Liquid Dispenser Calibration via Photometric Absorbance
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Solution Overview
Problem
Current methods for calibrating liquid handling devices are not adequately suited for precise and accurate volume determination of aqueous, complex, or non-aqueous liquids, leading to variability in dispensing performance across different solvent types, and lack standardization, making it difficult to ensure consistent volumetric delivery.
Innovation Solution
A method and system involving the creation of a test-stock mixture by mixing a test liquid with a stock solution containing dyes, allowing for precise volume determination using photometric techniques, which includes an analytical balance, spectrophotometer, and computing system to calculate the volume based on absorbance measurements, ensuring accurate and traceable results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gravimetric analysis is used for calibration, then it can measure small volumes, but it does not provide information about individual channel performance for multichannel dispensing devices and is difficult to perform at low volumes
Solution Approach 1:
The patent divides the calibration process into individual channel measurements using a multichannel liquid handling device. Each channel is measured separately by dispensing test liquid into individual wells of a microtiter plate, allowing independent performance assessment of each channel while maintaining the ability to measure small volumes through photometric detection.
Solution Approach 2:
The patent introduces a test liquid containing a dye as an intermediary substance that enables photometric measurement of liquid volume. The dye absorbs light at specific wavelengths, allowing the volume dispensed by each channel to be quantified through absorbance measurements, thereby providing individual channel performance information that gravimetric methods cannot obtain.
2Measurement precision
If fluorescence approach is used for calibration, then it provides information about each channel and extends to low volumes, but variability inherent in fluorescent dyes caused by quenching and photobleaching makes accurate volume determination difficult
Solution Approach 1:
The patent changes the detection parameter from fluorescence emission to photometric absorbance measurement. By measuring absorbance at specific wavelengths (e.g., 520 nm and 730 nm) rather than fluorescence intensity, the method eliminates the variability and non-linearity issues associated with fluorescent dyes, achieving reliable and standardized volume determinations across different channels and instruments.
3Measurement precision
If photometric approach is used for calibration, then it allows for volume measurements traceable to national and international standards, but none is particularly well-suited for calibrating liquid handling devices to precisely and accurately dispense non-aqueous and/or complex liquids
Solution Approach 1:
The patent creates a universal calibration method by formulating a test liquid that can be used across all channels and for all liquid types being calibrated. The test liquid contains a dye with known absorbance characteristics that works regardless of the solvent type (aqueous, organic, complex), allowing the same photometric calibration procedure to accurately measure volumes dispensed by liquid handlers for any liquid type while maintaining traceability to standards.
4Adaptability or versatility
If liquid handler software algorithms are used to compensate for solvent-dependent performance differences, then adjustment is possible, but without accurate measurement of liquid handler performance, these parameters could lead to a false-sense of performance
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual volume dispensed by the liquid handler using photometric detection of the test liquid, then using this measured value to calculate a correction factor. This correction factor is fed back into the software algorithm to adjust future dispensing calculations, ensuring that compensation for solvent-dependent variations is based on actual measured performance rather than assumptions, thereby eliminating false-sense of performance.
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
Enables precise and accurate volume determination of liquids, ensuring consistent performance across different solvent types, and allows for frequent verification of liquid handling device accuracy with minimal downtime, addressing the limitations of existing calibration methods.
Implementation Method 1
The absorbance of the sample solution is measured at a first wavelength and at a second wavelength by a spectrophotometer
Data Source
AI summary
A method for determining the volume of a test liquid aliquot used to calibrate a liquid delivery device. The method is useful for determining the volume of an aliquot of a test liquid which is complex, non-aqueous or both. A mixture contains the test liquid and a stock solution including a first dye, the first dye having absorbance characteristics which are measurably distinguishable from the absorbance characteristics of a second dye. The mixture is mixed with a diluent including the second dye to form a sample solution used to measure absorbances of the first dye and the second dye. The test liquid and the stock solution are combined gravimetrically in a controlled ratio so that the flow characteristics of the test-stock mixture correspond to the flow characteristics of the test liquid and without affecting the ability to distinguish the absorbance characteristics between the first dye and the second dye.