A piezoelectric transducer for measuring a force includes a base element; a pre-loading element; at least one effective main seismic mass aggregation of pre-loaded parts capable of producing the force when being accelerated; a main piezoelectric ceramic element including a first piezoelectric ceramic; at least one compensation seismic mass aggregation of pre-loaded parts capable of producing a compensation force when being accelerated; a compensation piezoelectric ceramic element including a second piezoelectric ceramic. The first piezoelectric ceramic has a thermal sensitivity shift smaller than the second piezoelectric ceramic. The main piezoelectric ceramic element is oriented with respect to the force to be measured and the compensation piezoelectric ceramic element is oriented with respect to the compensation force such that the main electric charge and the compensation electric charge are opposite in polarity.

In a method to measure changes of the pair of differential transmission lines, an in-phase signal is generated by combining first and second signals transmitted through the pair of differential transmission lines, a phase of the second signal being opposite to the first signal. In a transmission line diagnostic device, a signal combiner extracts the first and second signals received by a communication unit, combines the extracted those signals, and generates an in-phase signal, a detector detects the generated in-phase signal, and a determination unit determines an error when a magnitude of the detected in-phase signal is equal to or greater than a threshold value. In a liquid level detection device, a combining unit combines the first and second signals and generate an in-phase signal, a detection unit detects a voltage of the generated in-phase signal, and a calculation unit calculates a liquid level from the detected voltage.

Resonating sensors for use in high-pressure and high-temperature environments are provided. In one embodiment, an apparatus includes a sensor with a double-ended tuning fork piezoelectric resonator that includes a first tine and a second tine. These tines are spaced apart from one another so as to form a slot between the first and second tines. The width of the slot from the first tine to the second tine varies along the lengths of the first and second tines. Various other resonators, devices, systems, and methods are also disclosed.

A microelectromechanical system (MEMS) sensor includes a substrate having a piezoelectric layer thereon; a MEMS piezoelectric resonator including a reference electrode on a first side of the piezoelectric layer, a first port (port 1) including a capacitor coupling electrode on a side of the piezoelectric layer opposite the first side, and a second port (port 2) for excitation signal coupling including another electrode on the side opposite the first side. The MEMS piezoelectric resonator has a natural resonant frequency. A variable capacitor on the substrate is positioned lateral to the MEMS piezoelectric resonator having a first and a second plate are connected to port 1. An antenna or an oscillator circuit is connected to port 2. Responsive to a physical parameter a capacitance of the variable capacitor changes which changes a frequency of the MEMS piezoelectric resonator relative to the natural resonant frequency to generate a frequency shift.

A system, method and device for interrogating a downhole environment in a borehole beneath a surface includes a source of electromagnetic energy, operable to transmit an electromagnetic signal in the borehole, a sensor module, including a passive resonating circuit including a crystal oscillator having a resonant frequency that varies with changes in the condition in the downhole environment to reflect the electromagnetic signal and to modulate the electromagnetic signal in response to a condition in the downhole environment in the borehole and a detector positionable to receive the reflected modulated electromagnetic signal.

A pressure transducer comprises a housing including a body section and at least one end cap at one end of the body section, which are made of piezoelectric crystal, and a piezoelectric resonator in the housing. The body section and the end cap are bonded by an atomic diffusion bonding method.

A flow sensor comprises an electroactive material device. A driver controls the electroactive material device to deliver heat locally to the flowing medium for which the flow is to be sensed. Temperature sensing signals are obtained and these are used to derive a flow measurement. The way the heat is dissipated relates to the flow, and it is measurable based on the temperature sensing signals. The temperature sensing involves measuring an electrical characteristic which comprises an impedance or an impedance phase angle of the electroactive material device at at least a first frequency and at a second frequency different from the first frequency. The influences of temperature and pressure can in this way be decoupled so that the temperature can be measured at any pressure.

A sensor for use in a fluid flow application is provided. The sensor includes an inlet chamber configured to receive a fluid flow from a first conduit, an outlet chamber configured to provide the fluid flow to a second conduit, and a membrane separating the inlet chamber from the outlet chamber, the membrane including a fluid passage to allow the fluid flow from the inlet chamber to the outlet chamber. The sensor also includes a circuit component disposed on the membrane, having an electrical property configured to change according to a deformation of the membrane, and a conductor formed on a substrate and coupled with the circuit component, to provide an electrical signal based on a change in the electrical property of the circuit component. The membrane includes an epitaxial layer formed on the substrate. Methods for fabricating and using the above sensor are also presented.

Oscillators that use resonator elements formed from langasite or one of its isomorphs are described herein. The resonator elements include crystal orientations that are stress and/or temperature compensated. The resonators vibrate at an oscillating frequency in a thickness-shear mode of vibration. The oscillating frequency can be used to derive temperature, derive pressure, and/or for frequency control applications.

A pressure sensor includes a piezoelectric substrate having a generally planar structure and an anchor location fixing the piezoelectric substrate at the periphery of the planar structure of the piezoelectric substrate. The planar structure of the piezoelectric substrate has a first region having a first characteristic thickness adjacent to the anchor location, and a second region have a second characteristic thickness at a middle region of the substrate. The second characteristic thickness is less than the first characteristic thickness such that the planar structure in the second region is displaced relative to the neutral axis of the planar structure such that while undergoing bending the second region has either mostly compressive or mostly tensile stress.