COVID-19 rapid diagnostic test for instrumentation-free virus detection in saliva

Abstract

Widespread home point of care (POC) testing for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is pivotal to control the coronavirus disease 2019 (COVID-19). The reverse transcription polymerase chain reaction, as the current gold-standard tool for diagnosis of COVID-19, even with excellent sensitivity and specificity is not well-suited for home POC diagnostics as it is expensive, hard to administer and limited to a peripheral instrument. Here, we developed a fully-autonomous capillary microfluidic chip, called domino capillaric circuits (DCC), to perform on-chip enzyme-linked immunosorbent assay. The DCC enables fluidic operations such as sample metering, aliquoting, reagent incubation and washing. We also developed a cell phone readout platform to analyze the time-insensitive colorimetric signal and used commercially-available antibodies and materials to detect SARS-CoV-2 nucleocapsid protein in saliva sample with the limit of detection of 0.28 ng/mL. The DCC is fully-automated, user-friendly, enables rapid and quantitative detection of SARS-CoV-2 in saliva and has the potential to be employed for home POC diagnostics.