なぜ猫を撫でると静電気が起こるのか?(Why petting your cat leads to static electricity)

2024-09-19

2004-09-18 ノースウェスタン大学

ノースウェスタン大学の研究者が、物体を擦ることで静電気が発生するメカニズムを解明しました。物体の前後で異なる力が働き、異なる電荷が蓄積され、これが静電流を生み出すというものです。古代ギリシャの哲学者タレスが初めて摩擦による静電気を発見して以来、長らく未解明でしたが、今回の研究で「弾性せん断」という概念が静電気発生の鍵であることが判明しました。この発見は、静電気による火災などの防止にも応用が期待されています。

<関連情報>

トライボ電気に「トライボ」を入れるものは何か? What Puts the “Tribo” in Triboelectricity?

Karl P. Olson,and Laurence D. Marks
Nano Letters Published: September 17, 2024
DOI:https://doi.org/10.1021/acs.nanolett.4c03656

Abstract

An enduring question in science has been why sliding plays a major role in the triboelectric generation of static electricity–the “tribo” in triboelectricity. We provide here a general explanation which is rooted in established science. When sliding is taking place, there is symmetry breaking due to elastic shear, so the front of the sliding body experiences different elastic strains from the back. Consequently the polarization and associated charges at the front and back are not the same, and the difference between the two leads to current flow similar to the difference in air pressure above and below a plane’s wing leading to lift. Specific calculations are provided which show good agreement with prior experimental measurements of size and shape dependencies, and reasonable quantitative agreement with experimental current measurements.

フレキソ電気はトライボ電気を駆動するか? Does Flexoelectricity Drive Triboelectricity?

C. A. Mizzi, A. Y. W. Lin, and L. D. Marks
Physical Review Letters Published 12 September 2019
DOI:https://doi.org/10.1103/PhysRevLett.123.116103

Abstract

The triboelectric effect, charge transfer during sliding, is well established but the thermodynamic driver is not well understood. We hypothesize here that flexoelectric potential differences induced by inhomogeneous strains at nanoscale asperities drive tribocharge separation. Modeling single asperity elastic contacts suggests that nanoscale flexoelectric potential differences of ±1–10 V or larger arise during indentation and pull-off. This hypothesis agrees with several experimental observations, including bipolar charging during stick slip, inhomogeneous tribocharge patterns, charging between similar materials, and surface charge density measurements.