Spatially Selective Acoustic Pressure Reporting Using Antibubbles

TL;DR

This paper introduces antibubbles as innovative optical reporters for non-invasive, spatially precise measurement of ultrasound pressure fields, enabling visualization and quantification of ultrasound effects in complex environments.

Contribution

The study presents a novel antibubble-based method for optical reporting of local ultrasound pressure, demonstrating spatial control, real-time release, and potential for mapping ultrasound fields.

Findings

Antibubbles can encapsulate and release payloads in response to ultrasound.

Payload release is controlled spatially using acoustic holograms.

The release mechanism occurs within 20-50 ultrasound cycles.

Abstract

Ultrasound offers promising applications in biology and chemistry, but quantifying local ultrasound conditions remains challenging due to the lack of non-invasive measurement tools. We introduce antibubbles as novel optical reporters of local ultrasound pressure. These liquid-core, air-shell structures encapsulate fluorescent payloads, releasing them upon exposure to low-intensity ultrasound. We demonstrate their versatility by fabricating antibubbles with hydrophilic and hydrophobic payloads, revealing payload-dependent encapsulation efficiency and release dynamics. Using acoustic holograms, we showcase precise spatial control of payload release, enabling visualization of complex ultrasound fields. High-speed fluorescence imaging reveals a gentle, single-shot release mechanism occurring within 20-50 ultrasound cycles. It is thus possible to determine via an optical fluorescence marker what the applied ultrasound pressure was. This work thereby introduces a non-invasive method for mapping ultrasound fields in complex environments, potentially accelerating research in ultrasound-based therapies and processes. The long-term stability and versatility of these antibubble reporters suggest broad applicability in studying and optimizing ultrasound effects across various biological and chemical systems.