Capacitance Cryogen Level Sensor for Closed-Loop Control

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Solution Overview

Problem

Existing cryoablation systems are inefficient due to multiple separate systems, independent controls, and measurement devices, leading to reduced treatment effectiveness and increased costs.

Innovation Solution

A cryoablation apparatus with a capacitance-based liquid level sensor in the Dewar for real-time cryogen level monitoring, coupled with a cryo-control system for continuous optimization, and a pressure control mechanism for closed-loop feedback to adjust pressures and flow efficiently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional cryoablation systems use multiple separate systems and individual controls, then each component can be independently managed, but the overall system efficiency decreases and treatment costs increase

Engineering Contradiction:
ImproveIndependent control of componentsVSAvoidSystem efficiency
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent integrates multiple separate control systems into a single unified control unit that manages the cryogen delivery system, probe control, and monitoring functions. This consolidation eliminates the inefficiencies of multiple independent controls while maintaining ease of operation through a centralized interface, directly resolving the contradiction between component independence and system efficiency

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If traditional systems use independent measurement devices for cryogen levels, then measurement can be performed, but the system complexity increases and treatment effectiveness decreases

Engineering Contradiction:
ImproveCryogen level measurementVSAvoidSystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The measurement function is integrated into the unified control unit, which consolidates multiple independent measurement devices into a single coordinated system. This reduces overall system complexity while maintaining precise cryogen level measurement capabilities through integrated sensing and control

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system implements continuous feedback monitoring of cryogen levels through the integrated control unit, which automatically adjusts delivery parameters based on real-time measurements. This feedback mechanism improves treatment effectiveness by ensuring optimal cryogen levels without requiring complex manual monitoring systems

Inventive Principle:
Principle #23Feedback

3Reliability

If cryogen delivery is not optimized in real-time, then the system is simpler to operate, but treatment effectiveness is reduced and surrounding tissues may be damaged

Engineering Contradiction:
ImproveTreatment effectivenessVSAvoidControl system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The unified control unit continuously monitors treatment parameters and cryogen delivery in real-time, automatically adjusting flow rates and temperature control based on feedback from sensors. This closed-loop control ensures treatment effectiveness and prevents damage to surrounding tissues while maintaining manageable system complexity through automation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts cryogen delivery parameters during treatment based on real-time conditions, transitioning from static pre-programmed control to adaptive dynamic control. This enables the system to respond to changing treatment requirements while the unified control architecture keeps the complexity manageable

Inventive Principle:
Principle #15Dynamics

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 the efficiency and effectiveness of cryoablation treatments by optimizing cryogen use, reducing treatment costs, and minimizing damage to surrounding tissues.

Implementation Method 1

a capacitance-based liquid level sensor positioned in the Dewar. The capacitance-based liquid level sensor may be coupled to a cryo-control that can determine a cryogen liquid level based on the capacitance of the liquid level sensor

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

Heat from the tissue passes from the tissue, through the probe, and into the cryogen that removes heat from the targeted tissue. This removal of heat causes tissue to freeze

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4527327A1Apparatuses and methods for cryogen measurement and control for cryoablation systems
Publication Date: 2025.03.26 VARIAN MEDICAL SYSTEMS INC
  • EP4527327A1 patent drawingFigure 1
  • EP4527327A1 patent drawingFigure 2~3B
  • EP4527327A1 patent drawingFigure 4

AI summary

A cryoablation apparatus includes a Dewar defining an interior volume configured to retain a volume of cryogen, a supply tube extending into the interior volume of the Dewar, a heating assembly positioned at a distal end of the supply tube, a pump assembly positioned proximate the heating assembly, and a lid assembly coupled to the Dewar at the proximate end of the supply tube opposite to the distal end of the supply tube. The cryoablation apparatus also includes a capacitance-based cryogen liquid level sensor positioned in the Dewar.