Shape stabilization and laser triggered shape transformation of magnetic particle functionalized liquid metal motors

Liquid metal motors made from biologically benign gallium are promising candidates for various applications ranging from drug delivery to targeting and killing cancer cells directly. One of the main problems with this novel technology is the need to utilize a membrane, making it possible to maintain a defined shape in order to perform the required functions. For magnetic remote guidance, liquid metal motors can be doped with magnetic iron microparticles, forming a transition magnetic liquid. In an alternative approach liquid metal structures are coated with magnetite nanoparticles. We hereby present an approach to laminate biologically benign gallium-based magnetic liquid metal motors with a biodegradable and biocompatible macromolecular thin film to retain the initial shape. Thanks to the polymer lamination and by the help of magnetic fields, the presented liquid metal motors can be remotely guided. The shape retaining macromolecular thin film can be liquefied by photothermal effects such as laser irradiation in order to change the shape of the liquid metal motor into a droplet due to surface energy minimization, allowing for penetration of structures smaller than the initial motor size. This work uses a relatively large technical demonstrator to show the technical realization and properties of this novel system, which opens up new paths and potential applications.