Acoustomicrofluidic separation of tardigrades from raw cultures for sample preparation

TL;DR

This paper introduces a two-step acousto-microfluidic method for efficiently isolating tardigrades from raw culture samples, enabling cleaner samples for biological research with high recovery and purity rates.

Contribution

It presents a novel combined passive and active microfluidic approach for rapid, contactless separation of tardigrades from complex biological samples.

Findings

Achieved 96% recovery rate of tardigrades.

Reduced algae impurity to 4% in the separated samples.

Demonstrated continuous, automated, and biocompatible separation process.

Abstract

Tardigrades are microscopic animals widely known for their survival capabilities under extreme conditions. They are the focus of current research in the fields of taxonomy, biogeography, genomics, proteomics, development, space biology, evolution, and ecology. Tardigrades, such as Hypsibius exemplaris, are being advocated as a next-generation model organism for genomic and developmental studies. The raw culture of H. exemplaris usually contains tardigrades themselves, their eggs, and algal food and feces. Experimentation with tardigrades often requires the demanding and laborious separation of tardigrades from raw samples to prepare pure and contamination-free tardigrade samples. In this paper, we propose a two-step acousto-microfluidic separation method to isolate tardigrades from raw samples. In the first step, a passive microfluidic filter composed of an array of traps is used to remove large algal clusters in the raw sample. In the second step, a surface acoustic wave-based active microfluidic separation device is used to continuously deflect tardigrades from their original streamlines inside the microchannel and thus selectively isolate them from algae and eggs. The experimental results demonstrated the efficient tardigrade separation with a recovery rate of 96% and an algae impurity of 4% on average in a continuous, contactless, automated, rapid, biocompatible manner.