Nanogap capacitors : Sensitivity to sample permittivity changes

In this article, detailed models for a number of nanogap capacitor geometries are presented, and their agreement with impedance spectroscopy data is evaluated. The detection limit is investigated using a technique for the modification of inter-electrode permittivity. Precise changes in permittivity of the sample region are introduced by timed etching of the capacitor spacer and measured in order to determine the system’s sensitivity to changes in sample permittivity. We have focused on a frequency range far below the relaxation frequencies of the dielectric materials used and we were concerned solely with the real part of the complex permittivity of the materials used . The models developed here can be used to determine the sensitivity of nanogap capacitors to dielectric changes of biomolecular materials present in the sample region. Additionally, it is demonstrated that such devices could function as metrology tools for monitoring the rate of removal/deposition of material in nanocavities, thus aiding in fabrication accuracy. The sensitivity of the measured parameters Z impedance magnitude and phase shift to permittivity changes is measured and compared to model predictions. In conjunction with standard deviation of Z and data over a number of devices 3‐6, sensitivity values can be used to determine detection limits for such sensors. These validated models will be useful to researchers using nanogap-based sensors, and will enable the optimization of such devices as they are developed into genomic or proteomic sensor arrays.