Researchers develop highly conductive metallic gel for 3D printing

Researchers has achieved a significant breakthrough in 3D printing technology by developing a metallic gel that exhibits high electrical conductivity. This remarkable innovation allows for the creation of three-dimensional solid objects at room temperature in a single printing step. The research paper titled “Metallic Gels for Conductive 3D and 4D Printing” has been published in the prestigious journal Matter.

According to Michael Dickey, the co-corresponding author of the paper and the Camille & Henry Dreyfus Professor of Chemical and Biomolecular Engineering at North Carolina State University, previous technologies did not enable the printing of 3D metal objects at room temperature without multiple steps. This groundbreaking advancement paves the way for manufacturing various electronic components and devices.

To fabricate the metallic gel, the scientists initiate the process with a solution containing micron-scale copper particles suspended in water. They then introduce a small quantity of an indium-gallium alloy, which remains in a liquid state at room temperature. The resulting mixture is thoroughly stirred.

During the stirring process, the liquid metal and copper particles adhere to each other, forming a network of metallic gel within the aqueous solution. The gel-like consistency plays a crucial role by ensuring a uniform distribution of copper particles throughout the material. This has two essential effects: the formation of electrical pathways through the interconnected particles and the prevention of particle settling, which could obstruct the printer.

The resulting gel can be conveniently printed using a standard 3D printing nozzle and retains its shape upon printing. Moreover, when left to dry naturally at room temperature, the printed 3D object becomes even more robust while maintaining its shape.

However, applying heat to the printed object during the drying process leads to intriguing outcomes. The researchers discovered that the alignment of the particles influences the drying behavior of the material. For instance, if a cylindrical object is printed, its sides contract more than the top and bottom during drying. This phenomenon does not cause any structural changes when drying at room temperature due to the slow drying process. However, if heat is applied—for instance, by placing the object under an 80°C heat lamp—the rapid drying can induce controlled structural deformations. This means that by manipulating the printing pattern and the amount of heat exposure during drying, it is possible to alter the shape of a printed object after it is created.

Dickey emphasizes that this development represents a four-dimensional printing technique, incorporating the traditional three dimensions plus time. This new capability offers additional flexibility in creating structures with desired dimensions. However, the most exciting aspect of this material lies in its conductivity.

The printed objects consist of up to 97.5% metal, resulting in high electrical conductivity. While they may not match the conductivity of conventional copper wire, the ability to 3D print copper wire at room temperature is currently impossible. Nevertheless, the conductivity of the developed material surpasses any other printable alternatives. The potential applications of this breakthrough are vast and hold great promise.

Dickey expresses openness to collaborations with industry partners to explore potential applications and welcomes discussions with potential collaborators regarding future research directions.

Source: North Carolina State University

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