Automatic Analyzer Suction Pressure Detection
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Solution Overview
Problem
Existing automatic analyzers face difficulties in accurately detecting dispensation abnormalities during conditions with small suction quantities, such as suction of minute foreign objects or air bubbles, due to limited pressure information and short operation times, making it challenging to distinguish between normal and abnormal dispensations.
Innovation Solution
The implementation of an automatic analyzer equipped with a pressure sensor and signal processing unit that acquires suction pressure data, calculates characteristic variables, and compares them with reference data to judge dispensation abnormalities, especially by incorporating information from previous dispensations to improve detection accuracy in subsequent dispensations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the probe's immersion depth in the sample is increased to avoid dispensation abnormality caused by air bubbles or liquid membranes, then the reliability of sample suction is improved, but the contamination of the probe increases and adversely affects the analysis result
Solution Approach 1:
The system performs preliminary detection of the liquid surface position using a capacitance change method before the probe begins suction. By detecting the liquid surface in advance and positioning the probe tip slightly below it, the system achieves reliable sample suction without excessive immersion depth, thereby preventing contamination while ensuring consistent sample acquisition.
Solution Approach 2:
The invention replaces mechanical immersion-based detection with a capacitance-based electrical field detection method. The liquid level sensor detects the liquid surface through capacitance changes without requiring the probe to be deeply immersed in the liquid, thus achieving reliable detection while minimizing probe contamination.
2Ease of operation
If the liquid level sensor is used to detect the liquid surface, then the operation control of the probe is simplified, but the sensor erroneously detects air bubbles or liquid membranes as the liquid surface causing dispensation abnormality
Solution Approach 1:
The system uses feedback from the capacitance change method to verify liquid surface detection. By monitoring the capacitance changes as the probe approaches the liquid surface, the system can distinguish between actual liquid surfaces and false targets like air bubbles or liquid membranes, thereby improving detection accuracy while maintaining ease of operation.
Solution Approach 2:
The capacitance-based detection method detects changes in electrical properties (analogous to color changes in optical detection) when the probe nears the liquid surface. This allows the system to identify the true liquid surface through characteristic capacitance patterns, preventing erroneous detection of air bubbles or liquid membranes while keeping the control system simple.
3Reliability
If pressure sensor-based abnormality detection is used, then dispensation abnormalities can be detected, but detection accuracy is insufficient in conditions with small suction quantities such as suction of minute foreign objects or air bubbles
Solution Approach 1:
The system performs preliminary detection of the liquid surface position using capacitance changes before suction begins. This preliminary action provides accurate baseline information about the true liquid surface position, which is then used to correct or supplement pressure-based abnormality detection, thereby improving detection accuracy for small suction quantities like air bubbles or minute foreign objects.
Solution Approach 2:
The invention introduces capacitance-based liquid surface detection as an intermediary mechanism that bridges the gap between simple pressure sensing and complex multi-sensor systems. The capacitance detection provides intermediate verification of liquid surface position, enhancing the pressure sensor's ability to detect small abnormalities without requiring a fully complex sensor array.
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 configuration enables highly reliable analysis by accurately detecting dispensation abnormalities in conditions with small suction quantities, particularly in second and subsequent dispensations, enhancing the analyzer's performance and reducing false positives/negatives.
Implementation Method 1
As a method for detecting the liquid surface of the sample, the capacitance change method (detecting a change in capacitance when the probe makes contact with the liquid surface) is the most commonly used.
Implementation Method 2
Many technologies have been proposed as means for judging the occurrence of the above-described dispensation abnormality, in which a pressure sensor is arranged in a dispensation channel including the sample probe and the dispensation abnormality (e.g., the clogging of the sample probe) is detected based on pressure fluctuation.
Data Source
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AI summary
Implemented is an automatic analyzer capable of performing highly reliable analysis by accurately detecting dispensation abnormality in dispensation conditions with small suction quantities. A statistical distance calculation unit 206a calculates characteristic variables regarding a sucking operation in the first dispensation and calculates a statistical distance D from reference data to the characteristic variables extracted from a memory 206b by a reference data selection unit 206f. A comparison unit 206c compares the statistical distance D with a preset threshold value stored in the memory 206b and supplies the result of the comparison to a judgment unit 206d. If the statistical distance D is less than the preset threshold value, the judgment unit 206d performs the first discharging operation. A controller judges whether a single-handed judgment based on a dispensation quantity condition of the second or subsequent dispensation is possible or not. If the single-handed judgment is impossible, reference data is selected based on a judgment quantity regarding the first dispensation. Whether the sucking operation in the second or subsequent dispensation is normal or abnormal is judged based on the selected reference data.