Embedded Hydrogel Printing With Shear-Thinning 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 during the printing process.
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, using thermo-reversible materials like gelatin slurries, to provide buoyant support during printing, followed by removal at controlled temperatures.
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 due to lack of structural support
Solution Approach 1:
A support bath material acts as an intermediary medium that provides buoyant support to soft hydrogel structures during printing. The support bath material has a density matched to the hydrogel, allowing the soft material to be deposited without collapsing while maintaining structural integrity throughout the printing process.
Solution Approach 2:
The density and viscosity parameters of the support bath material are carefully adjusted to match and slightly exceed the hydrogel properties. This parameter matching enables the support bath to provide adequate buoyant support while allowing easy removal after printing by changing temperature or chemical conditions.
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 after printing adding process complexity
Solution Approach 1:
The support bath material undergoes a phase transition from solid-like to liquid-like state through temperature change or chemical treatment. This phase transition allows the support material to be easily removed from the printed structure after printing without damaging the hydrogel, reducing overall process complexity despite providing structural support during printing.
3Productivity
If conventional printing methods are used for soft hydrogels, then printing can be performed, but cell viability cannot be maintained due to lack of pH, ionic, temperature, and sterility control
Solution Approach 1:
The support bath serves multiple functions simultaneously: it provides structural support during printing, maintains pH and ionic composition for cell viability, controls temperature, and ensures sterility. This multi-functionality allows conventional printing hardware to be used while maintaining high cell viability throughout the printing process.
4Ease of manufacture
If FDM techniques are used to print hydrogels, then some tissue structures can be created, but true freeform fabrication capability is limited
Solution Approach 1:
The support bath material acts as a universal intermediary that enables true freeform fabrication of any hydrogel structure regardless of geometric complexity. Unlike FDM that requires layer-by-layer deposition with support structures, the support bath allows direct freeform printing of complex anatomical structures with interpenetrating networks of tubes, membranes, and protein fibers.
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
Enables true freeform fabrication of complex geometries with soft materials, maintaining structural integrity and cell viability, and allows for the creation of anatomically correct scaffolds and tissues.
Implementation Method 1
The support bath material is configured to provide buoyant support for the deposited structure material
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.