Contactless micro-elastography of single cells using oscillating microbubbles as shear wave sources

TL;DR

This paper introduces a novel contactless micro-elastography technique using oscillating microbubbles as shear wave sources to measure the mechanical properties of single cells, achieving unprecedented miniaturization and real-time monitoring capabilities.

Contribution

It presents the first fully contactless, microbubble-based elastography method capable of measuring the mechanics of single cells as small as megakaryocytes, surpassing previous size limitations.

Findings

Successfully performed micro-elastography on cells up to five times smaller than prior methods.

Generated 15 kHz elastic waves using oscillating microbubbles near cells.

Demonstrated robustness and reproducibility across multiple cells from the same line.

Abstract

The mechanical properties of cells play key roles in their physiology, function, physiological and pathological transformations. Micro-elastography has recently emerged as a promising tool to estimate cellular viscoelastic properties within a millisecond, without the need for mechanical modeling. Here, we report a fully contactless approach to single-cell micro-elastography, using acoustically oscillating gas microbubbles positioned near individual cells (20~\textmu m diameter megakaryocytes) as localized shear wave sources. Using this approach, we successfully performed micro-elastography on cells up to five times smaller than those studied in previous works, establishing the smallest single-cell elastography measurements to date. Spherical or non-spherical bubble oscillations generated 15~kHz elastic waves, which we detected using a high-speed camera coupled to a standard bright-field microscope. Noise correlation elastography enabled the measurement of average and local shear-wave velocities within single cells. Our results demonstrate that this method is robust and reproducible across multiple cells from the same cell line, paving the way for real-time, label-free mechanical monitoring of single cells during fast biological processes.