Hydrogels are prepared as described in the previous work[35 (link)]. Briefly, for elastic substrate 8% acrylamide and 0.1% bis-acrylamide (Bio-Rad), 2% N-hydroxysuccinimide (dissolved in DMSO) (Sigma), 0.375 % 3-Aminopropylsilyl (Thermo Fisher Scientific), 0.125% tetramethylethylenediamine (Millipore Sigma) added into water to prepare elastic gel of stiffness 5kPa (G’=5kPa and G” =0Pa) and for viscoelastic gel (G’ = 5kPa, G” =600Pa) 14.3 % linear acrylamide (5%stock) and 0.15% bis-acrylamide (instead 0.1%) added to the same protocol as elastic substrate recipe (Fig 1(a)). Gels are laminated with (100 μg/ml) collagen type I (Corning) by incubation overnight at 4 °C.