Acoustically Actuated Soft Robots for Biomedical Applications

Abstract

Micro/nano robots and soft robots represent not only crucial areas of research but also pivotal technologies in advancing human healthcare. The utilization of external stimuli and fields, including chemical reactions, light, heat, humidity, electric fields, and magnetic fields, provides a viable option for the design and implementation of soft microrobots. Remarkably, acoustically actuated microrobots developed in the past decade have demonstrated diverse functionalities and maneuvering abilities. Because acoustic technologies are capable of generating large forces, simplifying robotic design, facilitating rapid prototyping, enabling remote and wireless operation, offering versatile programmability and multiscale scalability, and providing ultrafast reversible responses within milliseconds. However, acoustically actuated soft robots, representing a new conceptual research, have been largely unexplored, despite their potential to achieve groundbreaking advancements in robotics, wearable technology, flexible electronics, healthcare, and more. In this dissertation, we review recent strides and investigate new design strategies, potential applications, and future challenges for acoustically actuated soft robots. We start with an extensive literature review on the progress of acoustic actuating techniques, summarizing their advantages, limitations, and application scenarios. In the following, we highlight the latest advances in acoustic robots and analyze the fundamental design principles and physical effects that govern their operation. We then propose and demonstrate new actuation concepts, design paradigms, fabrication methods, modeling theories, and applications for acoustically actuated soft robots across various scales. Chapter 2 introduces the concept of acoustic virtual walls, allowing microparticle swarms to roll along reprogrammable virtual paths in liquids using combined magnetic and acoustic fields, circumventing the need for physical boundaries. Chapter 3 discusses the 'SonoTransformer,' an acoustically activated micromachine that uses preprogrammed soft hinges of varying stiffnesses for selective shape transformation, enhancing control and versatility in design and function. Finally, Chapter 4 presents the development of artificial muscles that utilize over 10,000 resonant microbubbles activated by targeted ultrasound to achieve programmable deformations and dynamic movements, highlighting their potential for underwater robotic design and applications. Our research presents promising opportunities across multiple scientific domains, including robotics, acoustics, fluidics, engineering, biomedicine, and more. Finally, we summarize the significant achievements and key contributions of our research and present prospects for the development of acoustic soft robots.