On-Chip RF Detection of DNA Hybridization Based on Interdigitated Al/Al2O3 Capacitors

On-chip hybridization of very low concentrations of single-strand DNA targets has been detected by RF electrical measurements of interdigitated aluminum electrodes covered by Al₂O₃ and gold nano-labels around which silver precipitation is performed for signal enhancement The extraction procedure is based on the detection of the interdigitated capacitor self-resonance frequency through the wideband measurement of its inter-electrodes capacitance. Results show an excellent correlation between the sensing area covered by the silver grains, the low-frequency capacitance value and the self-resonance frequency change. Significant self-resonance frequency shifts for the proposed capacitive sensor are still measured for target DNA concentration as low as 50 pM. Based on these experimental results, the great capability of the present method is demonstrated and potential improvements are proposed to detect even lower DNA concentrations