The innovation engine for new materials

Madeleine Allen

Madeleine Allen


University of California, Santa Barbara



Site Abroad: 

Leibniz Institute for New Materials, Saarbruecken, Germany


Eduard Arzt
René Herzel

Faculty Sponsor(s): 

Roland Bennewitz

Project Title: 

Friction Measurements for Haptic Exploration of Microstructured Samples

Project Description: 

Haptics is the study of how humans perceive and explore materials using touch. The friction coefficient is used in haptics to quantify the interactions between materials and skin. In this project, 10 different test subjects haptically evaluated various combinations of 11 microstructured samples and 6 non-structured samples. The focus of the experiment was to determine the friction coefficient of the samples as a function of material and structure, skin moisture, contact area, and anisotropy in the sample. A custom-built apparatus used spring forces to measure and record data on lateral forces and normal forces. A corneometer was used to record skin moisture. The patterns that emerged in the data analysis revealed that different people have distinct trends that ranged from .5 for individuals with the lowest friction coefficients to 2.0 for individuals with the highest friction coefficients on a normalized scale. Once skin moisture was accounted for, the relative friction coefficients for each sample became consistent, ranging from .5 to 2.2 on a normalized scale. The friction coefficient is also proportional to the shear stress, and to a lesser extent, to the contact area involved in the haptic exploration. Additionally, it was discovered that the coefficient of friction for all of the samples is the most directionally dependent when only a small amount of normal force is applied to the structures, but overall the effect of anisotropy on the friction coefficient was limited.