Poisson's ratio in skin

Poisson's ratio of cow teat skin was measured uni- and biaxially and shown to be anisotropic and dependent on aspect ratio. At strains below 0.1 (where Cauchy and Hencky strain are indistinguishable) the Poisson's ratio of cow teat skin measured biaxially is very much greater than 1.0, whereas the Poisson's ratio of distending artery is between 0.5 and 0.3. Knitted fabric behaves similarly to cow teat skin in that it can give a negative Poisson's ratio at low strains. Skin is therefore probably to be considered mechanically as an open feltwork of fibres rather than some sort of continuum.