Miniature soft robot with magnetically reprogrammable surgical functions

Miniature robots are untethered actuators, which have significant potential to make existing minimally invasive surgery considerably safer and painless, and enable unprecedented treatments because they are much smaller and dexterous than existing surgical robots. Of the miniature robots, the magnetically actuated ones are the most functional and dexterous. However, existing magnetic miniature robots are currently impractical for surgery because they are either restricted to possessing at most two on-board functionalities or having limited five degrees-of-freedom (DOF) locomotion. Some of these actuators are also only operational under specialized environments where actuation from strong external magnets must be at very close proximity (< 4 cm away). Here we present a millimeter-scale soft robot where its magnetization profile can be reprogrammed upon command to perform five surgical functionalities: drug-dispensing, cutting through biological tissues (simulated with gelatin), gripping, storing (biological) samples and remote heating. By possessing full six-DOF motions, including the sixth-DOF rotation about its net magnetic moment, our soft robot can also roll and two-anchor crawl across challenging unstructured environments, which are impassable by its five-DOF counterparts. Because our actuating magnetic fields are relatively uniform and weak (at most 65 mT and 1.5 T/m), such fields can theoretically penetrate through biological tissues harmlessly and allow our soft robot to remain controllable within the depths of the human body. We envision that this work marks a major milestone for the advancement of soft actuators, and towards revolutionizing minimally invasive treatments with untethered miniature robots that have unprecedented functionalities.