Composite Shell Cuff Structure for Low-Friction Hemodynamic Monitoring
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Solution Overview
Problem
Hemodynamic monitoring shell cuffs coated with low friction materials are expensive and time-consuming to produce, and sliding friction between overlapping parts can disrupt pressure readings.
Innovation Solution
A shell cuff design with a flexible sheet composed of two different materials, where the first interface portion extends through more than 20% of the thickness, and the second interface portion through a similar proportion, reduces friction by using materials like HDPE and polyamide or plastics with PTFE particles, eliminating the need for additional coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the shell cuff is coated with low friction materials, then friction between overlapping parts is reduced, but production cost and manufacturing time increase
Solution Approach 1:
The sheet is constructed as a composite material structure with a first material forming the first face and a second material forming the second face. The second material has lower friction characteristics than the first material, providing low friction properties at the overlapping portion without requiring additional coating processes. This integrates the friction-reducing function directly into the base structure through material composition rather than surface treatment.
2Object-generated harmful factors
If coating with low friction materials is applied, then friction is reduced, but manufacturing process becomes more time-consuming
Solution Approach 1:
The friction-reducing function is merged with the base structure by making the second face of the sheet itself from a low friction material. This eliminates the separate coating process that would be required to achieve the same effect, integrating the functional property directly into the structural component during the primary manufacturing process.
3Measurement precision
If friction between overlapping parts is reduced, then measurement accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The sheet uses a composite material structure where the second material forms the second face that contacts the first face at the overlapping portion. This provides the low friction surface needed for measurement accuracy while maintaining a relatively simple two-layer structure that can be manufactured using conventional extrusion or injection molding processes, avoiding excessive manufacturing complexity.
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 design enhances measurement accuracy and sensitivity by minimizing friction, allowing for easier manufacturing and reducing production costs.
Implementation Method 1
One of the first interface portion and the second interface portion may comprise a compressible material impregnated with silicone oil which is configured to be released on application of pressure to the compressible material
Implementation Method 2
One of the first face and second face may comprise a textured surface on at least the respective first interface portion or the second interface portion
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
According to an aspect, there is provided a shell cuff for use with an actuator cuff and sensor pad in hemodynamic monitoring, the shell cuff comprising: a flexible sheet comprising a first face and an opposing second face, the sheet being curved such that a first end of the sheet and an opposing second end of the sheet overlap to form an overlapping portion in which a first interface portion of the first face interfaces with a second interface portion of the second face; wherein the sheet is configured to be tightened on application of force so as to increase the size of the overlap between the first face and the second face; wherein the first interface portion comprises a first material and the second interface portion comprises a second material which is different to the first material.