Minute Level Ultra-Rapid and Thousand Copies Level High-Sensitive Pathogen Nucleic Acid Identification Based on Contactless Impedance Detection Microsensor

Abstract

Early screening for pathogens is crucial during pandemic outbreaks. Nucleic acid testing (NAT) is a valuable method for keeping pathogens from spreading. However, the long detection time and large size of the instruments involved significantly limited the efficiency of detection. This work described an integrated NAT microsensor that facilitated rapid and extremely sensitive detection based on nucleic acid amplification (NAA) on a chip. The biochip consisted of two layers incorporating a heater, a thermometer, an interdigital electrode (IDE) and a reaction chamber. The heater and thermometer were utilized to maintain a specific temperature for the sample in the chamber. The thermometer exhibited a good linear correlation with a sensitivity of 9.36 Ω/℃ and the heater achieved a heating efficiency of approximately 6.5 °C/s. IDE was employed for real-time monitoring of the in-chip reaction system impedance and NAA process. Specific nucleic acids from two pathogens (SARS-CoV-2, Vibrio vulnificus) were detected with this microsensor. The samples were qualitatively analyzed on microchip within 3 minutes, with a limit of detection (LOD) of 103 copies/μL. The proposed sensor presented several advantages, including reduced NAT time and increased sensitivity. Consequently, it revealed significantly potential in the field of epidemic prevention.

Keywords: Nucleic acid testing sensor, Nucleic acid amplification, Impedance monitoring, Pathogen diagnosis