A Ferroelectric-Capacitor-Based Approach to Quasistatic Electric Field Sensing

A new sensor for quasistatic electric field (E-field) measurements based on a ferroelectric capacitor (which acts as a nonlinear active dynamic element) is discussed in this paper. The device was theoretically modeled and experimentally characterized, and the data that were gathered were used to refine the model parameters. The E-field sensing strategy is based on the exploitation of a mechanism to convert the external target E-field into a perturbation on the polarization state of a ferroelectric material: a detailed analytical description of this process is given together with its experimental validation. Optimal results have been obtained with a driving (i.e., reference) signal of 10 V at 100 Hz, which was used to polarize the device. The noise floor of the device has been evaluated through an analysis of the power spectral density, which yields a value of 0.4 (V/m)/Hz^1/2. The hysteretic capacitor in this paper is the cornerstone of an innovative system for detecting weak E-fields (assumed to be dc throughout this paper, although it can also be applied to detect time-periodic E-fields) through the exploitation of the nonlinear behavior of a coupled oscillator system wherein the active (nonlinear) elements are the ferroelectric capacitors. Our results cover the basic building blocks that were necessary for the optimal realization of this coupled circuit.