Iso-acoustic focusing of cells for size-insensitive acousto-mechanical phenotyping

Mechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells’ interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance of si...

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Bibliographic Details
Main Authors: Augustsson, Per, Karlsen, Jonas T., Su, Hao-Wei, Bruus, Henrik, Voldman, Joel
Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
Format: Article
Language:en_US
Published: Nature Publishing Group 2016
Online Access:http://hdl.handle.net/1721.1/103074
https://orcid.org/0000-0002-9028-3117
https://orcid.org/0000-0001-8542-7924
https://orcid.org/0000-0001-8898-2296
Description
Summary:Mechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells’ interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance of single cells in continuous flow. While flowing through a microchannel, cells migrate sideways, influenced by an acoustic field, into streams of increasing acoustic impedance, until reaching their cell-type specific point of zero acoustic contrast. We establish an experimental procedure and provide theoretical justifications and models for iso-acoustic focusing. We describe a method for providing a suitable acoustic contrast gradient in a cell-friendly medium, and use acoustic forces to maintain that gradient in the presence of destabilizing forces. Applying this method we demonstrate iso-acoustic focusing of cell lines and leukocytes, showing that acoustic properties provide phenotypic information independent of size.