Dielectrophoretic response and electro-deformation of soft bioparticles interacting with a metallo-dielectric Janus active particle

Active (self-propelling) particles have emerged as innovative microscale tools in the field of single cell analysis with the advantages of being untethered, remotely controlled, hybrid powered, with sub-cellular precision. This study investigates the dielectrophoretic (DEP) response and electro-mechanical deformation of cell nuclei interacting with active metallo-dielectric Janus Particles (JPs) under an externally applied electric field. An "equivalent droplet" two-phase model is employed to simulate the bioparticle, coupling the Navier-Stokes equations with the phase field model to capture fluid motion and interface dynamics. Good qualitative agreement is obtained among experimental, analytical, and numerical results. The findings reveal a nonlinear relationship between nucleus deformation and its surface coverage of the JP with respect to the applied voltage. The overall coverage ratio of the JP's dielectric hemisphere increases with voltage as the positive DEP force on the dielectric side strengthens, exhibiting a maximum at a certain voltage. The strong correlation between nucleus flexibility and JP surface coverage suggests that the JP coverage ratio could serve as a biomechanical marker for nucleus deformability, providing a novel method for <i>in situ</i> evaluation of nucleus mechanics.