Differential Capacitance Spectroscopy for Real-Time Monitoring of RNA Amplification

RNA amplification is central to viral diagnostics, yet current optical and fluorometric methods, such as PCR and RT-qPCR, remain costly, complex, and resource-intensive. Here, we introduce differential capacitance spectroscopy (DCS) as a real-time electrochemical method for RNA detection using loop-mediated isothermal amplification. By applying sinusoidal currents to flexible carbon fiber electrodes (0.05 cm², 1 mm apart), DCS monitors changes in electrode-electrolyte interface capacitance, generating a unique arm-shoulder diagram (ASD) for RNA amplification. The ASD reveals exponential and polynomial capacitance variations, distinguishing amplified RNA under isothermal conditions. Our method eliminates the need for sophisticated instrumentation and reduces diagnostic costs while enabling rapid, high-sensitivity detection. Validated with COVID-19 patient samples, DCS provides a promising platform for affordable, scalable, and real-time RNA-based diagnostics, positioning itself as a transformative tool for disease surveillance and clinical applications.