Microfluidic Chip Layout for Stable Droplet Separation in Digital PCR
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Solution Overview
Problem
Current microfluidic technologies face challenges in digital PCR, including aerosol contamination, interference between reaction units, and poor dispersion stability due to lack of physical separation between droplets in array-type chips and insufficient physical separation in droplet-type chips.
Innovation Solution
A microfluidic chip design featuring a substrate layer with a drive electrode layer and a cover plate layer with solution inlet and outlet holes, limiting recesses, and a gas valve cavity, which allows for uniform droplet dispersion and physical separation by applying pressure to the cover plate, ensuring stable reaction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If array-type chips are used for digital PCR, then reaction units can be arranged in parallel, but aerosol contamination and interference between reaction units occur due to lack of physical separation
Solution Approach 1:
The chip is divided into multiple independent reaction units, each containing a reaction chamber and an oil phase barrier. The partition walls physically separate adjacent reaction units, preventing aerosol contamination and interference while maintaining parallel reaction capacity. Each reaction unit is segmented into distinct functional zones (reaction chamber, oil phase, waste chamber) that work together to isolate reactions.
Solution Approach 2:
An oil phase is introduced as an intermediary substance between the aqueous reaction mixture and the environment or other reaction units. This oil phase forms a physical barrier that prevents aerosol formation and contamination, while allowing the reaction to proceed in the aqueous phase below. The oil phase acts as a protective intermediary layer.
2Object-affected harmful factors
If droplet-type chips are used for digital PCR, then physical separation is achieved, but dispersion stability is poor due to insufficient physical separation
Solution Approach 1:
Different regions of the chip have different local properties optimized for specific functions. The reaction chambers have hydrophilic surfaces to contain aqueous droplets, while the partition walls and oil phase regions have hydrophobic properties to stabilize droplet formation and prevent coalescence. This local differentiation of surface properties enhances droplet dispersion stability.
Solution Approach 2:
The reaction chambers are designed with curved or spherical geometries that promote uniform droplet formation and stable dispersion. The curved surfaces of the partition walls and reaction chamber boundaries help maintain spherical droplet shapes, which are more stable and less prone to deformation or coalescence compared to angular geometries.
3Ease of operation
If conventional microfluidic chips are used, then fluid manipulation is achieved, but contamination risk increases due to shared solution pathways
Solution Approach 1:
The fluidic system is segmented into independent channels for each reaction unit, with separate solution inlets and waste outlets. This segmentation prevents cross-contamination between reaction units while maintaining ease of operation through integrated control. Each reaction unit has its own isolated fluid pathway.
Solution Approach 2:
The waste chamber is extracted and separated from the reaction chamber, with a dedicated waste outlet channel. This extraction of the waste pathway removes potential contamination sources from the reaction pathway, allowing clean reagent delivery while isolating waste removal in a separate channel that does not contact the reaction mixture.
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 microfluidic chip achieves accurate and reliable droplet separation, preventing interference and improving the stability and reliability of detection results by ensuring uniform droplet distribution and minimizing contamination.
Implementation Method 1
a substrate layer, where the substrate layer includes a substrate and a drive electrode layer disposed on the substrate
Implementation Method 2
applying pressure to the cover plate, ensuring stable reaction conditions
Data Source
AI summary
Provided are a microfluidic chip and a usage method thereof, and a microfluidic system. The microfluidic chip includes a substrate layer, the substrate layer includes a substrate and a drive electrode layer; and a cover plate layer arranged opposite the substrate layer, a space between the cover plate layer and the substrate layer form a solution accommodating space; the cover plate layer includes a solution inlet hole, a solution outlet hole, and limiting recesses arranged on a side of the cover plate layer facing the substrate layer, the solution inlet hole, the solution outlet hole and each limiting recess are in communication with the solution accommodating space, and an end surface of the solution inlet hole adjacent to the substrate layer, an end surface of the solution outlet hole adjacent to the substrate layer, and opening surfaces of the plurality of limiting recesses are arranged substantially flush with one another.