At‐Home COVID‐19 Rapid Antigen Test Down to 0.03 pg mL−1 of Nucleocapsid Protein

Abstract Rapid and ultra‐sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is critical for early screening and management of COVID‐19. Currently, the real‐time reverse transcription polymerase chain reaction (rRT‐PCR) is the primary laboratory method for diagnosing SARS‐CoV‐2. It is not suitable for at‐home COVID‐19 diagnostic test due to the long operating time, specific equipment, and professional procedures. Here an all‐printed photonic crystal (PC) microarray with portable device for at‐home COVID‐19 rapid antigen test is reported. The fluorescence‐enhanced effect of PC amplifies the fluorescence intensity of the labeled probe, achieving detection of nucleocapsid (N‐) protein down to 0.03 pg mL −1 . A portable fluorescence intensity measurement instrument gives the result (negative or positive) by the color of the indicator within 5 s after inserting the reacted PC microarray test card. The N protein in inactivated virus samples (with cycle threshold values of 26.6–40.0) can be detected. The PC microarray provides a general and easy‐to‐use method for the timely monitoring and eventual control of the global coronavirus pandemic.