn+1/xn, where xn denotes the distance of the nth band measured from the reaction centre. g, Evaluation of resistance to three-dimensional force interference. The inset schematically shows the test set-up, and the projection on the bottom plane indicates the signal intensity detected by the sensor. h, Four-quadrant plot and CRs for evaluating BP measurement accuracy using a commercial sphygmomanometer and a piezoelectric sensor with or without the metahydrogel. Diagonal black lines indicate the ±5 mm Hg error bars, and the grey area represents the ±3 mm Hg exclusion zone.
