Assay Device Sample-Absorbing Wick Flood Prevention
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Solution Overview
Problem
Assay devices are prone to flooding due to mishandling or improper use, leading to incorrect sample flow and potential false negative results, especially when users apply excessive sample or handle the device incorrectly, which existing solutions like drainage vents and rib members fail to adequately address.
Innovation Solution
Incorporating a sample-absorbing member made of porous, fibrous material that is not part of the assay flow path but positioned upstream or downstream of the sample receiving member to absorb excess sample during flooding events, thereby preventing incorrect flow and ensuring accurate results even under mishandling conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the device is designed to accept sample application by the user, then the assay can be performed with simple operation, but the device becomes susceptible to flooding when excessive sample is applied or mishandling occurs
Solution Approach 1:
A wick is introduced as an intermediary component between the sample application region and the porous carrier. The wick selectively absorbs excess sample through capillary action while allowing the correct amount to pass through to the assay flow path, thereby mediating between user application and the sensitive assay components downstream.
Solution Approach 2:
The wick is made of porous material with specific capillary properties that enable it to absorb excess liquid sample while controlling the flow rate. The porous structure allows the wick to take up oversampled liquid through capillary forces without disrupting the intended flow path or causing flooding of the assay zones.
2Reliability
If drainage vents or rib members are added to prevent flooding, then resistance to mishandling improves, but device complexity increases
Solution Approach 1:
The wick serves multiple functions simultaneously: it acts as a flow controller for the sample, provides a backup absorption path for excess sample, and protects the assay zones from flooding during mishandling. This multi-functionality achieves improved reliability without adding complex separate components like drainage vents or rib members.
3Reliability
If the wick is made longer to increase sample absorption capacity, then tolerance to oversampling improves, but the device length increases
Solution Approach 1:
The wick is positioned locally at the sample application region where excess sample first accumulates. By concentrating the absorption function at this critical location rather than distributing it throughout a longer structure, the wick effectively handles oversampling while maintaining a compact overall device length.
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 sample-absorbing member effectively reduces the incidence of flooding and ensures accurate analyte detection by absorbing excess sample during abnormal flow events, maintaining assay integrity even when the device is inverted, shaken, or oversampled.
Implementation Method 1
The wick is configured to take up oversampled liquid sample by capillary action
Implementation Method 2
the sample is subsequently conveyed along the flow path by capillary action
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4c
AI summary
The present invention relates generally to an assay device with improved tolerance to mishandling and/or improper use by the user. More particularly, the invention relates to an assay device with reduced susceptibility to flooding.