In soft robotics, gripper technology based on granular jamming offers the capability to adapt flexibly to objects of diverseshapes and material properties. Specifically, small-scale jamming grippers can address tasks challenging for conventionalgrippers either by enhancing gripping performance or by extending functionality when combined with rigid grippers. Thisstudy investigated effects of membrane morphology, thickness, and material on performances of small-scale jamminggrippers to identify optimal design parameters. Experiments were conducted with three membrane morphologies, twothickness levels, and two material types. Results indicated that a concentric-pocket membrane morphology, a membranethickness of 1.5 mm, and a soft material such as Dragon Skin 10 achieved a superior holding force of 430.7 gf. Thesefindings indicate that softer materials can improve the membrane's ability to conform to objects, while increasing thicknesscan minimize deformation due to tensile forces, thereby enhancing gripping stability. Furthermore, experimentsdemonstrated that this configuration could enable the gripper to safely grasp objects of various shapes and performadditional tasks, such as rotating valves and handles, with effectiveness.
