Enhanced gravitational trapping of bottom-heavy Janus particles over parallel microgrooves.
basic_science · Level V
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- Record sourced from PubMed, PMID 39535213.
- Also identified by DOI 10.1039/d4sm00989d.
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Abstract
We report a systematic study on the barrier-crossing dynamics of bottom-heavy self-propelled particles (SPPs) over a one-dimensional periodic potential landscape <i>U</i><sub>0</sub>(<i>x</i>), which is fabricated on a microgroove-patterned polydimethylsiloxane (PDMS) substrate. From the measured steady-state probability density function (PDF) <i>P</i>(<i>x</i>;<b>F</b><sub><b>0</b></sub>) of the SPPs with different self-propulsion forces <b>F</b><sub><b>0</b></sub>, we find that the escape dynamics of slow-rotating SPPs over the periodic potential <i>U</i><sub>0</sub>(<i>x</i>) can be well described by an activity-dependent potential <i>Ũ</i><sub>0</sub>(<i>x</i>;<b>F</b><sub><b>0</b></sub>) under the fixed angle approximation. A theoretical model is developed to include the effects of the gravitational-torque-induced alignment on the polar angle <i>θ</i> and the hydrodynamic wall alignment on the azimuthal angle <i>φ</i> as well as their influence on the self-propulsion speed <i>v</i><sub>0</sub>. By introducing a proper average of the activity-dependent potential <i>Ũ</i><sub>0</sub>(<i>x</i>;<b>F</b><sub><b>0</b></sub>) over all possible particle orientations, our model explains the enhanced trapping effect on the bottom-heavy Janus particles. The obtained theoretical results are in good agreement with both the experimental and active Brownian particle simulation results. This work thus provides a thermodynamics description of the non-equilibrium barrier crossing of the Janus particles with nonuniform angular distributions over periodic potentials.