Hybridization-based DNA biosensing with a limit of detection of 4 fM in 30 s using an electrohydrodynamic concentration module fabricated by grayscale lithography

Speeding up and enhancing the performances of nucleic acid biosensing technologies have remained drivers for innovation. Here, we optimize a fluorimetry-based technology for DNA detection based on the concentration of linear targets paired with probes. The concentration module consists of a microfluidic channel with the shape of a funnel in which we monitor a viscoelastic flow and a counter-electrophoretic force. We report that the technology performs better with a target longer than 100 nucleotides (nt) and a probe shorter than 30 nt. We also prove that the control of the funnel geometry in 2.5D using grayscale lithography enhances sensitivity by 100-fold in comparison to chips obtained by conventional photolithography. With these optimized settings, we demonstrate a limit of detection of 4 fM in 30 s and a detection range of more than five decades. This technology hence provides an excellent balance between sensitivity and time to result. Published under an exclusive license by AIP Publishing.

Automated summary

This study optimized a fluorimetry-based DNA detection technology by controlling the concentration of linear targets and probes. It was found that using specific lengths of target and probe, as well as chips fabricated with grayscale lithography, significantly enhanced sensitivity and detection range while maintaining a short detection time.