Hybrid Magnetic Hydrogels Used as Artificial Marine Animals for Noncontact Cleaning

Abstract

Here, we developed a one-step method to prepare a highly tough and magnetic (1.2 emu g–1) polyacrylamide-Fe3O4-alginate (PAAM-Fe3O4-ALG) double-network hydrogel. Magnetic Fe3O4 nanoparticles (MNPs) were intercalated into the double network, producing Fe3O4-intercalated hydrogels with ferromagnetism. These kinds of magnetic hydrogels are endowed with good mechanical properties, such as high tensile strength (90 kPa) and superior compressive strength (0.9 MPa). Although such gels contain 20 mg mL–1 magnetic nanoparticles, they could still be stretched more than eight times their original length. The noncontact soft robot, which is a magnetically driven hydrogel, was demonstrated. Two typical soft robots (a scallop and a starfish) were prepared with magnetic hydrogels. Under external magnetic stimulation, these soft robotic marine animals could clean a fish tank without the help of a hand in the water. This approach will extend the application of hydrogels in various fields, such as controlled drug delivery, underwater cleaning robots, and other integrated hydrogel devices.