Recently, we have shown the emergence of oscillations in overdamped undriven nonlinear dynamic systems subject to carefully crafted coupled schemes and operating conditions. Here, we summarize these results for a system of <i>N</i> = 3 coupled ferromagnetic cores, the underpinning of a "coupled-core fluxgate magnetometer" (CCFM): the oscillatory behaviour is triggered when the coupling constant exceeds a threshold value (bifurcation point), and the oscillation frequency exhibits a characteristic scaling behaviour with the "separation" of the coupling constant from its threshold value, as well as with an external "target" dc magnetic flux signal. We present assorted performance figures of the magnetometer, and also describe figure of merit (to characterize the device) that includes the effects of the sensor noise-floor as well its sensitivity.
This paper deals with a novel strategy for the detection of weak static electric fields. The approach proposed here is
based on the exploitation of the nonlinear behaviors shown by a circuit made up by the ring connection of an odd number
of elements containing a ferroelectric capacitor. The presence of a weak external dc perturbation interacting with the
system state can be detected and quantified via its effect on the oscillation frequency and on the asymmetry of the system
The dynamic behavior of the ferroelectric ring can be described by using the equations of the "quartic double well"
potential that model the ferroelectric capacitors where the target electric field is considered as a perturbation in the
polarization status of each ferroelectric element.
Simulation results have been obtained where it can be observed, for a coupling factor greater than the critical one, as
related to the external field amplitude, the change in the harmonic content of the permanent oscillation that the coupled
A detailed spice model of the ferroelectric capacitor and of the ring circuit will be described in this paper together with
some results regarding the experimental characterization and modeling of ferroelectric capacitors to be included in the
Several experimental confirmation have been already obtained. Work is currently in progress toward the realization of a
novel ring circuit that will include the ferroelectric capacitors presented here.
In this work we discuss the implementation of sensing devices based on ring-coupled hysteretic systems. In particular, the emergent oscillations in a ring coupled system formed by overdamped nonlinear devices having an hysteretic magnetic and electric behaviour are considered with applications to B-field and E-field measurements, respectively. Details on the implementation strategy, on the materials adopted and on the technologies will be given. The concept introduced is then extended to the area of E-field sensors taking into account nonlinear ferroelectric devices where oscillations can be obtained through a suitable connection topology in a similar way as for the magnetic field systems. The evaluation of the output signal dependence on the target electric field to be measured will be discussed and some device implementation issues will be reported. The proposed system combines benefits coming from reconsidering dated physical electro-static phenomena, with miniaturization levels provided by micro-technologies, to realize important electric field amplification. Devices based on different technologies, ranging from PCB to hybrid integrated microsystems, will be presented and discussed. Preliminary experimental results on E field sensor will be presented; the studies on B-field sensor are more mature and more comprehensive experimental results will be discussed to validate the working principle and to qualify the sensors in terms of sensitivity and noise floor.
Recently, we have shown the emergence of oscillations in overdamped undriven nonlinear dynamic systems subject to carefully crafted coupling schemes and operating conditions. Here, we summarize these results for a system of N = 3 coupled ferromagnetic cores, the underpinning of a "coupled-core fluxgate magnetometer"(CCFM); the oscillatory behaviour is triggered when the coupling constant exceeds a threshold value (bifurcation point), and the oscillation frequency exhibits a characteristic scaling behaviour with the "separation" of the coupling constant from its threshold value, as well as with an external "target" dc magnetic flux signal. We also present the first (numerical) results on the effects of a (gaussian, exponentially correlated) noise floor on the spectral properties of the system response, and extend our investigations to the large N case, wherein the noise is seen to mediate interesting spatio-temporal cooperative behavior.
Several studies have demonstrated the suitability of noise added methodology to improve the performances of bistable or quasi-linear devices. As an example, observations of the Stochastic Resonance phenomenon in the Brownian System reveal the possibility to use exogenous noise to improve the behaviour of several sensing devices or to adapt them to perform adequately in the presence of noise. Moreover, in the field of quasi-linear systems the possibility to use dithering to increase the device operating range was addressed. In this paper, an overview of the methodologies aimed to improve the performances of stochastically modulated systems is presented. In particular the possibility to improve the performance of both bistable or quasi-linear measuring systems is shown by using a number of examples that have been developed in a number of years by researchers working at DIEES of the University of Catania (Italy).
In this paper some recent results, regarding the research activity currently in progress in the field of MEMS at the DEES, University of Catania, are reported. In particular some microsystem prototypes, realized by using a standard CMOS process (AMS 0.8 micrometers CMOS) through the EuroPractice service, are described. A novel IC has been realized, it contains several different structures designed both for particular applications and for technology characterization purposes. A set of devices has been realized through 'front side bulk micromachining' and some other novel structures where the polysilicon layer is used as sacrificial layer have been investigated. In order to ensure fully compatibility with CMOS electronics, a wet etching process has been performed by using TMAH. Characterizations of the wet etching process are being performed in order to exploit the absence of crystallographic structure in polysilicon to allow for isotropic etching micromachining. Some applications of Microsystems in different fields are also presented.