Micro-Rheometer with Electrode Array for Viscosity Measurement
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Solution Overview
Problem
Current micro-rheometers for measuring viscosity are complex, expensive, and limited in measuring low viscosity fluids at low shear rates, with integrated pressure sensors causing accuracy issues and being difficult to manufacture, and optical methods face integration and control challenges.
Innovation Solution
A portable, easy-to-fabricate micro-rheometer using a microchannel with a sensor array of electrode pairs that function as electronic switches to detect fluid flow velocity and rheological properties, allowing operation over a wide range of shear rates and pressures, and fabricated using biocompatible materials like PET and glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integrated pressure sensors are used in micro-rheometers, then viscosity measurement capability is provided, but measurement accuracy deteriorates due to flow perturbation and sensor mounting issues
Solution Approach 1:
The patent removes pressure sensors from the system entirely and replaces them with electrode-based flow velocity detection. The electrodes detect fluid flow velocity through conductivity changes, eliminating the need for integrated pressure sensors that cause flow perturbation and mounting difficulties.
Solution Approach 2:
The patent replaces the mechanical pressure sensing system with an electrical detection system using electrodes. Instead of measuring pressure directly with sensors that perturb flow, the system uses electrical conductivity changes to infer flow velocity and calculate viscosity, substituting mechanical measurement with electrical measurement.
2Reliability
If conventional macroscopic rheometers are used, then reliable viscosity measurement is achieved, but device portability and material volume requirements deteriorate
Solution Approach 1:
The patent divides the traditional macroscopic rheometer into a miniaturized micro-rheometer with a microchannel and integrated electrode array. The device segments the measurement function into a compact format while maintaining reliability through careful design of the microchannel geometry and electrode configuration.
Solution Approach 2:
The patent transitions from macroscopic three-dimensional measurement to microscopic two-dimensional surface-based measurement using planar electrodes on a substrate. This dimensional change enables miniaturization while preserving measurement capability through surface-mounted electrode detection of flow velocity.
3Adaptability or versatility
If micro-rheometers are miniaturized, then device portability and material usage are improved, but manufacturing complexity and fabrication cost increase
Solution Approach 1:
The patent merges the microchannel structure and electrode array into a single integrated substrate. The electrodes are patterned directly onto the microchannel substrate, combining the fluidic channel and sensing elements into one fabricated component, which simplifies manufacturing compared to assembling separate parts.
Solution Approach 2:
The patent creates a universal micro-rheometer platform that can measure viscosity of various fluids (Newtonian and non-Newtonian) using the same device structure. The microchannel and electrode design is general-purpose, allowing the device to handle different fluid types without requiring custom fabrication for each application.
4Measurement precision
If pressure sensors are mounted in flow channel, then viscosity measurement is enabled, but surface roughness causes sample deposition and performance degradation
Solution Approach 1:
The patent removes pressure sensors from the flow channel entirely and replaces them with electrodes that detect flow velocity through conductivity changes. This extraction eliminates the surface roughness and deposition problems associated with pressure sensor mounting while maintaining viscosity measurement capability.
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 device accurately measures viscosity variations with high precision, is cost-effective, and can analyze fluids at different shear rates, providing rheological properties in under two minutes, with no damage to biological samples, and is suitable for medical diagnostics.
Implementation Method 1
a sensor array arranged along the microchannel to measure rheological properties of a fluid flowing through the microchannel; wherein the sensor array comprises a plurality of pairs of electrodes with a known physical disposition along the microchannel, the two electrodes of each pair of electrodes being placed face to face within the microchannel to function as an electronic switch when the fluid passes by
Data Source
AI summary
Apparatus comprising a micro-rheometer (1) with a microchannel (2) and a sensor array arranged along the microchannel to measure rheological properties of a fluid. The sensor array comprises a plurality of pairs of electrodes (8, 8′), each pair being placed face to face to function as an electronic switch when the fluid flows through them. It further comprises a data acquisition system (10) with an electronic circuit in which each pair of electrodes is connected to an amplifier electronic circuit (11) to ensure an ultra-low electrical current flow through the short-circuit created by the fluid and the pair of electrodes, to avoid damaging the fluid. The invention may be used as a small portable device for medical diagnosis in diseases associated to changes in blood viscosity, operating in a wide range of shear rates.