Abstract: A MEMS resonator active temperature compensation method is provided. The MEMS resonator active temperature compensation method includes: a MEMS resonator is provided, wherein a structural resistance of the MEMS resonator is varied with an environmental temperature; a structural resistance shift value is formed by a variation of the environmental temperature; an electrical circuit is provided, wherein the electrical circuit is electrically connected with the MEMS resonator for providing an adjustment mechanism to the MEMS resonator; and a compensation value is provided from the adjustment mechanism for controlling the structural resistance shift value.

Abstract: A vibration power generator includes: a fixed substrate; a first fixed electrode piece disposed on the fixed substrate, the first fixed electrode piece having a first width of 2w; a second fixed electrode piece disposed on the fixed substrate, the second fixed electrode piece having a second width of 2w; a cover substrate disposed with a space g from the fixed substrate, the cover substrate being opposed to the fixed substrate; a vibrating body disposed between the fixed substrate and the cover substrate; and an electret electrode piece disposed on a side opposed to the first fixed electrode piece and the second fixed electrode piece of the vibrating body, the electret electrode piece having a width that is greater than 2w and less than or equal to 2w+s.

Abstract: A vibration sensor has a first substrate, a second substrate relatively movable by an external vibration while opposed to the first substrate, an electret group having a plurality of electrets that are arrayed in a relative movement direction on a side of one of surfaces of the first substrate, and an electrode group having a plurality of electrodes that are arrayed in the relative movement direction on a side of a surface of the second substrate. The surface of the second substrate is opposed to the electret group. A positional relationship between the electret group and the electrode group changes with a relative change in position of the first and second substrates by the external vibration to output an external vibration detection signal.

Abstract: A MEMS vibrator includes: a vibrating portion; an electrode portion provided to face the vibrating portion with a gap therebetween; and a support portion extended in a first direction from the vibrating portion. The vibrating portion includes a functional portion having a different thickness viewed from the first direction.

Abstract: The device comprises a first actuating bump made from electrically conducting material with a first contact surface. A second actuating bump made from electrically conducting material is facing the first actuating bump. An electrostatic actuating circuit moves the actuating bumps with respect to one another between a first position and another position. The actuating circuit comprises a device for applying a higher potential on the second actuating bump than on the first actuating bump. A film of electrically insulating material performs electric insulation between the first and second bumps. The electrically insulating material film comprises an interface with a positive ion source and is permeable to said positive ions.

Abstract: A triboelectric generator includes a first contact charging member, a second contact charging member and an electrical load. The first contact charging member has a contact side and an opposite back side. The first contact charging member includes a material that has a first rating on a triboelectric series and also has a conductive aspect. The second contact charging member has a second rating on the triboelectric series, different from the first rating, and is configured to come into contact with the first contact layer and go out of contact with the first contact layer. The electrical load electrically is coupled to the first contact charging member and to a common voltage so that current will flow through the load after the second contact charging member comes into contact with the first contact charging member and then goes out of contact with the first contact charging member.

Abstract: Embodiments of the present invention generally relate to a MEMS device that is anchored using the layer that is deposited to form the cavity sealing layer and/or with the layer that is deposited to form the pull-off electrode. The switching element of the MEMS device will have a flexible or movable portion and will also have a fixed or anchor portion that is electrically coupled to ground. The layer that is used to seal the cavity in which the switching element is disposed can also be coupled to the fixed or anchor portion of the switching element to anchor the fixed or anchor portion within the cavity. Additionally, the layer that is used to form one of the electrodes may be used to provide additional leverage for anchoring the fixed or anchor portion within the cavity. In either situation, the movement of the flexible or movable portion is not hindered.

Abstract: The invention relates to an acoustic volume wave resonator configured to resonate at a predetermined work frequency comprising: a mounting (12), comprising a first surface (14) and a second surface (16), a resonating substrate (18), comprising a first surface (20) and a second surface (22), and a diaphragm (24) rigidly connecting the second surface (16) of the mounting on the one hand and the first surface (20) of the resonating substrate on the other hand, The mounting comprises an internal cavity (28) and an internal electrode (32), so as to form a gap area (34) between the internal electrode (24) and a portion (35) of the diaphragm.

Abstract: A reactive ionic liquid to be used as an ionic component that is contained in an ion-containing layer in a transducer arranged in contact with a high-resistance layer as a dielectric layer of the transducer, and is restrained from migrating from the ion-containing layer to the high-resistance layer on application of a voltage is provided. The reactive ionic liquid comprises an ion pair that consists of an anion and a cation. In the reactive ionic liquid, (a) the anion comprises (a1) a reactive group that consists of an alkoxysilyl group and (a2) an anionic group consisting of a carboxylate (—COO?) group or a sulfonate (—SO3?) group. (b) The cation (b1) consists of an imidazolium, ammonium, pyrrolidinium, morpholinium, or phosphonium cation, and (b2) does not comprise an N—H group or a P—H group.

Abstract: In one embodiment, a device is provided that includes: a cascaded electrostatic actuator defining a stack in a substrate having a plurality of gaps between parallel plate electrodes; and a controller configured to drive the cascaded electrostatic actuator to open and close selected ones of the gaps.

Abstract: A generator includes a first member, a second member and a sliding mechanism. The first member includes a first electrode and a first dielectric layer affixed to the first electrode. The first dielectric layer includes a first material that has a first rating on a triboelectric series. The second member includes a second material that has a second rating on the triboelectric series that is different from the first rating. The second member includes a second electrode. The second member is disposed adjacent to the first dielectric layer so that the first dielectric layer is disposed between the first electrode and the second electrode. The sliding mechanism is configured to cause relative movement between the first member and the second member, thereby generating an electric potential imbalance between the first electrode and the second electrode.

Abstract: The subject matter here is an actuation device (1) comprising an actuation element (3) including a fixed portion (31) and a driving portion (32); wherein the fixed portion (31) includes a crawling surface (311), the driving portion (32) includes a flexible moveable blade (321) positioned in parallel and at a distance from the crawling surface (311), and wherein, when a power supply voltage is applied between the moveable blade (321) and the crawling surface (311), the free end (3211) comes into contact with the crawling surface (311), and a contact area, between the moveable blade (321) and the crawling surface (311), increases by propagation of the crawling front (3213) along the moveable blade (321), the propagation of the crawling front displacing the moveable blade (321) according to a first orientation.

Abstract: According to one embodiment, there is disclosed an electrical component. The electrical component includes a substrate, a MEMS device on the substrate. The MEMS device includes a first electrode fixed on the substrate, a second electrode above the first electrode opposed to the first electrode and configured to be movable, an anchor member on the substrate and configured to support the second electrode, and a spring member continuously formed from a region on an upper surface of the second electrode to a region on an upper surface of the anchor member and configured to connect the second electrode and the anchor member. The electrical component includes a reinforcing member provided on a lower surface of the spring member and configured to reinforce strength of the spring member.

Abstract: On an upper surface of a fixed substrate, a plurality of strap-shaped base electrodes are arranged in parallel to each other. On each of the base electrodes, an electret is formed. The electret has a width wider than the width of each base electrode, and the electret covers an exposed surface of the base electrode. A movable substrate is disposed in parallel to and facing the surface of the fixed substrate where the electrets and others are formed. The movable substrate is movable relatively to the fixed substrate. On a facing surface of the movable substrate, strip-shaped counter electrodes are each formed so as to face each base electrode.

Abstract: A MEMS resonator includes two resonating masses having an anti-phase and in-phase resonance mode, each mode having a resonance frequency, and an anti-phase resonance levering system coupled to the two resonating masses to stiffen and/or dampen the in-phase resonance mode while leaving the anti-phase resonance mode compliant. This effectively raises the in-phase resonance frequency above the anti-phase resonance frequency, and potentially creates a large frequency separation between the two resonance modes. This reduces the energy transfer between the two modes, allowing for robustness to external acceleration, because the in-phase mode is of a higher frequency. The anti-phase resonance levering system is disposed between the two resonating masses as an internal levering mechanism, or is disposed around the two resonating masses as an external levering mechanism.

Abstract: In one embodiment, a transducer controller is configured to form an integrated distance measuring and diagnostic cycle that includes measuring a decay time of a transducer and to selectively adjust a period of the transmitted signal responsively to a value of a reverberation period.

Abstract: Monolithically integrated capacitive micromachined transducers (CMTs) offer combined process steps, shared layers, simplified packaging, and reduced die size by overlapping the CMTs with the integrated circuit (IC) electronics. Moreover, a CMT array directly above the electronics also allows for varying the excitation signal phase to each CMT element thereby enabling beam-forming techniques. Above-IC integration is particularly attractive by not requiring any alteration of the semiconductor fabrication process and allowing subsequent implementation independent of IC fabrication. Naturally, this scheme requires that the CMT technology limit itself to IC compatible materials and chemicals, as well as process step temperatures within a specific thermal budget.

Abstract: Devices and methods of operating partitioned actuator plates to obtain a desirable shape of a movable component of a micro-electro-mechanical system (MEMS) device. The subject matter described herein can in some embodiments include a micro-electro-mechanical system (MEMS) device including a plurality of actuation electrodes attached to a first surface, where each of the one or more actuation electrode being independently controllable, and a movable component spaced apart from the first surface and movable with respect to the first surface. Where the movable component further includes one or more movable actuation electrodes spaced apart from the plurality of fixed actuation electrodes.

Abstract: The present invention relates to a pre-collapsed capacitive micro -machined transducer cell (10) comprising a substrate (12) comprising a first electrode (16), a membrane (14) comprising a second electrode (18), wherein the cell has an outer region (22) where the membrane (14) is mounted to the substrate (12) and an inner region (20) inside or surrounded by the outer region (22), wherein the membrane (14) is collapsed to the substrate (12) in a first collapsed annular-shaped region (24) located within the inner region (20).

Abstract: A method and system for using a method of pre-equilibrium ballistic charge carrier refraction comprises fabricating one or more solid-state electric generators. The solid-state electric generators include one or more of a chemically energized solid-state electric generator and a thermionic solid-state electric generator. A first material having a first charge carrier effective mass is used in a solid-state junction. A second material having a second charge carrier effective mass greater than the first charge carrier effective mass is used in the solid-state junction. A charge carrier effective mass ratio between the second effective mass and the first effective mass is greater than or equal to two.

Abstract: A transducer, and a method for manufacturing the transducer are provided. The transducer includes a substrate-side electrode provided in one side of an insulative substrate and an opposite plate including an opposite electrode disposed opposite to the substrate-side electrode, and which performs a function such as a reduction in impedance, conversion of capacitance, signal amplification, thereby achieving size reduction of the transducer itself. An upper plate is made of a silicon monocrystal and is arranged so as to face a substrate-side electrode. In the upper plate, an integrated circuit section which is an impurity region of an IC circuit is formed by a thermal diffusion method or an ion implantation method. By this transducer, an improvement in conversion efficiency, an improvement in productivity, and a size reduction of a mount system are achieved.

Abstract: The present invention relates to volume and/or shape memory systems for which the volume and/or shape can be adjusted by controlling one or more variables such as applied voltage and temperature. In one embodiment, the volume and/or shape memory systems of the present invention are controlled and/or adjusted by way of a temperature mechanism. In another embodiment, the volume and/or shape memory systems of the present invention are controlled and/or adjusted by way of a voltage mechanism. In still another embodiment, the present invention provides a device that contains, in part, a smart volume and/or shape memory material that exhibits high energy densities, and can provide large displacements over broad temperature and/or voltage ranges.

Abstract: A Capacitive Micromachined Ultrasonic Transducer (CMUT) device includes at least one CMUT cell including a first substrate having a top side including a patterned dielectric layer thereon including a thick and a thin dielectric region. A membrane layer is bonded on the thick dielectric region and over the thin dielectric region to provide a movable membrane over a micro-electro-mechanical system (MEMS) cavity. A through-substrate via (TSV) includes a dielectric liner which extends from a bottom side of the first substrate to a top surface of the membrane layer. A top side metal layer includes a first portion over the TSV, over the movable membrane, and coupling the TSV to the movable membrane. A patterned metal layer is on the bottom side surface of the first substrate including a first patterned layer portion contacting the bottom side of the first substrate lateral to the TSV.

Abstract: A capacitive micromachined ultrasonic transducer (CMUT) is provided that includes a substrate, a bottom conductive layer disposed on a bottom surface of the substrate, a cavity disposed into a top surface of the substrate, a nonconductive layer disposed on the substrate top surface and on the cavity, a CMUT plate disposed on the nonconductive layer and across the cavity, a top conductive layer disposed on a top surface of the CMUT plate, a pressure control via that spans from the cavity to an ambient environment, and an active pressure controller connected to the pressure control via, wherein the active pressure controller is capable of actively varying a pressure differential across the CMUT plate.

Abstract: A Capacitive Micromachined Ultrasonic Transducer (CMUT) device includes at least one CMUT cell including a first substrate of a single crystal material having a top side including a patterned dielectric layer thereon including a thick and a thin dielectric region, and a through-substrate via (TSV) extending a full thickness of the first substrate. The TSV is formed of the single crystal material, is electrically isolated by isolation regions in the single crystal material, and is positioned under a top side contact area of the first substrate. A membrane layer is bonded to the thick dielectric region and over the thin dielectric region to provide a movable membrane over a micro-electro-mechanical system (MEMS) cavity. A metal layer is over the top side substrate contact area and over the movable membrane including coupling of the top side substrate contact area to the movable membrane.

Abstract: A two-dimensional comb-drive actuator and manufacturing method thereof are described. The two-dimensional comb-drive actuator includes a supporting base, a frame and a movable body. The supporting base has first comb electrodes and the frame has internal comb electrodes and external comb electrodes. The external comb electrodes of the frame are interdigitated to the first comb electrodes of the supporting base. The movable body has second comb electrodes which are interdigitated to the internal comb electrodes of the frame. The thicknesses of the second comb electrodes of the movable body are unequal to the internal comb electrodes of the frame and the external comb electrodes of the frame are unequal to the first comb electrodes of the supporting base. The two-dimensional comb-drive actuator utilizes a conducting layer for the above-mentioned comb electrodes in order to increase the rotation angle and operation frequency thereof.

Abstract: There is provided an actuator that can deform as an electrolyte moves, wherein at least one of a pair of electrode layers contains polymer fibers, and the polymer fibers contain an electroconductive material and are porous.

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 power generation apparatus includes a dielectric, a movable member being opposed to the dielectric with a predetermined distance, and an electret and an opposing electrode that are formed on the surface of the movable member facing the dielectric so as to generate a fringe electric field penetrating the dielectric between the two electrodes. When the volume occupancy of the dielectric between the electret and the opposing electrode varies in accordance with a displacement of the movable member, the power generation apparatus outputs the electric charge induced in the opposing electrode as electric current.

Abstract: An energy collection system may collect and use the energy generated by an electric field. Collection fibers are suspended from a support wire system supported by poles. The support wire system is electrically connected to a load by a connecting wire. The collection fibers may be made of any conducting material, but carbon and graphite are preferred. Diodes may be used to restrict the backflow or loss of energy.

Abstract: A vibration power generator includes a first substrate, a first electrode on the first substrate, a second substrate spaced from and opposite the first substrate, and a second electrode on the second substrate. The first electrode vibrates with respect to the second substrate, and the first electrode and the second electrode include a film retaining electric charges. The vibration generator includes a third electrode with a film retaining electric charges on the first substrate, and a fourth electrode with a film retaining electric charges on the second substrate. The third electrode and the fourth electrode are arranged so that the first substrate is retained in a predetermined position when an external force does not act on the first substrate, while an electrostatic force for returning the first substrate to a predetermined position acts on the first substrate and the first substrate moves with respect to the second substrate.

Abstract: An electromechanical transducer includes a plurality cells that are electrically connected to form a unit. Each of the cells includes a first electrode and a second electrode provided with a gap being disposed therebetween. Dummy cells that are not electrically connected to the cells are provided around the outer periphery of the unit of the cells.

Abstract: A method for making an actuator capable of dry actuation is provided. The method includes providing a first nanoscale fiber film, providing a second nanoscale fiber film, positioning a solid polymer electrolyte at least partially between and adjacent to the first nanoscale fiber film and the second nanoscale fiber film, and then affixing the solid polymer electrolyte to the first nanoscale fiber film and the second nanoscale fiber film. The nanoscale fiber films may be buckypapers, made of carbon nanotubes. The actuator is capable of dry actuation.

Abstract: A resonant transducer includes a resonator, a resonator electrodes connected to an end part of the resonator, at least one fixed electrode arranged in the vicinity of the resonator, and a buried part formed between the fixed electrode and the resonator electrode. The resonator, the resonator electrodes and the fixed electrode are formed by the same active layer on a substrate.

Abstract: Electrostatic generators/motors designs are provided that generally may include a first rippled stator centered about a longitudinal axis; a second rippled stator centered about the axis, a first rippled rotor centered about the axis and located between the first rippled stator and the second rippled stator. A magnetic field having field lines about parallel with the average plane of at least one of the first rippled stator or the second rippled stator is provided with either a Halbach array configuration or a conductor array configuration.

Abstract: An energy harvesting device utilizing a monolithic, mesoscale, single-degree-of-freedom inertial based resonator in which the support structure, beam-spring, and proof mass are a single component without joints, bonds, or fasteners. Frequency tuning features include holes in the proof mass in which mass can be added to change the devices resonance frequency as well as levers which add curvature to the beam-spring system and adjust system stiffness. Robustness is increase by designing the resonator to exhibit nonlinear behavior such that its power density is maximized for low vibration amplitudes and minimized for high amplitudes. The device structural resonance modes are designed to be much higher than the resonators proof mass-spring resonance frequency. Electromechanical transducers are used to convert the resonators mechanical energy to electrical energy. Electrical circuitry is included to extract and condition the electrical charge.

Abstract: A conformable medical data acquisition pad and configurable imaging system. The conformable pad may comprise a carrier base having a plurality of transceivers in operative association with an interconnection network that communicates with a computer system. The data acquisition pad may be constructed with a flex circuit and at least one ultrasound data collection device to carry out a variety of medical procedures. Different types of signal transmitting and receiving elements can be selected to provide ultrasound systems, including scalable capacitive micromachined ultrasound transducers arranged in a variety of configurations in combination with controlling electronics which interface with a translator board and software for signal processing. The resulting ultrasound data, such as a three-dimensional model, can be transmitted via an industry standard high speed bus to standard interfaces on various ultrasound systems.

Abstract: An electromechanical transducer of the present invention includes a first electrode, a vibrating membrane formed above the first electrode through a gap, a second electrode formed on the vibrating membrane, and an insulating protective layer formed on a surface of the second electrode side. A region where the protective layer is not formed is present on at least part of a surface of the vibrating membrane.

Abstract: A micro-image acquisition and transmission system is provided. In a preferred embodiment, the system is comprised of an image acquisition chip comprising an electronic imager, control electronics and a micro powered rotary stage comprising a transceiver array that acts as a hub to optically link a group of distributed image acquisition chips. A preferred embodiment is further comprised of a transceiver array chip comprising one or more micro-powered rotary stages having a transceiver array assembly disposed thereon. The micro-powered rotary stage is supported by a micro-brush bearing.

Abstract: A method for constructing a MEMS system includes first depositing on a surface of a substrate a first plurality of thin film layers formed of dielectric material. The first plurality of thin-film layers includes at least one conductive trace extending a distance on the substrate, parallel to the surface. A second plurality of layers is then deposited to form at least one MEMS device. The MEMS device is responsive to a control signal applied to a first input terminal and an electrical connection is formed from the conductive trace to the input terminal.

Abstract: A MEMS vibration element 100 includes a substrate 1, a fixing part 23 provided on a principal surface of the substrate 1, a supporting part 22 extending from the fixing part 23, and an upper electrode 21 (a vibration body) supported by the supporting part 22, isolated from the substrate 1. The upper electrode 21 includes a cut section extending from the peripheral portion of the upper electrode 21 toward the central portion of the upper electrode 21, the cut section 30 exposing a side surface portion of the upper electrode 21. The upper electrode 21 includes a joining part provided at a side surface portion 31 oriented in a direction from the central portion toward the peripheral portion, among the side surface portion exposed by the cut section 30, and the joining part is connected to the supporting part 22.

Abstract: A vibrator includes: a vibrating portion; a support portion extended from the vibrating portion; and a fixing portion disposed at the support portion, wherein the support portion includes a first beam portion extending in a first direction from the vibrating portion and a second beam portion extending in a second direction intersecting the first direction.

Abstract: A MEMS vibration element 100 includes a substrate 1, fixing parts 23 provided on a principal surface of the substrate 1, supporting parts (supporting beams 22 and connection beams 21) extending from the fixing parts 23, and an upper electrode (a vibration body) supported by the supporting parts, isolated from the substrate 1. The upper electrode 20 includes cut sections 30 each extending from the peripheral portion of the upper electrode 20 toward the central portion of the upper electrode 20, the cut sections 30 exposing side surfaces 31 of the upper electrode 20. The upper electrode 20 includes joining parts provided at the side surfaces 31 oriented in a direction from the peripheral portion toward the central portion of the upper electrode 20, and the joining parts are connected to the supporting parts 22.

Abstract: An energy conversion apparatus configured to convert energy from a mechanical energy source into electrical energy is provided. The energy conversion apparatus includes a transducer comprising a dielectric elastomer module made of stretchable electroactive polymer material. The dielectric elastomer module comprising at least one dielectric elastomer film layer is disposed between at least first and second electrodes. A transmission coupling mechanism is configured to couple the mechanical energy source and is operatively attached to the transducer to cyclically strain and relax the transducer in response to the mechanical energy acting on the transmission coupling mechanism.

Abstract: Methods, compositions, and apparatus for generating electricity are provided. Electricity is generated through the mechanisms nuclear magnetic spin and remnant polarization electric generation. The apparatus may include a material with high nuclear magnetic spin or high remnant polarization coupled with a poled ferroelectric material. The apparatus may also include a pair of electrical contacts disposed on opposite sides of the poled ferroelectric material and the high nuclear magnetic spin or high remnant polarization material. Further, a magnetic field may be applied to the high nuclear magnetic spin material.

Abstract: An electret having an electric charge injected to a laminate having a resin layer (A) and a resin layer (B) laminated directly on the resin layer (A), wherein the resin layer (A) contains a reaction product of a fluorinated polymer with a silane coupling agent, the resin layer (B) does not contain a reaction product of a fluorinated polymer with a silane coupling agent and contains a fluorinated polymer, the resin layer (B) is disposed as the outermost layer so as to be in contact with air, and the total thickness of the resin layer (B) is from 5 to 55% of the total thickness of the resin layer (A); and an electrostatic induction-type conversion device provided with the electret.

Abstract: Provided is an actuator formed in a substrate including a handle layer, an elastic body layer, and an insulating layer, the actuator including a movable portion supported to a support portion by an elastic body, a movable comb electrode formed on the movable portion, a fixed comb electrode supported by the support portion, and electrode wirings connected to the respective comb electrodes in which the elastic body supports the movable portion such that the movable portion is displaceable in a direction perpendicular to the substrate in accordance with voltages applied to the comb electrodes; the comb electrodes are made up of the handle layer, and the elastic body is made up of the elastic body layer; and a handle layer separation groove is provided to electrically separate between the handle layers of the support portions supporting the comb electrodes, and a structure reinforcing portion is formed across the separation groove.

Abstract: A sensor assembly including one or more capacitive micromachined ultrasonic transducer (CMUT) microarray modules which are provided with a number of individual transducers. The microarray modules are arranged to simulate or orient individual transducers in a hyperbolic paraboloid geometry. The transducers/sensor are arranged in a rectangular or square matrix and are activatable individually, selectively or collectively to emit and received reflected beam signals at a frequency of between about 100 to 170 kHz.

Abstract: A vibration power generator is provided that increases output power by improving the electrostatic capacitance when the area of the overlap between electret electrodes and counter electrodes is maximum while having the function of limiting the spread of the electric field from the electret electrodes.

Abstract: Provided is a micro-electro-mechanical generator including: a first substrate configured to hold an electric charge on a surface of the substrate, and to have an electret film continuously provided on the surface; a second substrate having a collecting electrode provided on a surface facing the electret film; and a movable substrate having conductive property, disposed between the first and the second substrates, and supported movably along a predetermined direction with respect to the first and the second substrates. The movable substrate includes an opening penetrating through the movable substrate from a side of the first substrate to a side of the second substrate and allowing an electric field emitted from the electret film to pass through.