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It takes two to tribo: Stochastic charge evolution in repeated binary collisions of acoustically levitated particles

Tom F. O'Hara1,*, Adrian C. Barnes2, James W. E. Drewitt2, Nathan Croll Dawes3, and Karen L. Aplin1

  • *Contact author: tom.ohara@bristol.ac.uk
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Phys. Rev. E 114, 045409 – Published 23 October, 2026

DOI: https://doi.org/10.1103/p9zp-hf26

Abstract

The mechanisms governing triboelectric charging between insulating particles of the same material remain an open question in nonequilibrium physics, with several competing models proposed to explain observed charging behavior. Here, we investigate charge evolution in a minimal system consisting of two acoustically levitated particles undergoing repeated binary collisions. To quantify particle charge transfer, purpose-built Faraday cage picoammeters were developed and calibrated. The MultiLev acoustic levitation system was used alongside Ultraino simulations to generate transducer control signals, enabling controlled collision and separation of polystyrene (PS) particles. Although individual collision events exhibit stochastic charge transfer, described by skew-normal distributions, we demonstrate that the cumulative charge evolution of an individual acoustically levitated particle pair follows the saturation behavior predicted by the condenser model of triboelectric charging, with fits achieving R2>0.99. Under identical conditions, conductive graphite-coated PS particles also undergo charge transfer, but accumulate substantially less charge, consistent with the distinct charging behavior expected for conductive materials.

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Physics Subject Headings (PhySH)

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Tiny Particles Charge Like Capacitors

Published 23 October, 2026

Lab experiments provide new details about the charge-transfer process that occurs in ash clouds and other collections of particles.

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Outline

Information

Phys. Rev. E 114, 045409– Published 23 October, 2026
  • Received 5 August 2026
  • Accepted 27 August 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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