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Evidence of topological charge polarization at active-passive interfaces in acoustically powered active liquid crystals

Andrey Sokolov1,*, Tadej Emersic2, Paul Nealey2, Juan de Pablo2, and Alexey Snezhko1

  • *Contact author: sokolov@anl.gov
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Phys. Rev. Research 8, 023060 – Published 20 April, 2026

DOI: https://doi.org/10.1103/nzfb-3cps

Abstract

Theoretical and computational studies predict topological charge separation at active-passive interfaces in active nematics, but reliable experimental validation has been lacking. We utilize a synthetic acoustically energized liquid crystal to experimentally investigate the dynamics of topological defects across an active-passive interface. The interference pattern induced by the acoustic wave inside the experimental cell creates a spatial distribution of activity, resulting in the formation of active-passive interfaces with the liquid-crystalline director field aligned parallel to those interfaces. The activity gradient drives the reorientation of positively charged topological defects along its direction, causing them to migrate into the passive zone and form a layer with net topological charge. That layer “discharges” upon cessation of activity through annihilation of positive and negative topological charges, resembling the discharge of a capacitor.

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References (42)

  1. S. P. Thampi, R. Golestanian, and J. M. Yeomans, Instabilities and topological defects in active nematics, Europhys. Lett. 105, 18001 (2014).
  2. L. Giomi, M. J. Bowick, P. Mishra, R. Sknepnek, and M. Cristina Marchetti, Defect dynamics in active nematics, Philos. Trans. R. Soc. A 372, 20130365 (2014).
  3. T. Sanchez, D. T. N. Chen, S. J. DeCamp, M. Heymann, and Z. Dogic, Spontaneous motion in hierarchically assembled active matter, Nature (London) 491, 431 (2012).
  4. S. Zhou, A. Sokolov, O. D. Lavrentovich, and I. S. Aranson, Living liquid crystals, Proc. Natl. Acad. Sci. USA 111, 1265 (2014).
  5. M. V. Kurik and O. D. Lavrentovich, Defects in liquid crystals: Homotopy theory and experimental studies, Sov. Phys. Usp. 31, 196 (1988).
  6. A. Doostmohammadi, J. Ignés-Mullol, J. M. Yeomans, and F. Sagués, Active nematics, Nat. Commun. 9, 3246 (2018).
  7. S. Shankar, S. Ramaswamy, M. C. Marchetti, and M. J. Bowick, Defect unbinding in active nematics, Phys. Rev. Lett. 121, 108002 (2018).
  8. S. Shankar and M. C. Marchetti, Hydrodynamics of active defects: From order to chaos to defect ordering, Phys. Rev. X 9, 041047 (2019).
  9. N. Kumar, R. Zhang, S. A. Redford, J. J. de Pablo, and M. L. Gardel, Catapulting of topological defects through elasticity bands in active nematics, Soft Matter 18, 5271 (2022).
  10. L. Giomi, M. J. Bowick, X. Ma, and M. C. Marchetti, Defect annihilation and proliferation in active nematics, Phys. Rev. Lett. 110, 228101 (2013).
  11. M. M. Genkin, A. Sokolov, O. D. Lavrentovich, and I. S. Aranson, Topological defects in a living nematic ensnare swimming bacteria, Phys. Rev. X 7, 011029 (2017).
  12. S. J. DeCamp, G. S. Redner, A. Baskaran, M. F. Hagan, and Z. Dogic, Orientational order of motile defects in active nematics, Nat. Mater. 14, 1110 (2015).
  13. F. C. Keber, E. Loiseau, T. Sanchez, S. J. DeCamp, L. Giomi, M. J. Bowick, M. C. Marchetti, Z. Dogic, and A. R. Bausch, Topology and dynamics of active nematic vesicles, Science 345, 1135 (2014).
  14. L. Giomi, Geometry and topology of turbulence in active nematics, Phys. Rev. X 5, 031003 (2015).
  15. D. J. G. Pearce, J. Nambisan, P. W. Ellis, A. Fernandez-Nieves, and L. Giomi, Orientational correlations in active and passive nematic defects, Phys. Rev. Lett. 127, 197801 (2021).
  16. D.-Q. Zhang, P.-C. Chen, Z.-Y. Li, R. Zhang, and B. Li, Topological defect-mediated morphodynamics of active–active interfaces, Proc. Natl. Acad. Sci. USA 119, e2122494119 (2022).
  17. M. M. Genkin, A. Sokolov, and I. S. Aranson, Spontaneous topological charging of tactoids in a living nematic, New J. Phys. 20, 043027 (2018).
  18. A. Mozaffari, R. Zhang, N. Atzin, and J. J. De Pablo, Defect spirograph: Dynamical behavior of defects in spatially patterned active nematics, Phys. Rev. Lett. 126, 227801 (2021).
  19. L. J. Ruske and J. M. Yeomans, Activity gradients in two- and three-dimensional active nematics, Soft Matter 18, 5654 (2022).
  20. S. Shankar, L. V. D. Scharrer, M. J. Bowick, and M. C. Marchetti, Design rules for controlling active topological defects, Proc. Natl. Acad. Sci. USA 121, e2400933121 (2024).
  21. A. Partovifard, J. Grawitter, and H. Stark, Controlling active turbulence by activity patterns, Soft Matter 20, 1800 (2024).
  22. R. Zhang, S. A. Redford, P. V. Ruijgrok, N. Kumar, A. Mozaffari, S. Zemsky, A. R. Dinner, V. Vitelli, Z. Bryant, M. L. Gardel, et al., Spatiotemporal control of liquid crystal structure and dynamics through activity patterning, Nat. Mater. 20, 875 (2021).
  23. K. V. S. Chaithanya, A. Ardaševa, O. J. Meacock, W. M. Durham, S. P. Thampi, and A. Doostmohammadi, Transport of topological defects in a biphasic mixture of active and passive nematic fluids, Commun. Phys. 7, 302 (2024).
  24. A. Sokolov, J. Katuri, J. J. de Pablo, and A. Snezhko, Synthetic active liquid crystals powered by acoustic waves, Adv. Mater. 37, 2418846 (2025).
  25. J. Katuri, A. Snezhko, and A. Sokolov, Motility of acoustically powered micro-swimmers in a liquid crystalline environment, Soft Matter 18, 8641 (2022).
  26. R. A. Simha and S. Ramaswamy, Hydrodynamic fluctuations and instabilities in ordered suspensions of self-propelled particles, Phys. Rev. Lett. 89, 058101 (2002).
  27. S. Ramaswamy and M. Rao, Active-filament hydrodynamics: Instabilities, boundary conditions and rheology, New J. Phys. 9, 423 (2007).
  28. Ž. Krajnik, Ž. Kos, and M. Ravnik, Spectral energy analysis of bulk three-dimensional active nematic turbulence, Soft Matter 16, 9059 (2020).
  29. C. Rorai, F. Toschi, and I. Pagonabarraga, Coexistence of active and hydrodynamic turbulence in two-dimensional active nematics, Phys. Rev. Lett. 129, 218001 (2022).
  30. See Supplemental Material at http://link.aps.org/supplemental/10.1103/nzfb-3cps for additional figures, notes, and videos.
  31. S. Ramaswamy, The mechanics and statistics of active matter, Annu. Rev. Condens. Matter Phys. 1, 323 (2010).
  32. E. Putzig, G. S. Redner, A. Baskaran, and A. Baskaran, Instabilities, defects, and defect ordering in an overdamped active nematic, Soft Matter 12, 3854 (2016).
  33. S. Ramaswamy, Active matter, J. Stat. Mech. (2017) 054002.
  34. M. O. Lavrentovich and L. Tran, Undulation instabilities in cholesteric liquid crystals induced by anchoring transitions, Phys. Rev. Res. 2, 023128 (2020).
  35. A. Sokolov, A. Mozaffari, R. Zhang, J. J. De Pablo, and A. Snezhko, Emergence of radial tree of bend stripes in active nematics, Phys. Rev. X 9, 031014 (2019).
  36. M. E. Cates and J. Tailleur, Motility-induced phase separation, Annu. Rev. Condens. Matter Phys. 6, 219 (2015).
  37. J. Tailleur and M. E. Cates, Statistical mechanics of interacting run-and-tumble bacteria, Phys. Rev. Lett. 100, 218103 (2008).
  38. M. P. Magiera and L. Brendel, Trapping of interacting propelled colloidal particles in inhomogeneous media, Phys. Rev. E 92, 012304 (2015).
  39. A. Sharma and J. M. Brader, Brownian systems with spatially inhomogeneous activity, Phys. Rev. E 96, 032604 (2017).
  40. J. Grauer, H. Löwen, and L. M. C. Janssen, Spontaneous membrane formation and self-encapsulation of active rods in an inhomogeneous motility field, Phys. Rev. E 97, 022608 (2018).
  41. R. Zhang, A. Mozaffari, and J. J. de Pablo, Logic operations with active topological defects, Sci. Adv. 8, eabg9060 (2022).
  42. X. Tang and J. V. Selinger, Alignment of a topological defect by an activity gradient, Phys. Rev. E 103, 022703 (2021).

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Phys. Rev. Research 8, 023060– Published 20 April, 2026
  • Received 19 August 2025
  • Accepted 22 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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