Fig. 6: Graftable end-effector: Airway foreign body removal.

a Illustration of the foreign body removals at the airway. b The design principle of the graftable end-effector. The end-effector consists of a P-root and four N-stems with F-tips. Red arrows denote the magnetization profile of N-stems. c The end-effector can respond to external magnetic fields, performing opening and grasping motions. To provide sufficient grasping forces, the F-tips of the end-effector can bond to each other by self-mergences and unlock by self-divisions. Scale bar: 1 cm. d Foreign body removal process at an ex vivo pig bronchi system. (i) The end-effector was inserted into the trachea and approached the foreign body. (ii) Responding to an external magnetic field, the end effector opened and covered the object without any disturbances. (iii) The end-effector grasped the foreign body and locked its F-tips to firmly constrain the object. (iv) The object was stably removed by pulling the P-root. Scale bar: 1 cm. e–g Objects with different properties were successfully removed. ① Objects with high surface energy can be removed by the bonding strategy. ② An animal tissue with low surface energy can be removed by the grasping strategy. ③ A sharp body can be removed by the bonding strategy of a single N-stem. Scale bar: 1 cm. h A case showing the necessity of the tip locking. Without the locking, tips were observed with insufficient force to remove the object. Testing results showed that the end-effector with a lock can gain ~400% strength enhancement than that without a lock. i In situ gripper assembling by regrafting and alignment strategy. The processes include (i) navigating through the glottis to the trachea under magnetic guidance, (ii-v) multiple times regrafting and alignment to structure an end-effector, (vi) grasping under magnetic actuation, and (vii) shape locking for removal.