High-Density Nanoliter Chip for Digital PCR Throughput
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Solution Overview
Problem
Conventional PCR methods in microplates are not cost-effective or efficient for high-throughput biological reactions, and digital PCR requires smaller sample volumes to increase accuracy and reproducibility, necessitating a system that can handle a large number of small reaction volumes with high sensitivity and specificity.
Innovation Solution
A chip with a substrate featuring a high-density array of reaction sites, each capable of holding at most one nanoliter of liquid, integrated with a control system for initiating biological reactions and a detection system for analyzing these reactions, allowing for simultaneous processing of thousands to millions of reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional PCR methods in microplates are used, then the system is simple to operate, but the throughput and efficiency are insufficient for high-volume analysis
Solution Approach 1:
The system divides the PCR analysis into two distinct stages: (1) bulk amplification in a small number of large-volume wells (96-well or 384-well microplates), and (2) digital quantification in a large number of small-volume reaction sites (20,000+ sites per chip). This segmentation allows each stage to be optimized independently, achieving high throughput without excessive complexity.
Solution Approach 2:
The invention extracts the digital quantification function from the conventional PCR process by transferring a small aliquot of amplified product from the bulk reaction to the high-density reaction chip. This separation allows the bulk amplification to use simple, well-established microplate technology while the digital analysis uses the specialized high-density array for precise quantification.
2Measurement precision
If sample volume is reduced to increase dPCR accuracy, then the sensitivity and reproducibility improve, but the total reaction capacity decreases
Solution Approach 1:
The system transitions from a single-dimension approach (one large reaction volume) to a multi-dimensional approach by creating a high-density array of thousands of small reaction sites on a single chip. This dimensional transformation allows the system to achieve both small individual volumes (for accuracy) and large total capacity (for throughput) simultaneously.
Solution Approach 2:
The invention changes the volume parameter from microliters in conventional PCR to nanoliters in the high-density array, while compensating for total capacity by increasing the number of reaction sites from hundreds to tens of thousands. This parameter transformation maintains sensitivity and reproducibility while preserving or enhancing total reaction capacity.
3Productivity
If the number of reaction sites is increased for high-throughput analysis, then the productivity increases, but the sample volume per site must be reduced
Solution Approach 1:
The system segments the PCR process into bulk amplification (maintaining adequate total volume) and digital analysis (using small volumes). The high-density chip with 20,000+ sites is used only for the digital quantification stage, where small nanoliter volumes are sufficient because the target DNA has already been amplified in the bulk reaction.
Solution Approach 2:
The bulk amplification step is performed first in large-volume microplate wells, generating sufficient amplified DNA product. Only after this preliminary amplification is the small-volume digital analysis performed on the high-density chip, ensuring that adequate target material is available even though each individual site contains minimal volume.
4Measurement precision
If digital PCR is used to detect rare alleles and provide absolute quantitation, then the measurement precision improves, but the system complexity and cost increase
Solution Approach 1:
The invention extracts the digital quantification capability from complex automated systems and implements it using a relatively simple high-density chip that can be read with standard fluorescence microscopy or plate reader equipment. This approach achieves dPCR-level precision without requiring the complex automated liquid handling and imaging systems typically associated with digital PCR platforms.
Solution Approach 2:
The system creates thousands of identical copies of the reaction conditions across the high-density chip array, with each site serving as an independent replicate. This massive parallelization of identical reactions provides statistical power for detecting rare alleles and achieving absolute quantitation, while the uniformity of the copies reduces the complexity of individual reaction sites.
Data Source
AI summary
A system for performing biological reactions is provided. The system includes a chip including a substrate and a plurality of reaction sites. The plurality of reaction sites are each configured to include a liquid sample of at most one nanoliter. Further, the system includes a control system configured to initiate biological reactions within the liquid samples. The system further includes a detection system configured to detect biological reactions on the chip. According to various embodiments, the chip includes at least 20000 reaction sites. In other embodiments, the chip includes at least 30000 reaction sites.