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Updated: May 31, 2025

Two-Step Reverse Transcription Droplet Digital PCR Protocols for SARS-CoV-2 Detection and Quantification
Published on: March 31, 2021
A Contracted Channel Droplet Reinjection Chip-Based Simple Integrated ddpcr System for SARS-CoV-2 and H1N1 Detection
Fengyi Liu1,2,3,4, Anle Ge1,2,3,4, Xixian Wang1,2,3,4
1CAS Key Laboratory of Biofuels, Shandong Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101, China.
None:
Droplet microfluidics is a powerful method for digital droplet polymerase chain reaction (ddPCR) applications. However, precise droplet control, bulky peripherals, and multistep operation usually required in droplet detection process hinder the broad application of ddPCR. Here, a contracted channel droplet reinjection chip is presented, where droplets can be self-separated and detected one by one at intervals. Based on that, a Simple Integrated ddPCR (SI-ddPCR) system is established, including surface-wetting-based droplet generation, tube heating, and droplet signal detection. To assess the system's performance, we quantified SARS-CoV-2 and H1N1 simultaneously using duplex-ddPCR. The results exhibited a good linearity (R2 = 0.999) at concentrations ranging from 101 to 104 copies/μL. By employing the SI-ddPCR system, we detected SARS-CoV-2 and H1N1 in clinical samples isolated from 20 swab specimens with an accuracy of 97.5%. Thus, the developed SI-ddPCR system offers simple droplet detection, eliminates complicated peripherals and multistep operations, and promises to be a portable, low-cost, and easy-to-deploy toolbox for high-accuracy ddPCR.

