Lab Automation Liquid Level Detection via Optical and Tip Sensing
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Solution Overview
Problem
Existing laboratory automation systems face challenges in accurately determining the liquid level of samples in containers, particularly when samples contain transition phases like foam or bubbles, leading to inaccuracies in pipetting and sample processing.
Innovation Solution
An apparatus equipped with an optical sensing unit to measure transmittance at different wavelengths and a tip sensing unit to provide liquid level detection signals, controlled by a process control unit to differentiate between the sample and transition phases, ensuring precise liquid level determination and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensing method is used to detect liquid level, then the device complexity is reduced, but the measurement precision deteriorates due to inability to distinguish between sample and transition phases
Solution Approach 1:
The patent divides the liquid level detection task into two separate sensing methods: optical sensing for detecting the meniscus position and capacitive sensing for detecting the actual liquid level. This segmentation allows each sensor to specialize in detecting specific phases (transition phase vs. liquid phase), thereby improving overall measurement precision without requiring a single complex sensor to handle all detection tasks
Solution Approach 2:
The patent combines optical sensing and capacitive sensing into a unified detection system that processes signals from both sensors. By merging the strengths of optical detection (sensitive to meniscus and transition phases) and capacitive detection (sensitive to actual liquid contact), the system achieves accurate liquid level measurement while managing device complexity through integrated control
2Reliability
If optical sensing alone is used, then the device complexity is reduced, but the reliability deteriorates due to misinterpretation of transition phases as liquid levels
Solution Approach 1:
The patent implements feedback control by continuously monitoring both optical and capacitive signals and using the capacitive sensor's ability to distinguish liquid contact to correct and verify the optical sensor's liquid level determination. The control unit compares signals from both sensors and uses capacitive feedback to confirm actual liquid presence, preventing false readings from transition phases
Solution Approach 2:
The capacitive sensor acts as an intermediary verification mechanism that confirms whether the optical sensor's detected meniscus position corresponds to actual liquid contact. This intermediary check prevents the system from mistakenly identifying foam or bubbles as liquid levels, thereby improving reliability
3Measurement precision
If multiple sensing units are combined, then the measurement precision is improved, but the ease of operation deteriorates due to complex signal processing requirements
Solution Approach 1:
The control unit is designed with multi-functionality to handle both optical and capacitive sensing signals through a unified processing algorithm. This universal control approach integrates multiple sensing functions into a single operational interface, maintaining ease of operation despite the complexity of processing signals from multiple sensing units
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
The solution enables accurate detection of liquid levels, preventing errors in pipetting and sample processing by distinguishing between the sample and transition phases, thereby ensuring reliable aspiration and discarding of samples based on defined thresholds.
Implementation Method 1
an optical sensing unit for sensing a transmittance at different vertical positions through the laboratory sample container
Implementation Method 2
a tip sensing unit having a tip. The tip sensing unit can be adapted to provide a tip sensing signal (tLDS) depending on a position of the tip relative to the sample
Data Source
AI summary
An apparatus for processing a laboratory sample contained in a laboratory sample container is presented. The apparatus comprises an optical sensing unit for sensing a transmittance at different vertical positions through the laboratory sample container and a tip sensing unit having a tip. The tip sensing unit is adapted to provide a tip sensing signal (tLDS) depending on a position of the tip relative to the sample. The apparatus also comprises a process control unit adapted to control the secure and reliable pipetting of the laboratory sample in response to both the transmittance and the tip sensing signal (tLDS) provided by the tip sensing unit.