Abstract: An ultrasound converter, especially of the axial oscillating type, with at least one piezoelectric element disposed between two tensioning segments and at least one tensioning member which prestresses the piezoelectric element via the tensioning segments. The tensioning element is a ring-shaped tensioning spring the walls of which have at least one peripheral recess.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. A resonator is fabricated on a substrate, and its top electrode 56 is oxidized to form a oxide layer 58. For a substrate having multiple resonators, the top electrode 56 of only selected resonator is oxidized to provide resonators having different resonance frequencies on the same substrate.

Abstract: A method for adjusting the frequency of a piezoelectric resonator allows for frequency adjustments to be individually made for each of a plurality of elements disposed on a piezoelectric substrate before the resonator is completed. Moreover, the frequency adjustments can be made with high accuracy in a relatively short time. When adjusting the frequency of each element, an ion beam is irradiated onto a plurality of electrodes disposed on the piezoelectric substrate to etch the electrodes.

Abstract: The present invention discloses a vibration measuring device for measuring a vibration of an object. Such device includes a sensing body generating a dynamic information in response to the vibration, and a piezoelectric sensing layer disposed on the sensing body to construct a sensor and formed in a distributed mode to measure the dynamic information in a selected specific bandwidth. The present invention also discloses a vibration measuring method.

Abstract: A sensor and associated method is disclosed for detecting presence of a sheet which is being advanced on a photoreceptor of an electrophotographic printing device. The sensor includes a vibratory member which is configured to be positioned in contact with the photoreceptor. The sensor further includes a drive circuit operable to generate an input signal on a signal line which is coupled to the vibratory member. In addition, the sensor includes a sensing circuit operable to (i) determine if a current level of the input signal falls below a threshold value, and (ii) generate a control signal in response thereto. The control signal may be used to stop advancement of the photoreceptor such as in the case where the control signal indicates that the sheet is improperly being advanced on the photoreceptor such as into a cleaning station.

Abstract: A method and system for tuning a bulk acoustic wave device at wafer level by reducing the thickness non-uniformity of the topmost surface of the device using a chemical vapor deposition process. A light beam is used to enhance the deposition of material on the topmost surface at one local location at a time. Alternatively, an electrode is used to produce plasma for locally enhancing the vapor deposition process. A moving mechanism is used to move the light beam or the electrode to different locations for reducing the thickness non-uniformity until the resonance frequency of the device falls within specification.

Abstract: A method of tuning a bulk acoustic wave device having a piezoelectric layer formed between a top electrode and a bottom electrode, wherein the top electrode has a frame-like structure at an edge portion for reducing spurious resonance in the electrical response of the device. The frame-like structure surrounds a center zone of the top electrode. In order to down-shift the resonance frequency of the device, a tuning layer is provided on the top electrode. In particular, the tuning layer is designed such that it covers at least the entire center zone in order to reduce the spurious resonance introduced by the tuning layer itself. Preferably, the tuning layer covers the center zone as well as the frame-like structure to further reduce the spurious resonance.

Abstract: A method and system for tuning a bulk acoustic wave device at wafer level, wherein the thickness of topmost layer of the device is non-umiform. The thickness non-unifornity causes the resonant frequency of the device to vary from one location to another location of the topmost layer. A laser beam, operatively connected to a beam moving mechanism, is used to locally trim the topmost layer, one location at a time.

Abstract: In an array of acoustic resonators, the effective coupling coefficient of first and second filters are individually tailored in order to achieve desired frequency responses. In a duplexer embodiment, the effective coupling coefficient of a transmit band-pass filter is lower than the effective coupling coefficient of a receive band-pass filter of the same duplexer. In one embodiment, the tailoring of the coefficients is achieved by varying the ratio of the thickness of a piezoelectric layer to the total thickness of electrode layers. For example, the total thickness of the electrode layers of the transmit filter may be in the range of 1.2 to 2.8 times the total thickness of the electrode layers of the receive filter. In another embodiment, the coefficient tailoring is achieved by forming a capacitor in parallel with an acoustic resonator within the filter for which the effective coupling coefficient is to be degraded.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricated on a substrate by introducing a mass loading electrode to a bottom electrode layer. For a substrate having multiple resonators, mass loading bottom electrode is introduced for only selected resonator to provide resonators having different resonance frequencies on the same substrate.

Abstract: An object of the present invention is to provide a quartz resonator unit and a quartz oscillator having a small size and a light weight and having the capability of oscillating in the overtone mode, and also to provide a quartz element for use in the quartz resonator unit and quartz oscillator. Thus, a further object is to determine the optimum width-to-thickness ratio of the quartz element at which the quartz element having a width less than 1.5 mm and a length less than 4.7 mm does not show coupling with spurious vibrations over the entire range of operation temperature. From the experiments and evaluation performed repeatedly, it has been concluded that an AT-cut rectangular quartz element having the width-to-thickness ratio w/t in a range selected from the group consisting of 8.48 0.05, 12.18+/−0.05, 13.22+/−0.07, 14.78+/−0.07, and 15.57 0.07 is suitable as a small-sized quartz element that can oscillate at a high frequency and has excellent temperature characteristics.

Abstract: A method and system for tuning a bulk acoustic wave device at wafer level, wherein the thickness of topmost layer of the device is non-uniform. The thickness non-uniformity causes the resonant frequency of the device to vary from one location to another location of the topmost layer. A laser beam, operatively connected to a beam moving mechanism, is used to locally trim the topmost layer, one location at a time.

Abstract: The integrated microactuator has a stator and a rotor having a circular extension with radial arms which support electrodes extending in a substantially circumferential direction and interleaved with one another. For the manufacture, first a sacrificial region is formed on a silicon substrate; an epitaxial layer is then grown; the circuitry electronic components and the biasing conductive regions are formed; subsequently a. portion of substrate beneath the sacrificial region is removed, forming an aperture extending through the entire substrate; the epitaxial layer is excavated to define and separate from one another the rotor and the stator, and finally the sacrificial region is removed to release the mobile structures from the remainder of the chip.

Abstract: A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the device thickness. In particular, the device thickness has a non-uniformity profile across the device surface. A mask with an aperture is placed over the device surface and a particle beam is applied over the mask to allow part of the particle beam to make contact with the device surface at a localized area beneath the aperture. The particles that pass through the aperture are deposited on the device surface to add material on the device surface, thereby increasing the surface thickness to correct for thickness non-uniformity. Alternatively, the particles that pass through the aperture remove part of the device surface in an etching process, thereby reducing the surface thickness. Prior to thickness adjustment, a frequency measurement device or thickness measurement device is used to map the device surface for obtaining the non-uniformity profile.

Abstract: A method for fabricating a resonator, and in particular, a thin film bulk acoustic resonator (FBAR), and a resonator embodying the method are disclosed. An FBAR is fabricated on a substrate by mass loading piezoelectric (PZ) layer between two electrodes. For a substrate having multiple resonators, only selected resonator is mass loaded to provide resonators having different resonance frequencies on the same substrate.

Abstract: A method and system for tuning a bulk acoustic wave device at the wafer level by adjusting the thickness of the device. In particular, the thickness of the device has a non-uniformity profile across the device surface. A mask having a thickness non-uniformity profile based partly on the thickness non-uniformity profile of the device surface is provided on the device surface for etching. A dry etching method is used to remove part of the mask to expose the underlying device surface and further removed the exposed device surface until the thickness non-uniformity of the device surface falls within tolerance of the device.

Abstract: The present invention provides a method for tuning a thin film resonator (TFR) filter comprising a plurality of TFR components formed on a substrate. Each of the TFR components has a set of resonant frequencies that depend on material parameters and construction. TFR bandpass filter response for example can be produced by shifting the set of resonant frequencies in at least one of the series branch TFR components so as to establish the desired shape of the bandpass response and the desired performance of the filter. The shifting may be advantageously performed by removing piezoelectric material from the series branch TFR component, providing a TFR filter with bandwidth and attenuation advantages over that conventionally achieved by down-shifting resonant frequency sets of the shunt TFR components by adding metal material.

Abstract: An ultrasonic motor includes a stator, which includes a piezoelectric element, and a rotor, which opposes the stator. The piezoelectric element vibrates the stator to rotate the rotor. The rotor has an annular thin section. An elastic ring is secured to the thin section. The mass of the elastic ring is selected from a predetermined range of masses. The motor speed at which a predetermined level of noise is produced by the motor is substantially constant for the range of the masses. This reliably damps undesirable vibration of the motor.

Abstract: A method of improving an output characteristic of an angular rate sensor including, for example, a fork oscillator and an improved structure of an angular rate sensor are provided. The improvement of the output characteristic is achieved by adjusting a physical structure of the oscillator to minimize unwanted vibrations of the oscillator or noises of a sensor output. The adjustment of the physical structure is achieved by trimming away an edge portion of the oscillator or a supporter for supporting the oscillator on a base.

Abstract: A method of adjusting a frequency of an energy-trap type piezoelectric resonance element includes the steps of preparing a piezoelectric resonance element including first and second vibration electrodes formed partially on both of the main surfaces of a piezoelectric plate, the thickness of the first vibration electrode being larger than that of the second vibration electrode, and modifying the first vibration electrode or the second vibration electrode in such a manner that the thicknesses of the first and second vibration electrode electrodes are substantially equal to each other such that the piezoelectric resonance element has a desired frequency.

Abstract: A monolithic bulk acoustic wave (BAW) duplexer, and a method for fabricating same, the duplexer having a, transmitter section as a first component filter and a receiver section as a second component filter, both component filters fabricated on a single substrate and both including at least one shunt BAW resonator and one series BAW resonator, each BAW resonator including a resonator section atop an isolation structure provided so as to separate the resonator section from the substrate, including: a patterned bottom electrode material for use as the bottom electrode of each of the resonators of the duplexer; a patterned piezoelectric material for use as the piezolayer of each of the resonators of the duplexer; a patterned top electrode material for use as the top electrode of each of the resonators of the duplexer; a tuning layer for the shunt resonator of each of the two component duplexer filters; and a tuning layer for both the series and shunt resonators of one of the two component duplexer filters.

Abstract: A thin film resonator (TFR) filter circuit including a plurality of TFRs connected in a series-shunt or shunt-series arrangement between input and output ports of the filter. A method is provided that allows for the shifting of resonant frequency sets in each TFR in respective series arms and shunt legs of the TFR filter circuit, as opposed to a conventional concatenating approach using a plurality of chained-up building blocks of TFRs, where resonant frequency sets in each of the series arms are equal, and where resonant frequency sets in each of the shunt legs are equal. Additionally, each TFR in the filter may have a unique parallel plate electrode capacitance, as opposed to the conventional concatenating approach where all series arm electrodes in the root filter design have equal capacitance, and where all shunt leg electrodes have equal capacitance.

Abstract: A group-delay-characteristics adjusting method allows group-delay characteristics of piezoelectric resonators to be easily adjusted without affecting the electrical characteristics thereof. Piezoelectric resonators are arranged on an insulating substrate and are connected in a ladder arrangement, thereby defining a piezoelectric filter. Silicon sheets, each of which has a Young modulus that is about 100 MPa or smaller, are prepared to adjust the group-delay characteristics of the piezoelectric resonators. Then, characteristics of the piezoelectric resonators are measured. The silicon sheets having a size that is appropriate to achieve the required group-delay characteristics are selected, and adhered onto the individual piezoelectric resonators.

Abstract: A method for manufacturing a thin plate includes steps of: securing the thin plate at a mounting platform; forming a metal plating film in contact with an external circumferential surface of the thin plate on a surface of the mounting platform; and grinding the thin plate until the thin plate achieves a specific thickness.

Abstract: A film bulk acoustic wave device, comprising: a substrate; a bottom electrode formed on one surface of the substrate; a piezoelectric film formed on the bottom electrode; and a first top electrode formed on the piezoelectric film, further comprises a second top electrode having a larger mass load than the first top electrode, and formed on the first top electrode on the piezoelectric film when viewed from the center of the first top electrode, wherein the piezoelectric film has a high-band-cut-off-type dispersion characteristic.

Abstract: A method for manufacturing an electronic device includes the steps of: forming a base film comprising a material capable of reactive-ion etching with a fluorine-based gas on a substrate; forming a thin film comprising a material capable of reactive-ion etching with a chlorine-based gas on the base film; etching the thin film by a reactive ion etching with a gas containing the chlorine-based gas; and etching the base film exposed by the etched thin film by a reactive ion etching with a gas containing the fluorine-based gas.

Abstract: A system and method of precisely adjusting the properties of a device using a gas cluster ion beam (GCIB) are described. Use of the invention permits the precise removal or addition of small amounts of material without significantly damaging or degrading the performance of the device. The system is capable of adjusting the properties of a single device or multiple devices and the devices may be processed serially, in small groups, or all at once. The system is also capable of delivering a single dose or a variety of doses depending on the amount of material needed to be removed or added to adjust the properties.

Abstract: The present invention is a method for adjusting the resonant frequency of a mechanical resonator whose frequency is dependent on the overall resonator thickness. Alternating selective etching is used to remove distinct adjustment layers from a top electrode. One of the electrodes is structured with a plurality of stacked adjustment layers, each of which has distinct etching properties from any adjacent adjustment layers. Also as part of the same invention is a resonator structure in which at least one electrode has a plurality of stacked layers of a material having different etching properties from any adjacent adjustment layers, and each layer has a thickness corresponding to a calculated frequency increment in the resonant frequency of the resonator.

Abstract: The present invention is a method for adjusting different resonant frequencies of a plurality of mechanical resonators formed on a common substrate, in a case where the resonant frequencies of the resonators are a function of each resonator thickness. According to this method the resonators are each formed with an etchable top electrode layer which includes a material having different etching properties as a topmost layer for each of the resonators having different resonant frequencies. By selectively etching these etchable layers one at a time in the presence of the others, one may adjust the resonant frequencies of each of the resonators without need to mask the resonators during the etching process. Associated with this method there is a resonator structure having a top electrode structure having a topmost layer having different etching characteristics for different resonators.

Abstract: In a small rotary actuator having a rotor and a plurality of oscillators, each having a piezoelectric element that is excited by application of energy thereto so that the piezoelectric element oscillates at a resonance frequency thereof, the resonance frequency of the respective oscillators varies to some degree. This variation reduces the efficiency of rotation of the rotor. In order to reduce this variation, one or more of the piezoelectric elements of the oscillators is etched so that its resonance frequency is increased to match the resonance frequency of the other oscillators.

Abstract: A method of manufacturing high power sandwich type ultrasonic transducers and, more particularly, a new method of tuning high power sandwich type ultrasonic transducers without the need for a trimming process. A method in accordance with the present invention includes the steps of assembling a sandwich type ultrasonic transducer, measuring the resonant frequency of the ultrasonic transducer, and selecting from a plurality of tuning elements, whereby a dimension or material property of a selected tuning element alters the measured resonant frequency of the ultrasonic transducer to a desired resonant frequency after the tuning element is attached to the ultrasonic transducer.

Abstract: A transducer for use in an ultrasonic gas flow meter includes a housing having an open end and a closed end with a side wall extending therebetween. The closed end of the housing is shaped to receive and transmit sound waves during operation of the transducer. A resonator is positioned in the housing with a transmitting and receiving end facing the closed end of the housing. A thickness of the side wall of the housing at the closed end is less than at a position further toward the open end in order to divert and diffuse spurious vibrations that might otherwise occur near the resonating frequency of the transducer. Generally, such vibration diversion and diffusion is best achieved when the thickness of the side wall housing gradually decreases toward the closed end of the housing. Further, an outer diameter of the housing side wall may gradually decrease toward the closed end of the housing to improving ringing and bandwidth properties.

Abstract: In a method for forming the electrode pattern of a piezoelectric element for an ultrasonic motor, metal pattern masks made of a metal material of a low expansion coefficient are disposed on the surfaces of piezoelectric elements for the ultrasonic motor, and the electrode patterns are formed on the surfaces of the piezoelectric elements through the metal pattern masks by means of a vacuum evaporation device which is equipped with a physical assistance device for rendering physical assistance with ion beams or ion plating.

Abstract: A piezoelectric resonator (10) having a sacrificial mass-loading layer (16). Material is removed from the mass-loading layer (16) to raise a resonator frequency to a desired target. The sacrificial layer (16) is of a dense material, such as silver or gold, but is of such a relative thin layer that it can be used on high frequency aluminum electrodes (14) of a resonator (10) without increasing adverse spurious frequency problems. It is not necessary that the mass-loading layer (16) be conductive. In addition, the silver or gold sacrificial layer (16) can be removed by ion milling at practical and economical rates, unlike aluminum or aluminum oxide. Preferably, a diffusion barrier (18) is interposed between the electrodes (14) and the mass-loading layer (16).

Abstract: A piezoelectric vibration device utilizes a thickness-shear vibration available for communication devices or the like. The piezoelectric vibration device has a structure wherein at least one of each peripheral zone of an input electrode (21) and an output electrode (22), or a common electrode (23), where the non-harmonic overtone mode is relatively strongly excited, is partially provided with either a weight reducing portion (231, 232) or a weight adding portion. Moreover, an area of the common electrode (23) is larger than a total area of the input electrode (21) and the output electrode (22), and either the weight reducing portion (231, 232) or the weight adding portion reaches the common electrode (23) opposed to the input electrode (21) and the output electrode (22). Preferably, the common electrode formed on one principal plane of a quartz plate (1) is twice to 10 times as thick as the input electrode (21) and the output electrode (22) formed on the other principal plane.

Abstract: The chemical and/or physico-chemical determination of the ageing of a motor oil is very expensive and requires measuring methods which cannot be carried out on board a motor vehicle. The determination of only one oil condition parameter, for example the viscosity, only enables conditional statements to be made with respect to oil quality since conflicting effects may exist to varying degrees in this case. According to the invention, oil quality can be determined by a quartz base coated with a sensitive layer. The sensitive layer has a surface or volume which is adapted to an oil component and is suitable for the repeated incorporation and release of the oil component according to the concentration thereof. When the oil component is present, it is incorporated in the sensitive layer causing the resonant frequency of the layer to decrease via a mass effect or causing an effective increase of the component thickness or mass.

Abstract: A method and apparatus for manufacturing high-frequency oscillator elements from a workpiece material includes a tool holder formed of magnetic material providing a magnetic field at a tip thereof and a spherical whetstone made of a magnetic material. A grinding mount is made of a magnetic material installed on a main rotating shaft proximate the tool holder through which flux of the magnetic field is channeled. The spherical whetstone held at the tip of the tool holder by magnetic attraction. The workpiece material is mounted on the grinding mount and the tool holder is rotated around an axis coincident with a center of the spherical whetstone while bringing the spherical whetstone into engagement with the workpiece material to lap the workpiece material.

Abstract: A transducer includes a vibratory energy producing element that generates vibratory energy and a waveguide member coupled to the vibratory energy producing element and transmitting the vibratory energy. The waveguide member has a longitudinal axis and is divided along the longitudinal axis into a plurality of waveguide segments. The transducer is tuned, i.e., brought into specification, by altering a mass of at least one of the waveguide segments relative to a mass of the other waveguide elements.

Abstract: A method of manufacturing a surface acoustic wave device having a piezoelectric substrate and an interdigital transducer provided thereon, includes the steps of forming a coating layer made of inorganic material or organic material on the piezoelectric substrate so as to cover the interdigital transducer and etching the coating layer via a laser light to adjust an operation frequency of the surface acoustic wave device.

Abstract: A resonator device having an insulating substrate, a strip-shaped vibrating element which is mounted on said insulating substrate and is provided with driving electrodes formed on the main opposing surfaces of a piezoelectric substrate, and terminal electrodes which are provided on said insulating substrate so as to be electrically connected with said driving electrodes and to which driving signals are applied by an external signal source. At least the longitudinal side portions of said vibrating element are coated with a surface active agent. With such a constitution, fluctuations in resonant resistance which are due to the excitation level can be suppressed, thereby contributing to the stable operation of the device, reducing the number of producing steps, and raising the yield rate in production.

Abstract: A piezoelectric resonator includes a base member in which piezoelectric layers and internal electrodes are laminated. At one side surface of the base member, the internal electrodes are alternately covered with a first insulating film and with a second film, and first and second external electrodes are disposed thereon alternately connecting the internal electrodes to the first and second external electrodes. An additional material is disposed on the side surface of the base member opposite from the side surface on which the external electrodes are formed by applying ink via an ink jet printer or the like. The additional material is disposed at the opposite ends of the base member in the longitudinal direction. A metal film may also be disposed at a central portion of the base member by a thick film forming method.

Abstract: A piezoelectric component having resonance characteristics adjusted to a high degree of accuracy is provided. A piezoelectric substrate is provided with a resonating part. A deposit is added onto a surface of the resonating part and is provided with a plurality of indented portions at its surface enclosed by outer edges. The deposit is constituted of a resin which may contain a carbon filler. The indented portions are formed through laser machining.

Abstract: In an AT-cut quartz resonator having excitation electrodes formed on two principal surfaces of an AT-cut quartz substrate, the two electrodes are displaced a predetermined amount apart in a direction orthogonal to the X-axis direction so that a frequency deviation in a temperature range of from -10.degree. C. to 50.degree. C. is less than .+-.2.5 ppm. Further, in an AT-cut quartz resonator in which vertically opposed electrodes on both principal surfaces of a quartz substrate are slightly displaced apart in opposite directions along the Z' axis of quartz crystal, a balancing load is formed on a piezoelectric substrate on the side opposite to the direction of displacement of the electrodes.

Abstract: In a piezoelectric vibrator which has excitation electrodes respectively disposed on the top surface and undersurface of a piezoelectric substrate, at least one of the excitation electrodes being an inverted-mesa electrode that has a recess formed in the opposite side of the electrode from the side which contacts the piezoelectric substrate. Thus, an AT-cut quartz resonator in which the capacitance ratio .gamma. is reduced to a value below the limit value can be provided as a result of use of the inverted-mesa electrodes as excitation electrodes.

Abstract: A piezoelectric resonator having a small spurious resonance and a large difference .increment.F between the resonant frequency and the antiresonant frequency is constructed that a resonant frequency or antiresonant frequency can be easily and accurately adjusted to a low frequency. The piezoelectric resonator has a base member which includes a plurality of laminated piezoelectric layers and a plurality of inner electrodes disposed substantially perpendicularly to the longitudinal direction of the base member. The plurality of piezoelectric layers are polarized in the longitudinal direction of the base member. A first external electrode and a second external electrode are located on a surface of the base member and connected to the plurality of electrodes. The resonant frequency of the piezoelectric resonator is adjusted by cutting an intermediate portion in the longitudinal direction of the base member.

Abstract: A unit for suppressing harmonic vibration of a lower order which does not have desired frequency in an overtone resonator consisting main electrodes and sub electrodes. Harmonic vibration of a lower order suppressing piezoelectric vibrator comprises main electrodes arranged on a piezoelectric substrate and sub electrodes arranged in the vicinity of the main electrodes with gaps provided therebetween. If the electric equivalent circuit of the resonator is expressed by a coupling circuit which connects in series a circuit, which connects in parallel a series resonance circuit by the sub electrodes and coupling capacity indicating that the main electrodes are coupled with the sub electrodes, to a series resonance circuit by the main electrodes, then their loop frequencies substantially coincide with each other.

Abstract: A base member of a piezoelectric resonator includes a laminated body having a plurality of piezoelectric layers which are alternately polarized in opposite directions along the longitudinal direction of the base member and inner electrodes provided between the piezoelectric layers. On a first side surface of the base member, each of two external electrodes is arranged so as to be connected to one of two groups of alternate inner electrodes. Cut portions for adjusting a frequency of the piezoelectric resonator to a higher frequency are respectively formed at edge portions of the base member at opposite ends in the longitudinal direction of a second side surface opposite from the first side surface of the base member.

Abstract: A method for tuning a Thin Film Bulk Acoustic Wave Resonator (FBAR) located on a wafer. The FBAR comprises a plurality of layers having respective thicknesses. The FBAR exhibits at least one of a series resonance and a parallel resonance at respective frequencies that are a function of the thickness of at least one of the layers. A first step of the method includes measuring a frequency at which the FBAR exhibits one of a series resonance and a parallel resonance. A next step includes calculating an amount (A) by which the thickness of the at least one layer needs to be altered in order to minimize a difference between the measured frequency and a reference frequency. A further step includes altering the thickness of the at least one layer by the amount (A).

Abstract: A piezoelectric sensor and assembly for measuring chemical, biochemical and physical measurands is disclosed. The piezoelectric sensor comprises a piezoelectric material, preferably a crystal, a common metal layer attached to the top surface of the piezoelectric crystal, and a pair of independent resonators placed in close proximity on the piezoelectric crystal such that an efficacious portion of acoustic energy couples between the resonators. The first independent resonator serves as an input port through which an input signal is converted into mechanical energy within the sensor and the second independent resonator serves an output port through which a filtered replica of the input signal is detected as an electrical signal. Both a time delay and an attenuation at a given frequency between the input signal and the filtered replica may be measured as a sensor output.

Abstract: A resonator having piezoelectric properties is tuned to respond at a specific overtone of its parallel plate resonant frequency. A channel is etched in a blank to confine the oscillations to a predefined area thereby maximizing a predetermined overtone. The position and dimension of the channel are selected to confine the oscillation to a radius that maximizes the response at a desired frequency. The desired frequency is a predetermined overtone of the fundamental frequency. The channel limits the area of oscillation of the blank. The channel may be formed using grooves or slots. The slots are arranged to form a ring. The channel may be positioned inside or outside an electrode.