Microfluidic Device Flow Path Interruption for Sensor Protection
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Solution Overview
Problem
Existing microfluidic devices require complex setup and are prone to errors, with risks of drying out and damage from excessive flowrates, especially in compact designs.
Innovation Solution
A microfluidic device is designed with a sensor in a sensing chamber, a flow path with a sample input port, a liquid collection channel, and a flow path interruption, allowing the device to be activated by completing the flow path and maintaining the sensor in a wet state without exposure to gas or gas/liquid interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor is provided in a wet state to maintain sensor functionality and prevent drying out, then sensor reliability is improved, but device complexity increases due to the need for additional buffer liquid management systems
Solution Approach 1:
The sensor is pre-filled with buffer liquid during manufacturing to create a wet state before use. This preliminary action ensures the sensor is ready for immediate use without requiring complex buffer liquid management systems during operation, thus improving reliability while avoiding increased device complexity
Solution Approach 2:
The sensing chamber is nested within the device body and pre-filled with buffer liquid, creating a self-contained wet environment for the sensor. This nested structure maintains sensor functionality without requiring additional external buffer liquid management components
2Volume of moving object
If the sample input port is placed close to the sensor in compact devices, then device size is reduced, but the risk of sensor damage from excessive flowrates increases
Solution Approach 1:
A flow restriction element is introduced as an intermediary component between the sample input port and the sensing chamber. This element mediates the flow of sample liquid, allowing compact device design while protecting the sensor from excessive flowrates by controlling the flow rate through the restriction
Solution Approach 2:
The flow restriction is applied locally at the inlet to the sensing chamber, creating a localized flow control zone. This allows the rest of the device to remain compact while specifically addressing the flow rate issue at the critical sensor interface
3Ease of operation
If a closed chamber is used to easily flow aqueous solution into and out of the device, then ease of operation is improved, but the risk of the sensor drying out increases
Solution Approach 1:
The sensing chamber is designed to maintain continuous liquid contact with the sensor throughout operation. The buffer liquid remains in the chamber and continuously wets the sensor, ensuring uninterrupted liquid flow and preventing drying out while maintaining ease of operation
Solution Approach 2:
The closed chamber creates a protected environment for the sensor, isolating it from external drying conditions. The buffer liquid in the closed chamber maintains a stable, humid environment that prevents sensor drying while allowing easy solution flow
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 remains unexposed to gas or gas/liquid interfaces, reducing the risk of sensor damage and maintaining the sensor in a wet state, even when tilted, allowing for efficient introduction of test liquids without additional positive pressure.
Implementation Method 1
a liquid test sample applied to the device is transported to the sensor region within the device by capillary flow
Implementation Method 2
aqueous solution 10 is introduced into the chamber 7 and a layer 11 of amphiphilic molecules is formed across the recess 5 separating aqueous solution 10 in the recess 5 from the remaining volume of aqueous solution in the chamber 7
Implementation Method 3
The electrodes 21 and 24 make electrical contact with aqueous solution in the recess 5 and chamber 7. This allows measurement of electrical signals across the layer 11 of amphiphilic molecules
Implementation Method 4
Each layer can be provided with a nanopore, to allow other molecules to pass through the layer (which affects the electrical signal measured)
Data Source
Figure 1~2
Figure 3~4b
Figure 5a~5d
AI summary
A microfluidic device comprises: a sensor provided in a sensing chamber; a liquid inlet and liquid outlet connecting to the sensor chamber for respectively passing liquid into and out of the sensing chamber and; a sample input port in fluid communication with the liquid inlet; a liquid collection channel downstream of the sensing chamber outlet; a flow path interruption between the liquid outlet and the liquid collection channel, preventing liquid from flowing into the liquid collection channel from upstream; a buffer liquid filling from the sample input port to the sensing chamber, and filling the sensing chamber and filing from the liquid outlet to the flow path interruption; an activation system operable to complete the flow path between the liquid outlet and the liquid collection channel such that the sensor remains unexposed to gas or a gas/liquid interface.