Cryogenic Dispensing Head Porous Wick Flow Regulation
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Solution Overview
Problem
Conventional cryosurgical devices are complex, require specialized equipment, and have issues with flow regulation, leading to inefficient and costly delivery of cryogenic fluids for effective skin lesion treatment.
Innovation Solution
A dispensing head with a porous member as the primary flow regulation mechanism, allowing for controlled dispensing of cryogenic fluids like nitrous oxide and liquid nitrogen, which can be actuated to align the flow passage outlet with the dispensing member inlet, regulating the flow rate and reducing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cryosurgical devices use liquefied gases with lower boiling points (e.g., liquid nitrogen), then colder temperatures and more aggressive freezing effects are achieved, but device complexity and manufacturing cost increase due to complicated valving mechanisms and dispensers
Solution Approach 1:
The patent employs a porous wick material within the dispensing tip to replace complex valving mechanisms. The porous structure naturally regulates flow through capillary action, allowing liquid nitrogen to be delivered without complicated mechanical components while maintaining effective cryogenic temperatures for tissue freezing
Solution Approach 2:
The invention substitutes mechanical flow control systems (valves, regulators) with a passive porous wick system that relies on capillary forces and pressure differential. This eliminates moving parts and complex assembly while achieving reliable flow regulation of the cryogenic fluid
2Device complexity
If compressed gases (e.g., DME) are used in cryosurgical devices, then device structure is simpler, but evaporation rates are relatively long (15-30 seconds) and effective freezing temperature is achieved for only a short period
Solution Approach 1:
The patent changes the physical parameter of the cryogenic fluid from compressed gas (DME) to liquid nitrogen, which has a lower boiling point and provides sustained cold temperatures. The porous wick system maintains liquid nitrogen in a controllable state, extending the duration of effective freezing beyond the 15-30 second limitation of gas-based systems
3Ease of operation
If liquefied gases are dispensed through complicated valving mechanisms, then flow control is achieved, but cryogenic fluid waste increases during transfer from container to dispensing tip
Solution Approach 1:
The porous wick system provides self-regulating flow control without external valves or actuators. The capillary forces within the porous material automatically draw liquid nitrogen from the container through the dispensing tip, eliminating the need for complex control mechanisms that cause fluid loss during operation and transfer
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 enables efficient, uniform, and prolonged dispensing of cryogenic fluids at effective temperatures for cryosurgical treatments, reducing the need for complex structures and minimizing waste, while being simple to use and economically viable.
Implementation Method 1
at least one porous member disposed in the flow passage, the at least one porous member being configured as a primary flow regulation mechanism to limit a flow rate of the cryogenic fluid
Implementation Method 2
as the compressed gas flows to and contacts a surface of an applicator, such as, for example, a porous applicator bud, rapid evaporation of the gas causes the applicator surface to cool to temperatures which are lower than the temperature of the liquefied gas alone
Implementation Method 3
based on the principles of 'heat of vaporization.' In other words, as the compressed gas flows to and contacts a surface of an applicator, such as, for example, a porous applicator bud, rapid evaporation of the gas causes the applicator surface to cool
Implementation Method 4
The applicator can be placed in contact with the skin surface of the lesion for a period of time sufficient to reduce the temperature of the skin lesion tissue to temperatures that freeze the skin, such that permanent, irreversible rupture of the cellular membranes of the tissue occurs
Data Source
AI summary
A dispensing head for dispensing a cryogenic fluid may comprise a flow passage configured to be placed in flow communication with a reservoir containing a cryogenic fluid, the flow passage defining a flow passage inlet opening configured to receive the cryogenic fluid from the reservoir, and a flow passage outlet opening opposite the flow passage inlet opening. The dispensing head may further comprise a dispensing member configured to dispense the cryogenic fluid, the dispensing member defining a lumen having a lumen inlet opening and a lumen outlet opening; and at least one porous member disposed in the flow passage, the at least one porous member being configured as a primary flow regulation mechanism to limit a flow rate of the cryogenic fluid as it flows from the reservoir to the lumen outlet opening.