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Contact electrification of individual dielectric microparticles measured by optical tweezers in air.



Haesung Park, Thomas W. LeBrun


We have measured the charging of a dielectric microparticle after interacting with a glass substrate using optical tweezers to control the particle, measure its charge with sensitivity of a few electrons and precisely position the particle on the substrate. Polystyrene (PS) microparticles adhered to the substrate can be selected based on size, shape, or optical properties and repeatedly loaded into the optical trap using a piezoelectric (PZT) transducer in a controlled manner. These separations from the substrate lead charge transfer between the particle and substrate through contact electrification. The charge on the trapped microparticles is easily measured from the transient response of the particle motion to a step excitation of a uniform electric field. The particle is then placed onto a desired location of the substrate in a controlled manner. Thus, the triboelectric charging profile of the selected PS microparticle can be measured through repeated cycles of trap loading followed by charge measurement. Reversible optical trap loading and manipulation of the selected particle leads to new capabilities to study and control successive and small changes in surface interactions.
ACS Applied Materials and Interfaces


contact electrification, optical tweezers, charge measurement, microparticles


Park, H. and LeBrun, T. (2016), Contact electrification of individual dielectric microparticles measured by optical tweezers in air., ACS Applied Materials and Interfaces, [online], (Accessed May 21, 2024)


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Created November 28, 2016, Updated October 12, 2021