Abstract: Disclosed are systems and methods of operation for capacitive radio frequency micro-electromechanical switches, such as CMUT cells for use in an ultrasound system. An RFMEMS may include substrate, a first electrode connected to the substrate, a membrane and a second electrode connected to the membrane. In some examples, there is a dielectric stack between the first electrode and the second electrode and flexible membrane. The dielectric stack design minimizes drift in the membrane collapse voltage. In other examples, one of the electrodes is in the form of a ring, and a third electrode is provided to occupy the space in the center of the ring. Alternatively, the first and second electrodes are both in the form of a ring and there is a support between the electrodes inside the rings.

Abstract: An ultrasonic transducer including a membrane film and a perforated baseplate. The baseplate can have a conductive surface with a plurality of perforations formed through the baseplate. The membrane film can have a conductive surface and be positioned under tension proximate to the perforations formed through the baseplate. The tension of the membrane film can be controlled to provide a restoring force to counteract the moving mass of the membrane film, and the moving mass of air in the perforations of the baseplate. By selecting the diameter(s) of the perforations of the baseplate, the thickness of the baseplate, the thickness of the membrane film, the tension of the membrane film, and/or the bending stiffness of the membrane film, a wide bandpass frequency response of the ultrasonic transducer centered at an ultrasonic frequency of interest can be obtained and tailored to a desired application.

Abstract: There is provided a force sensor including a substrate and a polymer material layer. The substrate has a circuit layout that includes a first electrode and a second electrode configured to form a capacitor therebetween. The polymer material layer covers at least on a space between the first electrode and the second electrode, and is used to change capacitance of the capacitor while being pressed. The force sensor is arranged inside a stem of an earphone for detecting the user input.

Abstract: Harmonics of a power output of a power plant at a point of common coupling between the power plant and a utility grid, wherein the power plant comprises a plurality of energy production units. The method comprises determining an electrical characteristic at the point of common coupling; determining the electrical characteristic at an output terminal of each of the energy production units and dispatching a control signal to at least one of the energy production units to control the electrical characteristic at an output terminal of the respective energy production units. The control signal is based on the measurement of the electrical characteristic at the point of common coupling and arranged for damping the harmonic of the power output of the power plant at the point of common coupling, wherein the control signal is determined on the basis of a predetermined prioritizing sequence of said electrical characteristic.

Abstract: An autonomous underwater seismic wave generation system includes a housing, and an autonomous navigation system, a propulsion system and a seismic wave generator, each connected to the housing. The autonomous navigation system can navigate the autonomous underwater seismic wave generation system to subsea locations including a location on a seabed. The propulsion system can drive the autonomous underwater seismic wave generation system to the location on the seabed. The seismic wave generator can couple to the location on the seabed to generate seismic waves at the location on the seabed.

Abstract: A system for seismic surveying, method for performing seismic and a non-transitory computer readable medium having instructions stored therein that, when executed by one or more processors, cause the one or more processors to perform a method for performing seismic surveying including emitting seismic waves into a substrate, receiving seismic waves reflected from discontinuities within the substrate, converting the seismic waves into seismic traces, and representing the seismic traces by superimposed multiple tone sinusoidal waves using a parameter estimation. An optimized residual of the modelling is compressed using entropy coding or quantization coding techniques, and the optimized residual and the parameter sets are transmitted to a remote processing station for reconstruction and analysis of the discontinuities.

Abstract: A tactile vibration generator includes a supporting block, a vibration plate, and a vibration actuator. The vibration plate includes two parts. The vibration actuator is attached to a surface of the first part and the first part is not in contact with the supporting block to reduce transferring vibration to the supporting block. The second part is fixed to the supporting block.

Abstract: A sound producing device includes a first sound producing cell, driven by a first driving signal and configured to produce a first acoustic sound on a first audio band, and a second sound producing cell, driven by a second driving signal and configured to produce a second acoustic sound on a second audio band different from the first audio band. A first membrane of the first sound producing cell and a second membrane of the second sound producing cell are Micro Electro Mechanical System fabricated membranes. The first audio band is upper bounded by a first maximum frequency; the second audio band is upper bounded by a second maximum frequency. A first resonance frequency of the first membrane is higher than the first maximum frequency of the first driving signal. A second resonance frequency of the second membrane is higher than the second maximum frequency of the second driving signal.

Abstract: A motor includes a shaft, at least two bearings supporting the shaft, a magnet supported by the shaft between the at least two bearings, a stator surrounding the magnet, and a magnetic member arranged between the magnet and at least one of the bearings in a longitudinal direction of the shaft. The magnetic member has a large outer diameter with respect to an outer diameter of the magnet.

Abstract: The present invention provides a MEMS microphone, having a base and a capacitive system provided on the base. The capacitive system includes a diaphragm and a back plate. The MEMS microphone is further provided with a supporting frame located between the back plate and the diaphragm. One end of the supporting frame is connected with the back plate, and the other end is connected with the diaphragm. The supporting frame divides the cavity into a first cavity body and a second cavity body. The supporting frame is provided with a connection channel. During the production process of the MEMS microphone, the etchant enters the first cavity body, and then enters the second cavity body, which prevents oxides from remaining in the microphone product and affecting the use of MEMS microphone.

Abstract: Ultrasonic transducers that include membrane films and perforated baseplates. An ultrasonic transducer includes a baseplate having a conductive surface with a plurality of apertures, openings, or perforations formed thereon or therethrough, and a membrane film having a conductive surface. The membrane film is positioned adjacent to the apertures, openings, or perforations formed on or through the baseplate. By applying a voltage between the conductive surface of the membrane film and the conductive surface of the baseplate, an electrical force of attraction can be created between the membrane film and the baseplate. Varying this applied voltage can cause the membrane film to undergo vibrational motion. The dimensions corresponding to the size and/or shape of the apertures, openings, or perforations formed on or through the baseplate can be varied so that different regions of the baseplate produce different frequency responses, allowing the net bandwidth of the ultrasonic transducer to be increased.

Abstract: An ultrasound transducer module includes: an ultrasound transducer configured to transmit and receive ultrasound; a substrate electrically connected with the ultrasound transducer and including a first wiring pad at a portion different from a connection portion with the ultrasound transducer; and a casing that includes an accommodation hole for accommodating the ultrasound transducer and the substrate and that includes a holding hole continued to the accommodation hole and capable of holding a portion of the substrate, the casing having a plurality of electrode pads provided on an outer surface of the casing and having a plurality of second wiring pads provided in the holding hole, each second wiring pad being electrically connected with a corresponding electrode pad among the plurality of electrode pads, and electrically connected with the first wiring pad.

Abstract: A solution is provided for suppressing audio noise in a DC-DC switching converter. A means for limiting the minimum switching frequency of a pulse-frequency modulation (PFM) control is described. A first order gm amplifier dissipates the excess energy added to the inductor, when magnetizing at faster rate than the native PFM. A higher resistance, low-side scaled switch helps reduce wasted energy losses. The low-side scaled switch reduces the rise in the inductor current during magnetization, and hence keeps efficiency up at low loads, when the PFM minimum switching frequency is active.

Abstract: A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

Abstract: A method for use in marine seismic surveying includes: towing at least a portion of a marine seismic survey spread; imparting a composite swept seismic signal from the marine seismic survey spread, the composite swept seismic signal including a plurality of randomized subsweeps having different frequencies relative to one another and being emitted in parallel; and receiving a respective return for each of the subsweeps.

Abstract: Ultrasonic transducers that are capable of generating increased levels of ultrasound, as well as receiving ultrasonic waves with increased sensitivity. The ultrasonic transducers include a back cover, a protective front cover, a backplate, and a vibrator film layer disposed between the backplate and the protective front cover. The backplate includes a plurality of grooves formed on a surface thereof facing the vibrator film layer. Each groove includes upper edges having cross-sectional contours that gradually tend toward the deepest part of the groove to allow a larger area of the backplate to be closer to the vibrator film layer, thereby increasing the resulting electric field, and, consequently, increasing the output power and sensitivity of the ultrasonic transducer.

Abstract: Method, source array and seismic vibro-acoustic source element for seismic data acquisition. The number of beams of acoustic energy to be generated for the seismic data acquisition are determined or selected. A different pilot signal is generated for each of the number of beams of acoustic energy. A plurality of drive signals are generated using the different pilot signals. An array of source elements are driven using the plurality of drive signals to generate the two or more beams of acoustic energy.

Abstract: Method for generating an excitation signal for a first vibratory seismic source so that the first vibratory seismic source is driven with no listening time. The method includes a step of determining a first target spectrum for the first vibratory seismic source; a step of setting a first group of constraints for the first vibratory seismic source; and a step of generating a first excitation signal for the first vibratory seismic source based on the first group of constraints and the first target spectrum. The first seismic traces recorded with plural receivers can be identified when the first vibratory seismic source is driven with no listening time, based on the first excitation signal.

Abstract: Imperfect separation at the higher frequencies has been observed and was eventually was tracked down to the poor GFE signal that is normally used in the inversion. The invention thus uses a “derived GFE” for each source, obtained by comparing the shot records and remove the differences, instead of the prior estimated GFE signal put out by the controller, thus accurately maximizing the separation of the data.

Abstract: Method for separating signals recorded by a seismic receiver and generated with at least two vibratory seismic sources driven with no listening time. The method includes receiving seismic data that includes data d recorded by the seismic receiver and data related to the first and second vibratory seismic sources; computing a source separation matrix based on the data related to the first and second vibratory seismic sources; calculating first and second earth impulse responses HA and HB corresponding to the two vibratory seismic sources, respectively, based on the data d recorded by the seismic receiver, the data related to the two vibratory seismic sources and the source separation matrix; and separating the signals recorded by the seismic receiver based on the first and second earth impulse responses HA and HB such that signals the two vibratory seismic sources are disentangled.

Abstract: Marine seismic survey using one or more marine seismic vibrators, where the vibrator sweep function is based on a quality requirement, which may be a final image quality requirement or an environmental requirement. The sweep function may be nonlinear and the energy spectrum may not match the energy spectrum of an airgun.

Abstract: A seismic source of the present disclosure includes a first rotation member and a second rotation member having a common axis of rotation and rotated at a same rotational rate in mutually opposite directions. In addition, the seismic source may include a first mass that is eccentrically coupled to the first rotation member and rotates along with the first rotation member. A second mass may be eccentrically coupled to the second rotation member and configured to rotate along with that member. The second mass may be configured such that the center of gravity of the second mass is located radially external to the center of gravity of the first mass relative to the common axis of rotation. The center of gravities of the first and second mass may be located at the same location along a length of the common axis of rotation.

Abstract: An electrostatic transducer comprises an electrically conductive first layer (1), a flexible insulating second layer (25) disposed over the first layer, and a flexible electrically conductive third layer (26) disposed over the second layer. Between the first and the second layers are provided spacers (24) and between the second and the third layers are provided spacers (27). The spacers may be provided by strips of adhesive or by bonding the layers together by welding, for example. The first layer (1) is provided with an array of through apertures (5) each having an inlet (6) facing the second layer (2) and an outlet (7). In response to signals applied to the first and third layers, the second and third layers have portions which are displaced towards the outlets of the apertures by electrostatic forces. The apertures (5) may have conducting walls and the walls may converge.

Abstract: A seismic source signal apparatus for generating a seismic source signal may include a seismic source component for coupling a reaction mass to the earth; a controllable valve operatively connected to the seismic source component; and a controller controlling the controllable valve with a primary control signal generated by using a model of a response of the controllable valve over a selected operating range. The model is used to reduce nonlinearity in flow versus displacement response of the controllable valve.

Abstract: A marine seismic survey using one or more moving marine seismic vibrators, where the vibrator sweeping function is based on smearing error criteria and is a downward-sweeping non-linear sweep function. The acquired seismic data can either be used as is without desmearing or desmeared easily.

Abstract: A system and method are described herein for generating a frequency sweep signal set for use in seismic data gathering. Low frequency sweep rate modifications are combined to compensate for vibrator limitations and vibrator far-field responses with high frequency sweep rate modifications to compensate for absorption, and then the frequency sweep signal set is generated based on the combination of high and low frequency sweep rate modifications.

Abstract: A shock absorber including a damping force generation mechanism (30a) includes a spring member (106a) having radially extending spring portions (117) having high spring constants and circumferentially extending spring portions (118) having low spring constants. The radially extending spring portions and the circumferentially extending spring portions are integrally configured so that biasing forces thereof act dynamically linearly. An annular stepped portion limits strokes of the circumferentially extending spring portions and is provided on a cylindrical wall portion of a pilot body. As a result, within a range of damping force control, only the radially extending spring portions of the spring member are elastically deformed, whereby the durability of the spring member is enhanced, and only biasing forces of the radially extending spring portions of the spring member act on a pilot valve member, and thereby variation in a damping force is reduced so that the performance is improved.

Abstract: A method for electromagnetic geophysical surveying according to one aspect of the invention includes disposing a plurality of electromagnetic receivers in a selected pattern above an area of the Earth's subsurface to be evaluated. An electromagnetic source is repeatedly actuated proximate the electromagnetic receivers. Signals generated by the receivers, indexed in time with respect to each actuation of the at least one electromagnetic energy source, are recorded. The recorded signals are processed to generate an image corresponding to at least one point in the subsurface. The processing includes stacking recordings from each receiver for a plurality of actuations of the sources and beam steering a response of the receivers such that the at least one point is equivalent to a focal point of a response of the plurality of receivers.

Abstract: The invention is an improved technique for measuring near surface attributes of the ground while conducting a seismic survey. The improved technique is enabled by an electric vibe using a number of linear electric motors that direct a rod or piston to contact the ground in a recurring fashion. By applying constant force on the rods of the linear electric motors against the ground, the penetration into the ground may be measured for both rate and overall deformation. This information provides an accurate indication of viscosity and stiffness. In addition shear velocity and compression velocity may be measured and in some conditions, even the type of prominent shear wave may be identified for the area.

Abstract: A vibration member (140) has a sheet shape. A piezoelectric element (130) is attached to one surface of the vibration member (140). A support member (110) supports the edge of the vibration member (140). The support member (110) includes a first facing portion (112) and a second facing portion (114). The first facing portion (112) faces the surface of the vibration member (140) to which the piezoelectric element (130) is attached. The second facing portion (114) faces the surface of the vibration member (140) which is located on the opposite side to the piezoelectric element (130). A first spring (152) is provided between the first facing portion (112) and the vibration member (140) or the piezoelectric element (130). A second spring (154) is provided between the second facing portion (114) and the vibration member (140).

Abstract: Computer software, controller and method for generating a desired pilot signal for driving a vibratory source. The method includes steps for selecting a pilot target amplitude spectrum for the vibratory source; determining an initial pilot signal that matches the pilot target amplitude spectrum; associating the initial pilot signal with first and second frequency bands, the second frequency band including a high-frequency end of a range of the vibratory source; band-passing a first part of the initial pilot signal associated with the first frequency band with a first band-pass configuration; band-passing a second part of the initial pilot signal associated with the second frequency band with a second band-pass configuration; level compressing the first and second parts of the initial pilot signal; recombining the first and second parts of the initial pilot signal to form a recombined pilot signal; and processing the recombined pilot signal to obtain the desired pilot signal.

Abstract: An ultrasonic transducer comprises a metal plate; an acoustic matching member fastened to one of surfaces of the metal plate, a piezoelectric substrate which is fastened to the other surface of the metal plate and generates a vibration; and an insulating damping member covering a surface of the piezoelectric substrate which surface is on an opposite side of a surface fastened to the metal plate; wherein a thickness of the insulating damping member is set to a length which is n/2 of a wavelength of the vibration propagating through the insulating damping member.

Abstract: A passive and wireless sensor is provided for sensing at least one of magnetic field, temperature or humidity. The sensor can provide only one of the sensing functions, individually or any combination of them simultaneously. It can be used for various applications where magnetic field changes, temperature and/or humidity need to be measured. In one or more embodiments, a surface acoustic wave (SAW) sensor is provided that can measure one or more of a magnetic field (or current that generates the magnetic field), temperature and humidity. In one or more embodiments, a magnetoimpedence (MI) sensor (for example a thin film giant magnetoimpedance (GMI) sensor), a thermally sensitive (for example a Lithium Niobite (LiNbO3)) substrate, and a humidity sensitive film (for example a hydrogel film) can be used as sensing elements.

Abstract: A system and method for resolving and/or mechanically manipulating molecular bonds. A method for resolving molecular bonds includes applying ultrasound to molecules to be manipulated. A magnetic signal associated with the molecules is measured. Whether ultrasound causes dissolution of the bonds of the molecules is determined based on measurements of the magnetic signal.

Abstract: An acoustic transducer includes a base plate, a vibrating membrane and a back plate. The vibrating membrane covers an opening of the base plate and has a plurality of conjoint vibratile portions. The acoustic transducer further has a connecting portion that is connected to a boundary between each two of the adjacent vibratile portions so as to allow the vibratile portions to generate vibration independently. The vibratile portions are geometrically different. Thereby, the vibratile portions can vibrate independently. This allows a designer to easily enhance the dynamic range of the acoustic transducer by geometrically modifying the vibrating membrane without increasing the total area of the vibrating membrane while maintaining a certain good degree of sensitivity and signal-to-noise ratio.

Abstract: A method and related apparatus are described for generating acoustic signals for use in a vibratory seismic survey, including at least two different sweep signals for the control of at least two different types of vibrators; and matching the phases of the different sweep signals at a transition frequency from one sweep signal to another.

Abstract: Provided is a signal generation device used for an information input method using an ultrasonic signal. Contact electrodes which are formed in a flexible printed circuit board to be in contact with an ultrasonic wave generation unit and reference signal generation units are disposed in a row, so that a length of the flexible printed circuit board can be reduced. Accordingly, in comparison with a signal generation module in the related art, a length of the signal generation module can be reduced, so that the signal generation device can be miniaturized. In addition, in order to maintain the contact between contact electrodes of the flexible printed circuit board and the ultrasonic wave generation unit, the contact electrodes which are in contact with the ultrasonic wave generation unit and the flexible printed circuit board are surrounded by a contact maintaining member which is constructed with a cylindrical elastic member.

Abstract: The output spectrum of a controllable swept-frequency acoustic source at a given frequency can be controlled by making the rate of change of frequency equal to the desired output power spectrum divided by the squared envelope amplitude of the source output signal, both measured at the time after the start of its frequency sweep at which the sweep frequency passes through the given frequency. The system and method can also be used to correct for propagation effects outside the source by dividing the desired spectrum by the propagation effect. The method can further be used either to obtain an output spectrum of a desired shape from a source operating at maximum output or to design a sweep of a minimum feasible duration that will result in an output spectrum of a specified shape and with a specified amplitude.

Abstract: Aspects described herein relate to an electromagnetic seismic vibrator (EMSV) architecture that provide wide frequency range operation, ground force application with high fidelity, and low environmental impact. The EMSV architecture can include a base member that can support a force coil and mitigate electrical heating due, at least in part, to spurious currents. The EMSV architecture can include means for restricting movement of a reaction member included in the EMSV architecture relative to the base member. Such means can permit mitigation of damage of the EMSV architecture in scenarios in which control of the EMSV architecture may fail.

Abstract: Disclosed are embodiments of a marine vibrator and methods of using. Embodiments of the marine vibrator may comprise a containment housing; a piston plate, wherein an internal volume of the marine vibrator is at least partially defined by the containment housing and the piston plate, the internal volume containing a first gas at a first gas pressure; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and the fixture; a driver coupled to the piston plate and the fixture, wherein the driver is configured to move the piston plate back and forth; and a compliance chamber in contact with the first gas, wherein the compliance chamber comprises a second gas at a second gas pressure.

Abstract: Embodiments relate to relate to marine vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine vibrator may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and the fixture; a driver disposed in the marine vibrator, wherein the driver is coupled to the piston plate and the fixture; and a container coupled to the piston plate, wherein the container is configured to hold a variable mass load; wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable mass load.

Abstract: Embodiments relate to the restriction of gas flow in a piston-type marine vibrator to compensate for air-spring effects. An embodiment provides marine vibrator comprising: a containment housing; a piston plate; a fixture coupled to the containment housing; a mechanical spring element coupled to the piston plate and to the fixture; a driver coupled to the piston plate and to the fixture; and a variable gas flow restrictor disposed in an interior volume of the marine vibrator, wherein the marine vibrator has a resonance frequency selectable based at least in part on the variable gas flow restrictor.

Abstract: Embodiments relate to marine acoustic vibrators that incorporate one or more piston plates that act on the surrounding water to produce acoustic energy. An example marine acoustic vibratory may comprise: a containment housing; a piston plate; a fixture coupled to the containment housing; a spring element coupled to the piston plate and the fixture; and a driver coupled to the piston plate and the fixture and configured to move the piston plate back and forth.

Abstract: Evaluating utilities involves generating an acoustic or seismic source signal, communicating the source signal to a first underground utility, moving a receiver through a second underground utility situated in proximity to the first utility, and monitoring for a cross bore involving the first and second utilities in response to receiving the source signal emanating from the first utility as the receiver progresses through the second utility. Utility evaluation may further involve detecting a cross bore involving the first and second utilities using monitoring data acquired by the receiver.

Abstract: An electromechanical transducer according to an embodiment of the present invention is capable of selectively performing a transmitting and receiving operation by using elements of different shapes. The electromechanical transducer has a plurality of cells, each of which has a vibrating film including two electrodes provided with a gap therebetween, two driving and detecting units, a potential difference setter, and a switch. Each of the driving and detecting units implements a transmitting and/or a receiving function. A first or second element includes first or second electrodes which are electrically connected and further connected to the common first or second driving and detecting unit, respectively. The potential difference setter sets a predetermined potential difference between the reference potentials of the first and second driving and detecting units, respectively, and the switch switches between the first and second driving and detecting units to perform the transmitting and receiving operation.

Abstract: Temperature stability at the temperatures prevailing in a motor and stability that is required over an entire temperature range are provided by an attenuating mass. This enables continuous use at temperatures of approximately 150° C. while providing ultrasonic attenuation at low temperatures.

Abstract: An ultrasound probe contains an ultrasound transducer arrangement that is formed with a plurality of transducer elements. The transducer elements are arranged next to one another in a row and they can be controlled with a time delay. The transmitting/receiving surfaces of the transducer elements are inclined relative to one another such that the angle of inclination between the transmitting/receiving surfaces of two transducer elements increases with the number of transducer elements located between the transducer elements. At least two of the incremental angles of inclination between each pair of adjacent transducer elements are different.

Abstract: A vibration member (140) has a sheet shape. A piezoelectric element (130) is attached to one surface of the vibration member (140). A support member (110) supports the edge of the vibration member (140). The support member (110) includes a first facing portion (112) and a second facing portion (114). The first facing portion (112) faces the surface of the vibration member (140) to which the piezoelectric element (130) is attached. The second facing portion (114) faces the surface of the vibration member (140) which is located on the opposite side to the piezoelectric element (130). A first spring (152) is provided between the first facing portion (112) and the vibration member (140) or the piezoelectric element (130). A second spring (154) is provided between the second facing portion (114) and the vibration member (140).

Abstract: A seismic vibrator has a baseplate composed at least partially of a composite material. The baseplate has a body composed of the composite material and has top and bottom plates composed of a metallic material. The top plate supports isolators for isolating the vibrator's mass and frame from the baseplate. Internally, the composite body has a central structure to which couple stilts for supporting the mass and a piston for the vibrator's actuator. A lattice structure surrounds the central structure. This lattice structure has radial ribs extending from the central structure and has radial ribs interconnecting the radial ribs.

Abstract: The present invention relates to a pre-collapsed capacitive micro-machined transducer cell (10) comprising a substrate (12), and a membrane (14) disposed above a total membrane area ((Atotal), wherein a cavity (20) is formed between the membrane (14) and the substrate (12), the membrane (14) comprising a hole (15) and an edge portion (14a) surrounding the hole (15), the edge portion (14a) of the membrane (14) being collapsed to the substrate (12). The cell further comprises a plug (30) arranged in the hole (15) of the membrane (14), the plug (30) being located only in a subarea (Asub) of the total membrane area (Atotal). The present invention further relates to a method of manufacturing such pre-collapsed capacitive micro-machined transducer cell (10).