Microfluidic Cassette Single Heating Zone PCR Inhibitor Removal
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Solution Overview
Problem
Molecular point of care (POC) diagnostic systems face challenges in efficiently removing PCR inhibitors from biological samples, which can lead to decreased sensitivity and false-negative results, particularly when testing samples like saliva and nasal swabs that contain proteins and other inhibitory substances, requiring significant pre-processing that complicates user workflow and increases errors.
Innovation Solution
A microfluidic test device with a single heating zone that performs both thermal conditioning to remove or reduce PCR inhibitors and subsequent PCR thermocycling, allowing for minimal or no off-device sample pre-processing, and incorporating a thiol reducing agent like TCEP to inactivate pathogens such as SARS-CoV-2, thereby simplifying the testing process and enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If significant pre-processing is performed to remove PCR inhibitors from samples, then PCR sensitivity is improved, but device complexity and user workflow complexity increase
Solution Approach 1:
The patent combines the inhibitor removal function with the existing heating zone used for PCR thermocycling. The heating zone performs dual functionality: first heating the sample to remove inhibitors, then performing PCR amplification. This merging eliminates the need for separate pre-processing devices or steps, reducing device complexity while maintaining PCR sensitivity.
Solution Approach 2:
The heating zone is designed to perform multiple functions: thermal conditioning for inhibitor removal, PCR thermocycling, and potentially other processing steps. This multi-functionality reduces the number of separate components needed, simplifying the overall device while ensuring effective inhibitor removal for sensitive PCR detection.
2Reliability
If multiple heating zones are used for thermal conditioning and PCR thermocycling, then processing effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent merges the thermal conditioning function and PCR thermocycling function into a single heating zone. The heating zone sequentially performs inhibitor removal by heating to a first temperature, then performs PCR by cycling through required temperatures. This eliminates the need for multiple simultaneous heating zones, reducing device complexity while maintaining processing effectiveness through sequential operation.
Solution Approach 2:
The single heating zone dynamically changes temperature through time to achieve different functions. The control system varies the temperature profile: maintaining a first temperature for inhibitor removal, then cycling through PCR temperatures. This dynamic temperature control allows one heating zone to replace multiple static heating zones, simplifying device architecture.
3Loss of time
If on-cassette thermal conditioning is performed, then sample processing time is reduced, but energy consumption increases
Solution Approach 1:
The patent combines thermal conditioning and PCR thermocycling into a single heating process that occurs within the PCR heating zone. By performing inhibitor removal during the same heating cycle used for PCR, the system avoids separate heating steps that would consume additional energy. The sequential temperature profile is optimized to achieve both goals within a single energy input cycle.
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 enables cost-effective, on-device molecular identification with reduced PCR inhibition, minimizing sample pre-processing, and ensuring safe, rapid testing of pathogens like SARS-CoV-2 at the point of care, reducing the risk of errors and increasing testing efficiency.
Implementation Method 1
a sample flow path arranged such that at a first time point a sample will be within at least a portion of the first heating zone and be heated to a thermal conditioning temperature
Implementation Method 2
at a second time point said sample and one or more polymerase chain reaction reagents will be within the same first heating zone and be heated as part of at least one part of a thermocycling profile
Implementation Method 3
incorporating a thiol reducing agent like TCEP to inactivate pathogens such as SARS-CoV-2
Data Source
AI summary
Disclosed herein are microfluidic test cassettes or chips that are received within a POC diagnostic device, and that can directly test biological samples that have had no or minimal processing to remove PCR inhibitor. The microfluidic test cassettes or chips allow for on-cassette/on-chip processing within the size confines of the cassette/chip by utilizing a same heating zone for multiple processing steps.