Automatic Analyzer Bubble Detection via Oscillation Waveform Analysis
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Solution Overview
Problem
Conventional capacitance methods for detecting liquid levels in automatic analyzers often inaccurately identify the presence of bubbles, leading to erroneous liquid level detection, which can result in incorrect sample concentration readings and delays in clinical test results.
Innovation Solution
An automatic analyzer system that includes a dispensing probe, an oscillation circuit, a detector, and a processing unit capable of analyzing time-series data of oscillation frequency to differentiate between normal and abnormal waveforms, specifically identifying bubble contact through correlation with abnormal waveform models, thereby improving the accuracy of liquid level detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional capacitance method is used to detect liquid level, then the detection speed is fast, but the measurement precision deteriorates due to erroneous detection of bubbles
Solution Approach 1:
The patent segments the liquid level detection process into multiple phases: initial rapid capacitance-based detection, followed by waveform analysis of the oscillation signal, and finally correlation comparison with reference waveforms. This segmentation allows the system to maintain fast initial detection while adding precision through subsequent analysis stages that specifically identify bubble contacts.
Solution Approach 2:
The patent introduces an intermediary analysis layer between the raw capacitance signal and the final liquid level determination. The oscillation waveform serves as an intermediary that contains detailed information about the interaction between the probe and liquid surface, allowing the system to distinguish between true liquid contact and bubble contact by analyzing the waveform characteristics.
2Measurement precision
If the dispensing probe stops at the liquid level to avoid contamination, then the liquid level detection is accurate, but the device complexity increases due to additional detection and analysis systems
Solution Approach 1:
The patent makes the oscillation circuit serve multiple functions: it generates the capacitance signal for liquid level detection, simultaneously creates an oscillation waveform that records the interaction history between the probe and liquid surface, and provides the basis for both bubble detection and liquid level determination. This multi-functionality reduces the need for separate detection systems.
Solution Approach 2:
The oscillation circuit self-generates the diagnostic waveform by responding to the actual physical interaction between the probe and the liquid surface. The waveform automatically contains the information needed for bubble detection without requiring external sensors or complex additional hardware, as the system uses its own operational signal to diagnose its own performance.
3Productivity
If bubble contact is not detected, then the liquid level detection is simple, but the reliability deteriorates due to erroneous concentration readings
Solution Approach 1:
The patent implements feedback by continuously monitoring the oscillation waveform during the dispensing process and comparing it against reference waveforms. When bubble contact is detected through waveform analysis, the system provides feedback to correct the liquid level determination, preventing erroneous concentration readings while maintaining efficient test processing.
Solution Approach 2:
The patent performs preliminary analysis of the oscillation waveform during the dispensing process itself, before the liquid level determination is finalised. By detecting bubble contacts in advance through waveform comparison, the system can correct potential errors before they affect the final concentration reading, ensuring reliability without significant delay to test processing.
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 accuracy of detecting erroneous liquid level detection caused by bubbles, allowing for timely correction and reducing delays in clinical test results by providing precise identification of deviation factors such as bubbles, static electricity, or contact issues.
Implementation Method 1
monitoring a capacitance between a suction portion (tip portion) of the dispensing probe and a peripheral portion (for example, a ground of a device housing) and detecting a change
Implementation Method 2
an oscillation circuit connected to the dispensing probe to output an AC signal of an oscillation frequency according to a capacitance between the tip portion of the dispensing probe and a peripheral portion, a detector that detects whether the tip portion of the dispensing probe has come into contact with the liquid level in the container based on the oscillation frequency of the AC signal
Data Source
AI summary
A feature amount extraction unit outputs, as a data series, a feature amount of time-series data of an oscillation frequency of an AC signal of an oscillation circuit until a certain time elapses from when a dispensing probe starts to be lowered. Then, a bubble contact determination processing unit determines whether a liquid level has been normally detected based on a correlation between a waveform of the data series of the feature amount and an abnormal waveform model. Further, based on a determination result, a second controller determines a deviation between a tip portion of the dispensing probe and the liquid level in a container and a factor of the deviation.