A study in blood at pinch

TL;DR

This study explores the complex physics of blood droplet formation, revealing two distinct breakup modes and their scaling laws, which could impact forensic and microfluidic applications.

Contribution

It uncovers two unique blood breakup modes and characterizes their universal scaling dynamics, advancing understanding of blood physics at pinch.

Findings

Identified two modes of blood breakup: collapsing neck and filament thinning.

Described each mode with power law and exponential law scaling.

Potential implications for forensic science and microfluidic technology.

Abstract

The complex fluidic nature of blood, though necessary to serve different physiological purposes, gives rise to daunting challenges in developing unified conceptual paradigm describing the underlying physics of blood at pinch, which may otherwise be essential for understanding various bio-technological processes demanding precise and efficient handling of blood samples. Intuitively, a blood-drop may be formed simply by dripping. However, the pinch-off dynamics leading to blood-drop-breakup is elusively more complex than what may be portrayed by any unique model depicting the underlying morpho-dynamics, as our study reveals. With blood samples, here we observe two distinctive modes of the breakup process. One mode corresponds to incessant collapsing of a liquid-neck, while in other mode formation and thinning of an extended long thread leads to the breakup and drop formation. We further show that these modes are respectively described by power law and exponential law based universal scaling dynamics, depicting the temporal evolution of the neck thickness of the blood filament. Our results are likely to bear far-reaching consequences in diverse applications, ranging from forensic sciences to droplet based microfluidic technology.