Automatic Analyzer Malfunction Detection via Multi-Suction Liquid Level Verification
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Solution Overview
Problem
Automatic analyzers face challenges in accurately determining the proper execution of sample suction operations due to variations in liquid surface states, such as foam coverage, which can lead to incorrect sample quantity and quality dispensing.
Innovation Solution
The implementation of a malfunction determination method that uses a control device with a liquid level sensor and pressure sensor to compare liquid level heights and pressure changes across multiple suction operations, identifying deviations from set thresholds to determine if the suction operations were executed correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a liquid level sensor is used to detect the liquid surface position during sample dispensing, then the automation of the inspection process is improved, but the measurement precision deteriorates when foam is present on the liquid surface
Solution Approach 1:
The patent introduces an intermediary verification mechanism by performing multiple suction operations and comparing liquid level changes between them. Instead of relying solely on the liquid level sensor's direct detection (which is fooled by foam), the system uses the liquid level sensor to detect initial level, performs suction, detects final level, and verifies the change matches expected values. This intermediary comparison step acts as a mediator to identify when foam causes incorrect detection.
Solution Approach 2:
The system implements feedback by measuring the liquid level before and after suction operations, calculating the change, and comparing it against expected thresholds. When the liquid level change falls outside the predetermined range, the system identifies a malfunction and can request re-suction or notify the user. This feedback loop allows the automated system to self-correct or self-diagnose issues caused by foam interference.
2Ease of operation
If the liquid level sensor identifies foam as the liquid surface, then the ease of operation is improved, but the quality and quantity of sample dispensing deteriorates
Solution Approach 1:
The patent performs preliminary verification actions by conducting multiple suction operations (at least two times) on the same sample and comparing the liquid level changes between them. This preliminary repeated action allows the system to identify inconsistencies caused by foam before finalizing the sample dispensing. The first suction operation serves as a preliminary test, and subsequent operations verify consistency.
Solution Approach 2:
The system uses feedback by comparing liquid level changes from multiple suction operations against predetermined thresholds. When the change in liquid level between operations falls outside the expected range, the system identifies a malfunction in sample suction and can trigger corrective actions such as re-suction or user notification, ensuring accurate sample dispensing despite foam presence.
3Reliability
If multiple suction operations are performed on the same sample to verify proper execution, then the reliability of test results is improved, but the loss of time increases
Solution Approach 1:
The patent applies partial verification by performing a minimum of two suction operations rather than requiring exhaustive multiple operations. The system checks liquid level changes after each suction and stops when verification is sufficient (i.e., when changes are consistent within predetermined thresholds). This partial action approach provides adequate reliability without excessive time consumption.
Solution Approach 2:
The system skips unnecessary verification steps by using predetermined thresholds to quickly determine when liquid level changes are within acceptable ranges. When measurements fall within expected parameters, the system rapidly proceeds without requiring extensive repeated measurements, thus reducing time loss while maintaining reliability.
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 method allows for the reliable determination of proper sample suction operations, enhancing the quality and quantity of sample dispensing and improving the reliability of measurement results by identifying and alerting to potential malfunctions caused by foam or other surface variations.
Implementation Method 1
a liquid level sensor configured to detect a liquid level of the sample
Implementation Method 2
pressure sensor to compare liquid level heights and pressure changes
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An automatic analyzer which performs a suction operation a plurality of times on a same sample has a sample dispensing unit 9, a liquid level sensor which detects the liquid level of the sample in a sample vessel 8, an arithmetic unit 5 which computes a liquid level height h1 at the end of a first suction operation of the two consecutive suction operations from a liquid level height h0 and a sample suction volume V1 detected at the start of the first suction operation, a storage unit 7 which stores the liquid level height h1 computed by the arithmetic unit 5, and a determination unit 18 which compares a liquid level height h2 detected at the start of a second suction operation following the first suction operation with the liquid level height h1 at the end of the first suction operation. The automatic analyzer further determines the presence or absence of a failure in the first or second suction operation according to whether the difference between both liquid level heights h1 and h2 exceeds a threshold value d set in advance. Thus, it is possible to determine whether the suction operation of the sample dispensing unit has been performed properly.