Static and Dynamic Surface Tension Analysis of Whole Blood: Implications for Bloodstain Pattern Analysis

AMARNATH MISHRA, DARPIKA SHARMA, KOMPAL AND B. S. SIKARWAR

Associate Professor, Amity Institute of Forensic Sciences, Amity University Uttar Pradesh, Noida, India

Background:

Surface tension is a critical physical property of blood that significantly influences bloodstain pattern formation, including droplet spreading, breakup, deformation, and drying. Despite its forensic relevance, limited information is available on the dynamic surface tension of whole blood.

Methods:

Static and dynamic surface tension of swine blood were measured using the pendant drop method and a bubble tensiometer, respectively. Static measurements were obtained by analyzing droplet images with ImageJ software. The methodology was validated using water and Silicon AR-20. The effect of blood aging on surface tension was also evaluated.

Results:

The static surface tension of whole blood was successfully determined. Dynamic measurements revealed a reproducible peak in surface tension at approximately 100–200 ms, followed by a gradual decline with increasing surface age. The initial peak may result from ionic interactions, whereas the subsequent decrease is likely associated with the diffusion of proteins and lipids to the blood-air interface. The findings demonstrated both qualitative and quantitative agreement with previously reported blood plasma data.

Conclusion:

This study provides valuable data on the static and dynamic surface tension of whole blood and highlights the influence of blood aging on these properties. The results have important implications for improving the accuracy and interpretation of forensic bloodstain pattern analysis.

Keywords: Surface Tension, Whole Blood, Blood Aging, Bloodstain Pattern Analysis, Forensic Science.