Hydrophobic Paper Microfluidic Diagnostic Strip
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Solution Overview
Problem
Point-of-care (POC) diagnostic devices are expensive to manufacture due to complex manufacturing processes and high costs, limiting their accessibility for rapid medical testing outside laboratory settings.
Innovation Solution
The development of substrate-based diagnostic devices using a hydrophobic paper substrate with a microfluidic component and detection zone, featuring a sensor with electrodes and a hydrophilic ink channel for capillary fluid transport, which are printed using cost-effective methods like rotary screen printing, reducing the complexity and cost of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automated diagnostic analyzers are used, then diagnostic testing can be performed, but the cost, size, and complexity increase significantly
Solution Approach 1:
The diagnostic system is divided into separate functional components: a disposable test strip containing the microfluidic channel and sensor, and a separate reader device. This segmentation allows the complex diagnostic functionality to be maintained while simplifying the permanent infrastructure needed, as the test strip can be manufactured independently using low-cost techniques and disposed of after use.
Solution Approach 2:
The invention employs disposable test strips that contain the microfluidic channel and sensor components. These test strips are manufactured at low cost using simple techniques like inkjet printing and are discarded after a single use, eliminating the need for expensive, complex, and reusable automated analyzers while maintaining diagnostic capability.
2Loss of time
If POC testing devices are developed with microfluidic chips and sensors, then rapid testing can be performed, but manufacturing cost increases
Solution Approach 1:
The invention replaces complex mechanical microfluidic pumping and control systems with passive capillary action for fluid transport. The microfluidic channel is designed with appropriate hydrophobicity and capillary forces to automatically draw sample fluid through the test strip without requiring external pumps or complex mechanical actuation, significantly simplifying manufacturing.
Solution Approach 2:
The invention modifies the surface properties of the microfluidic channel by making it hydrophobic through treatment with materials like wax or silicone oil. This parameter change enables passive capillary flow control, eliminating the need for active pumping mechanisms and reducing manufacturing complexity and cost while maintaining rapid fluid transport for POC testing.
3Manufacturing precision
If complex manufacturing processes are used for POC devices, then device performance can be improved, but production cost and complexity increase
Solution Approach 1:
The invention uses printing techniques (inkjet or screen printing) to deposit sensor patterns, electrodes, and hydrophobic coatings directly onto the test strip substrate. This copying approach creates precise microfluidic channels and sensor structures without requiring complex lithography or micromachining processes, achieving necessary manufacturing precision through simpler, more cost-effective methods.
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
These devices are more affordable and easier to manufacture, enabling rapid, cost-effective POC testing with results in a short time, improving accessibility for medical diagnostics beyond laboratory settings.
Implementation Method 1
a channel comprising hydrophilic ink disposed on the first surface of the substrate, the channel having an inlet section adjacent the first end of the substrate, a middle section, and an outlet section in contact with the layer of hydrophilic ink
Data Source
Figure 1
Figure 2A~2D
Figure 2E~3B
AI summary
A paper substrate, microfluidic device (100) for POC diagnostics is disclosed herein along with related methods and systems. In one embodiment. the device includes a hydrophobic substrate (102) having a first end and a second end opposite the first end. The device includes a detection zone (116) on a first surface of the substrate, the detection zone defining an area to sense an analyte in a sample, the detection zone comprising a first electrode (120; WE) and a second electrode (122; CE) disposed on the first surface of the substrate and a layer of hydrophilic ink (138) disposed on the two electrodes and an area between the first and second electrodes. There is also a channel (144) comprising hydrophilic ink disposed on the first surface of the substrate, the channel having an inlet section (142) adjacent the first end of the substrate, a middle section, and an outlet section in contact with the layer of hydrophilic ink (138). The channel is to transfer a fluid sample from the inlet section to the layer of hydrophilic ink.