Figure 2.

Gel point (GP) trace. This represents a typical GP result for one sample of blood. The illustration demonstrates how phase angle, δ, changes as coagulation progresses. δ has a range of 0° to 90°, where 90° identifies a purely viscous response and 0° identifies a purely elastic response with any value in between being a measure of the viscoelastic response to imposed stress. In a material that is changing from a liquid to a solid such as blood, there will be a decrease in δ. At the establishment of the incipient clot, when the clot becomes a viscoelastic solid, there is a point where the value of δ will be independent of frequency called the GP. The structural property of the incipient clot (in terms of its fractal dimension, d_f) is derived from this frequency independent value of δ_GP.