Wet Adhesion of Micro-patterned Interfaces for Stable Grasping of Deformable Objects

Stable grip of wet, deformable objects is a challenging task for robotic grasping and manipulation, especially for food products' handling. The wet, slippery interfaces between the object and robotic fingers may require larger gripping force, resulting in higher risk of damaging the grasped object. This research aims to evaluate the role of micro-patterned soft pad on enhancement of wet adhesion in grasping a food sample in wet environment. We showcased this scenario with a tofu block 19.6×19.6×15mm3 that is soft, and deformable object, gripped by a soft robotic gripper with two fingers. Each fingertip's surface, which directly makes contact with the tofu, was deposited soft pads in two cases: normal pads (flat surface) and a micropatterned pads. The micropatterned pad comprises of 14400 square cells, each cell has four 85 µm edges, surrounded by a channel network with 44 µm in depth. We conducted estimation of grasped force generated by pads in two cases, then verified by actual setup in griping the tofu block. Both estimated and experimental results reveal that the micropatterned pad decreased necessary load acting on the tofu’s surface 2.2 times lower than that of the normal one, while maintaining the stability of the grasped tofu. The showcase in this paper supported the potential of micro patterns on soft fingertip in grasping deformable objects in wet environments without complicated control strategy, promising wider applications for robot in service section or food industry.