Superparamagnetic hydrogels for Two-Photon Polymerization and their application for the fabrication of swimming microrobots

This work reports on superparamagnetic hydrogel composites suitable for Two-Photon Polymerization (TPP) and their application for the fabrication of helical swimming microrobots, also known as Artificial Bacterial Flagella (ABFs). Suitable hydrogel compositions consisting of multifunctional monomers were identified based on percolation theory and prepared accordingly. Hydrogel ABFs 28 μm in length and 3 μm in diameter were fabricated and actuated in DI water. The investigated hydrogel (polyethylene glycol (PEG)) is of particular interest to the biomedical MEMS community. PEG can absorb/release water-soluble drugs and is highly resistant to protein adsorption. The combination of PEG and superparamagnetic nanoparticles enables corkscrew propulsion of ABFs, making them ideal candidates for biomedical applications in vivo and in vitro.