Systems and methods are described herein. The method generally includes generating frequency responses of one or more sample fluids having known fluid properties, selecting an equivalent circuit model for modeling the frequency responses, the equivalent circuit model including one or more model elements, calculating an equivalent impedance of the equivalent circuit model, generating a correlation between the one or more model elements and the known fluid properties, measuring an impedance of a drilling fluid, and determining at least one property of the drilling fluid based on the correlation between the one or more model elements and the known fluid properties.

An apparatus for determining a characteristic of a material within a region comprises a first plurality of electrodes disposed within or about the region, an energisation source arranged to apply an applied stimulation signal to at least one of said first plurality of electrodes, a stimulation monitor arranged to monitor an electrical parameter at a second plurality of said first plurality of electrodes in response to said applied stimulation signal, the stimulation monitor being configured to generate a received stimulation signal for each of said second plurality of electrodes, a monitor configured to generate a series of data values, each data value being indicative of a phase difference and/or an amplitude relationship between the applied stimulation signal and a received stimulation signal associated with one of the second plurality of electrodes, said series of data values defining an electromagnetic fingerprint, and a controller configured to: receive the electromagnetic fingerprint, identify an interrelationship between at least some of the data values of the electromagnetic fingerprint, and determine the characteristic based on the interrelationship.

The invention discloses an impedance spectrum in-situ measuring device for the dielectric constant of solid materials at high temperature and high pressure conditions. The device comprises a cube-shaped pyrophyllite, a cylindrical opening penetrates between one end face of the pyrophyllite and the other end face opposite to the end face; a heater formed by sleeving annular stainless steel sheets is arranged in the opening; a first plate-shaped platinum electrode and a second plate-shaped platinum electrode are arranged in the cavity of the innermost ring-shaped stainless steel sheet. The first plate-shaped platinum electrode is electrically connected with one end of the Solartron 1260 Impedance/Gainphase Analyzer through a first lead, and the second plate-shaped platinum electrode is electrically connected with the other end of the Solartron 1260 Impedance/Gainphase Analyzer through a second lead. Several layers of machinable alumina fillers are filled between the sample of the solid material to be measured and the innermost annular stainless steel sheet. The device also comprises a first cylindrical plug and a second cylindrical plug. The device can be considered as a useful tool in study on the properties of the dielectric constant of the solid material to be measured at high temperature and high pressure conditions.

A sensing system for monitoring an industrial fluid is presented. The sensing system includes a housing and a sensor probe disposed at least partially in the housing, where the sensor probe includes a substrate, a sensing region disposed on the substrate, a first coil disposed on the substrate and coupled to the sensing region, and a second coil disposed on the substrate and coupled to the first coil. A method for operating the sensing system is also presented.

Certain disclosed methods include: transmitting an excitation signal into the MUT and transmitting a reference signal to a set of magnitude and phase (M/P) detectors; receiving the response signal; separately comparing a magnitude and phase for each of the excitation signal and the reference signal with corresponding detection ranges for a first one of the M/P detectors; separately comparing a magnitude and phase for each of the response signal and the reference signal with corresponding detection ranges for a second one of the M/P detectors; iteratively adjusting the excitation signal until the response signal has both a magnitude and a phase within the corresponding detection ranges for the second M/P detector; and iteratively adjusting the reference signal until the reference signal has both a magnitude and a phase within the corresponding detection ranges for the first and the second M/P detectors.

A device for measuring an electrical impedance of biologic tissue may include electrodes configured to contact the biologic tissue and generate a differential voltage thereon. The device may include a first circuit coupled to the electrodes and configured to force an oscillating input signal therethrough, and a differential amplitude modulation (AM) demodulator coupled to the plurality of electrodes. The differential AM demodulator may be configured to demodulate the differential voltage, and generate a base-band signal representative of the demodulated differential voltage. The device may further include an output circuit downstream from the differential AM demodulator and may be configured to generate an output signal representative of the electrical impedance as a function of the base-band signal.

A method and apparatus are described for a reconfigurable architecture analog front end architecture for electrochemical sensors. In one example, an analog front end includes an electrode driver stage coupled to electrodes of an electrochemical sensor, and measurement channels coupled to the electrode driver stage to receive an electrode signal from the electrodes of the electrochemical sensor and to generate measurement results, the measurement channels configured to switch configurations to perform different measurements.

The present disclosure provides a method and an apparatus for measuring electrical conductivity of liquids. In one aspect, the apparatus includes a waveform generator module configured to generate a first waveform signal and to supply the first waveform signal to a sensor; a phase adjustment module configured to receive the first waveform signal from the waveform generator module and to generate a phase-shifted signal from the first waveform signal, said phase-shifted signal having a phase that is adjusted based upon expected or measured properties of the liquid and further adjusted to eliminate phase error induced inaccuracies in the measurement; and a signal combination module configured to receive a return signal from the sensor and the phase-shifted signal from the phase adjustment module and to sum the return signal and the phase-shifted signal to produce an adjusted return signal containing information associated with the electrical property of the liquid.

A level measuring device for level and/or limit determination and for measuring an impedance of a filling material is provided. The level measuring device comprises a measuring probe, arranged for measuring the impedance of the filling material. Further comprising a signal generation unit, arranged for generating a first frequency signal with variable frequency, wherein the measuring probe is supplied with the first frequency signal and outputs a measuring signal. Further, a measurement converter arranged to convert the measurement signal into a mixed signal, wherein the mixed signal has a phase difference with respect to the first frequency signal. Furthermore, the level measuring device comprises a phase difference measuring unit, which is arranged to determine an amplitude-phase characteristic of the filling material measured by the measuring probe, by means of the phase and amplitude difference between the first frequency signal and the mixed signal.

An applied voltage control device is used for a sensor, in which a direct current corresponding to an oxygen amount flows when a DC voltage is applied to the sensor, and an alternating current corresponding to a sensor impedance flows when an AC voltage is applied to the sensor. The applied voltage control device includes: a filtering unit that sets a cutoff frequency of the AC voltage applied to the sensor variable.