Figure 2.

Measurement of elastic and inelastic mechanical behaviour of thin floating collagen gels. Cyclic indentation of floating gels of (a) 1 mg ml⁻¹ and (b) 3 mg ml⁻¹ collagen concentrations at indentation rates of 15 µm s⁻¹, 1 µm s⁻¹ and 1 µm min⁻¹. A six-order polynomial was fitted to loading and unloading data. (c) The irreversible deformation was measured by calculation of the point where unloading function intersects x-axis. (d) The maximum supported force was measured from the value of loading function at maximum indentation depth (30 µm). Data are presented as mean ± s.d., minimum five measurements per each indentation rate per sample.