title: Passive Drip Stain Formation Dynamics of Blood onto Hard Surfaces and Comparison with Simple Fluids for Blood Substitute Development and Assessment<sup/>.
abstract: The spreading dynamics of blood dripping onto hard surfaces is compared to two spreading models. Samples of human blood, porcine blood, and Millipore®water were dripped onto cardboard, foamcore, and glass surfaces in low velocity passive drip simulations. Final stain diameter, the total number of spines and scallops, and angle of impact were measured and analyzed. Spreading is best predicted by applying the concept of effective viscosity to the Scheller and Bousfield (R2= 0.91) and Roisman (R2= 0.89) spreading models. In the tested conditions, blood spreads with Newtonian tendencies; however, has quantifiable differences in stain appearance to Newtonian fluids like water. This is encouraging for the development of water-based fluids as synthetic blood substitutes (SBSs). The work presents an assessment platform to quantify and score the performance of simple water-based fluids using final stain diameter (6 points) and number of spines and scallops (6 points) at six dripping heights between 20 and 120 cm. The angle of impact of a stain alone is not a sensitive measure of SBS performance, but stain formation scores the SBS's performance with another 1 point. Together these features generate a quantitative relative ranking system, of a maximum possible 13 points, that can be used to support the use of a particular fluid for the creation of a drip stain. The performance of twenty simple fluids in the simulated dripping assessment test is described.
authors.affiliation: Forensic Science, The University of Auckland, Auckland, 1011, New Zealand.
authors.forename: Theresa
authors.initials: T
authors.lastname: Stotesbury
authors.affiliation: Christchurch Service Centre, Institute of Environmental Science and Research Ltd., 27 Creyke Road, Ilam, Christchurch, 8041, New Zealand.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Taylor
authors.affiliation: Department of Mechanical Engineering, The University of Canterbury, Ilam, Christchurch, 8041, New Zealand.
authors.forename: Mark C
authors.identifier: 0000-0002-9374-7570
authors.initials: MC
authors.lastname: Jermy
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001801:Blood Stains; D044707:Forensic Sciences; D006244:Hardness; D006801:Humans; D008954:Models, Biological; D013499:Surface Properties; D013500:Surface Tension; D013552:Swine; D014783:Viscosity; D014867:Water
chemical_list: D014867:Water
keywords: bloodstain pattern analysis; droplet spreading; forensic science; passive drop; spines and scallops; stain diameter; synthetic blood substitutes