# Capturing the shear and secondary compression wave: High frame rate ultrasound imaging in saturated foams

## TL;DR

This study uses high frame rate ultrasound imaging to observe shear and secondary compression waves in saturated foams, with implications for medical imaging of lung tissue.

## Contribution

It provides experimental evidence of shear and secondary compression waves in saturated foams supporting Biot theory predictions.

## Key findings

- Both waves supported by foam's weak frame
- Opposite polarity of compression waves observed
- Potential for improved lung tissue imaging

## Abstract

We experimentally observe the shear and secondary compression wave inside soft porous water-saturated melamine foams by high frame rate ultrasound imaging. Both wave speeds are supported by the weak frame of the foam. The first and second compression waves show opposite polarity, as predicted by Biot theory. Our experiments have direct implications for medical imaging: Melamine foams exhibit a similar microstructure as lung tissue. In the future, combined shear wave and slow compression wave imaging might provide new means of distinguishing malignant and healthy pulmonary tissue.