A Nonlinear Electric Field Sensor That Exploits Coupled Oscillator Dynamics: The Charge Collection Mechanism

In this paper, we investigate the exploitation of nonlinear behavior in ferroelectric (FE) materials in the realization of innovative transducers for detecting weak and low-frequency electric fields (E-fields). Specifically, we describe a nonlinear dynamical system based on FE capacitors coupled into a unidirectional ring circuit which, under the appropriate operating conditions, exhibits an oscillating regime of behavior in the response variable (the electric polarization). In this device, a weak target E-field induces a perturbation of the polarization of the FE material; in turn, the target signal can be detected and quantified via its effect on the coupled system response. Hence, the device entails the synergetic use of bistable FE materials, micromachining technologies that allow for addressing charge density amplification, and novel sensing strategies based on coupling nonlinear elemental cells. The “charge collector” strategy has been employed to detect the target field. An experimental characterization of the sensing device, including three cells (each cell corresponds to an FE capacitor) coupled in a ring configuration, is presented as a function of the charge collector configuration.