Capillary Liquid Measurement Device for Pipettor Calibration
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Solution Overview
Problem
Current methods for calibrating fluid dispensing devices like pipettors are arduous, prone to inaccuracies, especially at small volumes, due to environmental factors and indirect measurement techniques.
Innovation Solution
A measuring device with a capillary and well system that directly measures the volume dispensed by comparing the liquid/air interface meniscus with markings or sensors, allowing for high throughput automation and easy validation of calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gravimetric calibration method is used, then measurement accuracy can be achieved, but the process becomes arduous, time-consuming, and prone to inaccuracies due to environmental factors
Solution Approach 1:
The patent replaces the mechanical gravimetric measurement system (weighing scales) with an optical measurement system. The capillary tube with meniscus markings provides direct visual volume measurement, eliminating the need for weighing and subsequent calculation conversions. This optical-mechanical direct reading system resolves the contradiction by providing both accuracy and speed without environmental sensitivity.
Solution Approach 2:
The patent creates a visual copy of the volume measurement through the capillary tube meniscus alignment with markings. Instead of measuring weight and calculating volume indirectly, the system provides a direct visual copy of the actual volume dispensed through the meniscus position, enabling rapid verification without time-consuming intermediate steps.
2Measurement precision
If gravimetric calibration is performed at small volumes, then precision measurement is possible, but environmental factors like air currents and vibrations introduce errors
Solution Approach 1:
The patent replaces the sensitive mechanical weighing system with an optical visual inspection system. The capillary tube method allows direct observation of the meniscus position against markings, which is not affected by air currents or vibrations that plague electronic scales at microgram sensitivity levels. This provides both precision and reliability for small volumes.
3Ease of manufacture
If indirect measurement methods are used, then calibration can be performed, but the process is complex and prone to inaccuracies
Solution Approach 1:
The patent replaces indirect mechanical measurement (weighing) with direct optical measurement (meniscus position). The capillary tube provides a simple, direct visual indication of volume that is both easy to manufacture and highly accurate, eliminating complex calculation conversions and reducing sources of error.
4Extent of automation
If photometer-based absorbance system is used, then calibration verification can be automated, but the equipment becomes expensive
Solution Approach 1:
The patent employs a simple, inexpensive capillary tube with markings that can be disposable or reusable. This replaces expensive photometer equipment with a low-cost visual measurement system. The simplicity of the capillary tube design allows for easy manufacturing and potential automation without requiring expensive optical instruments.
Solution Approach 2:
The patent replaces the expensive photometer-based optical system with a simpler visual inspection system using capillary tubes. The meniscus alignment method provides automated-measurement-capability at a fraction of the cost, maintaining automation potential while dramatically reducing equipment complexity and cost.
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
Facilitates fast, accurate, and inexpensive verification of pipettor calibration, ensuring accuracy and repeatability within specified limits, reducing errors associated with environmental factors and indirect measurement methods.
Implementation Method 1
a capillary (4) extending from the funnel shaped well (2) toward and beyond a viewing window
Data Source
AI summary
A measurement device containing one or more capillaries to measure the volume of a dispensed fluid and determine the volumetric accuracy of the dispensing device. The measurement device can contain a reservoir containing the fluid to be measured and there may be an additional reservoir for a secondary fluid. A viewing window is necessary to complete a manual measurement and may include a magnifying lens. The liquid well by the capillary inlet may be shaped such that the measurement fluid is directed toward the capillary. The well may have features designed to position the dispensing device toward the capillary, or to position the well proximal to the capillary after it is filled. The well may also have surfaces or coatings which attract or do not attract various types of substances. The measurement device may interface with sensors to output measurement data.