Portable Heating System Based on a Liquid Metal Bath for Rapid PCR

With the outbreak of COVID-19 around the world, rapid and accurate detection of new coronaviruses is the key to stop the transmission of the disease and prevent and control the novel coronavirus, among which polymerase chain reaction (PCR) is the mainstream nucleic acid detection method. A temperature cycling device is the core of the PCR amplification micro-device. The precision of the temperature control and temperature change rate directly affect the efficiency of PCR amplification. This study proposes a new PCR method based on rapid PCR chip optimization of a liquid metal bath, which realizes precise and rapid temperature rise and fall control. We systematically explored the feasibility of using liquid metals with different melting points in the system and proposed a 47 °C bismuth-based liquid metal bath as the heat conduction medium of the system to optimize the system. The heat conduction properties of the thermally conductive silicone oil bath were compared. Compared with the thermally conductive silicone oil bath, thermal cycle efficiency is improved nearly 3 times. The average heating rate of the liquid metal bath is fast, and the temperature control stability is good, which can significantly reduce the hysteresis, and the temperature change curve is more gentle, which can greatly improve the efficiency of PCR amplification. The results of gene amplification using rat DNA as the template and SEC61A as the target also indicate that the system can be successfully used in PCR devices, and the types of PCR containers can be not limited to PCR tubes. Based on the experiment, we proved that the PCR method optimized by the liquid metal bath multi-gene rapid PCR chip can further improve the temperature response speed. It has the advantages of accurate data, fast response speed, low price, safety, and environmental protection and can effectively reduce the time of PCR and improve the application efficiency. As far as we know, this is the first international report on using a liquid metal bath to do rapid-cooling PCR.