Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
Tribology Group, Department of Mechanical Engineering, Imperial College London, London SW7 2AZ, UK.
J R Soc Interface. 2022 Mar;19(188):20210783. doi: 10.1098/rsif.2021.0783. Epub 2022 Mar 23.
Human beings often explore and perceive the characteristics of objects by touching with their fingers. During this process, the contact pressure and shear stress acting on the skin also modulate the tactile sensation. The external environment is an important factor that influences tactile perception as well as the finger friction characteristics. The purpose of this study was to investigate the effects of fluid environments, such as air, deionized water (DW) and thickened water (TW), on perceived roughness and relevant friction behaviour during finger movement. Two studies were performed to analyse the effect of fluid environment as well as the influence of lubricant viscosity on finger tactile friction behaviour. Participants conducted perception and sliding friction tests with their index finger in air and submerged in DW and TW, respectively. Perception tests were performed using a pairwise comparison, scoring the perceived roughness difference between a reference sample and the test sample. The statistical analysis showed that there was no significant difference in the roughness perception between air and DW, while the sensitivity of perception reduced with increasing lubricant viscosity. An approximate calculation of the film thickness was combined with classical lubrication theory to investigate the relationship between perception and friction. In TW, the thick film formed between the finger and the polytetrafluoroethylene plate changed the contact of the asperities with the skin, thus changing the subjective judgement and friction.
人类通常通过手指触摸来探索和感知物体的特性。在这个过程中，作用于皮肤的接触压力和切向应力也会调节触觉。外部环境也是影响触觉感知以及手指摩擦特性的重要因素。本研究旨在探讨空气、去离子水（DW）和稠化水（TW）等流体环境对指部运动时感知粗糙度和相关摩擦行为的影响。进行了两项研究，以分析流体环境的影响以及润滑剂粘度对指部触觉摩擦行为的影响。参与者分别在空气和 DW 以及 TW 中用食指进行感知和滑动摩擦测试。感知测试采用成对比较的方法，对参考样本和测试样本之间的感知粗糙度差异进行评分。统计分析表明，空气和 DW 之间的粗糙度感知没有显著差异，而感知灵敏度随着润滑剂粘度的增加而降低。通过近似计算薄膜厚度并结合经典润滑理论，研究了感知与摩擦之间的关系。在 TW 中，手指和聚四氟乙烯板之间形成的厚膜改变了凸起与皮肤的接触，从而改变了主观判断和摩擦。
