Liquid Aspiration Volume Compensation via Pressure Detection
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Solution Overview
Problem
Laboratory automation devices face challenges in accurately and efficiently aspirating liquids due to inaccuracies in liquid level detection and subsequent aspiration processes, leading to systematic errors and increased time consumption.
Innovation Solution
The method involves using a pressure generating device to create under or overpressure in a pipette, measuring pressure changes to detect the liquid surface, and calculating a compensation volume to correct for pressure imbalances within the pipette's compartments, allowing for precise aspiration without retracting or blowing out the pipette.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If liquid level detection is performed by surveying pressure changes when the pipette touches the liquid surface, then liquid level detection can be achieved, but some liquid enters the pipette and additional steps (retracting and blowing out) are required
Solution Approach 1:
The patent applies preliminary action by performing liquid level detection through pressure measurement before the aspiration process begins. The pressure change is detected as the pipette approaches the liquid surface, allowing the system to prepare for aspiration without yet making contact. This prevents liquid from entering the pipette during detection, eliminating the need for subsequent retracting and blowing out steps.
Solution Approach 2:
The patent replaces the traditional mechanical contact-based liquid level detection with a pressure-based detection system. Instead of physically touching the liquid surface with the pipette tip, the system uses pressure sensors to detect liquid level by measuring pressure changes in the pressure distribution system, thereby avoiding mechanical contact that would cause liquid to enter the pipette.
2Reliability
If the pipette is retracted and blown out after liquid level detection to remove liquid, then no liquid remains in the pipette tip, but the aspiration procedure becomes slower and more complex
Solution Approach 1:
The patent replaces mechanical operations (retracting and blowing out) with a pressure-based compensation system. By measuring pressure changes during liquid level detection and calculating the corresponding compensation volume, the system can directly adjust the aspiration volume without needing to mechanically retract or blow out the pipette, thereby maintaining reliability while increasing productivity.
Solution Approach 2:
The patent introduces pressure measurement and compensation volume calculation as an intermediary between liquid level detection and aspiration. Instead of directly contacting the liquid and then removing excess, the system uses pressure data as an intermediary to calculate the precise compensation volume needed, enabling direct aspiration without intermediate mechanical steps.
3Measurement precision
If pressure is generated in the pipette during lowering to detect liquid surface, then liquid surface detection is enabled, but pressure imbalances within the pressure distribution system cause systematic errors in aspiration volume
Solution Approach 1:
The patent applies feedback by continuously monitoring pressure changes in the pressure distribution system during liquid level detection and using this information to calculate compensation volume. The pressure measurement provides feedback about the liquid surface position, and this feedback is used to adjust the aspiration parameters, thereby eliminating systematic errors caused by pressure imbalances.
Solution Approach 2:
The patent changes the parameter used for liquid level detection from mechanical contact to pressure measurement. By detecting pressure changes as the pipette approaches the liquid surface, the system can determine liquid level without creating pressure imbalances that would affect aspiration volume. The compensation volume calculation further adjusts for any pressure effects, maintaining precision.
4Reliability
If additional steps like retracting and blowing out are performed after liquid level detection, then liquid is removed from the pipette, but the number of operations increases and time consumption increases
Solution Approach 1:
The patent extracts the liquid removal function from the mechanical operations (retracting and blowing out) and integrates it into the pressure-based detection and compensation system. By calculating compensation volume based on pressure changes, the system inherently accounts for and removes the need for separate liquid removal steps, simplifying the overall process while maintaining reliability.
Solution Approach 2:
The patent merges liquid level detection, liquid removal, and aspiration into a single integrated process. By using pressure measurement for detection and compensation volume calculation for removal, the system combines multiple functions into one coordinated operation, eliminating the need for separate retracting and blowing out steps.
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 enhances the precision and speed of liquid aspiration, reducing systematic errors and eliminating the need for additional steps like retracting and blowing out, thereby increasing the throughput and accuracy of laboratory automation devices.
Implementation Method 1
generating an underpressure or overpressure in the pipette with a pressure generating device of the laboratory automation device and measuring a pressure in a pressure distribution system interconnecting the pressure generating device with the pipette; and detecting a liquid surface of the liquid in the vessel by evaluating a pressure change of the pressure
Data Source
Figure 1~2
Figure 3A~3C
Figure 4A~4C
AI summary
A method for aspirating a liquid (22) with a laboratory automation device (10) comprises: lowering a pipette (14) of the laboratory automation device (10) into a vessel (18) containing the liquid (22); during lowering, generating an underpressure or overpressure in the pipette (14) with a pressure generating device (26) of the laboratory automation device (10) and measuring a pressure (46) in a pressure distribution system (30) interconnecting the pressure generating device (26) with the pipette (14); detecting a liquid surface (40) of the liquid (22) in the vessel (18) by evaluating a pressure change (48) of the pressure (46); calculating a compensation volume from compartment volumes of compartments (38) of the pressure distribution system (30) and/or of the pipette (14) and from pressure losses between the compartments (38); and aspirating the liquid (22) from the vessel (18) into the pipette (14) by controlling the pressure generating device (26) to aspirate a specific volume altered by the compensation volume.