Stiffness-tunable velvet worm–inspired soft adhesive robot

Considering the characteristics and operating environment of remotely controlled miniature soft robots, achieving delicate adhesion control over various target surfaces is a substantial challenge. In particular, the ability to delicately grasp wrinkled and soft biological and nonbiological surfaces with low preload without causing damage is essential. The proposed adhesive robotic system, inspired by the secretions from a velvet worm, uses a structured magnetorheological material that exhibits precise adhesion control with stability and repeatability by the rapid stiffness change controlled by an external magnetic field. The proposed adhesion protocol involves controlling soft-state adhesion, maintaining a large contact area, and enhancing the elastic modulus, and the mechanical structure enhances the effectiveness of this protocol. Demonstrations of the remote adhesive robot include stable transportation in soft and wet organs, unscrewing a nut from a bolt, and supporting mouse tumor removal surgery. These results indicate the potential applicability of the soft adhesive robot in biomedical engineering, especially for targeting small-scale biological tissues and organisms.