"Terminator" stills data map

The little robot changed from a solid state to a liquid state, passed through the "cage" under the guidance of a magnetic field, and re-solidified through a mold placed outside the railings, successfully "breaking out."

This kind of plot in the sci-fi movie "Terminator" appeared in the experiment of "Magnetic Control Solid-Liquid Phase Change Material" jointly proposed by Chinese and American scientists. The research was completed in collaboration with the Guangdong Provincial Key Laboratory of Sensing Technology and Biomedical Instruments at Sun Yat-sen University, the State Key Laboratory of Fluid Power and Electromechanical Systems at Zhejiang University, and the Soft Robotics Laboratory at Carnegie Mellon University. Related research papers were recently published in the international journal Matter.

Solid-liquid-gas state "switching freely"

A phase transition is the transition of matter from one state to another. Phase change materials refer to materials that can switch between solid, liquid and gas states.

One of the corresponding authors of the paper, Professor Jiang Lelun of Sun Yat-sen University, told the Science and Technology Daily reporter that according to the chemical composition, phase change materials can be divided into inorganic phase change materials using inorganic substances such as metal alloys and inorganic salts, and organic phase change materials using organic substances such as paraffin and polyols. Phase change materials and composite phase change materials.

Since phase change materials absorb or release a large amount of energy when they undergo a phase change, a typical application of phase change materials is energy storage.

"Phase change materials mainly use latent heat energy storage, which has the characteristics of high heat storage density, compact structure of heat storage device, basically unchanged temperature during phase change process, and easy management. Its application scenarios include solar energy storage systems, air conditioning and cold storage systems Wait." Jiang Lelun said.

Another application of phase change materials is heat transfer. "Heat pipes can use internal working fluids, such as water, alcohol, etc., to achieve a reversible phase change from liquid to gas. During this process, heat pipes will absorb and release a large amount of heat and become efficient heat transfer elements. At present, heat pipes have Widely used in notebook CPU heat dissipation, high-power electronic components heat dissipation and other fields." Jiang Lelun said.

Strong rigidity in solid state, deformable in liquid state

"We propose a magnetically controlled solid-liquid phase change material. The main source of inspiration is the movie "Terminator" and animal sea cucumbers." Jiang Lelun said, "The hand of the liquid metal robot in "Terminator" can be switched between solid and liquid. At the same time, the robot can also become a liquid and then escape. Sea cucumbers are also very interesting, and can change the shape of the body wall by changing the hardness of the protein-rich interfibrillar matrix."

The magnetron solid-liquid phase change material is manufactured on the basis of liquid metal. According to Jiang Lelun, liquid metal can usually switch between solid and liquid at lower ambient temperatures, and is an inorganic phase change material.

In order to make full use of the solid-liquid switching characteristics of liquid metals under specific conditions, the research team mixed magnetic particles, such as NdFeB, Fe_3O_4, etc., into the liquid metal gallium. Heated by a high-frequency magnetic field, the liquid metal will change from a solid state to a liquid state. After it turns into a liquid state, the research team can cool it down through semiconductor refrigeration (Peltier effect) or natural cooling, so that it can change from a liquid state to a solid state.

"Through an external magnetic field, we can perform complex manipulations on the movement, deformation, splitting, healing, etc. of the magnetron liquid metal solid-liquid phase change material. In addition, the phase change material also has high thermal conductivity and electrical conductivity, and can also pass Alloying adjusts the phase transition temperature." Jiang Lelun said. It is understood that this magnetically controlled solid-liquid phase change material has high stiffness in the solid state, and can be like water in the liquid state, combining the advantages of solid and liquid metals.

During the research process, the team encountered many challenges, from how to quickly cool the liquid metal to how to make the material biocompatible. "Finally, through continuous adjustment and refinement of the formula, we have achieved faster cooling of the material, and it is expected to be applied in the human body in the future." Jiang Lelun said.

It is expected to be applied in industry

Jiang Lelun introduced that the magnetron solid-liquid phase change materials will be applied in three aspects in the future.

One is the repair of electronic circuits. "In a magnetic field environment, a robot made of a magnetron solid-liquid phase change material can push electronic components into a closed inoperable space. After heating, the robot changes from a solid state to a liquid state to weld these electronic components, thereby repairing circuit." Jiang Lelun said.

The second is the assembly of parts. The robot made of magnetron solid-liquid phase change material, under the guidance of the magnetic field, arrives at the damaged position, heats and liquefies and deforms into a universal screw through the alternating magnetic field, and then fixes the two parts to complete the damaged part assembly.

The third is the application in biomedicine. "For example, after a child swallows some foreign objects by mistake, we can use the magnetic control solid-liquid phase change material to wrap the foreign objects after liquefaction, and then take out the foreign objects after solidification." Jiang Lelun said, "In addition, this phase change material can also be used in the solid state. The drug is encapsulated down, and the drug can be released in a fixed-point and controlled manner after liquefaction."

Jiang Lelun told reporters that the magnetically controlled liquid metal solid-liquid phase change material has a relatively high technical maturity in the repair of electronic circuits and the assembly of parts, and it is expected to be quickly applied in industry. However, in the field of biomedicine, such as the extraction of foreign substances in the human body and the controlled release of drugs, it is still immature, especially the biocompatibility and safety need to be further verified.

"In the next few years, we will further carry out safety tests on magnetically controlled solid-liquid phase change materials, and at the same time combine image navigation technology to realize the controllable, Visible manipulation and drug release will bring the research results to the clinic," Jiang Lelun said.

(Original title "Robot "Prison Break" After Liquefied, The Terminator Comes True")