An investigation of human palmar skin friction and the effects of materials, pinch force and moisture

Abstract

A study was conducted to determine the friction characteristics for various materials against human palmar skin. Seven materials were tested using two pinchforce levels under both moist and dry conditions. Using a two-fingered pinch grip, subjects held a specially designed dynamometer covered with one of the test materials. They maintained a constant pinch force as load force was increased at a constant rate until the dynamometer slipped from their fingers. The load force at the slip point was then used to determine the coefficient of friction from Amonton's Law. The: effects of subject, material, moisture, pinch force and the materialmoisture and pinch iorce-moisture interactions were all significant. The coefficient of friction decreased with increased levels of pinch force for every material-moisture combination. The coefficient of friction for porous materials showed a significant increase when moisture was present. This information may be applicable in tool handle and work station surface design.

Scopolamine increases prehensile force during object manipulation by reducing palmar sweating and decreasing skin friction

“…For textures which have very small surface areas in contact with the skin, or where there is sufficient moisture to form a lubricating boundary layer between the skin and the surface, the coefficient of friction will be reduced (Comaish and Bottoms 1971;Highley et al 1977;Nacht et al 1981). However, most studies of moisture on the skin indicate that hydration of the cells of the stratum corneum substantially increases skin adhesiveness to most surfaces (Cussler et al 1977;Highley et al 1977;Wolfram 1983;Gerrard 1987;Buchholz et al 1988). The data from the present study suggest that, in general, subjects are able to detect and compensate for losses in skin friction due to changes in the intrinsic mechanical properties of the skin itself.…”

“…Altering the friction of the skin has also been the subject of extensive study by the cosmetic industry, and these investigations have clearly demonstrated that moisture, and in particular sweat, can increase skin friction (Cussler et al 1977;Highley et al 1977;Wolfram 1983;Gerrard 1987;Buchholz et al 1988). Gerrard (1987 found that water alone increased the friction of skin on smooth steel from 0.20 to 0.70.…”

Digit cooling influences grasp efficiency during manipulative tasks

“…Sensory information signalling object weight and surface texture is also used to economically scale fingertip forces during dynamic manipulation of a hand-held object. Sensory feedback is used to update the internal neural representation of the physical object properties, such as weight, surface texture and shape (Buchholz et al 1988;Cadoret and Smith 1996;Johansson and Westling 1984), gained during prior manipulative experience with similar objects. Recently, we demonstrated that the absence of sensory feedback from the grasping digits during digit anaesthesia results in an uneconomical increase of grip forces during arm movements with a grasped object (Nowak et al 2001).…”

Frictional Properties of Human Forearm and Vulvar Skin: Influence of Age and Correlation with Transepidermal Water Loss and Capacitance

“…First, friction is the force that enables man to work with objects in his environment, which, with out friction, would slip through his fingers. The occupa tional dermatologist may assist in the design of tools by advising on optimal skin-tool interfaces (1,2]. Secondly, cosmetic products may influence tactile skin properties (smoothness, greasiness), which correspond to frictional properties.…”