Humidifier Heater Plate Assembly With Thermal Water-Out Sensing
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Solution Overview
Problem
Respiratory humidifier systems often fail to detect a water-out condition effectively, leading to prolonged exposure to dry gases, discomfort, and potential system failure, especially in scenarios where minimal sensors are used.
Innovation Solution
The implementation of a water-out detection method using a supplementary power input waveform and the determination of the specific heat capacity of the humidifier chamber, allowing for water-out detection with as few as one temperature sensor, independent of flow rate and humidity delivery, and incorporating an improved heater plate structure for enhanced thermal coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-out detection is implemented using thermal conductivity sensors in multiple locations, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple detection functions (temperature monitoring, water-out detection, thermal conductivity measurement) into a single integrated heater plate assembly. The heater plate serves both as a heating element and as a sensor substrate, eliminating the need for separate sensors in multiple locations while maintaining detection reliability.
Solution Approach 2:
The heater plate is designed to perform multiple functions simultaneously: it heats the humidifier chamber, monitors temperature changes, and detects water-out conditions through thermal conductivity variations. This multi-functional design reduces the overall sensor count while improving system integration.
2Measurement precision
If multiple flow and temperature sensors are used for water-out detection, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system performs self-diagnosis by monitoring thermal conductivity changes through the heater plate itself. The heater plate automatically detects water-out conditions by measuring changes in its own thermal environment, eliminating the need for external sensors and complex setup procedures while maintaining accurate detection.
3Ease of manufacture
If heater plate structure is simplified, then ease of manufacture is improved, but thermal coupling efficiency deteriorates
Solution Approach 1:
The heater plate assembly uses composite construction with a PTFE layer combined with aluminum or stainless steel. The PTFE provides electrical insulation and thermal coupling properties, while the metal provides structural integrity and heat conduction. This composite structure maintains manufacturing simplicity while achieving optimal thermal coupling efficiency.
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
This solution enables reliable water-out detection without additional sensors, ensuring patient comfort and system integrity, even in low flow or low humidity conditions, and reduces the risk of system failure by providing an adjustable detection time and minimal disruption to normal operation.
Implementation Method 1
a heating element configured to generate heat
Implementation Method 2
an electrical insulation arrangement between the top heating plate and the heating element, wherein the electrical insulation arrangement thermally couples the heating element and the top heating plate such that heat generated by a power signal to the heating element is transmitted to the top heating plate
Implementation Method 3
a thermistor located at or near the top heating plate
Data Source
AI summary
An improved system and method of determining a low water and/or water-out condition in a humidifier chamber of a respiratory or surgical humidifier system can use a specific frequency band to detect changes in a temperature of a heater plate. The temperature changes can correlate to the specific heat capacity value of the humidifier chamber. The low water and/or water-out detection process can be performed without having to determine the gases flow rate and/or can be run continuously. A heater plate assembly of the system can include a compliant insulation sheet to improve thermal coupling between the heating element and the top heating plate of the heater plate assembly, thereby improving the low water and/or water-out detection process.