Liquid Level Sensor for Nebulizer Cup Overheat Prevention
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Solution Overview
Problem
Ultrasonic sterilizers face issues with overheating due to liquid depletion and reduced efficiency from overfilling, along with the challenge of accurately sensing the liquid level in a corrosive environment, which can lead to damage or inadequate sterilization.
Innovation Solution
A nebuliser cup with a liquid level sensor system comprising two electrically isolated elements that form a circuit when the cup is filled, triggering the dispensation of additional liquid when the level drops below a threshold, ensuring optimal liquid levels and preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the sterilizing liquid is fully consumed and the cup becomes empty, then the device continues to operate, but the transducer and cup overheat causing irreversible damage
Solution Approach 1:
The liquid level sensor detects the liquid level in advance before complete depletion occurs. When the liquid level reaches a predetermined low threshold, the sensor triggers a warning signal or automatically shuts off the ultrasonic transducer, preventing overheating and irreversible damage to the transducer and cup assembly.
Solution Approach 2:
The liquid level sensor provides continuous feedback on the liquid level status to the control system. This feedback mechanism enables real-time monitoring and automatic adjustment of the ultrasonic nebulization process, ensuring the transducer operates only when sufficient liquid is present to prevent harmful overheating.
2Quantity of substance
If the sterilizing liquid overfills the cup, then the transducer experiences increased load, but system efficiency reduces causing undersupply of sterilizing aerosol
Solution Approach 1:
The liquid level sensor is positioned to detect when the liquid reaches an optimal fill level before overfilling occurs. When this predetermined level is reached, the system can stop liquid dispensation or trigger a warning, preventing the transducer from experiencing excessive load and maintaining optimal aerosol generation efficiency.
Solution Approach 2:
The sensor provides feedback on liquid level status to the control system, enabling real-time adjustment of liquid dispensation or ultrasonic power. This ensures the liquid volume remains within the optimal range for efficient nebulization, preventing both underfilling and overfilling conditions that would compromise sterilizing aerosol supply.
3Measurement precision
If a sensor is used to detect liquid level, then liquid level monitoring is achieved, but the sensor must withstand repeated exposure to toxic and corrosive peroxide liquid and vapour
Solution Approach 1:
The liquid level sensor is positioned to detect liquid level through non-contact means or through a protective barrier that isolates the sensor from direct contact with corrosive hydrogen peroxide liquid and vapour. This intermediary approach enables accurate liquid level monitoring while protecting the sensor from degradation by the toxic and corrosive sterilizing agent.
Solution Approach 2:
The sensor system is designed with components that can be easily replaced or are inherently resistant to corrosion from hydrogen peroxide exposure. The sensor may be positioned in a protected environment or use materials specifically selected for their resistance to peroxide degradation, ensuring long-term reliable operation in the harsh sterilization chamber environment.
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 effectively maintains a consistent liquid level, preventing overheating and ensuring efficient sterilization by triggering the refill of the nebuliser cup when the liquid level falls, thus maintaining optimal performance and extending the lifespan of the ultrasonic transducer.
Implementation Method 1
The application of alternating current to the crystal at high frequencies (of the order of several MHz) leads to the crystals vibrating at a corresponding frequency. This energy is in turn transferred to the sterilization liquid.
Implementation Method 2
Typically, the ultrasonic transducer is a piezoelectric crystal that changes size or shape in response to electrical stimulus.
Implementation Method 3
when the cup is filled with a liquid to the filled liquid level, the first element, the liquid and the second element together form an electrically coupled circuit
Data Source
AI summary
A nebuliser cup for maintaining a safe level of liquid during nebulization, the cup comprising a liquid level sensor comprising: a first element sensing liquid at or below a position corresponding to a filled liquid level in the nebuliser cup; a second element electrically isolated from the first element and located at a position corresponding to a filled liquid level in the nebuliser cup; and wherein when the cup is not filled with a liquid to the filled liquid level, the first element, the liquid and the second element do not form an electrically coupled circuit; and when the cup is filled with a liquid to the filled to liquid level, the first element, the liquid and the second element together form an electrically coupled circuit.