Sub-cooling coil for pressurized cryogenic ablation
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Solution Overview
Problem
Current cryogenic medical devices for cryoablation therapies face inefficiencies in delivering ablative temperatures due to high pressure requirements, costly rare gases, and issues with selective freezing, leading to ineffective cooling and collateral tissue damage.
Innovation Solution
A cryogenic system that uses a sub-cooling coil immersed in a liquid cryogen reservoir to produce a pressurized, mixed-phase cryogen, which is then delivered to a cryoprobe, allowing for precise temperature control and efficient heat extraction while minimizing damage to surrounding tissues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high pressure (3,000-6,000 psi) is used in Joule-Thomson based systems, then gas cryogen can be delivered, but cooling effectiveness is insufficient and ablative temperatures cannot be achieved
Solution Approach 1:
The system changes the physical state parameter of the cryogen from gas to liquid, and changes the pressure parameter from high pressure (3,000-6,000 psi) to low pressure (15-450 psi). This parameter transformation allows the cryogen to achieve ablative temperatures while maintaining system reliability and cooling effectiveness
Solution Approach 2:
The invention utilizes phase transition by delivering liquid cryogen instead of gas cryogen. The liquid phase provides superior heat extraction capacity and enables the system to achieve the required ablative temperatures without relying on high-pressure Joule-Thomson expansion, thereby resolving the contradiction between temperature achievement and cooling effectiveness
2Temperature
If liquid cryogen is used, then colder temperatures and greater freezing capacity are achieved, but the system is slow to achieve target temperature and causes over-freezing of tissue
Solution Approach 1:
The system dynamically controls the flow rate and delivery timing of liquid cryogen to optimize the freezing process. By adjusting these dynamic parameters, the system achieves rapid temperature reduction with precise control, preventing over-freezing while maintaining high freezing capacity
Solution Approach 2:
The system incorporates feedback control mechanisms to monitor temperature and adjust cryogen delivery in real-time. This feedback loop enables precise temperature control, allowing the system to achieve target temperatures quickly while preventing excessive freezing of surrounding tissues
3Speed
If critical or supercritical state cryogens are used, then more powerful and quicker freeze is achieved, but device architecture becomes complicated and larger reservoirs are required
Solution Approach 1:
The system uses readily available liquid cryogen (such as liquid nitrogen) that can be easily stored and delivered without requiring complex critical or supercritical state equipment. This approach achieves rapid freezing through optimized liquid delivery while avoiding the need for complicated device architecture and large reservoirs associated with critical/supercritical systems
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 system achieves precise and efficient freezing of target tissues with reduced collateral damage and extended cryogen supply time, using a closed-loop recirculating cryogen fluid system that conserves cryogen and allows for multiple probe operations.
Implementation Method 1
A sub-cooling coil is immersed in the liquid cryogen. A cryogen is supplied to the sub-cooling coil and is cooled within the sub-cooling coil under pressure to produce a pressurized mixed phase cryogen
Implementation Method 2
The pressurized mixed phase cryogen is delivered to the cryo-device by a supply line... achieves precise and efficient freezing of target tissues with reduced collateral damage
Data Source
AI summary
A method of generating a pressurized, sub-cooled mixed-phase cryogen is disclosed, including providing a cryogenic system including a reservoir containing a liquid cryogen; and a heat exchange coil immersed in the liquid cryogen, the heat exchange coil having an input end and an output end not immersed in the liquid cryogen; introducing a pressurized gas cryogen to the input end of the heat exchange coil; cooling the pressurized gas cryogen within the heat exchange coil; and collecting the pressurized gas cryogen at an output end of the heat exchange coil.