Figure 2: Effects of stiffness and size.
(a) Indentation depth versus particle radius and (b) contact radius versus particle radius for silica microspheres on silicone substrates of differing stiffnesses. Points show measured data for substrates with stiffness 3 kPa (blue), 85 kPa (magenta), 250 kPa (black) and 500 kPa (cyan). Dashed curves are the best-fit predictions from the JKR theory. Inset: schematic showing the definitions of indentation, d, contact radius, a, and particle radius R.
