Figure 1

Schematic representation of the Yoshida effect. The Yoshida effect is defined as the formation of complexes called penetrons, which are bacterial cells, each impaled by a single nano-sized acicular material in a friction field formed at a hydrogel interface. The hydrogel, interface forming material, nano-sized acicular material, bacterial cells, sliding friction, and an energy source to provide the friction force are each essential to the formation of penetrons. The hydrogel (e. g., agar, gellan gum, κ-karagenan) involved shear stress at more than 2.1 N. The interface forming material could comprise polymer material such as polystyrene, polyethylene, or acrylonitrile butanediene rubber. The optical vertical reaction force against hydrogel was around 40 gf/cm². Multi-walled carbon nanotube, maghemite, or α-sepiolite are each nano-sized acicular materials that can generate a Yoshida effect. The sliding friction force can be represented with the following formula: F = μW, where μ and W denote the frictional coefficient and the vertical reaction force, respectively. When using 2 and 5% agar hydrogel, frictional coefficient value increased 0.038 to 0.078 and 0.081 to 0.233 respectively by given sliding stimulus for 15 seconds. The rapid increase in frictional resistance was essential for the Yoshida effect.