Shape-Reconfigurable Ferrofluids

Ferrofluids (FFs) can adapt their shape to a magnetic field. However, they cannot maintain their shape when the magnetic field is removed. Here, with a magneto-responsive and reconfigurable interfacial self-assembly (MRRIS) process, we show that FFs can be structured by a magnetic field and maintain their shape, like solids, after removing the magnetic field. The competing self-assembly of magnetic and nonmagnetic nano-particles at the liquid interface endow FFs with both reconfigur-ability and structural stability. By manipulating the external magnetic field, we show that it is possible to write and erase the shape of the FFs remotely and repeatedly. To gain an in-depth understanding of the effect of MRRIS on the structure of FFs, we systematically study the shape variation of these liquids under both the static and dynamic magnetic fields. Our study provides a simple yet novel way of manipulating FFs and opens opportunities for the fabrication of all-liquid devices.

Automated summary

Ferrofluids can form structures and maintain their shape in a magnetic field, exhibiting reconfigurability and structural stability. By manipulating the external magnetic field, the shape of ferrofluids can be remotely written and erased repeatedly. This study provides a new method for manipulating ferrofluids and opens possibilities for the fabrication of all-liquid devices.