# gst: controlling particles with sound waves

<< Contactless manipulation of particles and cells using sound radiation forces that can be tuned and adjusted in real time has become important in various applications  (display tech, biomed sensors, imaging devices, diagnostic tools) >>

AA << use phononic crystals to tune sound fields in a microfluidic channel for controllable manipulation of microparticles and cells. An arbitrary stop-and-go motion of particles and cells along a predefined path in the channel is experimentally demonstrated. >>

Fei Li, Feiyan Cai, et al.  Phononic-Crystal-Enabled Dynamic Manipulation of Microparticles and Cells in an Acoustofluidic Channel.  Phys. Rev. Applied 13, 044077. Apr 30, 2020.

https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.13.044077

Controlling Particle Movements with Sound Waves. Physics 13, s58. Apr 30, 2020.

https://physics.aps.org/articles/v13/s58

# gst: weird matter, the 'ballistic resonance' paradox; amplitude of mechanical vibrations can grow without external influence

AA << discovered a new physical phenomenon of 'ballistic resonance', where mechanical oscillations can be excited only due to internal thermal resources of the system. >>

<< The discovered phenomenon describes that the process of heat equilibration leads to mechanical vibrations with an amplitude that grows with time. The effect is called ballistic resonance. >>

<< Over the past few years, our scientific group has been looking into the mechanisms of heat propagation at the micro and nano levels. We found out that at these levels, heat doesn't spread in the way we expected it to: for example, heat can flow from cold to hot. This behavior of nanosystems leads to new physical effects, such as ballistic resonance, >> Vitaly Kuzkin.

Scientists have discovered a new physical paradox. Peter the Great Saint-Petersburg Polytechnic University. Jul 13, 2020.

https://phys.org/news/2020-07-scientists-physical-paradox.html

<< coupling between macroscopic dynamics and quasiballistic heat transport gives rise to mechanical vibrations with growing amplitude. This phenomenon is referred to as ballistic resonance. At large times, these mechanical vibrations decay monotonically >>

Vitaly A. Kuzkin, Anton M. Krivtsov. 

Ballistic resonance and thermalization in the Fermi-Pasta-Ulam-Tsingou chain at finite temperature. Phys. Rev. E 101, 042209. Apr 16, 2020.

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.101.042209