Metal

Selective laser melting

Calcination

Catalysis

Mathematics education

Polymerization

Polymer chemistry

Curing (chemistry)

Fabrication

Metallurgy

Materials science

Layer (electronics)

3D printing

Biochemistry

Photopolymer

Polymer

Alternative medicine

Nanotechnology

Self-healing hydrogels

Mathematics

Microstructure

Composite material

Microscale chemistry

Sintering

Medicine

Chemistry

Pathology

Nature

Metal additive manufacturing (AM) enables the production of high value and high performance components1 with applications from aerospace2 to biomedical3 fields. Layer-by-layer fabrication circumvents the geometric limitations of traditional metalworking techniques, allowing topologically optimized parts to be made rapidly and efficiently4,5. Existing AM techniques rely on thermally initiated melting or sintering for part shaping, a costly and material-limited process6–8. We report an AM technique that produces metals and alloys with microscale resolution via vat photopolymerization (VP). Three-dimensional-architected hydrogels are infused with metal precursors, then calcined and reduced to convert the hydrogel scaffolds into miniaturized metal replicas. This approach represents a paradigm shift in VP; the material is selected only after the structure is fabricated. Unlike existing VP strategies, which incorporate target materials or precursors into the photoresin during printing9–11, our method does not require reoptimization of resins and curing parameters for different materials, enabling quick iteration, compositional tuning and the ability to fabricate multimaterials. We demonstrate AM of metals with critical dimensions of approximately 40 µm that are challenging to fabricate by using conventional processes. Such hydrogel-derived metals have highly twinned microstructures and unusually high hardness, providing a pathway to create advanced metallic micromaterials. An additive manufacturing technique that infuses 3D printed hydrogels with metallic precursors leads to metallic micromaterials, providing new opportunities for the fabrication of energy materials, micro-electromechanical systems and biomedical devices.

Additive manufacturing of micro-architected metals via hydrogel infusion