Fig. 1. Mechanical properties of the silicone substrate. The bead displacement in response to the force applied by a microneedle was plotted. The slope of the line represents the stiffness of silicone substrate. (a) The stiffness of the softest substrate is 5.74 nN/µm. (b) The stiffness of the hardest substrate is 8.59 nN/µm. (c,d) Percent recovery of the beads toward their original position of the softest (c) and the hardest (d) substrates. The average of percent recovery was 87% in both cases.