Microwaves trigger thermo-acoustic ultrasound generation

Frederic Cegla

doi:10.1117/1.ap.2.3.030501

Abstract

In volume 2, issue 3 of Advanced Photonics, Lan et al. reveal that a split ring resonator can be used as a very efficient thermo-acoustic source compared to other configurations. This commentary provides a quick overview of the work and how it sits in context with other forms of ultrasonic signal acquisition.

Highlights

Ultrasound is one of the most common modalities for diagnostic imaging of the body and engineering structures
As strongly absorbing parts of the tissue heat up more than their surroundings they expand and emit a pressure pulse that travels through the tissue
By considering the physics of energy absorption and Poynting’s relation of energy conservation, they stipulated that high intensity electric or magnetic fields are required to maximize the thermo-acoustic source strength. They showed that a split ring resonator (SRR) is an effective way of increasing the magnitude of the electric field in a small spatial area, i.e. where a ring of a wire conductor is split

Summary

Introduction

Ultrasound is one of the most common modalities for diagnostic imaging of the body (biomedical imaging) and engineering structures (non-destructive evaluation–NDE). PA imaging is a mixed technique that uses the high spatial resolution of electromagnetic waves in the visible or near visible part of the spectrum and the different absorption coefficient of structures inside tissue to turn the tissue itself into ultrasound sources. As strongly absorbing parts of the tissue heat up more than their surroundings they expand and emit a pressure pulse that travels through the tissue.

Results

Conclusion