Automatic and integrated detection of nucleic acid by using a dual-mode thermal controlled digital microfluidic chip

The detection of nucleic acids, which typically consists of nucleic acid extraction, reverse transcription and amplification, is a crucial component of molecular diagnostics. However, traditional methods have several limitations, including high reliance on skilled personnel, low degree of automation and lengthy assay times. Additionally, these methods also require separate areas for the different steps to avoid contamination. Though a number of digital microfluidic (DMF) chips have been reported to detect the nucleic acids, but there is a noticeable absence of fully integrated DMF platforms capable of concurrently performing nucleic acid extraction, amplification, and signal detection. Here, a DMF chip combined with a dual-mode thermal control module was developed to realize the automatic and integrated detection of nucleic acids. The dual-mode thermal control module provided the required temperatures (with a range from 4 °C to 95 °C) for all the steps of nucleic acid detection. Pseudoviruses of SARS-CoV-2 and monkeypox were chosen to demonstrate the feasibility of the DMF chip, and all assays were completed within 40 min. The results confirmed that the products extracted under 4 °C exhibited high concentration and integrity, which were comparable to those by traditional methods. And the analytical performance of amplify was comparable to that of traditional methods with a more compact design, shorter time, smaller size and more automatic operation. With the ability of dual-mode thermo control and full automatic operation, nucleic acid detection with the characteristics of sample-in-result-out was realized on the DMF chip, which holds great promise in fields such as in vitro diagnostics and point-of-care testing.