Development and validation of a new method for measuring friction between skin and nonwoven materials

• Published in: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine Journal of engineering in medicine, 2008-07, Vol.222 (5), p.791-803
• Main Authors: Cottenden, A M, Wong, W K, Cottenden, D J, Farbrot, A
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Arms; Coefficient of friction; Coefficient of variation; Correlation; Diapers, Adult; Drying; Equipment Failure Analysis - methods; Fabrics; Female; Forearm; Friction; Humans; Incontinence Pads; Male; Materials Testing - methods; Nonwoven fabrics; Pressure; Reproducibility; Reproducibility of Results; Sensitivity and Specificity; Skin; Skin friction; Skin Physiological Phenomena; Standard deviation; Static friction; Textiles; Time measurement; Urinary incontinence
• ISSN: 0954-4119; 2041-3033
• DOI: 10.1243/09544119JEIM313

A new method for measuring the coefficient of friction between nonwoven materials and the curved surface of the volar forearm has been developed and validated. The method was used to measure the coefficient of static friction for three different nonwoven materials on the normal (dry) and over-hydrated volar forearms of five female volunteers (ages 18–44). The method proved simple to run and had good repeatability: the coefficient of variation (standard deviation expressed as a percentage of the mean) for triplets of repeat measurements was usually (80 per cent of the time) less than 10 per cent. Measurements involving the geometrically simpler configuration of pulling a weighted fabric sample horizontally across a quasi-planar area of volar forearm skin proved experimentally more difficult and had poorer repeatability. However, correlations between values of coefficient of static friction derived using the two methods were good (R = 0.81 for normal (dry) skin, and 0.91 for over-hydrated skin). Measurements of the coefficient of static friction for the three nonwovens for normal (dry) and for over-hydrated skin varied in the ranges of about 0.3–0.5 and 0.9–1.3, respectively. In agreement with Amontons' law, coefficients of friction were invariant with normal pressure over the entire experimental range (0.1–8.2 kPa).