Microbubbles as Swimming Champions through Ultrasound
In the pursuit of overcoming the limitations of slow mobility, maneuverability, and biocompatibility in microswimmers, a group of researchers from around the world has made an exciting discovery: the utilization of the buckling instability of a lipid layer on microbubbles for propulsive force, achieving displacements in the m/s range. This achievement marks a significant leap forward in the realm of microswimmers, offering a promising solution for precise drug delivery and molecular imaging within the human body.
The dream of clinicians to activate and control microcarriers in the bloodstream is now within reach. Existing proposals often grapple with technical complexity or compromise speed, maneuverability, and biocompatibility. However, lipid-coated microbubbles, already established as ultrasound contrast agents, have emerged as a versatile solution.
Traditionally employed for enhancing vascular visualization through ultrasound, these microbubbles, when subjected to ultrasonic waves, can now be harnessed for controlled propulsion. The research, led by G. Chabouh and colleagues, unveils the potential of microbubbles to achieve substantial net displacement through controlled cycles of deflation and re-inflation. Importantly, the direction of propulsion can be independently manipulated, offering a breakthrough in controlled steering for ultrasound molecular imaging and drug delivery.
Numerical simulations, complemented by rigorous experimental studies, validate the feasibility of well-designed microbubbles achieving speeds in the m/s range. This capability holds promise for efficient motion within the bloodstream, revolutionizing the landscape of biomedical applications.
The LIPhy team, in collaboration with partners from the University of Twente, is at the forefront of exploring three-dimensional steering using these microbubbles. This collaborative effort aims to advance the implementation of this revolutionary technology in practical experiments.
The paper delves into the challenges faced by microswimmers in biomedical applications and highlights the potential of lipid-coated microbubbles. Drawing inspiration from Richard Feynman's challenge from decades ago, the paper emphasizes the shift from science fiction to reality in the development of microrobots. Soft microrobots, particularly those with adaptable configurations, present a promising avenue for seamless interaction with the intricate vasculature of the human body.
While bio-inspired microswimmers mimic natural motions, their inherent flaw lies in their sluggish speed. The paper explores the fundamental limitations imposed by fluid mechanics at the microscale, emphasizing the need for a compromise between biocompatibility and swimming performance.
The proposed approach, activating microbubbles through cyclic overpressure, offers a novel solution. By capitalizing on the anisotropy of lipid shells, the researchers induce a deflation-inflation pattern that results in controlled displacements. This innovative technique holds the potential to revolutionize drug delivery systems, providing specificity and sensitivity crucial for accurate drug delivery.
In conclusion, the research signifies a transformative step forward in the field of microswimmers. By unlocking the propulsive potential of lipid-coated microbubbles, the team has paved the way for controlled and efficient motion within the bloodstream, holding immense promise for the future of biomedical applications.
Coated microbulles swim via shell buckling
Communications Engineering 2, 63 (2023)
Georges Chabouh1, Marcel Mokbel2, Benjamin van Elburg3, Michel Versluis3, Tim Segers4, Sebastian Aland2, Catherine Quilliet1, and Gwennou Coupier1
1 CNRS/Université Grenoble-Alpes, LIPhy UMR 5588, Grenoble F-38401, France.
2 Technische Universität Bergakademie Freiberg, Akademiestrasse, 609599 Freiberg, Germany.
3 Physics of Fluids Group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
4 BIOS/Lab-on-a-Chip Group, Max Planck Center Twente for Complex Fluid Dynamics, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.