Electrical properties of hydrated collagen. II. Semiconductor properties

The dc conductivity of hydrated bovine Achilles' tendon collagen has been determined as a function of hydration over a limited temperature range. At ambient temperature the conductivity changes from 10 −15 (Ω cm) −1 in the dry state to about 10 −8 (Ω cm) −1 at ∼24% water content by weight. For all temperatures the conductivity increases exponentially with hydration obeying σ( h ) = A exp (β h ), where h is a measure of the hydration, A is independent of temperature, and the parameter β ∼ T −1 . It is shown that the data may be described by an impurity‐type mechanism in which the effective activation energy for the process is dependent on temperature and hydration. Conduction is assumed to be electronic with the impurity (water) acting as a donor. In the solid state the effect of water on the conductivity is reversible indicating the absence of chemical alteration of the hydrated collagen.