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. 2021 Dec 28;200:113925. doi: 10.1016/j.bios.2021.113925

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© 2021 Elsevier B.V. All rights reserved.

Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

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Fig. 1 — A PaGeR device for COVID-19 detection by RT-LAMP. (A) Schematic illustration of the PaGeR device, which was composed of two similar heating parts for virus inactivation and RT-LAMP reaction, one programmed control part (microcontroller unit), and one result readout part. (B) Principle of the RT-LAMP reaction with loop primers. Specially designed nested primers combined with target regions formed hairpins to permit subsequent amplification. Forward Inner Primer (FIP) consists of a F2 region at the 3'end and a F1c region at the 5'end. Backward Inner Primer (BIP) consists of a B2 region at the 3'end and a B1c region at the 5'end. Forward Outer Primer (F3) region is complementary to the F3c region of the template sequence. Backward Outer Primer (B3) is complementary to the B3c region of the template sequence. (C) Four types of result readout methods: real-time fluorescence readout, fluorometric readout, colorimetric readout, and lateral dipstick readout. (D) The principle of visual lateral flow nucleic acid detection after RT-LAMP. Neg., negative; Pos., positive; Ctrl, control.