Microfluidic Nucleic Acid Concentration Measurement
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Solution Overview
Problem
Current methods for determining nucleic acid concentrations, such as PCR, have a limited dynamic range, requiring serial dilutions and being time-consuming, and face challenges in accurately measuring concentrations due to sigmoidal time course profiles and reagent depletion.
Innovation Solution
A process involving a microfluidic device that amplifies nucleic acids in cycles, transfers a defined volume to a second chamber with fresh reagents, and repeats until the concentration is within the measurement range, using PCR or LCR, with concentration determination by optical or electrochemical means, including microarrays for sequence-specific detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR methods are used to determine nucleic acid concentrations, then the measurement can be performed with standard equipment, but the dynamic range is limited and serial dilutions are required
Solution Approach 1:
The patent divides the measurement process into multiple stages: initial amplification in a first chamber, intermediate transfer of defined volumes to a second chamber, and iterative concentration measurements. This segmentation allows the system to handle a broader dynamic range by processing samples in discrete steps rather than requiring all measurements to occur simultaneously in a single chamber.
Solution Approach 2:
The patent introduces a temporal dimension to the measurement process by performing iterative concentration determinations at different stages of amplification. Instead of measuring all concentrations at once, the system performs measurements sequentially over time, transferring samples between chambers and repeating the process until the desired concentration range is achieved.
2Adaptability or versatility
If serial dilutions are performed to extend the measurement range, then the dynamic range increases, but the time required and resources needed increase significantly
Solution Approach 1:
The patent performs preliminary amplification in the first chamber before transferring samples to the second chamber for concentration determination. This preliminary action ensures that sufficient amplified nucleic acid is available for measurement, eliminating the need for time-consuming serial dilutions to achieve measurable concentrations.
Solution Approach 2:
The system maintains continuous useful action by iteratively performing amplification, transfer, and measurement cycles. Rather than interrupting the process for separate dilution steps, the system continuously cycles through amplification and measurement, transferring samples only when concentration thresholds are met, thereby minimizing idle time and maintaining productive workflow.
3Quantity of substance
If the concentration determination is performed after complete PCR reaction, then the full amplification benefit is achieved, but the sigmoidal time course profile causes loss of meaningful concentration data
Solution Approach 1:
The patent implements feedback control by continuously monitoring nucleic acid concentration during the amplification process and using this information to control further amplification cycles. The system measures concentration at intermediate stages and uses this feedback to determine when to transfer samples or continue amplification, preventing the system from entering the saturation phase where concentration data becomes meaningless.
Solution Approach 2:
The system dynamically adjusts the amplification process by performing iterative cycles of amplification and concentration measurement. Rather than using a fixed amplification protocol, the system adapts the number of cycles and transfer timing based on real-time concentration data, allowing optimal measurement points to be captured before saturation occurs.
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 process extends the dynamic range of nucleic acid concentration measurement, reducing the need for serial dilutions and reagent depletion issues, allowing for accurate and efficient determination of nucleic acid concentrations over a broader range.
Implementation Method 1
the polymerase chain reaction (PCR) which is described inter alia in U.S. Pat. No. 4,683,195
Implementation Method 2
Another process for amplifying nucleic acids is the ligase chain reaction (LCR) which is carried out similarly to a PCR but in which the enzyme used is a nucleic acid ligase
Implementation Method 3
determining the concentration of the amplified nucleic acids in a second chamber equipped with a way of/device for determining concentrations
Implementation Method 4
the increase in concentration of the amplified nucleic acids can be monitored in real time, for example by incorporation of a fluorescent dye
Data Source
AI summary
A process is disclosed for determining the concentration of nucleic acids in a sample in a microfluidic device. In at least one embodiment, the method includes a) introducing the sample into a first chamber, b) carrying out a number of cycles of an amplification reaction to be carried out in cycles for amplifying nucleic acids, c) transferring a defined volume which is a fraction of the volume of the first chamber and which has amplified nucleic acids into a second chamber and replacing the transferred defined volume with fresh reagents for the amplification reaction, d) determining the concentration of the amplified nucleic acids in a second chamber equipped with an element to determine concentrations, and e) repeating steps b)-d) until a concentration of the amplified nucleic acids which is within a range is determined in the second chamber. An arrangement is further disclosed.