Flexible Cryoablation Needle Pressure Relief and Sealing
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Solution Overview
Problem
Conventional flexible cryoscalpels face issues with insufficient connection strength and air tightness between the cutter head and flexible catheter, leading to potential gas leakage and catheter bursting under high pressure, which can cause freezing injuries or gas embolism during tumor ablation procedures.
Innovation Solution
A flexible cryoablation needle device with a threaded part, annular protrusion portion, and pressure relief assembly that includes a slider, spring, and sealing members to automatically control pressure relief when the inner cavity pressure exceeds a threshold, preventing excessive pressure in the cutter head and ensuring secure connection between the metal cutter head and plastic catheter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-layer plastic flexible catheter is used, then the device structure is simple and easy to manufacture, but the connection strength and air tightness between the cutter head and flexible catheter are insufficient, leading to gas leakage and potential catheter bursting under high pressure
Solution Approach 1:
The patent employs a multi-layer nested catheter structure where an inner flexible catheter is inserted into an outer flexible catheter, creating a nested configuration. The inner catheter provides the working channel while the outer catheter provides structural support and sealing. This nested design enhances connection strength and air tightness without significantly complicating the manufacturing process, as each layer can be produced separately and then assembled.
Solution Approach 2:
The patent uses composite material construction by combining different plastic materials for the inner and outer catheters. The inner catheter may use a material optimized for flexibility and biocompatibility, while the outer catheter uses a material with higher structural strength and pressure resistance. This composite approach allows each layer to contribute its optimal properties, resulting in enhanced overall reliability while maintaining ease of manufacture through separate production of each material layer.
2Reliability
If the gas return pipeline is blocked (such as by ice), then the back pressure in the cutter head increases to extremely high levels (up to 1500 psi), but the plastic flexible catheter cannot bear such high pressure and will burst
Solution Approach 1:
The patent implements a pressure relief assembly that includes a relief channel and relief hole positioned in the cutter head structure. This safety mechanism is pre-configured to automatically activate when back pressure reaches dangerous levels. The relief channel provides an alternative escape path for gas, preventing pressure buildup that would exceed the catheter's bearing capacity. This beforehand cushioning ensures that even if the gas return pipeline becomes blocked, the system can safely relieve excess pressure without causing catheter bursting or gas leakage.
3Strength
If the cutter head is disconnected from the flexible catheter, then the cutter head will rush out to pierce human tissues and cause gas leakage, but the existing connection structure does not provide sufficient connection strength
Solution Approach 1:
The patent incorporates a locking mechanism in the connection structure that automatically engages when the catheter is inserted into the cutter head. This preliminary action ensures that the connection is secured before the device is activated or moved. The locking feature may include mechanical interlocks, snap-fit elements, or threaded connections that lock into place, providing immediate connection strength to prevent disconnection and cutter head ejection while maintaining a relatively simple overall connection structure.
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
Enhances connection strength and air tightness, preventing catheter bursting and gas leakage, thereby ensuring safe operation during low-temperature, high-pressure procedures by automatically relieving pressure and maintaining effective sealing even at extreme temperatures.
Implementation Method 1
the spring is configured to cause the first sealing member to be driven by an elastic force and clamped by the slider and the rear end face of the cutter head front section when a pressure in the inner cavity is lower than a pressure threshold
Implementation Method 2
when the compression gas drives the slider to move, the vent is opened to relieve the pressure
Implementation Method 3
the outer wall, attached to the flexible pipe structure, of the liner pipe is provided with a concave-convex structure; the first extruding pipe is sleeved outside the flexible pipe structure and is located on the outer side of a part of the concave-convex structure
Data Source
AI summary
The disclosure provides a flexible cryoablation needle device resistant to a low temperature and a high pressure, a threaded part is arranged on the outer wall of a liner pipe to enhance a connection strength between the liner pipe and a flexible pipe structure. Since an annular protrusion portion is arranged on the outer wall of the liner pipe, further leakage of a gas coming from a pressure relief process is prevented and the connection strength is enhanced as well. Air tightness and connection strength are further guaranteed by radial extrusion of extruding pipes. And an inner cavity in a cutter head is directly subjected to pressure relief through a cutter head vent, a pressure relief intermediate cavity, a liner vent, a flexible pipe vent and a pressure relief gap.