Embedded Material Additive Manufacturing in Yield-Stress Support Baths
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Solution Overview
Problem
Conventional 3D printing techniques struggle to deposit and support soft materials with low elastic moduli, such as hydrogels, without deformation or the need for additional supports, and maintain cell viability in controlled environments.
Innovation Solution
The method of Embedded Fusion Modeling (EFM) or Freeform Reversible Embedding of Suspended Hydrogels (FRESH) involves embedding materials within a support bath that transitions to a solid state post-deposition, using thermo-reversible materials like gelatin slurries to provide buoyant support and enable true freeform fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional 3D printing techniques are used to deposit soft materials with low elastic moduli, then the materials can be printed, but the materials deform or collapse under their own weight
Solution Approach 1:
The patent introduces a support bath material as an intermediary medium that temporarily supports soft printed materials during the printing process. The support bath has a yield stress that allows it to behave as a solid when supporting the printed material, preventing deformation and collapse under gravity, while allowing the printed material to be deposited and shaped without direct mechanical contact or rigid fixtures
Solution Approach 2:
The patent utilizes changes in the rheological parameters of both the support bath and printed materials. The support bath is designed with specific yield stress and viscosity characteristics that change based on temperature or composition, allowing it to transition from a flowing state during printing to a supportive solid state during fabrication. Similarly, printed soft materials may undergo gelation or crosslinking after deposition, changing their mechanical properties from fluid-like to solid-like
2Stability of the object's composition
If support materials are used to prevent deformation of soft structures during printing, then structural stability is improved, but the support materials must be removed afterward
Solution Approach 1:
The patent employs phase transitions of the support bath material to enable easy removal after printing. The support bath undergoes a phase change from a solid-like state (providing structural support during printing) to a liquid state (allowing easy removal). This is achieved through temperature changes, pH adjustments, or chemical treatments that cause the support bath to melt, dissolve, or degrade, leaving the printed structure intact without requiring mechanical removal processes
Solution Approach 2:
The support bath is designed as a temporary, disposable medium that serves its purpose during printing and then is easily removed or discarded. The support material is chosen to be inexpensive and readily removable through simple processes such as washing, melting, or degradation, making the overall manufacturing process easier despite the added step of support removal
3Manufacturing precision
If conventional AM techniques are used for freeform fabrication of tissues, then some structures can be created, but true tissue complexity with interpenetrating networks cannot be achieved
Solution Approach 1:
The patent introduces dynamic capabilities to the printing system, allowing the support bath properties and printing parameters to be adjusted in real-time during fabrication. This enables the creation of complex, multi-material, and multi-scale structures with interpenetrating networks by dynamically changing deposition patterns, material properties, and support bath conditions to accommodate varying geometric requirements throughout the printing process
Solution Approach 2:
The patent utilizes the third dimension and spatial relationships in novel ways to create complex tissue structures. By printing within the support bath environment, the system achieves true freeform fabrication capability, allowing interpenetrating networks and multi-layered structures that cannot be created with conventional layer-by-layer additive manufacturing. The support bath enables simultaneous support of multiple materials and geometries in three-dimensional space
4Reliability
If cells are kept alive during printing using controlled aqueous environments, then cell viability is maintained, but the printing process becomes more complex and expensive
Solution Approach 1:
The patent uses a homogeneous aqueous support bath environment that provides uniform conditions for cell viability throughout the printing process. The support bath composition is designed to be isotonic and physiologically compatible, providing consistent pH, ionic strength, and temperature control across the entire printing volume, eliminating the need for complex localized environmental control systems
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
EFM allows for the 3D printing of complex geometries with soft materials, maintaining structural integrity and cell viability, and enables the creation of anatomically correct scaffolds and tissues without destructive removal of supports.
Implementation Method 1
The provided support material is stationary at an applied stress level below a threshold stress level and flows at an applied stress level at or above the threshold stress level during fabrication of the structure
Implementation Method 2
The provided support material is stationary at an applied stress level below a threshold stress level and flows at an applied stress level at or above the threshold stress level
Implementation Method 3
The deposited structure material is suspended in the support material at a location where the structure material is deposited. The structure material comprises a fluid that transitions to a solid or semi-solid state after deposition of the structure material
Data Source
AI summary
In one aspect, a method includes providing support material within which the structure is fabricated, depositing, into the support material, structure material to form the fabricated structure, and removing the support material to release the fabricated structure from the support material. The provided support material is stationary at an applied stress level below a threshold stress level and flows at an applied stress level at or above the threshold stress level during fabrication of the structure. The provided support material is configured to mechanically support at least a portion of the structure and to prevent deformation of the structure during the fabrication of the structure. The deposited structure material is suspended in the support material at a location where the structure material is deposited. The structure material comprises a fluid that transitions to a solid or semi-solid state after deposition of the structure material.