Aspiration Needle Error Detection via Pressure Signal Deviation
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Solution Overview
Problem
Existing methods for aspirating liquid samples into an aspiration needle often fail to detect clogging states, leading to uncertainties in aspirating the desired sample volume due to particles or solid components, especially when dealing with limited sample volumes.
Innovation Solution
A method involving continuous pressure sensor signal measurement during and after the aspiration process, using a reference signal curve to determine a deviation measure and detecting error states based on predefined threshold values, which helps in identifying partial or complete clogging of the aspiration needle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a negative pressure is generated in the aspiration needle for a predetermined time period to aspirate a specific volume of liquid, then the desired sample volume can be aspirated into the needle, but clogging of the aspiration needle by particles or solid components cannot be detected
Solution Approach 1:
The patent applies preliminary action by extending the pressure measurement beyond the aspiration phase into a post-aspiration evaluation phase. The system measures pressure during aspiration to ensure volume accuracy, then continues measuring after aspiration to detect clogging states that may have developed during the process, enabling detection before the clogged needle is used for analysis
Solution Approach 2:
The patent implements feedback by continuously monitoring pressure sensor signals during and after aspiration, comparing the measured pressure curve against expected pressure characteristics. When deviations indicate clogging (such as pressure not returning to baseline or abnormal pressure patterns), the system provides feedback to flag the aspiration as compromised, allowing corrective action before analysis
2Reliability
If the sensor signal falls below a threshold value during aspiration to detect clogging, then clogging can be detected, but incomplete aspiration or partial clogging may be missed
Solution Approach 1:
The patent applies dynamics by transitioning from a static threshold check during aspiration to a dynamic evaluation of the entire pressure curve including the post-aspiration phase. The system evaluates how the pressure evolves over time after aspiration stops, looking for characteristic patterns that indicate complete versus partial aspiration or different types of clogging, rather than relying on a single threshold value
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 effectively detects error states, ensuring accurate aspiration of the desired sample volume by differentiating between partial and complete clogging, even for small volumes, thereby preventing incomplete aspiration.
Implementation Method 1
continuously acquiring a sensor signal curve via continuous measurement of a sensor signal which indicates a pressure in the aspiration needle
Data Source
AI summary
A method for detecting an error state when aspirating a liquid to identify whether a pre-determined volume of liquid was aspirated. The method including: immersing a tip of an aspiration needle in the liquid, aspirating a predetermined partial volume of the liquid in the aspiration needle, continuously acquiring a sensor signal curve, which indicates a pressure in the aspiration needle, during an overall time period, detecting the error state in the case that the sensor signal falls below a first threshold value during the predetermined time period, characterized by providing a reference signal curve, determining a deviation measure, which indicates a deviation of the sensor signal curve from the reference signal curve during the further time period, providing a predetermined second threshold value, detecting the error state as a function of the deviation measure and the second threshold value.