Ha1016

The LAMP reactions primarily used a commercial kit that detects Proteus mirabilis (051011M, Guangzhou Double Helix Gene Technology Co.). The primer sequences and reagent composition are tabulated in Table S1 and S2, Supporting Information, respectively. Detection samples were prepared by serial dilution of plasmids with target sequences. The DNA concentration of the stock plasmids was (1.12 ± 0.09) × 10⁴ copies µl⁻¹, as measured by fluorescence‐based droplet digital LAMP. The detection of SARS‐CoV‐2 used a proprietary primer kit and plasmid (LP1002, HaiGene Biotech Co.), targeting the ORF1ab gene. The sequence of the target gene is tabulated in Table S3, Supporting Information. The continuous phase of the emulsions used a commercial droplet generation oil (1864006, Bio‐Rad Laboratories, Inc.). FITC‐conjugated IgG (A16097, Invitrogen; 0.04 mg ml⁻¹) and TRITC‐conjugated IgG (HA1016, HuaBio; 0.01 mg ml⁻¹) were used for droplet tracing in the examination of droplet coalescence.