Fin interdigital capacitors

Interdigital capacitors have many fascinating applications, such as humidity detection, molecular detection, and biomedical sensing. The fascinating applications rely on the large sensitivities of the interdigital capacitors to the dielectric constants of analytes. Large sensitivities can be achieved by modifying the geometrical parameters of interdigital capacitors. This work proposes another method for increasing the sensitivities of interdigital capacitors by introducing nanowalls into interdigital capacitors. A fin interdigital capacitor that comprises an array of silver strips stacked with silver nanowalls with a high aspect ratio of 22.8 is designed in this work. Simulation and theoretical analysis reveal that the nanowalls generate strong electric field in the gap between the electrodes of the fin interdigital capacitor, increasing its sensitivity to the dielectric constants of analytes. A fin interdigital capacitor is fabricated in this work. The fin interdigital capacitor exhibits low impedance across frequencies ranging from 1 kHz to 20 kHz, indicating high capacitance, minimal energy loss, excellent thermal efficiency, and suitability for high-frequency sensor applications. The fin interdigital capacitor has an experimental dielectric sensitivity up to 122.1 %/Δε, and senses bovine serum albumin (BSA) and the protein binding of BSA and anti-BSA as BSA and anti-BSA solutions with a low concentration of 0.150 μmol/L are sequentially deposited onto it. As a result, nanowalls with high aspect ratios are an excellent design for improving the dielectric sensitivities of interdigital capacitors.