Iterative Liquid Aspiration Using Pressure-Based Interface Detection

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Solution Overview

Problem

Existing laboratory automation devices face challenges in accurately detecting and aspirating a first liquid medium from a sample container containing two liquid media of different densities, often leading to contamination from the second liquid medium due to delayed detection of the interface and laminar flow issues.

Innovation Solution

A method involving a laboratory automation device that uses pressure measurements to detect the interface between two liquid media by lowering a pipette, applying underpressure, and adjusting aspiration rates to prevent contamination, allowing for precise aspiration and dispensing of the first liquid medium into a separate container.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pressure measurements are used to detect the interface between two liquid media, then the detection reliability is improved, but the interface is only detected after some of the second liquid medium has already reached the interior of the pipette

Engineering Contradiction:

Improveinterface detection reliabilityVSAvoidcontamination of first liquid medium with second liquid medium

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The system performs preliminary actions by continuously monitoring pressure changes during the aspiration process and predicting interface approach before actual contact occurs. The control unit calculates the rate of pressure change and extrapolates to determine when the interface will reach the pipette tip, allowing preventive stopping of aspiration before contamination happens.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control by continuously measuring pressure changes in the pipette, comparing the rate of change against expected values, and automatically adjusting or stopping the aspiration process when interface approach is detected. This closed-loop feedback mechanism prevents contamination while maintaining reliable interface detection.

Inventive Principle:

Principle #23Feedback

2Quantity of substance

If the pipette tip is immersed deeper into the liquid medium to ensure complete aspiration, then the aspiration completeness is improved, but the amount of sample entrained at the outer surface of the pipette tip increases

Engineering Contradiction:

Improveaspiration completenessVSAvoidsample entrainment on pipette tip surface

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The system performs preliminary detection of the interface position using pressure measurements before completing the aspiration. By knowing the interface location in advance, the system can stop aspiration at the optimal point where the pipette tip is sufficiently immersed to aspirate the required volume but not so deep as to cause excessive surface entrainment.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the aspiration process based on real-time pressure feedback. The aspiration depth and duration are optimized by continuously monitoring pressure changes and adapting the aspiration parameters to achieve complete aspiration with minimal surface entrainment.

Inventive Principle:

Principle #15Dynamics

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 method ensures accurate and reliable separation of the first liquid medium by detecting the interface through pressure changes, minimizing contamination from the second medium, and enabling iterative refinement to achieve high purity in the aspirated sample.

Implementation Method 1

measuring a pressure in the pipette during the lowering of the pipette and detecting a position of the interface, when a slope of the pressure changes

Methodology Applied

Scientific EffectPressure measurement:

Implementation Method 2

aspirating liquid from the sample container during the lowering of the pipette by generating an underpressure in the pipette

Methodology Applied

Scientific EffectUnderpressure generation:

Data Source

PatentUS12455293B2Iterative liquid aspiration

Publication Date: 2025.10.28 TECAN TRADING AG

AI summary

A method for aspirating a first liquid medium of two liquid media of different density from a sample container comprises: lowering a pipette of the laboratory automation device into the sample container until a pipette tip of the pipette has passed a lowering distance from the surface of the first liquid medium in the sample container, wherein the lowering distance is chosen, such that the pipette tip passes at least an aspiration volume in the sample container; aspirating liquid from the sample container during the lowering of the pipette by generating an underpressure in the pipette, wherein the first liquid medium is aspirated, and after the interface and the pipette tip pass each other, the second liquid medium of the two liquid media is aspirated; measuring a pressure in the pipette during the lowering of the pipette and detecting a position of the interface, when a slope of the pressure changes; when the lowering distance has been passed and no interface is detected, aspirating the aspiration volume from the first liquid medium and dispensing the aspiration volume of the first liquid medium into a further sample container.