Pre-Compressed Foam Actuators With Fracturing Coating
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Solution Overview
Problem
Existing foam actuators, particularly fluidic elastomer actuators, face limitations in fabrication complexity and require costly mold fabrication for prismatic structures, and have not been effectively utilized for fluidic actuation in medical applications like cardiac compression devices.
Innovation Solution
The use of pre-compressed elastomeric foam with a coating that constrains and fractures upon inflation, combined with an impermeable elastomer seal, allows for increased actuation deformation and force while simplifying the fabrication process and enabling medical applications like cardiac compression devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluidic elastomer actuators are used to achieve large deformations and complex motions, then actuation capability is improved, but fabrication complexity and cost increase due to complex mold requirements
Solution Approach 1:
The patent uses porous elastomeric foam as the actuator material, which naturally forms compliant chambers that can be inflated to produce large deformations. The porous structure eliminates the need for complex internal air chamber fabrication while maintaining the desired actuation capabilities, directly resolving the contradiction between actuation performance and fabrication complexity
Solution Approach 2:
The elastomeric foam is pre-compressed during fabrication to a specific density before the actuator is finalized. This preliminary compression creates the necessary strain gradient and structural configuration that enables complex motions upon inflation, allowing the actuator to achieve sophisticated deformations without requiring complex molds or assemblies during the fabrication process
2Force
If pre-compressed elastomeric foam is used with coating and seal, then actuation deformation and force increase, but manufacturing steps increase
Solution Approach 1:
A thin elastomeric coating is applied to the surface of the pre-compressed foam to create an impermeable seal that contains the actuating fluid. This thin film approach provides the necessary containment for achieving high actuation forces while adding minimal complexity to the manufacturing process, as the coating can be applied through simple dip-coating or spray methods
Solution Approach 2:
The actuator combines pre-compressed elastomeric foam with an elastomeric coating to create a composite structure. The foam provides the compliant, deformable body while the coating provides fluid containment. This composite approach enables high actuation forces through a relatively simple two-material construction process
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 enhances actuation deformation and force efficiency with reduced fabrication complexity, enabling the development of efficient and effective foam-based actuators for medical applications such as cardiac compression devices.
Implementation Method 1
The elastomeric foam is a pre-compressed porous material
Implementation Method 2
low elastic modulus silicone rubber
Implementation Method 3
The coating is configured to constrain the elastomeric foam and is configured to break or fracture when the elastomeric foam inflates
Implementation Method 4
The elastomer seal is configured to be impermeable to actuating fluid
Data Source
AI summary
Foam-based pneumatic actuators can be formed in a state of mechanical compression prior to actuation. An actuator includes an elastomeric foam; a coating disposed on the elastomeric foam; and an elastomer seal disposed on the coating. The coating constrains the elastomeric foam and can be configured to break or fracture when the elastomeric foam inflates. The elastomer seal can be configured to be impermeable to the actuating fluid. Such a foam actuator can be used in a cardiac compression device. These foam actuators possess increased actuation deformation and an actuation exerted force for a given inflation pressure. A large deformation can be provided from materials having low ultimate strains.