# Representative subsampling of sedimenting blood

## TL;DR

This paper develops a sedimentation model to guide the design of subsampling methods for blood, ensuring representative samples over time and enabling concentration or dilution of sedimenting suspensions.

## Contribution

It introduces a Kynch sedimentation model for blood subsampling that accounts for hematocrit variations and provides practical design guidelines.

## Key findings

- Model ensures representative subsampling across hematocrit levels
- Design can be modified for concentration or dilution of blood samples
- Provides a simple, practical tool for handling sedimenting suspensions

## Abstract

It is often necessary to extract a small amount of a suspension, such as blood, from a larger sample of the same material for the purposes of diagnostics, testing or imaging. A practical challenge is that blood sediments noticeably on the time scale of a few minutes, making a representative subsampling of the original sample challenging. Guided by experimental data, we develop a Kynch sedimentation model to discuss design considerations that ensure a representative subsampling of blood for the entire range of physiologically relevant hematocrit over a specified time of interest. Additionally, we show that this design may be modified to exploit the sedimentation and subsample either higher or lower hematocrit relative to that of the original sample. Thus, our method provides a simple tool to either concentrate or dilute small quantities of blood or other sedimenting suspensions.