Fluidic Property Estimation for Precision Metering
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Solution Overview
Problem
Diagnostic analyzers face challenges in achieving precise and accurate fluid aspiration and dispensation, particularly at small volumes, due to issues like bubbles, clots, and viscosity variations, which affect the accuracy of assay results and require robust failure mode detection.
Innovation Solution
A method that estimates fluidic properties such as viscosity and surface tension through monitoring pressure profiles during metering operations, using sensed data to adjust control parameters and improve precision and accuracy, and detect failure modes by modifying thresholds based on estimated properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If test volumes are reduced below 5 μL to conserve sample and reagent, then sample consumption and reagent usage are minimized, but precision and accuracy of fluid delivery become significantly more difficult to maintain
Solution Approach 1:
The system dynamically adjusts metering parameters such as pump speed, pressure, and timing based on real-time feedback from pressure sensors and flow monitors. This allows the system to maintain precise fluid delivery at reduced volumes by optimizing parameters for each specific aspiration and dispensing event, compensating for the increased sensitivity to deviations at small volumes.
Solution Approach 2:
The system incorporates pressure detection systems and flow-based monitoring that provide real-time feedback during aspiration and dispensing operations. This feedback loop allows the system to detect and correct deviations from target volumes, maintaining precision even when operating at reduced test volumes below 5 μL.
2Reliability
If pressure detection systems are used to monitor aspiration and dispensing, then failure detection capability is improved, but system complexity increases
Solution Approach 1:
The pressure detection system serves multiple functions: it monitors aspiration events, detects dispensing completion, identifies failure modes such as clots or bubbles, and provides feedback for volume correction. By using a single pressure sensing mechanism for multiple purposes, the system achieves high reliability without proportionally increasing complexity.
Solution Approach 2:
The system combines pressure detection with flow-based monitoring and control logic into an integrated monitoring framework. This merging of functions allows the system to leverage multiple sensing approaches without requiring separate independent systems, thereby improving failure detection while managing overall system complexity.
3Device complexity
If flow-based systems with non-pressure sensors are used to monitor flow rate, then system simplicity is maintained, but failure detection robustness deteriorates
Solution Approach 1:
The system uses pressure sensors as intermediary elements that translate complex fluid dynamics (including viscosity changes, bubble formation, and clot detection) into measurable electrical signals. This intermediary approach allows robust failure detection without requiring direct observation of all fluid properties, maintaining system simplicity while improving reliability.
Solution Approach 2:
The system replaces purely mechanical flow sensors with pressure-based detection that can sense both mechanical and physiological fluid properties. This substitution enables more robust failure mode detection by capturing pressure anomalies that indicate clots, bubbles, or viscosity changes, which mechanical flow sensors alone cannot reliably detect.
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 accuracy of fluid metering, reduces errors in small volume deliveries, and improves the detection of failure modes, leading to more reliable assay results by compensating for viscosity and surface tension effects.
Implementation Method 1
Some diagnostic analyzers use pressure detection systems to monitor the aspiration and dispense of sample and reagent liquids
Implementation Method 2
many analyzers use flow-based systems and sensors other than pressure sensors to monitor flow rate for aspirating and dispensing a fluid
Data Source
AI summary
A method for improving the accuracy or precision of a metered fluid includes: estimating a fluidic property of the fluid being metered; and adjusting one or more control parameters based on the estimated property to improve the accuracy or precision of a metered fluid. Preferably, the estimating the property of the fluid being metered includes: monitoring a physical event during the metering operation to collect sensed data; extracting features from the sensed data; and using the features to estimate fluid properties. In another preferred embodiment, the estimated fluidic property is viscosity and the sensed data is a pressure profile during a fluid aspiration. In another preferred embodiment, the method includes a diagnostic analyzer which includes a metering probe having a hard probe or a probe having a disposable tip and wherein the fluid is a body fluid sample. Another method includes: estimating a fluidic property of the fluid being metered; and adjusting one or more control parameters or thresholds that determine when an error is flagged based on the estimated property to improve the detection of the failure.