Code used in the Publication "Coated microbubbles exploit shell buckling to swim" submitted to Nature Communications Engineering 2023

This is the code used for the simulations that have been performed for the Article "Coated microbubbles exploit shell buckling to swim" submitted to Nature Communications Engineering 2023 authored by Georges Chabouh, Marcel Mokbel, Benjamin van Elburg, Michel Versluis, Tim
Segers, Sebastian Aland, Catherine Quilliet, and Gwennou Coupier. Responsible for the code are Marcel Mokbel and Sebastian Aland.

Paper abstract:

Cleverly engineered microswimmers show great promise in various biomedical applications. Current realizations are generally
either too slow, hardly manoeuvrable, or non biocompatible. To overcome these limitations, we consider lipid coated microbub-
bles that are already approved for clinical use as diagnostic ultrasound contrast agents. Through a combination of experiments
and numerical simulations, we investigate the swimming motion of these microbubbles under external cyclic overpressure.
Reproducible and non-destructive cycles of deflation and re-inflation of the microbubble generate a net displacement, through
hysteretic buckling events. Our model predicts swimming speeds of the order of m/s, which falls in the range of blood flow
velocity in large vessels. Unlike the acoustic radiation force technique, where the displacement is always directed along the
axis of ultrasound propagation, here, the direction of propulsion is controlled in the shell reference frame. This provides a
solution toward controlled steering in ultrasound molecular imaging and drug delivery.