A New Phenomenon of Ni–Ti Alloys and Its Application for Fabricating Thermally Responsive Microrobots

Ni–Ti alloys are widely applied in various fields due to their good biocompatibility and special shape memory function. To date, to make the Ni–Ti alloy ferromagnetic, the commonly used method is to add Fe or Ni particles to the Ni–Ti alloy. Within the knowledge, no reports have reported that the Ni–Ti alloys can possess ferromagnetism without adding magnetic particles. In the first half of this article, a process that can produce ferromagnetism in Ni–Ti alloys and explain the principle of the new process according to the Ni–Ti binary phase diagram is reported. On the other hand, magnetic micro‐robots have received widespread attention recent years and laser powder bed fusion (LPBF) technology makes it possible to fabricate Ni–Ti micro‐robots. The remainder of this article introduces a type of thermally responsive micro‐robot, which is fabricated by the LPBF technology and combined with this new Ni–Ti alloy phenomenon. Experiments are performed to confirm that Ni–Ti micro‐robots have the ability to transport cargo and target delivery under the control of an external magnetic field. The combination of this new Ni–Ti alloy phenomenon and LPBF technology can provide a new avenue for manufacturing magnetic micro‐robots.