Liquid Detection in Vibrating Membrane Nebulizers
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Solution Overview
Problem
Existing vibrating membrane nebulizers face challenges in reliably detecting the presence of liquid, leading to potential membrane damage or incomplete drug delivery due to variations in hardware and external conditions, affecting the accuracy of liquid detection methods that rely on pre-set values or stored spectra.
Innovation Solution
The method involves intermittently driving the aerosol generator to create periods of aerosol generation and little or no aerosol generation, scanning at multiple frequencies to obtain spectra before and during inhalation, and comparing these spectra to determine the presence of liquid based on transient changes related to standing wave formation and dissipation, which is less dependent on hardware properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pre-set values or stored spectra are used for liquid detection, then the detection method is simple to implement, but the detection accuracy deteriorates due to hardware variations and external conditions
Solution Approach 1:
The system dynamically adapts to hardware variations and external conditions by continuously learning the electro-mechanical behavior of the aerosol generator under different operating conditions. Instead of using fixed pre-set values, the system updates its detection parameters based on actual measured spectra, making the detection method both simple to implement and accurate despite environmental changes.
Solution Approach 2:
The system changes the detection parameters from fixed pre-set values to dynamically adjusted parameters that adapt to hardware variations. By monitoring changes in electro-mechanical behavior across multiple operating conditions and adjusting the detection thresholds accordingly, the system maintains high detection accuracy while keeping the implementation straightforward.
2Reliability
If dedicated sensors are used to measure liquid amount, then the detection reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The aerosol generator itself serves as the detection sensor by monitoring its own electro-mechanical behavior. The system uses the existing vibrator and measurement electronics to detect liquid presence through changes in resonance frequency, Q-factor, and power consumption, eliminating the need for separate dedicated sensors while maintaining high detection reliability.
Solution Approach 2:
The existing measurement electronics of the aerosol generator are made multi-functional by using them for both aerosol generation control and liquid detection. The same electronics that drive the vibrator also measure the electro-mechanical parameters needed for detection, making the device components serve multiple purposes and avoiding additional complexity.
3Measurement precision
If liquid detection is performed continuously during treatment, then the detection accuracy is improved, but the risk of membrane damage increases if detection fails
Solution Approach 1:
The system implements continuous feedback monitoring of the aerosol generator's electro-mechanical behavior during treatment. By constantly measuring resonance frequency, Q-factor, and power consumption and comparing these against learned patterns, the system accurately detects liquid presence in real-time and provides immediate feedback to control the treatment, preventing membrane damage while maintaining high detection accuracy.
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 approach provides a robust and reliable method for detecting the end of liquid in the reservoir, reducing errors from hardware variations and external changes, ensuring safe operation and complete drug delivery by accurately determining when the liquid is depleted.
Implementation Method 1
a vibrator, such as piezoelectric element which is excited at ultrasonic frequencies in order to induce vibration
Implementation Method 2
perform scans in which the membrane is vibrated at a plurality of frequencies, and in which at least one electrical parameter of the vibrator is measured at the plurality of frequencies to provide a spectrum
Data Source
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AI summary
The present invention provides a breath-actuated inhalation device comprising: an aerosol generator comprising a vibrator and a membrane; and a reservoir for liquid to be aerosolized which is in fluid communication with the membrane. A method for operating the device is also provided. The vibrator is driven intermittently so that the aerosol generator has periods of aerosol generation during a patient's inhalations and periods of little or no aerosol generation preceding and/or succeeding the inhalations. Scans are performed in which an electrical parameter of the vibrator is measured as the membrane is vibrated at a plurality of frequencies. The spectrum obtained from a scan during an inhalation is compared with a spectrum obtained from a scan during the period preceding or succeeding that inhalation in order to determine whether liquid is present in the reservoir.