Extended Data Fig. 2: TimSOM accurately measures viscous and viscoelastic properties.
a, Example of a triangular trajectory (i) used to generate constant drag forces (ii) to measure the viscosity of a purely viscous material. Viscosity was obtained from a linear fit (solid line, iii) to the averaged force values obtained for a series of triangles with different velocities (orange dots, iii). The viscosities derived from different methods for increasing glycerol concentrations are plotted in Fig. 2. b, Force clamp experiment to retrieve the G modulus of a soft PAA gel. The creep motion of the trapped bead (J(t), i) upon a feedback-controlled constant force (F0 = 40 pN, ii) can be used to retrieve the frequency- dependent G modulus shown in Fig. 2. c, Fourier and frequency domain analysis of TimSOM force signals. Power spectrum obtained from the force signals of the driving (F1) and static traps (F2) during an active microrheology measurement on a 1-µm microsphere in water (i, f = 2,…, 4096 Hz) and in a 21.1 Pa PAA gel (ii f = 0.5,…, 4096 Hz). The peaks are located at the imposed driving frequencies. The signal is clearly distinguishable and larger than the background noise.
