Friction Properties Of Human Skin With Commonly Used Prosthetic Materials

By using CETR UMT-2 multi-functional Tribometer, friction test were performed on the LT skin of normal volunteers and tibia amputate skin of disabled volunteers under ball-on-flat contact at various load, with 4 kinds of commonly used prosthetics materials. Measurement of skin and material surface topography and surface roughness were performed on Laser Confocal Scanning Microscope (LCSM), type OLS1100. Measurement of the hydrophobic and hydrophilic characteristics of skin and materials were performed on Drop Shape Analysis System DSA100, video frequency contact angle apparatus. After the test was over, using the digital camera to photo the friction area of the skin surface. Friction property of skin and commonly used prosthetic materials were studied, primarily establish the frictional comfort evaluation standard of human skin and materials. Main conclusions are drawn as follows:1. Surface roughness of 6 positions on normal volunteers has been measured. Results for the volunteers of this study shows that, skin surface roughness of residual limb is higher than the normal LT skin. Hydrophobic and hydrophilic characteristics measurement result shows that, water contact angle sequence is: silicone rubber > sock > polythene > Acrylate, skin of normal volunteer > amputee.2. Friction test result shows that, friction coefficient between skin and material decreased with the increase of normal load. Under normal load of 0.3N and 0.7N, due to the particularity of silicon rubber and remarkable difference between normal and amputee skin, such as surface roughness, dryness and elasticity, friction coefficient of silicon rubber and amputee skin is higher than normal skin, and occupied the maximum value among all the materials. Under normal load of 8N, skin contact with all the materials are under cohesion condition, here the infection element had transfer from surface property of skin and material to the hypodermic and intramuscular correspond ability. Friction coefficient between skin and all the materials has no remarkable difference (P>0.05). Material surface roughness together with hydrophobic and hydrophilic characteristics has remarkable influence on friction coefficient. Differentia surface property of skin has less influence on friction coefficient.3. Primarily establish the frictional comfort evaluation standard of human skin and materials. Skin frictional comfort evaluation test result shows that, the main sensation after 30 min test is drag and slight pain. Normal volunteers feel heat when contact with silicon rubber and sock material. Silicon rubber is more comfort than other materials for all the volunteers, similar sensation produced when contact with polythene and sock.