Ultrafast Microfluidic PCR Thermocycler for Nucleic Acid Amplification

The polymerase chain reaction (PCR) is essential in nucleic acid amplification tests and is widely used in many applications such as infectious disease detection, tumor screening, and food safety testing; however, most PCR devices have inefficient heating and cooling ramp rates for the solution, which significantly limit their application in special scenarios such as hospital emergencies, airports, and customs. Here, we propose a temperature control strategy to significantly increase the ramp rates for the solution temperature by switching microfluidic chips between multiple temperature zones and excessively increasing the temperature difference between temperature zones and the solution; accordingly, we have designed an ultrafast thermocycler. The results showed that the ramp rates of the solution temperature are a linear function of temperature differences within a range, and a larger temperature difference would result in faster ramp rates. The maximum heating and cooling ramp rates of the 25 mu L solution reached 24.12 degrees C/s and 25.28 degrees C/s, respectively, and the average ramp rate was 13.33 degrees C/s, 6-8 times higher than that of conventional commercial PCR devices. The thermocycler achieved 9 min (1 min pre-denaturation + 45 PCR cycles) ultrafast nucleic acid amplification, shortening the time by 92% compared to the conventional 120 min nucleic acid amplification, and has the potential to be used for rapid nucleic acid detection.

Automated summary

This article proposes a temperature control strategy to significantly increase the ramp rates of solution temperature by switching microfluidic chips between multiple temperature zones and increasing the temperature difference between zones and the solution. A thermocycler with ultrafast nucleic acid amplification capabilities has been designed. The results show that the ramp rates of solution temperature are linearly related to temperature differences, with larger differences resulting in faster ramp rates. The thermocycler achieves 92% reduction in nucleic acid amplification time compared to conventional methods.