# Acoustofluidic Plasmapheresis System Designed for Ultralow Blood Volume Applications

## TL;DR

A new acoustofluidic system enables efficient plasma separation from very small blood volumes, ideal for neonatal care.

## Contribution

An integrated acoustofluidic plasmapheresis system for ultralow blood volumes with high purity and throughput.

## Key findings

- The system achieves 27.5 μL/min plasma generation with ∼100% cell removal.
- It operates effectively with hematocrit levels up to 50%, typical in neonates.
- The system outperforms previous methods in purity, throughput, and minimal sample volume.

## Abstract

We present an integrated
acoustofluidic plasmapheresis system designed
for ultralow blood volume applications, such as neonatal care, enabling
in-line sampling and plasma separation from whole blood. The system
combines a two-stage acoustophoresis chip with microperistaltic pumps
and PDMS-based flow pulsation dampeners to ensure continuous, stable
operation. The input whole blood is acoustically separated into a
cell-free plasma fraction and a returnable cell fraction, enabling
closed-loop operation for neonates who have a circulating blood volume
as low as 50 mL. The system achieves a plasma generation rate of 27.5
μL/min with ∼100% cell removal, outperforming previous
microfluidic plasma separation approaches in terms of purity, throughput,
and minimal sample volume. Plasma quality was validated by quantifying
hemolysis and residual cellular content, while system robustness was
demonstrated across hematocrit levels up to 50%, which is close to
the average upper hematocrit value in neonates. Compared to previous
microfluidic techniques, our system achieves the fastest generation
of clinical quality undiluted plasma with the lowest required blood
volume, making it highly suitable for point-of-care integration in
neonatal intensive care units.