Microfluidic sieve and detector for rapid ultrasensitive assays with single-molecule sensitivity

The advent of ultrasensitive assays enabled many new research and clinical applications, but the time-to-result is hours and has not significantly improved over time, limiting their potential. We introduce the microfluidic sieve and detector (MSD) that can sieve 200 microlitres in just one minute, and quantify captured analytes in four minutes, down to zeptomolar (10-19M) concentration. The MSD comprises half a million 8-μm-diameter pores that bind analytes upon Brownian motion-induced wall collision. Digital sandwich assays are completed by sequentially flowing the sample, reagents, partitioning the pores, and digitally revealing single trapped analytes by enzymatic amplification. The MSD tests are specific and reproducible, exhibit a large dynamic range, and are easy-to-use, affordable, tuneable and versatile, enabling measurement of different proteins including influenza A nucleoprotein in clinical samples, and even nucleic acids while being both faster and more sensitive than PCR. As such, the MSD could open a new chapter for analysis and diagnostics.