Figure 4.

Drops of plasma dried on various commercially-available substrates (columns) at various concentrations of undiluted, 0.5 v/v and 0.25 v/v (rows). Visual inspection of the drop morphology for size, shape and features such as cracks or fern-shaped crystals was performed. The visual appearance of dried plasma is dependent on initial concentration and substrate wetting. Poor substrate wetting (θ_c ~ 89°, top row) resulted in a smaller-sized ~ 2mm drop, with extensive cracking throughout the drop. Moderate substrate wetting (θ_c ~ 50–70°, middle rows) resulted in slightly larger ~ 3mm sized drops with less cracking. Good substrate wetting (θ_c ~ 30°, bottom row) resulted in deposits that were not a uniform ring shape.