In transfer printing, robotics, and precision manufacturing, adhesion-controlled grasping of complex 3D surfaces is very challenging. Current adhesion systems are limited by a fundamental trade-off between 3D surface conformability and high adhesion strength.
In this work, we overcome this trade-off with an adhesion-based soft-gripping system that exhibits enhanced fracture strength without sacrificing conformability to nonplanar 3D surfaces. Composed of a gecko-inspired elastomeric microfibrillar adhesive membrane supported by a pressure-controlled deformable gripper body (a), the proposed soft-gripping system controls the bonding strength by changing its internal pressure and exploiting the mechanics of interfacial equal load sharing (b).
The soft adhesion system enabling manipulation of various objects with complex 3D geometries (c) such as convex or concave curvatures (I-IV), slightly rough (V) and deformable surfaces (VI). In general, the pull-off force of the soft adhesive system increases when the initial pressure decreases. The soft adhesion system can use up to $\sim$ 26\% of the maximum adhesion of the fibrillar membrane, which is $14\times$ higher than the adhering membrane without load sharing. Our proposed load-sharing method does not only enhance adhesion but also leads to an area scaling law similar to that of the natural geckos$'$ adhesive system. Such area scalability suggests that improved interfacial load sharing is critical when grasping 3D nonplanar geometries.
The proposed system pushes the upper limit on the maximum adhesion-controlled gripping strength and outperforms previous microfibrillar adhesive systems in handling complex 3D and deformable objects and surfaces.