Influence of grasping postures on skin deformation of hand

Abstract

Abstract To investigate the influence of different grasping postures on the hand’s skin deformation, a handheld 3D EVA SCANNER was used to obtain 3D models of 111 women in five postures, including a straight posture and grasping cylinders with various diameters (4/6/8/10 cm). Skin relaxation strain ratio ( $${\lambda }_{p}$$ λ p ) and surface area skin relaxation strain ratio ( $${\lambda }_{m}$$ λ m ) were used as measures of skin deformation between two landmarks and multiple landmarks, respectively. The effects of grasping posture on skin deformation in different directions were analyzed. The results revealed significant variations in skin deformation among different grasping postures, except for the width of middle finger metacarpal and the length of middle finger’s proximal phalanx. The $${\lambda }_{p}$$ λ p increased with decreasing grasping object diameter, ranging from 5 to 18% on the coronal axis, and from 4 to 20% on the vertical axis. The overall variation of $${\lambda }_{m}$$ λ m ranged from 5 to 37.5%, following the same trend as $${\lambda }_{p}$$ λ p except for the surface area of tiger’s mouth, which exhibited a maximum difference of 10.9% with significant differences. These findings have potential applications in improving the design of hand equipment and understanding hand movement characteristics.