Blanc SIMI 9 - Blanc - SIMI 9 - Sciences de l'Ingénierie, Matériaux, Procédés, Energie

Rheology, wetting and drying of human blood. – D-Blood

D-Blood and the study of the human blood wetting and drying

In the past, confessions and testimonies were sufficient to convince magistrates and members of the jury. Nowadays, the “scientific evidence” has become a basic element for criminal investigations. With an objective of investigation costs savings and manpower savings, a quick orientation for the investigators based on an accurate age determination of the bloodstain is inestimable. In order to improve forensic protocol, fundamental knowledge are requested on the blood physical properties.

Aging a crime scene

The expectations are important in the frame of the forensic community to have a reliable and efficiency aging method in crime scene. The approach that we choose here is very innovative allying the skills of fundamental laboratories (IUSTI, ENSCP, LRP) with applied ones (IRCGN and NFI). The outcomes on the rheology, wetting and spreading of complex fluids are also of great interest in the community. We intend to achieve at the end of the four years project several high quality papers raised in the frame of this proposal.

Blood is a complex fluid which physical properties are not well characterized. Its rheology is clearly non-Newtonian for people in good health, its wettability is close to water but exhibits differences on soft surfaces due to the presence of colloids that change the contact line dynamics. While whole blood surface tension is very close to pure water, human blood serum is very different. All these physical properties are required to understand the spreading, fragmentation of blood and its drying and cracking. This ANR proposal intends, in the frame of specific applications, to answer “open questions” in both the scientific and forensic communities. In order to do that, we spread the work into six tasks each of them focusing on a question/problem to answer/solve. The proposal makes use of four French partners with all different skills on rheology (LRP and ENSCP), wetting, spreading and (ENSCP and IUSTI), fragmentation (ENSCP, IRCGN and NFI) and drying (IUSTI and IRCGN). Besides to the four French partners, NFI is an international collaborator involved in the research and has interactions with ENSCP and IRCGN in the frame of the application side of the proposal on the drying dynamics of bloodstain pattern and the fragmentation of blood on crime scenes. NFI will not be funded in the frame of this proposal.

At the beginnign of the project, between T0 and T0+18, the teams have built their experimental set-up. Preliminary experimental campaigns are set in order to validate the set-up and obtain the first results. Some teams have more results than others since publications have been submited. The tasks are started.

In order to use only a important amount of « fresh blood » which coagulate, we established a collaboration with the « Etablissement Français du Sang » (EFS) in order to collect fresh blood (less than 24h after the extraction of the body). This blood is under coagulant then it will be re-activated using a procedure provided by partner LRP (F. Caton). The collaboration agreement document with EFS has been just signed and we should start this Sept. 2015 to collect the first sample for our experiments.

N Laan, KG de Bruin, D Slenter, J Wilhelm, M Jermy, D Bonn, Bloodstain Pattern Analysis: implementation of a fluid dynamic model for position determination of victims, Scientific reports 5, (2015).
N Laan, KG de Bruin, D Bartolo, C Josserand, D Bonn, Maximum Diameter of Impacting Liquid Droplets, Physical Review Applied 2 (4), 044018 (2014).
BouZeid W., Brutin D., Beyond Tanner’s law: role of contact line evaporation on the spreading of viscous droplet, submitted to IPHT.
Caton F., Ghiringhelli E, Polack, B. The Elasticity of Blood, submitted to PNAS.

In the past, confessions and testimonies were sufficient to convince magistrates and members of the jury. Nowadays, the “scientific evidence” has become a basic element for criminal investigations. A recent review made by Brummer et al, 2011 entitled “Forensic quest for age determination of bloodstains” clearly states that “until now, using bloodstains to determine the time elapsed since the crime was committed is still not possible”. This time elapsed since the bloody event was committee enables to check the witnesses’ statements, limits the number of suspects and assesses alibis. With an objective of investigation costs savings and manpower savings, a quick orientation for the investigators based on an accurate age determination of the bloodstain is inestimable. In order to improve forensic protocol, fundamental knowledge are requested on the blood physical properties such as its rheology, wetting, spreading, fragmentation and drying; this is the purpose of D-Blood.

Blood is a complex fluid which physical properties are not well characterized. Its rheology is clearly non-Newtonian for people in good health, its wettability is close to water but exhibits differences on soft surfaces due to the presence of colloids that change the contact line dynamics. While whole blood surface tension is very close to pure water, human blood serum is very different. All these physical properties are required to understand the spreading, fragmentation of blood and its drying and cracking. This ANR proposal intends, in the frame of specific applications, to answer “open questions” in both the scientific and forensic communities. In order to do that, we spread the work into six tasks each of them focusing on a question/problem to answer/solve. The proposal makes use of four French partners with all different skills on rheology (LRP and ENSCP), wetting, spreading and (ENSCP and IUSTI), fragmentation (ENSCP, IRCGN and NFI) and drying (IUSTI and IRCGN). Besides to the four French partners, NFI is an international collaborator involved in the research and has interactions with ENSCP and IRCGN in the frame of the application side of the proposal on the drying dynamics of bloodstain pattern and the fragmentation of blood on crime scenes. NFI will not be funded in the frame of this proposal.

D-Blood is composed of four fundamental tasks. The first tasks T1 will provide the driving mechanisms involved during the evaporation of drops and pools of blood and other complex fluids, the second task T2 will provide the delamination and cracking mechanisms occurring at the end of the blood evaporation. The blood rheology and wetting will be fully analyzed in the frame of task T3 while the blood fragmentation and spreading will be explained in Task T4. The first four tasks bring inputs useful in the frame of task T5. In task T5 we will provide new forensic protocols to be use on crime scenes. All the data collected in the frame of these five tasks T1 to T5 will be synthesized in task T6 under the supervision of D. Bonn to achieve a consistent review paper.

The expectations are important in the frame of the forensic community to have a reliable and efficiency aging method in crime scene. The approach that we choose here is very innovative allying the skills of fundamental laboratories (IUSTI, ENSCP, LRP) with applied ones (IRCGN and NFI). The outcomes on the rheology, wetting and spreading of complex fluids are also of great interest in the community. We intend to achieve at the end of the four years project several high quality papers raised in the frame of this proposal.

Project coordination

David BRUTIN (Centre National de la Recherche Scientifique Délégation Provence et Corse _ Institut Universitaire des Systèmes Thermiques Industriels) – david.brutin@univ-amu.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

LRP Laboratoire de Rhéologie et des Procédés
ENSCP Ecole Nationale Supérieure de Chimie de Paris - Paristech
NFI Netherlands Forensic Institute
CNRS DR12 _ IUSTI Centre National de la Recherche Scientifique Délégation Provence et Corse _ Institut Universitaire des Systèmes Thermiques Industriels

Help of the ANR 529,981 euros
Beginning and duration of the scientific project: January 2014 - 48 Months

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