Relative amounts of parts A and B of QGel 920 (by mass) and parts A and B of QGel 903 (both by Quantum Silicones) used to prepare silicone gels with different elastic moduli, E (in kPa).

The elastic moduli were measured with accuracies of 5–10% by applying a known shear hydrodynamic stress using a microfluidic device and measuring the resulting shear strain [26]. The gels with E = 0.4–18 kPa were prepared using QGel 920 only, whereas the gels with E = 30–130 kPa were prepared with a mixture of QGel 920 and QGel 903 components. The experiments with HUVEC were only performed on gel substrates with E of 0.4, 3.7, 18, and 130 kPa.