The ability to manipulate colloidal structures is crucial for further development of dynamically responsive self-assembled materials such as microrobots and some striking new features of this approach, which imitates the operation of much more complex biological and technological machines but with remarkably simple and inexpensive constituents, are the abilities to control assembly shape and locomotion in response to external stimuli.
The materials consist of magnetic microparticles confined between two non-mixing liquids which self-assemble into miniature star-like structures—asters—when energized by a magnetic field. By manipulating the magnetic field, individual asters and aster arrays can be directed to open and close around a target particle, swim and then release the captured particle as a desired location. This discovery potentially may influence the design and fabrication of materials with self-repair, multi-tasking and reconfiguring capabilities.
Read the paper, “Magnetic manipulation of self-assembled colloidal asters”, published in Nature Materials.