In this episode, we're joined by Dr. Ognjen Ilic, a leading scientist in the field of acoustic waves and metasurfaces, to discuss how waves exert force on obstacles in their path and how this can be manipulated. Conventionally, the radiation force exerted by waves is limited by the shape and size of the objects being manipulated. Dr. Ilic, however, has made a breakthrough discovery that challenges this fundamental rule.

Dr. Ilic explains how subwavelength-structured surfaces (metasurfaces) allow for the control of the radiation force exerted by acoustic waves, independent of the object's overall shape and size. The manipulation of this force is solely determined by the arrangement of the surface features on the metasurface.

We delve into Dr. Ilic's fascinating experiments demonstrating how this anomalous metasurface scattering can enable complex actuation phenomena such as self-guidance and tractor beaming. In self-guidance, a metasurface object is autonomously guided by an acoustic wave, while in tractor beaming, a metasurface object is pulled by the wave.

Join us as Dr. Ilic uncovers how the principles of metasurface acoustics can be applied to the domain of mechanical manipulation, ushering in new frontiers in contactless actuation and enabling diverse mechanisms that surpass the traditional limits of wave-matter interactions.

Key Words: Metasurface Acoustics, Acoustic Waves, Radiation Force, Anomalous Metasurface Scattering, Self-Guidance, Tractor Beaming, Contactless Actuation.

Stein, M., Keller, S., Luo, Y. et al. Shaping contactless radiation forces through anomalous acoustic scattering. Nat Commun 13, 6533 (2022). https://doi.org/10.1038/s41467-022-34207-7