Ultrafast polymerase chain reaction on MEMS microheater

Ultrafast polymerase chain reaction (PCR) is crucial for the rapid detection of pathogens, particularly in medical emergencies and public health scenarios. Conventional PCR systems, however, require extended processing times due to the inherent mass transfer rates of ∼10 µL scale liquids. This study aims to achieve ultrafast nucleic acid amplification using a MEMS microheater to significantly reduce reaction volumes from a typical 10 µL PCR system to 3 nL, resulting in a total duration of 304 s for 38 thermal cycles. Temperature mapping and calibrations were conducted using infrared microscopy, and COMSOL simulations were employed to analyze thermal behavior and fluid dynamics within the droplets. The droplets were heated at a rate of 254 °C/s and cooled at a rate of 122 °C/s through natural thermal balance. The calibrated microheater exhibited high-temperature stability with a variation of ± 0.1 °C, and efficient PCR amplification of Hepatitis B virus (HBV) DNA and Coronavirus RNA (CVR) samples were demonstrated, with Ct values significantly lower than those obtained using commercial equipment. As well, successful reverse transcription and PCR amplification of RNA samples were achieved. However, the amplification efficiency was calculated to be 88 %, likely limited by the use of commercial reagents not optimized for such rapid thermal cycling. This technology offers a viable solution for rapid pathogen detection and holds potential for widespread applications in medical diagnostics and public health, particularly during pandemic outbreaks.