2023-07-05 ノースカロライナ州立大学(NCState)
◆この金属ゲルは高い電気伝導性を持ち、電子部品やデバイスの製造に応用できる可能性があります。研究者たちは産業パートナーや共同研究先との協力を歓迎しており、将来の研究の方向性についても議論する意欲があると述べています。
＜関連情報＞
- https://news.ncsu.edu/2023/07/metallic-gel-for-3d-printing/
- https://www.sciencedirect.com/science/article/abs/pii/S259023852300303X?via%3Dihub
導電性3Dおよび4D印刷用金属ゲル Metallic gels for conductive 3D and 4D printing
Ruizhe Xing, Jiayi Yang, Dongguang Zhang, Wei Gong, Taylor V. Neumann, Meixiang Wang, Renliang Huang, Jie Kong, Wei Qi, Michael D. Dickey
Matter Published: July 5, 2023
DOI:https://doi.org/10.1016/j.matt.2023.06.015
Progress and potential
Four-dimensional (4D) printing refers to 3D-printed structures that change shape with respect to time in response to an external stimulus. To date, 4D printing techniques have focused primarily on electrically insulating materials such as polymers. Adding conductive fillers to polymers could increase the functionality of the printed parts, but the high loadings necessary to achieve conductivity represent a trade-off with printability. Here, we connect copper (Cu) particles with soft eutectic gallium indium alloy (EGaIn) bridges to form a conductive 4D printing ink (Cu-EGaIn) with gel-like properties that are well suited for printing. The final printed parts have a total metal content as high as 97.5 wt %, and the remainder is methylcellulose, a rheological modifier. The printed parts have an extremely high electrical conductivity (1.05 × 105 S/m) without requiring a sintering step. Cu-EGaIn addresses the contradiction between conductivity and printability and should open up new opportunities for electronic, thermal, and composite devices.
Summary
This paper reports printable metallic gels (pendular suspensions) consisting of an aqueous suspension of copper particles connected by bridges of liquid eutectic gallium indium alloy (EGaIn). Pendular suspensions rely on capillary forces to form networks between solid particles with a composition-dependent rheology, but prior studies have focused on insulating suspensions. Here, the rheology of a conductive solid-liquid-liquid suspension is tuned for 3D printing by varying the composition and the pH; the latter promotes metallic wetting. The dry printed parts have metallic electrical conductivity (<?XML:NAMESPACE PREFIX = “[default] http://www.w3.org/1998/Math/MathML” NS = “http://www.w3.org/1998/Math/MathML” />1.05×105 S/m) without requiring a sintering step. Drying at elevated temperatures can accelerate the removal of water while creating stress that drives shape change (i.e., 4D printing). As a demonstration, we print a conductive spider that lifts and assembles its own body from an initially flat shape. Such conductive inks are promising for printing metallic structures under ambient conditions.
