Digital Microfluidic Surfactant Segmentation for Biofouling Control
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Solution Overview
Problem
Digital microfluidic devices face limitations in handling biomolecules due to biofouling and evaporation issues, particularly when dealing with proteins and nucleic acids, as surfactants in the oil layer can be detrimental and high surfactant levels in the aqueous layer affect protein-protein interactions and detection efficiency.
Innovation Solution
Incorporating a non-ionic surfactant like Pluronic F127 in the aqueous layer and a surfactant such as Span85 in the oil layer, allowing for reduced surfactant levels in the aqueous phase while maintaining effective droplet manipulation and protein expression, enabling dilution-free cell-free protein synthesis and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surfactant is added to the oil layer to prevent biofouling, then droplet stability is improved, but protein-protein interactions and detection efficiency deteriorate
Solution Approach 1:
The system divides the surfactant application into two separate segments: a first surfactant (e.g., Pluronic F127) in the aqueous layer and a second surfactant (e.g., Span85) in the oil layer. This segmentation allows each surfactant to perform its specific function independently - the aqueous surfactant maintains protein interaction capability while the oil surfactant provides droplet stability, thereby resolving the contradiction between detection efficiency and droplet stability.
Solution Approach 2:
Different surfactant properties are applied to different locations/layers of the system. The hydrophilic first surfactant is localized in the aqueous layer where protein interactions occur, while the hydrophobic second surfactant is localized in the oil layer where droplet stability is needed. This local quality differentiation enables both protein-protein interactions and droplet stability to coexist without interference.
2Ease of operation
If high concentration of surfactant is used in the aqueous layer to reduce biofouling, then droplet manipulation is improved, but protein expression consistency deteriorates
Solution Approach 1:
The surfactant function is segmented between two layers: the first surfactant in the aqueous layer at optimized concentration for protein expression, and the second surfactant in the oil layer for droplet manipulation. This segmentation allows droplet manipulation to be achieved through the oil-layer surfactant without compromising protein expression consistency in the aqueous layer.
Solution Approach 2:
The second surfactant in the oil layer acts as an intermediary that enables droplet manipulation without directly contacting the proteins in the aqueous layer. This intermediary approach allows droplet handling to be facilitated while keeping the protein environment clean and consistent for reliable expression.
3Duration of action of moving object
If surfactant is added to enable prolonged droplet actuation, then operating duration is extended, but biofouling increases
Solution Approach 1:
The anti-biofouling function is segmented between two surfactants in two layers. The first surfactant in the aqueous layer provides sustained biofouling protection during prolonged actuation, while the second surfactant in the oil layer provides additional protection at the oil-aqueous interface. This segmented approach extends actuation time while maintaining low biofouling levels.
Solution Approach 2:
The system uses a composite surfactant system combining two different surfactants with complementary properties - a hydrophilic surfactant in the aqueous phase and a hydrophobic surfactant in the oil phase. This composite approach provides enhanced and sustained biofouling protection throughout the prolonged actuation period, addressing both duration extension and biofouling reduction.
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
This approach enhances the stability and movement of droplets, reduces biofouling, and improves the consistency and ease of protein expression and detection processes on digital microfluidic devices, allowing for prolonged protein synthesis and expression without dilution or adulteration.
Implementation Method 1
Electrowetting is the modification of the wetting properties of a surface (which is typically hydrophobic) with an applied electric field. Digital microfluidics utilizes alternating currents on an electrode array for moving fluid on the surface of the array by electrowetting.
Implementation Method 2
Incorporating a non-ionic surfactant like Pluronic F127 in the aqueous layer and a surfactant such as Span85 in the oil layer, allowing for reduced surfactant levels in the aqueous phase while maintaining effective droplet manipulation and protein expression.
Data Source
AI summary
Provided herein are methods, and compositions for the detection and analysis of biomolecule interactions a microfluidic device. The detection and analysis occurs in aqueous droplets having a first surfactant within an oil layer having a second surfactant.