A Novel Continuous-Flow PCR Microdevice Operated by a Single Heat Source

Area of Science:

• Biotechnology
• Microfluidics
• Molecular Diagnostics

Background:

• Polymerase Chain Reaction (PCR) is crucial for DNA amplification.
• Existing PCR methods often require bulky equipment and long run times.
• Point-of-care nucleic acid testing demands rapid, portable, and efficient solutions.

Purpose of the Study:

• To develop a constant-temperature, single-heat-source continuous-flow PCR (CF-PCR) microdevice.
• To achieve stable thermal control for all PCR steps (denaturation, annealing, extension) on a single platform.
• To create a portable and scalable solution for nucleic acid testing.

Main Methods:

• Utilized a metal-powder/PDMS thermal conduction block with trapezoidal geometry for programmable temperature gradients.
• Employed a thermoelectric cooler (TEC)-based Peltier system for distinct temperature zones.
• Integrated a self-pressurized gas-diffusion micropump for continuous sample flow.
• Developed on-chip, off-chip coiled-tube, and handheld system configurations.

Main Results:

• Achieved ~80% amplification efficiency for H7N9 and pGEM-3Zf(+) on-chip.
• Reached ~75% amplification efficiency in the off-chip configuration.
• Demonstrated comparable amplification intensities to benchtop devices with the portable system.
• The handheld system is battery-powered with a ~4-hour runtime.

Conclusions:

• The developed CF-PCR microdevice provides stable thermal control and efficient nucleic acid amplification.
• The portable, handheld system is suitable for point-of-care applications.
• This technology offers a practical and scalable approach for "sample-in-answer-out" nucleic acid testing.