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Metallic gel for 3D printing
Researchers have developed a metallic gel that is highly electrically conductive and can be used to print three-dimensional ( 3D ) solid objects at room temperature .
“ 3D printing has revolutionised manufacturing , but we ’ re not aware of previous technologies that allowed you to print 3D metal objects at room temperature in a single step ,” said Michael Dickey , co-corresponding author of a paper on the work and the Camille & Henry Dreyfus Professor of Chemical and Biomolecular Engineering at North Carolina State University , USA . “ This opens the door to manufacturing a wide range of electronic components and devices .”
To create the metallic gel , the researchers start with a solution of micron-scale copper particles suspended in water . The researchers then add a small amount of an indium-gallium alloy that is liquid metal at room temperature . The resulting mixture is then stirred together .
As the mixture is stirred , the liquid metal and copper particles essentially stick to each other , forming a metallic gel “ network ” within the aqueous solution .
“ This gel-like consistency is important , because it means you have a fairly uniform distribution of copper particles throughout the material ,” Dickey said . “ This does two things . First , it means the network of particles connect to form electrical pathways . And second , it means that the copper particles aren ’ t settling out of solution and clogging the printer .”
The resulting gel can be printed using a conventional 3D printing nozzle and retains its shape when printed . And , when allowed to dry at room temperature , the resulting 3D object becomes even more solid while retaining its shape .
However , if users decide to apply heat to the printed object while it is drying , some interesting things can happen . The researchers found that the alignment of the particles influences how the material dries . For example , if you printed a cylindrical object , the sides would contract more than the top and bottom as it dries . If something is drying at room temperature , the process is sufficiently slow that it doesn ’ t create structural change in the object . However , if you apply heat –
A metallic spider , with glowing LED on its head , sits on a white table .
for example , put it under a heat lamp at 80 degrees Celsius – the rapid drying can cause structural deformation .
“ Because this deformation is predictable , that means you can make a printed object change shape after it is printed by controlling the pattern of the printed object and the amount of heat the object is exposed to while drying . Video of the metallic gel printing and drying process can be found at https :// youtu . be / xFxo1Ah8EAc ,” explained North Carolina State University .
“ Ultimately , this sort of four-dimensional printing – the traditional three dimensions , plus time – is one more tool that can be used to create structures with the desired dimensions ,” Dickey added . “ But what we find most exciting about this material is its conductivity . Because the printed objects end up being as much as 97.5 % metal , they are highly conductive . It ’ s obviously not as conductive as conventional copper wire , but it ’ s impossible to 3D print copper wire at room temperature . And what we ’ ve developed is far more conductive than anything else that can be printed ,” he continued .
“ We ’ re pretty excited about the applications here . We ’ re also open to working with industry partners to explore potential applications and are always happy to talk with potential collaborators about future directions for research ,” Dickey concluded .
The paper , “ Metallic Gels for Conductive 3D and 4D Printing ”, is published in the journal ‘ Matter ’. First author of the paper is Ruizhe Xing , a former visiting scholar at NC State who is affiliated with Northwestern Polytechnical University and Tianjin University . Cocorresponding authors of the paper are Dickey , at NC State , and Renliang Huang and Wei Qi of Tianjin University .
The paper was co-authored by Jiayi Yang , a former visiting scholar at NC State , now at Xi ’ an University of Science and Technology ; Dongguang Zhang , a former visiting scholar at NC State , now at Taiyuan University of Technology ; Wei Gong , a former visiting scholar at NC State , now at the National University of Singapore ; Taylor Neumann , a former Ph . D . student at NC State ; Meixiang Wang , a postdoctoral researcher at NC State ; and Jie Kong of Northwestern Polytechnical University .
The work was done with support from the National Natural Science Foundation of China , under grant number 52203101 , and from the China Scholarship Council , under grant number 201906250075 . n
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