Advancing Nucleic Acid Amplification Assay Analysis on Electrowetting-on-Dielectric Digital Microfluidic System with Integrated Impedance Analyzer

The combination of Digital Microfluidics (DMF) and isothermal amplification assays is a promising approach for developing point-of-care (POC) diagnostic systems. The use of electrochemical impedance analysis for Recombinase Polymerase Amplification assays (RPA) allows the production of active compounds as a signal to monitor the reactions, making it a powerful detection strategy. In this study, a DMF system consisting of four main components was developed. A 12 V DC power supply was converted to 170V with the help of a boost circuit and connected to HV507, which generated a 170 V AC signal at 10 kHz. The Fluorine doped Tin Oxide (FTO) glass slide was used as the top electrode, and hexadecane oil was employed to reduce cross-contamination and droplet evaporation. The impedance of RPA droplets was measured using an integrated impedance analyzer circuit. Although the current DMF device is capable of performing basic RPA droplet actuation, heating for RPA assays, and measuring the RPA droplet impedance, the difference between before and after the reaction is not very significant due to the contribution of the dielectric layer to the impedance signal. While the system may not work perfectly in terms of impedance analyzing unit, this study provides valuable insights for further development and optimization in the field of Lab-on-Chip and Digital Microfluidics.