Figure 3: Collapse of indentation data.
(a) Indentation × Young’s modulus versus bead radius × Young’s modulus. (b) Contact radius × Young’s modulus versus bead radius × Young’s modulus. Inset: schematic of particle behaviour for 
. For both quantities, the data collapses on a smooth curve. The dotted line shows the best-fit JKR theory13. The dash-dotted curve shows Maugis’s extended JKR predictions43. The dashed curve is derived from equation 2. Points show measured data for substrates with stiffness 3 kPa (blue), 85 kPa (magenta), 250 kPa (black) and 500 kPa (cyan).
