Multi-scale Direct Ink Writing Technology
Direct ink writing (DIW) is an extrusion-based additive manufacturing technology. In DIW, the raw material is prepared into a viscoelastic ink and extruded as a continuous filament from a printing nozzle robotically controlled as per the designed computer-aided design (CAD) model. It allows for customization and accurate structural control of the geometric shape as well as the internal structure of the strut. Emerging at the interface of multiple research fields, DIW features an attractive multi-scale control capability from nano to macroscales via combinations of material, structural and manufacturing engineering approaches for the fabrication of advanced materials.
T Li†, Q Liu†, H Qi, W Zhai*, Prestrain programmable 4D printing of nanoceramic composites with bioinspired microstructure, Small. 2022 Sep 30:2204032, link In this work, we proposes a conventional combination of bioinspired microstructure design and a programmable prestrain approach for 4D printing of nanoceramics. To overcome the flexibility limitation, the bioinspired concentric cylinder structure in the struts of 3D printed lattices are replicated to develop origami nanoceramic composites with high inorganic content (95 wt%). Furthermore, 4D printing is achieved by applying a programmed prestrain to the printed lattices, enabling the desired deformation when the prestrain is released. Due to the bioinspired concentric cylinder microstructures, the printed flexible nanoceramic composites exhibit superior mechanical performance and anisotropic thermal management capability. Further, by introducing oxygen vacancies to the ceramic nanosheets, conductive nanoceramic composites are prepared with a unique sensing capability for various sensing applications. |
G Li, X Dong, AR Chuan, BW Chua, L Tao, W Zhai*, Bio-inspired tubular hierarchical porous materials with selective liquids absorption, Virtual and Physical Prototyping. 2022 Oct 28;18(1):e2129395, link In this work, we developed a one-step coaxial direct ink writing process, using silicone emulsion as the sample material. Hierarchical emulsion-tube-lattice (ETL) material, comprised of the lattice structure, tubular struts, and porous walls were produced. The ETL material possesses high oil absorption and retention capacity, and could allow the water of the water-oil mixture to pass through while absorbing the oil. Besides, the sample could reuse after squeezing out the oil and keep the soft mechanical properties. The materials showed promising application in water–oil separation and storage. |
Q Liu, W Zhai*, Hierarchical porous ceramics with distinctive microstructures by emulsion-based direct ink writing, ACS Applied Materials & Interfaces, 2022 July 5, link In this study, we developed emulsion-based direct ink writing by introducing gelling additives for facile preparation of 3D printable viscoelastic inks and effective modification of the microstructure of 3D printed hierarchical porous ceramics. The hierarchical porous ceramic lattices exhibited high porosity of 73.7% – 79.3% with compressive strength of 1.53 – 9.61 MPa and specific energy absorption of 0.33 – 2.67 J/g. Featuring two distinctive microstructures with tunable structural features and mechanical properties, the 3D printed hierarchical porous ceramics have potential in many applications, including lightweight structures, tissue engineering scaffolds, filtration, etc. |
Q Liu, WF Lu, W Zhai*, Toward stronger robocast calcium phosphate scaffolds for bone tissue engineering: A mini-review and meta-analysis, Materials Science and Engineering: C. 2021 Nov 29; 112578, link Direct ink writing (robocasting) has been extensively used for the fabrication of calcium phosphate scaffolds, but most of these 3D printed scaffolds do not meet the mechanical requirements for load-bearing bone tissue engineering applications. Applying the Gibson-Ashby model, this review performed a meta-analysis of the published literature on the compressive strength of robocast calcium phosphate scaffolds. Furthermore, this review evaluated different approaches to the mechanical strengthening of the robocast calcium phosphate scaffolds. Insightful data and analysis were provided for future research on mechanical strengthening of robocast calcium phosphate scaffolds and ultimately for their clinical applications. |