Extended Data Fig. 2: Mechanical characterizations of the ink and the printed materials.

a, b, Apparent viscosity as a function of applied shear rate (a) and storage modulus as a function of applied shear stress (b) for 20 vol% magnetized ink (red), 20 vol% nonmagnetized ink (black) and support ink (grey). c, Nominal tensile stress–stretch curves (solid lines) for specimens printed with the magnetic ink in the absence of external fields (black), with applied magnetic fields of 50 mT (red) at the nozzle tip generated by a permanent magnet, and the elastomer matrix with no magnetic particles (blue). The shear modulus µ of each material was obtained by fitting the experimental curves to a neo-Hookean model (dashed lines).