  Soft and lightweight grippers have greatly enhanced the performance of
robotic manipulators in handling complex objects with varying shape, texture,
and stiffness. However, the combination of universal grasping with passive
sensing capabilities still presents challenges. To overcome this limitation, we
introduce a fluidic soft gripper, named the ``Pac-Man'' gripper, based on the
buckling of soft, thin hemispherical shells. Leveraging a single fluidic
pressure input, the soft gripper can encapsulate slippery and delicate objects
while passively providing information on this physical interaction. Guided by
analytical, numerical, and experimental tools, we explore the novel grasping
principle of this mechanics-based soft gripper. First, we characterize the
buckling behavior of a free hemisphere as a function of its geometric
parameters. Inspired by the free hemisphere's two-lobe mode shape ideal for
grasping purposes, we demonstrate that the gripper can perform dexterous
manipulation and gentle gripping of fragile objects in confined environments.
Last, we prove the soft gripper's embedded capability of detecting contact,
grasping, and release conditions during the interaction with an unknown object.
This simple buckling-based soft gripper opens new avenues for the design of
adaptive gripper morphologies with applications ranging from medical and
agricultural robotics to space and underwater exploration.
