Drive Assembly Spring Brake Sheath Retraction
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Solution Overview
Problem
Existing introducer assemblies for implantable medical devices require substantial force to retract the sheath, leading to frictional issues and potential misalignment during deployment, which can result in incorrect positioning of the device, and automatic systems lack manual control and tactile feedback.
Innovation Solution
A drive assembly with a sprung element and brake mechanism that provides retraction assistance while maintaining manual operation, allowing clinicians to control the retraction force and speed, ensuring precise deployment by coupling the handle portions and using a spiral spring with a brake release mechanism to prevent unintended retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the components of the introducer assembly are made to be a tight fit to maintain integrity and minimize outer diameter, then the structural integrity and compactness are improved, but the friction between slidable components increases, requiring substantial operation force
Solution Approach 1:
A drive assembly with a sprung element (spring) is introduced as an intermediary mechanism between the operator and the sheath retraction system. The spring accumulates and releases energy to provide retraction assistance, mediating the force transmission and reducing the direct force requirement on the tight-fit components while maintaining their structural integrity
2Reliability
If haemostatic valves or seals are added to prevent fluid leakage, then the sealing performance is improved, but the friction between sliding components increases, augmenting the required operation force
Solution Approach 1:
The sprung element acts as a force-multiplying intermediary that compensates for the increased friction caused by haemostatic valves and seals. By storing elastic potential energy during compression and releasing it during retraction, the spring offset's the additional resistance from sealing components without compromising their reliability
3Length of moving object
If the introducer is made very long to reach distant treatment sites, then the accessibility is improved, but the friction between slidable components increases due to curvature and twisting, requiring substantial operation force
Solution Approach 1:
The drive assembly with sprung element serves as a force amplification intermediary that compensates for the cumulative friction effects along the entire length of the introducer. The spring's energy storage capacity allows it to overcome the distributed friction resistance generated by the long, curved, and twisted path through vasculature
Solution Approach 2:
The sprung element is pre-compressed or pre-loaded before use, storing elastic potential energy in advance. This preliminary energy storage enables the system to deliver the necessary retraction force without requiring the operator to apply substantial force during the actual deployment procedure
4Ease of operation
If manual control is maintained for tactile feedback, then the operator control and feedback are improved, but the retraction assistance is reduced, requiring substantial clinician effort
Solution Approach 1:
The drive assembly with sprung element and brake release mechanism acts as a cooperative intermediary that provides retraction assistance while preserving manual control. The operator maintains tactile feedback through direct mechanical connection but receives force multiplication from the spring, reducing effort while keeping control authority
Solution Approach 2:
The brake release mechanism provides tactile feedback to the operator about the state of the retraction assistance system. When the brake is engaged or disengaged, the operator can feel the change in resistance or movement characteristics, maintaining situational awareness and control while benefiting from spring assistance
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 solution reduces the effort required for sheath retraction, minimizes the risk of device misalignment, and maintains manual control and tactile feedback, allowing for precise and controlled deployment of medical devices.
Implementation Method 1
a spiral spring with a brake release mechanism
Implementation Method 2
a sprung element coupled between the first and second fittings, the sprung element providing a pulling force
Implementation Method 3
a brake mechanism that provides retraction assistance while maintaining manual operation, allowing clinicians to control the retraction force and speed
Data Source
Figure 1
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Figure 3
AI summary
A drive assembly (50, 100) for an introducer assembly (10) for the deployment of an implantable medical device (16) includes a sprung element (52) coupled to a yoke (56). The yoke (56) is coupled to a gripper element (58). The yoke (56) is coupled to a first handle unit (30) of the introducer (10). The sprung element (52) is coupled to a proximal handle unit (32). A brake element (66, 102) acts to prevent operation of the sprung element (52) when no manual force is being applied to retract a sheath (24) and the assembly (10). When manual retraction force is applied to the gripper element (58), the brake element (66, 102) releases the sprung element (52) so that the latter can apply a force assistance to assist in the retraction of the sheath (24) and thereby to assist in the deployment of a medical device.