Controlling Particle Aggregation and Separation in Liquid on Membrane Resonators

We design a dual-mode membrane resonator for non-invasively and fast manipulating microparticle aggregation and separation in liquid. By performing finite element modeling, we verify that the interaction between a pair of microspheres (d=20 μm, mimicking cancer cells) can be precisely controlled on our proposed rectangular membrane resonator. The model consists of Multiphysics coupling between mechanical vibration, fluid flow, and particle tracing. Stokes drag, acoustic radiation, and particle-particle interaction forces are analyzed to predict the microparticle trajectory (including aggregation and separation). When exciting the rectangular membrane (100×50 μm) at its 1
^st
mode (f
1,1
), a pair of microspheres are observed to aggregate at the device center (antinode of f
1,1
). While switching to its 2
^nd
mode (f
2,1
), the 2 microspheres tend to separate towards the opposite directions to 2 antinodes of f
2,1
. Our proposed membrane platform holds promise for high-precision, acoustically manipulating and analyzing cellular interactions in liquid.