Smartphone Microfluidic Viscometer Using Optical Imaging
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Solution Overview
Problem
Conventional viscometers face limitations such as bulkiness, sample volume requirements, cumbersome cleaning, limited shear rate range, and non-viscometric flow kinematics, making them unsuitable for onsite or field applications, especially for handling clinical and industrial-grade fluids, and current microfluidic viscometers either suffer from sample contamination issues or are not scalable for parallel measurements.
Innovation Solution
A smartphone-based microfluidic viscometer, 'iCapillary', using a capillary attached to a microfluidic chip and a digital camera to measure viscosity by monitoring fluid front motion, allowing for high-throughput, portable, and disposable viscosity determination without pressure sensors, suitable for resource-sparse environments and capable of handling complex fluids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are embedded in microfluidic channels for viscosity measurement, then viscosity can be determined through pressure drop and flow rate relation, but the device cannot handle clinical samples due to sample cross-contamination and is not scalable for parallel measurements
Solution Approach 1:
The patent replaces pressure sensors with an optical detection system using a digital camera to monitor fluid front motion. This substitution eliminates the need for embedded pressure sensors, enabling the device to handle clinical samples without cross-contamination risks and allowing parallel measurement of multiple samples through imaging capabilities.
Solution Approach 2:
The patent uses optical imaging to create a visual copy of the fluid flow state by capturing images of the fluid front position in capillaries. This optical copy allows viscosity determination through image analysis without physical contact between the sensor and the fluid, enabling disposable device design and parallel sample analysis.
2Measurement precision
If research-grade microscopes and cameras are used for image-based viscometry, then viscosity measurement is achieved, but the device is not simple and flexible enough for onsite or field applications
Solution Approach 1:
The patent employs inexpensive digital camera modules instead of research-grade microscopes, making the device simple and portable for field applications. The microfluidic chip itself can be designed as a disposable component, eliminating complex alignment and calibration requirements while maintaining measurement capability.
Solution Approach 2:
The patent extracts only the essential imaging function from complex microscope systems, using a simple digital camera to capture fluid front motion. This extraction eliminates unnecessary optical components and complexity while retaining the core measurement capability, enabling portable deployment.
3Ease of operation
If conventional viscometers are used for onsite viscosity characterization, then operation is simple and cost effective, but large sample volumes are required and cleaning procedures are cumbersome
Solution Approach 1:
The patent divides the measurement system into multiple parallel capillary channels, each requiring minimal sample volume. This segmentation allows simultaneous measurement of multiple samples or repeated measurements with small aliquots, reducing total sample volume requirements while maintaining operational simplicity.
Solution Approach 2:
The patent transitions from traditional bulk fluid measurement to microscale channel flow, utilizing the microfluidic dimension to reduce sample volume requirements. The capillary geometry confines the fluid to a controlled pathway, enabling accurate viscosity measurement with minimal sample while simplifying the measurement process.
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 efficient, real-time viscosity measurement of multiple samples in various industries, with high shear rate range accessibility and minimal sample volume, overcoming previous limitations by leveraging smartphone imaging for accurate and portable fluid rheology analysis.
Implementation Method 1
A smartphone-based microfluidic viscometer, 'iCapillary', using a capillary attached to a microfluidic chip and a digital camera to measure viscosity by monitoring fluid front motion
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~3
AI summary
The present invention includes a method and an apparatus for determining the viscosity of a fluid. The apparatus comprising that includes a microchannel connected to a glass capillary in fluid communication with the microchannel, a digital camera positioned with respect to the glass capillary to capture two or more images of a fluidic slug as a fluid travels within the glass capillary, and a processor communicably coupled to the digital camera that determines a viscosity of the fluid based on the two or more digital images.