This paper proposes a 4D printed untethered milli-gripper fabricated using an ink composed of a biocompatible and biodegradable chitosan hydrogel and biocompatible citric acid-coated superparamagnetic iron oxide nanoparticles (SPION). untethered milli-gripper that can be actuated by electric and magnetic fields. Therefore, a cargo delivery is demonstrated in which the untethered milli-gripper grips or release a cargo under the electric field and moves it to the desired position under the magnetic field. In addition, untethered milli- gripper can delivery cargoes of various shapes, and numbers. Furthermore, all materials that composed the untethered milli-gripper are biocompatible, and chitosan is also biodegradable.
