Converging-Diverging Cryogenic Nozzle for Focused Tissue Ablation
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Solution Overview
Problem
Current cryogenic devices lack efficiency and focus in cooling target tissue while protecting surrounding tissue, often causing damage due to inefficient expansion and pressure differentials.
Innovation Solution
A cryogenic device with a converging-diverging nozzle and multiple orifices, combined with a vacuum-insulated shaft, to create a focused jet of cryogenic fluid for efficient tissue ablation and analgesia, minimizing damage to non-target tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure differential is applied across a small nozzle, then cooling efficiency is improved, but tissue damage to surrounding areas increases
Solution Approach 1:
The patent applies local quality by creating a focused cryogenic jet through a specifically designed nozzle geometry (converging section followed by diverging section) that concentrates the cooling effect precisely at the target tissue site. The multiple orifices are strategically positioned and sized to deliver cryogenic fluid only where needed, while the insulated shaft prevents cold propagation to surrounding tissues, thus achieving high cooling efficiency at the target without collateral damage.
Solution Approach 2:
The nozzle is segmented into multiple functional sections: a converging portion that accelerates the cryogenic fluid, a diverging portion that focuses the jet, and multiple positioned orifices that distribute the fluid. This segmentation allows each section to optimize a specific aspect of the cryogenic delivery, achieving both high efficiency and precision while preventing widespread tissue damage.
2Quantity of substance
If a single large orifice is used, then fluid delivery is improved, but focus and precision of cooling is reduced
Solution Approach 1:
The single large orifice is segmented into multiple smaller orifices (at least two, preferably three or more) positioned at different locations and angles within the nozzle. This segmentation maintains adequate fluid delivery volume while creating multiple focused streams that can be precisely directed at the target tissue, thereby improving both fluid delivery and cooling precision simultaneously.
Solution Approach 2:
The multiple orifices are positioned in different spatial dimensions (different angles, heights, and radial positions) to create a three-dimensional pattern of cryogenic delivery. This dimensional arrangement allows the fluid to be delivered with both adequate quantity and precise spatial focus, covering the target area effectively while minimizing exposure to surrounding tissues.
3Area of stationary object
If cryogenic fluid flows freely through the shaft, then cooling coverage is improved, but energy loss increases
Solution Approach 1:
An insulating layer (such as vacuum insulation or thermal barrier material) is introduced as an intermediary between the cryogenic fluid pathway and the external environment along the shaft. This intermediary prevents unwanted heat transfer and pressure energy loss while allowing the cryogenic fluid to flow freely to the nozzle, thereby maintaining both adequate cooling coverage and energy efficiency.
Solution Approach 2:
The shaft interior is designed as an inert, insulated environment that protects the cryogenic fluid from external thermal influences. This inert environment maintains the fluid's pressure and temperature characteristics until it reaches the nozzle, reducing energy loss while preserving the ability to deliver adequate cooling coverage to the target tissue.
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 device achieves efficient and targeted tissue cooling with reduced collateral damage by using a converging-diverging nozzle and multiple orifices, ensuring precise ablation and analgesia with minimal impact on surrounding tissues.
Implementation Method 1
During expansion, primarily due to the Joule-Thomson Effect, there is significant irreversible pressure work done.
Implementation Method 2
A vacuum insulation layer can be between the inner shaft and the elongated shaft.
Implementation Method 3
Secondary cooling comes from reversible ideal gas expansion and vapor-liquid condensation or vapor-solid freezing.
Data Source
AI summary
Disclosed herein are systems and devices comprising a cryogenic device for ablating tissue. The cryogenic device can comprise a handle and an elongated shaft comprising a distal end and a proximal end. The elongated shaft can extend from the handle at the proximal end. The cryogenic device can further comprise an end effector at the distal end of the elongated shaft, wherein the end effector comprises a percutaneous probe. The cryogenic device can further comprise an inlet line tube within the elongated shaft. The cryogenic device can further comprise a nozzle at a distal end of the inlet line tube, wherein the nozzle comprises a plurality of orifices to deliver fluid through the inlet line tube to the end effector.