Last week, a video went viral with a Lego doll of the liquid metal Terminator T-1000; Recreate the scene from the movie Terminator 2: Judgment Day (1991) where he escapes from a cell through bars. A liquid metal (gallium) covered with neodymium-iron-boron (NdFeB) ferromagnetic particles was used; Since it is not a shape memory material, a mold was used so that the doll would regain its shape. It is published in the journal Theme (Click on the cell) as a magnetic material with a solid-liquid phase transition. The Lego doll moves using a magnet (static magnetic field); To melt it, it is heated using a changing magnetic field; The liquid passes through bars guided by a magnet that takes it in until it falls into the mould; There it regains its shape when cooled to room temperature; The whole process takes about 8 minutes (500 seconds). Besides this curiosity, this type of material promises multiple applications in welding and intelligent assembly, drug delivery, drug extraction, and object manipulation in robotics, among many others.
This magnetic liquid metal called MPTM for The magnetic transition, it has good mechanical properties in the solid state; It has a mechanical stress of 21.2 MPa (MPa) and a Young’s modulus of 1.98 GPa (GPa), which can support a weight of up to 30kg. In addition, in the liquid state it shows great morphological adaptability (the ability to elongate, divide and fuse). Various applications of this new material are presented in the article. Since gallium appears to be biocompatible, the new material may be biocompatible, which is why it is suggested that it be used to pick up foreign bodies in the stomach and take medications. It is also proposed to be used as a replacement for screws (in the article they are called universal screws) and for soldering electronic circuits. In these applications, gallium is not a good liquid metal, as it has a melting point of 30 °C; The authors of the article suggest using other liquid metals in such applications (but do not use them in their study), such as Bi32.5sn16.5in51 (62 °C) from Bi58sn42 (138 ° C). Undoubtedly, magnetically active liquid metals hold promise, but it is still a long time before we see them in practical applications.
This article could have gone unnoticed if the authors had not had the happy idea to recreate the Lego T-1000 and the famous movie scene. The article is very easy to read, so I recommend that you enjoy Qingyuan Wang, Chengfeng Pan, …, Lilon Jiang, “solid-solid magnetic phase transition material,” issue (January 25, 2023), doi: https://doi.org/10.1016/j.matt.2022.12.003. For those interested in biomedical applications, I recommend consulting Sen Chen, Ruiqi Zhao, …, Jing Liu, “Toxicity and Biocompatibility of Liquid Metals,” Advanced Healthcare Materials 12:2201924 (24 Jan 2023), doi: https://doi.org/10.1002/adhm.202201924.
This video combines all of the Supplementary Information videos for the article. The motion of a small cube of the new material can be controlled by a magnet so that it follows a path; With two independently controlled elements, you can manipulate an object; He can even jump over obstacles (if the person controlling the magnet is skilled at it). Of course, the most striking is the famous viral video of the T-1000 (watch how the liquid falls into the mold). In the end you have some applications in soldering general circuits and screws, removing foreign bodies in model stomach and dosage of medicines.
As usual with this type of article, the authors suggest that their material is inspired by nature; In this case in sea cucumbers or sea cucumbers they therefore take the opportunity to include a photo Holothuria arginensis And a funny cartoon. However, the idea of embedding tiny magnets in liquid metal does not seem to require biological inspiration. Small magnets allow movement to be controlled (by applying a constant external magnetic field) and facilitate heating of liquid metal so that it melts (by applying a changing magnetic field).
Biomedical applications of new materials always have two major limitations: the biocompatibility (which has not yet been demonstrated for the new material) and the enormous complexity of real biology (compared to models typically used in experiments). It seems to me that a liquid metal that can leave droplets inside the body is not promising.
The application that seems most logical to me is universal bolting and welding in intricate places, where it is easier for liquid to enter. But having to use magnets is a big challenge, because the magnetic field decreases very quickly with distance. In addition, liquid metals that can withstand much higher temperatures than the gallium used in these experiments are required. There’s not much to say about the article in Matter, which gives very little technical information about the new material, limiting itself to talking about its potential applications (with gaming experiences). It will be necessary to be familiar with this material. But in the meantime, maybe it’s time to enjoy the video that went viral again.