Using optical tweezers to simultaneously trap, charge and measure the charge of a microparticle in air

2025/07/23 by Andrea Stoellner, Stoellner, Andrea, Isaac C. D. Lenton +20
Engineering · Physics and Astronomy · #Experimental and Theoretical Physics Studies #FOS: Physical sciences #Microfluidic and Bio-sensing Technologies #Optics (physics.optics) #Soft Condensed Matter (cond-mat.soft)

paper · pdf · doi:10.48550/arxiv.2507.17591

openalex publication_date 2025/07/23 · openalex created_date 2025/10/16 · openalex updated_date 2026/07/28

Abstract

Optical tweezers are widely used as a highly sensitive tool to measure forces on micron-scale particles. One such application is the measurement of the electric charge of a particle, which can be done with high precision in liquids, air, or vacuum. We experimentally investigate how the trapping laser itself can electrically charge such a particle, in our case a ∼ 1 μm SiO₂ sphere in air. We model the charging mechanism as a two-photon process which reproduces the experimental data with high fidelity.

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