Phantom Production Tool Rigid Shell Flexible Mold
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Solution Overview
Problem
Existing phantom production tools for PVA hydrogel/cryogel anatomical phantoms have low mechanical strength, high weight-to-strength ratios, and poor thermal conductivity, leading to misshaping during curing due to unconstrained swelling in soft silicone molds, which limits their effectiveness and lifespan.
Innovation Solution
A phantom production tool with a rigid, thermally conductive outer shell and a flexible inner mold that allows for good thermal contact and expansion to manage pressure changes during curing, ensuring accurate and repeatable low temperatures and preventing misshaping, featuring aligned access ports and vents for gas release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If standard tools and molds for soft materials are formed entirely from silicone or silicone held by a plaster cast exterior, then the tools are flexible and easy to manufacture, but the thermal conductivity is poor leading to inaccurate and non-repeatable low temperatures
Solution Approach 1:
The mold assembly combines silicone flexible mold sections with a plaster cast exterior shell. The plaster cast provides high thermal conductivity for accurate temperature control, while the silicone sections provide flexibility and ease of manufacture. This composite structure resolves the contradiction between thermal performance and manufacturing ease.
2Duration of action of stationary object
If soft phantom production tools are used, then the tools are flexible and easy to manufacture, but the mechanical strength is low and the tool life is limited
Solution Approach 1:
The tool combines a rigid plaster cast exterior shell with flexible silicone interior mold sections. The plaster cast provides high mechanical strength and durability for long tool life, while the silicone sections maintain flexibility for easy manufacture and phantom release. This composite approach resolves the contradiction between strength and flexibility.
Solution Approach 2:
The mold is divided into multiple sections including a rigid exterior shell and flexible interior sections. This segmentation allows each part to be optimized for its specific function - the rigid shell for strength and the flexible sections for ease of manufacture and phantom release - while working together as an integrated system.
3Manufacturing precision
If soft silicone molds are used, then the molds are flexible and easy to manufacture, but they cannot support inserts for precise insertion of overmolded components
Solution Approach 1:
The plaster cast exterior shell provides the rigid structural support needed to hold inserts in precise positions, while the flexible silicone interior sections maintain ease of manufacture and allow for phantom release. The composite structure resolves the contradiction between support strength and manufacturing ease.
4Reliability
If the liquid precursor cures and generates pressure, then the phantom is formed, but the soft silicone mold cannot accommodate the pressure buildup
Solution Approach 1:
The rigid plaster cast exterior shell provides the structural strength to withstand pressure buildup during curing, while the flexible silicone interior sections allow for controlled expansion and pressure relief. This composite structure resolves the contradiction between pressure resistance and flexibility.
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 tool provides anatomical phantoms with improved mechanical strength and thermal conductivity, allowing for precise production of phantoms with realistic tactile properties and extended tool lifespan by managing pressure and temperature effectively during the curing process.
Implementation Method 1
The rigid shell sections and inner flexible mold sections each have aligned access ports for flowing a liquid precursor of a tissue mimic material of the anatomical phantom into the interior volume of the flexible mold. Each of the outer rigid shell sections and inner flexible mold sections have aligned vents to allow venting of any gases generated during setting or curing of the liquid precursor as it solidifies to form the anatomical phantom. The flexible mold is produced in a way which ensure the inner flexible mold sections are in thermal/physical contact with an inner surface of the outer rigid shell sections.
Implementation Method 2
Each of the outer rigid shell sections and inner flexible mold sections have aligned vents to allow venting of any gases generated during setting or curing of the liquid precursor as it solidifies to form the anatomical phantom.
Implementation Method 3
The locking mechanism is configured to allow the at rigid shell sections to expand away from each other during buildup of pressure as the liquid precursor cures, and to contract back towards each other as venting of the gases from the inner volume defined by the flexible mold occurs.
Data Source
AI summary
The present disclosure relates to a tool used to producing anatomical phantoms. The tool includes an inner flexible mold which sits inside a rigid, thermally conductive outer shell. The rigid shell may be made out of aluminum. The silicone mold and thermally conductive shell both include at least two interlocking components. The shell is held together by a locking mechanism which can expand upon internal pressure. An anatomical phantom is produced from polyvinyl alcohol hydrogel by freezing and thawing a PVA liquid precursor in the silicone mold and demolding it.