Digital PCR with Patterned Surfaces for Wide Dynamic Range
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Solution Overview
Problem
Current digital PCR methods face challenges in accurately quantifying low copy-number DNA due to limited dynamic range and the need for precise temperature control, which is costly and difficult to maintain, especially in resource-limited settings, and existing isothermal methods like LAMP require meticulous calibration for quantification.
Innovation Solution
The development of methods and systems that increase the dynamic range of digital measurements by creating concentration gradients and using digitized volumes of varying sizes, including the formation of patterned surfaces with hydrophobic and hydrophilic patches to generate droplets of different sizes, allowing for more accurate and efficient digital PCR, LAMP, and other nucleic acid amplifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If real-time PCR is used to quantify DNA concentration, then the measurement process is simple and widely applicable, but the accuracy deteriorates at low copy numbers due to exponential amplification errors and inability to distinguish signal from background
Solution Approach 1:
The patent divides the sample into many discrete digital volumes (e.g., 20,000 individual droplets or chambers), where each volume is independently amplified and detected. This segmentation transforms the continuous measurement problem into discrete binary outcomes (positive/negative), enabling accurate quantification at low copy numbers by statistical analysis of the distribution across all segments rather than relying on continuous signal intensity.
Solution Approach 2:
The patent replaces the continuous fluorescent signal detection mechanism with a digital counting mechanism. Instead of measuring continuous fluorescence intensity that is susceptible to background noise and amplification efficiency variations, the system uses binary detection (presence/absence of amplification product) in discrete volumes, substituting mechanical/continuous measurement with digital/discrete counting for superior precision at low concentrations.
2Measurement precision
If digital PCR with fixed volume arrays is used to increase dynamic range, then measurement precision improves, but device complexity increases due to the need for precise temperature control and volume fabrication
Solution Approach 1:
The patent employs parameter changes by varying the volume size of digital compartments rather than using fixed uniform volumes. By creating arrays with different volume sizes (e.g., 1 fL to 100 fL), the system can accommodate a wider dynamic range of DNA concentrations. This volume parameter variation allows the same digital PCR platform to accurately quantify both very low and moderate copy numbers without requiring separate instruments or complex temperature control systems.
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the system to automatically select appropriate volume sizes based on the sample concentration. The method can dynamically adjust which volume array to use or combine multiple volume arrays, making the system flexible and adaptable to different measurement scenarios without requiring manual calibration or complex fixed-configuration hardware for every possible concentration range.
3Device complexity
If isothermal methods like LAMP are used to simplify temperature control, then device complexity decreases, but measurement precision deteriorates due to requirement for meticulous calibration
Solution Approach 1:
The patent implements self-service by using the sample's own properties to determine the appropriate volume size for digital PCR. By measuring the initial concentration of the sample and using that information to select or calculate the optimal volume, the system eliminates the need for external calibration standards and manual calibration procedures. The method self-calibrates using the sample concentration information, achieving both simplified operation and high precision without requiring meticulous external calibration.
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 accuracy and efficiency of digital measurements, enabling precise quantification of DNA and RNA over a wider dynamic range without the need for complex temperature control, making it suitable for point-of-care diagnostics and resource-limited settings.
Implementation Method 1
patterned surfaces with hydrophobic and hydrophilic patches to generate droplets of different sizes
Implementation Method 2
patterned surfaces with hydrophobic and hydrophilic patches to generate droplets of different sizes
Data Source
AI summary
Methods and systems for digital measurements are provided. In an embodiment, the method includes producing a plurality of droplets, wherein at least one of the droplets of the plurality of droplets contains an analyte molecule from a sample; measuring at least a first portion of the plurality of droplets to determine individual volumes of droplets in the first portion of the plurality of droplets; analyzing at least a second portion of the plurality of droplets to determine a number of droplets in the second portion of the plurality of droplets that contain the analyte molecule; and using individual volumes of the droplets in the first portion of the plurality of droplets and the number of droplets in the second portion of the plurality of droplets that contain the analyte molecule to determine the concentration of the analyte molecule in the sample.