Shear stress measured on three different cushioning materials

Shear stress measured on three different cushioning materials 1 Summary Shear force is an important component of the mechanical load on a person that is supported by a surface. Too high shear force leads to occlusion of blood flow, which is seen as one of the most important factors behind pressure sores and discomfort. In the present study the influence of three different cushioning materials (LiquiCell of LiquiCell Technologies, Inc., gel and foam) on shear stress is evaluated with the shear sensor from the Erasmus University of Rotterdam. It is concluded that the LiquiCell cushion produces significant lower shear stress than the foam cushion in situations when a shear force acts forward (P=0.001), backward (P=0.038) and in the horizontal position of the seat (P=0.005). When using LiquiCell instead of foam there is a reduction of shear stress varying from 28% to 39%. It is concluded that the LiquiCell cushion produces significant lower shear stress than the gel cushion in situations when a shear force acts backward (P=0.038) and at the P=0.10-level in the horizontal position of the seat (P=0.07) and when the shear force acts forward (P=0.07). When using LiquiCell instead of gel there is a reduction of shear stress varying from 24% to 25%. No significant differences were found between the gel cushion and the foam cushion.