Fig. 2: TimSOM correctly measures known viscoelastic materials.
a, Representative experimental data of the G* modulus for water obtained from TimSOM compensated using Supplementary Equation (46). The dashed line indicates the fit to the data. b, Viscosity of different glycerol mixtures extracted from TimSOM (orange circles) and the classical drag force method (black circle). Viscosity was obtained from a linear fit to the averaged force values obtained for a series of triangles with different velocities (Extended Data Fig. 2a). The closed circles are the known references taken from ref. 24. c, Rheological spectra of different PAA gels. Real (solid circles) and imaginary part (open circles) of the G modulus derived from the creep compliance force-clamp measurement \((J(t)\rightarrow\hat{G}(\omega))\) on a 2% PAA gel (i). The solid or dashed line represents a fit of the data to the Fractional Kelvin–Voigt model with a low-frequency elastic modulus of Cα = 21.1 ± 8.83 Pa (mean ± confidence interval of 95%). TimSOM measurements on two different gels with varying stiffness values (ii). The orange gel is the exact same one as that in panel (i). The filled (open) circles correspond to the real (imaginary) part. The solid (dashed) lines are the real (imaginary) part of the fractional Kelvin–Voigt model, as specified in the legends. For the PAA gel, using the TimSOM method, we get Cα = 24.3 ± 1.28 Pa (confidence interval of 95%). The mint-coloured dots and lines correspond to a 20% acrylamide gel. The modulus is indicated in the figure, together with the trap stiffness G0 that was used to measure each gel. d, Representative raw data of the G modulus for PDMS obtained through equations (1a) and (1b), compensated using the FHA method (Supplementary Equation (46)). The filled (open) circles correspond to the real (imaginary) part. The solid (dashed) lines are the real (imaginary) part of the model specified in the legends.
