Table 1.

Stiffness and effective elastic modulus of gecko setal arrays as a function of loading and unloading direction

Along natural drag path and curvature (+45°)Vertical (0°)Against natural drag path and curvature (−45°)
Number of tokay geckos777
Number of setal arrays262626
Number of observations500504516
Array stiffness (karray) (N mm−1)
Loading1.0±0.031.0±0.031.28±0.04
Unloading stiffness0.9±0.031.05±0.031.31±0.04
Setal stiffness (kseta) (N m−1)
Loading0.08±0.0040.08±0.0030.11±0.004
Unloading0.08±0.0030.09±0.0030.11±0.004
Effective modulus (Eeff) (kPa)
Loading86±4.483±4.0110±4.7
Unloading78±3.889±3.8113±4.9
Coefficient of friction (μeff)0.29±0.01-0.24±0.004
  • Values are means ± s.e.m.

    Coefficient of friction values are for setal arrays sliding on PTFE. Motion protocols for loading and unloading are illustrated in Fig. 5.