Portable Viscometer Microfluidic Viscosity Measurement
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Solution Overview
Problem
Current viscosity measurement techniques for non-Newtonian liquids often yield apparent viscosity values rather than true viscosity, requiring large sample volumes and lengthy cleaning processes, with no portable solutions available for fast and accurate true viscosity measurement in small quantities.
Innovation Solution
A portable viscometer system incorporating a precision liquid dispensing system with a positive displacement pump and a miniature flow-through viscosity sensor, which measures true viscosity by controlling the flow rate and pressure drop in a micron-scale flow channel, allowing for small sample volumes and rapid testing without the need for extensive cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional viscosity measurement techniques are used, then apparent viscosity can be measured quickly, but true viscosity cannot be obtained and large sample volumes are required
Solution Approach 1:
The flow channel is divided into two distinct sections: an entrance region and a fully developed flow region. Pressure sensors are strategically placed to measure pressure drop specifically across the fully developed section, where flow conditions are stable and predictable. This segmentation allows accurate true viscosity measurement while using minimal sample volume.
Solution Approach 2:
The invention transitions from traditional bulk measurement approaches to micro-scale dimensional measurement. By using a flow channel with dimensions in the micrometer range (width 10-100 μm, depth 1-10 μm), the system achieves precise viscosity measurement in the fully developed flow region without requiring large sample volumes.
2Measurement precision
If conventional viscometers are used, then viscosity measurement can be performed, but extensive cleaning is required between samples
Solution Approach 1:
The micro-scale flow channel and associated components are designed as disposable or easily replaceable elements. After each measurement, the entire flow channel assembly can be discarded or quickly replaced, eliminating the need for time-consuming cleaning procedures while maintaining measurement accuracy.
Solution Approach 2:
The flow channel is extracted as a separate, removable component from the main viscometer body. This allows the flow channel to be easily removed and replaced between measurements, eliminating the need to clean the main instrument body while maintaining measurement precision.
3Measurement precision
If rheometers are used to measure true viscosity, then accurate measurements can be obtained, but the instruments are expensive and require large sample volumes
Solution Approach 1:
The invention replaces complex mechanical rheometer systems with a simplified microfluidic approach. Instead of using mechanical rotating elements and complex control mechanisms, the system uses a static micro-scale flow channel with pressure sensing to determine viscosity, dramatically reducing device complexity while maintaining measurement accuracy.
Solution Approach 2:
The invention transitions from macro-scale mechanical measurement to micro-scale fluidic measurement. By using a flow channel with dimensions in the micrometer range, the system achieves accurate true viscosity measurement without the complexity and sample volume requirements of traditional rheometers.
4Measurement precision
If capillary viscometers are used, then pressure drop measurement can be performed, but only apparent viscosity is obtained unless two different capillaries are used
Solution Approach 1:
The flow channel is segmented into an entrance region and a fully developed flow region, with pressure sensors positioned to measure pressure drop specifically across the fully developed section. This single-channel segmentation approach enables true viscosity measurement without requiring multiple capillaries of different length-to-diameter ratios.
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 fast, accurate, and portable measurement of true viscosity for small liquid samples, reducing sample volume requirements and cleaning time, while providing a compact and efficient solution for on-line applications.
Implementation Method 1
A portable precision liquid dispensing system with a positive displacement pump
Implementation Method 2
measures the pressure drop of a fully developed flow of the liquid in the flow channel. The pressure drop is proportional to the shear stress of the liquid flowing through the channel
Implementation Method 3
A portable viscometer system incorporating a precision liquid dispensing system with a positive displacement pump and a miniature flow-through viscosity sensor, which measures true viscosity by controlling the flow rate and pressure drop in a micron-scale flow channel
Data Source
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AI summary
A portable viscometer includes a pump mechanism which cooperates with a positive displacement sample container referred to as a positive displacement pipette, for dispensing, at a known flow rate, a sample of liquid for which viscosity is desired to be determined. The dispensed liquid flows through a flow through miniature viscosity sensor having at least two pressure sensors which measure the pressure drop of the liquid as it flows through a rectangular flow channel, the pressure drop at the known flow rate being proportional to the viscosity. A controller controls operation of the viscometer and processes sensor data, and the resulting measurements of viscosity can be displayed on a display. The positive displacement pipette is removably positioned in the viscometer so that it can be removed from the viscometer when a viscosity test is completed and replaced with another positive displacement pipette containing another liquid to be tested.