Microfluidic Sample Recirculation for Faster Sensor Detection
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Solution Overview
Problem
Microfluidic devices face challenges in efficient mixing and analyte detection due to laminar flow, which limits molecule interaction with sensors, necessitating longer diffusion times or reduced flow rates, thereby increasing sample-to-answer time.
Innovation Solution
A fluid recirculating cartridge device with a central chamber, microchannels, sensor regions, and an actuating chamber using a flexible membrane for recirculating fluid over sensor regions, enhancing interaction time and detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow rate is reduced to allow sufficient time for diffusion to occur, then molecule collection efficiency is improved, but overall test time increases
Solution Approach 1:
The system employs periodic recirculation of fluid through the microchannel, creating cycles of flow that repeatedly pass molecules over the sensor surface. This periodic action allows molecules to interact with sensors during each pass while maintaining overall faster flow rates, resolving the contradiction between collection efficiency and test time
Solution Approach 2:
The recirculation mechanism ensures continuous exposure of molecules to the sensor surface by looping the fluid path. Molecules that miss the sensor on one pass are carried around and presented again on subsequent passes, maintaining continuous useful interaction without requiring slow linear flow
2Productivity
If flow is maintained at higher rates for faster analysis, then sample-to-answer time is reduced, but molecule collection efficiency decreases
Solution Approach 1:
Periodic recirculation creates multiple opportunities for molecule-sensor interaction during faster flow conditions. The cyclic nature ensures that even at higher velocities, molecules are repeatedly presented to the sensor surface, maintaining collection efficiency while enabling faster overall analysis
Solution Approach 2:
The recirculating flow path ensures continuous molecular exposure to sensors throughout the test period. Rather than a single pass, molecules remain in the system circulating and interacting with sensors continuously, maintaining precision while allowing faster flow rates
3Device complexity
If unidirectional flow is used for simple device design, then device complexity is reduced, but molecule interaction with sensors is limited
Solution Approach 1:
The recirculation valve introduces periodic flow direction changes without requiring complex multi-path architecture. A relatively simple valve mechanism creates the recirculation effect, adding minimal complexity while dramatically improving molecule-sensor interaction through repeated passes
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 recirculating flow system improves analyte detection sensitivity and reduces sample-to-answer time by increasing interaction with sensor regions, demonstrating enhanced detection capabilities and precision.
Implementation Method 1
generating a pulsatile fluid flow in a microchannel by means of external actuation of a thin flexible film
Implementation Method 2
cycles of positive and negative actuation can be used to infuse or withdrawal fluid in a microchannel. Fluid can be recirculated over one or more microfluidic feature
Implementation Method 3
the at least one microchannel is configured to draw the liquid sample towards the at least one sensor region by capillary action
Data Source
AI summary
The present invention provides devices and methods for generating a pulsatile fluid flow in a microchannel by means of external actuation of a thin flexible film. With the devices described herein, cycles of positive and negative actuation can be used to infuse or withdrawal fluid in a microchannel. Fluid can be recirculated over one or more microfluidic feature, such as a chemical or molecular receptor, biosensor, electrode, cell or biological material, chromatography feature, mixer, etc., in a way that would represent an advantage over the single-pass flow techniques common to most microfluidic devices. The devices and methods are particularly useful in vitro diagnostics (IVD), analytical chemistry, chromatography, and mixing applications in a variety of fields.