Digital Microfluidic Device Solid Phase Extraction
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Solution Overview
Problem
Microchannel-based solid phase extraction methods are not suitable for preparative-scale applications due to difficulties in sample recovery and limited compatibility with organic solvents, and they require specific ionic strength buffers to avoid joule heating.
Innovation Solution
A digital microfluidic device with an array of electrically addressable elements integrates a solid phase material, such as a porous polymer monolith, formed in-situ, allowing for droplet-based solid phase processing, including sample extraction and concentration, using solvents like acetonitrile and formic acid, and enabling efficient mass transfer and preconcentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If microchannel-based solid phase extraction methods are used, then sample processing can be performed, but sample recovery becomes difficult and the method is not suitable for preparative-scale applications
Solution Approach 1:
The device segments the sample processing into distinct functional zones: a solid phase extraction region for analyte capture, a liquid junction for solvent exchange, and a collection region for recovered sample. This segmentation enables independent optimization of each function, allowing efficient extraction while maintaining sample recovery capability through controlled liquid flow paths.
Solution Approach 2:
A liquid junction is introduced as an intermediary component between the solid phase material and the collection system. This liquid junction facilitates controlled solvent exchange and sample recovery by acting as a mediator that transfers the extracted analyte from the solid phase to the collection region, solving the sample recovery problem inherent in direct microchannel methods.
2Adaptability or versatility
If microchannel-based methods are used, then high surface-to-volume ratios are achieved, but compatibility with organic solvents is limited and Joule heating occurs
Solution Approach 1:
The design transitions from planar microchannel geometry to a three-dimensional configuration with a solid phase layer positioned above the liquid junction. This vertical dimensionality allows organic solvents to flow through the solid phase material without generating significant Joule heating, as the solvent path is separated from the electrode surfaces where heating would occur.
Solution Approach 2:
The liquid junction serves as an intermediary barrier between the organic solvent flowing through the solid phase and the electrode surfaces. This intermediary layer prevents direct contact between the solvent and electrodes, eliminating Joule heating while maintaining solvent compatibility and flow through the solid phase extraction region.
3Reliability
If traditional solid phase extraction is used, then analyte purification can be achieved, but the process requires multiple steps and time-consuming operations
Solution Approach 1:
Multiple solid phase extraction steps are merged into a single integrated operation. The solid phase material, liquid junction, and collection region are positioned to enable simultaneous solvent exchange and analyte recovery in one continuous flow, eliminating the time-consuming sequential operations required by traditional multi-step SPE protocols while maintaining purification reliability.
Solution Approach 2:
The device enables continuous solvent exchange and analyte recovery operations without interruption. The liquid junction maintains continuous contact with the solid phase material, allowing uninterrupted flow of solvents through the extraction region and immediate collection of purified analyte, thereby eliminating idle time between extraction steps.
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 digital microfluidic device facilitates efficient sample preparation and preconcentration with high extraction efficiency, overcoming limitations of microchannel-based methods by allowing sequential solvent exposure and handling of organic solvents, making it suitable for preparative-scale applications.
Implementation Method 1
When a liquid sample is passed over or through the stationary phase, analyte is retained on the solid phase while matrix compounds are washed away
Implementation Method 2
After washing the solid phase, analyte retained within the solid phase may be eluted in a different solvent (which has high affinity for the analytes)
Implementation Method 3
A digital microfluidic device with an array of electrically addressable elements integrates a solid phase material... allowing for droplet-based solid phase processing
Data Source
AI summary
Devices and methods are provided for performing droplet-based solid phase processing steps on a digital microfluidic device. A solid phase material, which may be a porous solid phase material such as a porous polymer monolith is formed or located on a digital microfluidic element. The solid phase may be formed by an in-situ method in which the digital microfluidic array is actuated to transport a droplet of solid phase pre-cursor solution to a selected element on the array, and subsequently processed to form a solid phase on the array element. The integration of a solid phase material with a digital microfluidic array enables a wide range of applications including solid phase extraction and sample concentration.