Membrane-Based Device for Automated Multi-Step Assays
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Solution Overview
Problem
Conventional membrane-based microfluidic devices require multiple fluid additions and user input for performing multi-step assays like ELISA and enzyme inhibition assays, which limits their automation and ease of use.
Innovation Solution
A membrane-based device with integrated fluid storage zones that fill with fluid upon sample addition and release reagents sequentially to a test zone via capillary or evaporative wicking, enabling multi-step assays from a single sample addition without further user input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If conventional membrane-based microfluidic devices are used for multi-step assays, then the device structure is simple, but multiple fluid additions and user inputs are required
Solution Approach 1:
Reagents are pre-dried on the device in storage zones before use. Fluid storage zones are pre-filled with carrier fluid during device manufacturing. This preliminary preparation enables automated sequential delivery of reagents when sample fluid is added, eliminating the need for multiple user operations while maintaining relatively simple device structure
Solution Approach 2:
The device is divided into distinct functional zones: sample zone, fluid storage zones, test zones, and waste zone. Each zone performs a specific function in the assay sequence. This segmentation allows complex multi-step assays to be automated through spatial organization rather than mechanical complexity
2Ease of operation
If multiple fluid additions are required for multi-step assays, then the device structure remains simple, but the ease of operation deteriorates
Solution Approach 1:
The device performs self-service by automatically delivering reagents from fluid storage zones to test zones through capillary wicking and evaporative-driven flow. The system uses the evaporation of carrier fluid as a self-regulating mechanism to control reagent delivery timing and sequence without user intervention, significantly improving ease of operation
3Extent of automation
If fluid storage zones are integrated into the device, then automated single-sample addition is enabled, but the device complexity increases
Solution Approach 1:
Fluid storage zones are merged with the porous membrane structure of the device. Reagents are pre-dried directly on the membrane in designated areas, and carrier fluid is absorbed into the same porous structure. This merging eliminates the need for separate reservoir components, enabling automated multi-step assays while keeping the overall device structure relatively simple
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 automated, single-sample addition multi-step assays with no additional user input, demonstrating the sequential delivery of reagents in prototypes for ELISA and enzyme inhibition assays, with tunable reagent arrival times between 5 minutes to over an hour.
Implementation Method 1
the fluid from the sample zone may be wicked into both the test zone and the fluid storage zones
Implementation Method 2
Once the fluid is depleted from the sample zone, fluid from the fluid storage zone may be is wicked to the test zone
Implementation Method 3
fluid from the fluid storage zone may be is wicked to the test zone
Data Source
AI summary
A membrane-based device for multi-step assays including one or more reagents pre-dried on the device, and one or more one fluid storage zones intended to enable the automated sequential delivery of the reagents to a test zone from addition of a fluid to the device. Addition of the fluid to the device may include a single addition of the fluid to the device. The fluid storage zones may fill with the fluid when the fluid with a sample is added to the device, and then the fluid may be released to the device at a later time. In some cases, the fluid from the sample zone is wicked into both the test zone and the fluid storage zones. Preferably, the device includes multiple layers. At least one porous membrane may be disposed between at least two of the layers. Also, associated methods are disclosed.