Functionally Graded 3D Printed Foams With Controlled Void Architecture
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Solution Overview
Problem
Direct ink write (DIW) 3D printing faces challenges with void formation due to air entrapment during extrusion, affecting the mechanical and functional properties of printed structures, particularly in the case of liquid metal (LM) emulsions, where existing methods lack control over void content and material architecture.
Innovation Solution
A DIW process is developed to control both material architecture and LM microstructure by leveraging threshold nozzle print heights for creating porous structures with tunable stiffness and programmable LM microstructure, using precise control of print parameters to manipulate LM droplet orientation and geometric architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DIW printing is used to extrude liquid metal emulsions, then the printing process can be performed, but void formation occurs due to air entrapment during extrusion
Solution Approach 1:
The patent applies parameter changes by systematically varying nozzle height, extrusion pressure, and print speed to optimize the extrusion process. By adjusting these parameters, the method achieves controlled void formation or elimination depending on the desired structure, resolving the contradiction between reliable void control and ease of extrusion manufacturing
Solution Approach 2:
The patent intentionally creates porous structures with controlled porosity by adjusting printing parameters. This transforms the harmful void formation into a controlled material property, where the porous structure becomes a design feature rather than a defect, improving reliability while maintaining manufacturing ease
2Manufacturing precision
If nozzle height is increased to reduce surface roughness, then surface quality improves, but ink fracture occurs above a certain threshold height
Solution Approach 1:
The patent applies dynamics by making the nozzle height a variable parameter that can be dynamically adjusted during printing. Different nozzle heights are used at different stages or regions to balance surface quality and ink continuity, allowing the system to adapt to different printing requirements and resolve the contradiction between surface quality and ink strength
Solution Approach 2:
The patent determines optimal nozzle height thresholds before printing based on material properties and desired outcomes. This preliminary characterization of the relationship between nozzle height, surface roughness, and ink fracture allows for proactive parameter selection that prevents both excessive roughness and ink fracture
3Adaptability or versatility
If liquid metal microdroplets are aligned through shear-induced alignment, then anisotropic functional properties are achieved, but control over material architecture is lost
Solution Approach 1:
The patent applies local quality by enabling different regions of the printed structure to have different material architectures and liquid metal orientations. By controlling printing parameters locally, the method achieves both anisotropic functional properties in specific regions and precise overall material architecture control, resolving the contradiction between adaptability and manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the creation of functionally graded foams with improved surface quality, reduced density, and enhanced thermal conductivity, while maintaining geometric fidelity, suitable for applications in soft robotics and wearable electronics.
Implementation Method 1
Recently, shear-induced alignment has also been demonstrated during DIW printing of a variety of ink compositions and fillers such as liquid metal (LM) microdroplets. The alignment of the fillers allows for the creation of programmed anisotropic functional properties in a printed article.
Implementation Method 2
Direct ink write (DIW) three-dimensional (3D) printing is an additive manufacturing technique that allows for precisely controlled fabrication of intricate structures by extrusion of high-viscosity fluids through a fine nozzle.
Implementation Method 3
The occurrence of voids within a DIW printed structure is common. Voids can arise from entrapment of air during the extrusion process.
Data Source
AI summary
Embodiments of functionally graded pure and composite 3D printed articles having nonporous regions and porous regions are described. In one example, a printed composite article includes a polymer matrix including a porous region. The printed composite article further includes a plurality of liquid metal elements embedded in the polymer matrix. In another example, a printed article includes a polymer matrix including a nonporous region and a porous region adjacent to and at least partly integrated with or coupled to the nonporous region. The porous region includes porous polymer material having an increasing porosity or a decreasing porosity in at least one direction relative to a longitudinal axis of at least one of the polymer matrix or the printed article.