Biodegradable Hydrogel Actuator for Watertight Marine Shape Morphing
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Solution Overview
Problem
Existing soft robotic actuators for marine environments face challenges in being water-tight, exhibiting repeatable and reliable motion and force, and enabling design freedom, while also being non-biodegradable and potentially toxic.
Innovation Solution
Biodegradable actuators fabricated from calcium-alginate hydrogels sourced from brown seaweed, using a 3D printing process with a reversible chelation-crosslinking mechanism to tune mechanical properties and morphology, allowing for hydraulic or pneumatic actuation and safe deployment in marine ecosystems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hydrogels are used as actuator material, then biodegradability and environmental safety are improved, but structural strength and water-tightness deteriorate
Solution Approach 1:
The patent uses composite materials by combining hydrogel with reinforcement structures. The hydrogel provides biodegradability and environmental safety, while the reinforcement structures (such as porous polymer matrices or embedded frameworks) provide structural strength and water-tightness. This composite approach allows the actuator to simultaneously achieve environmental compatibility and mechanical integrity.
Solution Approach 2:
The patent employs flexible shells and thin films to enclose the hydrogel actuator material. These shells provide water-tight sealing while maintaining the biodegradable characteristics of the hydrogel. The thin film structure protects the hydrogel from degradation by water and mechanical stress, enabling the actuator to function reliably in marine environments while remaining environmentally safe.
2Adaptability or versatility
If hydrogels are extruded into fugitive support bath for embedded printing, then design freedom is improved, but manufacturing precision and reliability deteriorate
Solution Approach 1:
The patent introduces an intermediary substance or structure during the printing process. The fugitive support bath acts as an intermediary medium that enables the hydrogel to be extruded into complex geometries while maintaining structural integrity. This intermediary allows for design freedom in creating intricate actuator shapes while ensuring manufacturing precision through controlled support and removal processes.
Solution Approach 2:
The patent employs preliminary action by pre-preparing the hydrogel formulation and support bath conditions before printing. The hydrogel is pre-mixed with appropriate crosslinking agents and the support bath is pre-configured with optimal composition and concentration. This preliminary preparation ensures that during the printing process, the hydrogel maintains consistent properties and forms reliable actuators with repeatable performance, while still allowing for design freedom in the final structure.
3Strength
If alginate actuators are crosslinked to increase stiffness, then structural integrity is improved, but morphing capability and adaptability deteriorate
Solution Approach 1:
The patent applies dynamics by using dynamic crosslinking mechanisms that allow the alginate actuator to change its structural integrity based on operational needs. The crosslinking density can be adjusted or reconfigured during or after fabrication to provide the necessary stiffness for structural integrity while maintaining the ability to morph and adapt to different functional requirements. This dynamic adjustment enables the actuator to switch between rigid and flexible states as needed.
Solution Approach 2:
The patent utilizes parameter changes by modifying the crosslinking parameters of the alginate hydrogel. By controlling factors such as crosslinking concentration, temperature, and time, the actuator can be tuned to achieve the desired balance between structural integrity and morphing capability. The crosslinking parameters can be adjusted to provide sufficient stiffness for structural support while maintaining the flexibility needed for shape change and adaptation to different operational conditions.
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
The actuators demonstrate consistent motion and force profiles over multiple cycles, with tunable stiffness and geometry, ensuring safe interaction with marine organisms and environmental safety through biodegradability.
Implementation Method 1
A reversible chelation-crosslinking mechanism can be used to dynamically modify the alginate actuators' structural stiffness and morphology
Implementation Method 2
the actuators are biodegradable, safely edible, and digestible by marine organisms
Data Source
AI summary
A morphing, biologically-derived actuator can be used with soft robotics in a marine environment. The actuator is fabricated using a modified hydrogel additive manufacturing printing process, where the printed structure is exposed to various concentrations of crosslinking initiator to ensure a water-tight seal between adjacent printed layers. The actuator fabricated using the disclosed process is suitable for marine use and is safe for marine animals and is biodegradable.