MXPA97008359A - Elastomeri microelectromecanic system - Google Patents

Abstract

The present invention relates to an electromechanical transducer having a substrate (4) carrying a plurality of elastomeric microstructures (5) with a microelectrode (6) in each microstructure. An energy supply (11) is connected to the microelectrodes for controlled application thereto of an electrical potential that alternatively induces the attractive forces between the adjacent pairs of microelectrodes, causing the time-varying, controlled displacement of the microelectrodes. Alternatively, a further plurality of microelectrodes (14), or one or more macroelectrodes (32), is elastomerically held above the microelectrodes, with the power supply being connected to the macroelectrode (s) in such a way that the applied electrical potential between the microelectrodes and the macroelectrode (s), it induces alternatively attractive forces between the microelectrodes and the macroelectrode (s), causing a displacement that varies in controlled time of microelectrodes in relation to the macroelectrode (s). The macroelectrode (s) can also be applied to one side of the substrate opposite the microstructures

Description

"ELASTOMERICOS MICROELECTROMECANICOS SYSTEMS" FIELD OF THE INVENTION This invention relates to a microelectromechanical transducer comprising a number of microelectrodes elastically held in an elastomeric microstructure.

BACKGROUND OF THE INVENTION The past decade has seen rapid growth in the Microelectromechanical Systems branch, which is commonly referred to by its acronym "MEMS". As the name implies, MEMS are basically microsystems that incorporate a certain type of electromechanical transduction to achieve a certain function. In this case, the term "micro" refers to particulars of the micrometer order component. Examples of MEMS devices include micro-pumps, micromotors, micro-optical mirrors, etc. A recent review of the current state of the art in MEMS is provided in "Micromachines on the March", Spectrum of IEEE, May 1994, pages 20 to 31.

Many of the MEMS devices disclosed in the literature use electrostatic transduction. Like most electromechanical transducers, electrostatic transducers can be configured as actuators or as sensors. When configured as actuators, which are of specific importance to the present application, electrostatic transducers use the pull of opposite charges to produce an attractive force. For a parallel plate configuration, this force or pressure P is easily calculated as follows: 1 1 v --- e0E2 = -e0 (-] where e0 is the air permittivity (8.85 x 10 ~ 12 F / m) and E is the electric field. In the case of parallel electrodes E = V / d, therefore, the second ratio can be used. There are numerous examples in the literature of MEMS devices that use electrostatic driving forces. See for example: from R. Zengerle et al., 1992, "A Micro Membrane Pump with Electrostatic Actuation", IEEE Microelectromechanical Systems Workshop; K.J. Gabriel et al., 1992, "Surface Normal Electrostatic / Pneumatic Actuator", IEEE Microelectromechanical System Workshop; Bobbio et al., 1993, "Integrated Forcé Arrays", Proceedings of the MEMS Workshop 1993, IEEE, pages 149 to 154; and from K. Minami et al., 1993, "Fabrication of Distributed Electrostatic Micro Actuator (DEMA)" by MEMS, Volume 2, Number 3, 1993. Some of the main reasons for electrostatic selection instead of other transduction methods are the following: (1) Energy Density: For a given voltage applied between two electrodes, the electric field increases in proportion to the decrease in the separation between the electrodes. Since the electrostatic force is proportional to the square of the electric field, a single order of separation closest in magnitude to the electrodes results in two orders of electrostatic force greater in magnitude for the same voltage. Cooperating with this, the intensity of the electric field of most gases also rapidly increases with decreasing distance (see for example: H.L. Saums, "Materials for Electrical Insulating and Dielectric Functions," Hayden Book Co., 1973). Therefore, it is evident that electrostatic forces are well graduated for use in MEMS devices. (2) Efficiency: Electrostatic devices typically have a relatively high efficiency because they do not require large current densities and associated high internal resistance losses, which are associated with magnetic alloy or shape alloy based actuators. The efficiency of an electrostatic device is especially good when the movement of the relative electrode is a considerable fraction of the inter-electrode space, as is often the case in MEMS devices. (3) Cost: Unlike most other transducers, in particular, piezoelectric and magnetostrictive transducers, electrostatic transducers require only electrodes that retain opposite electrical charges to provide mechanical force. It is typically much less expensive to deposit the electrodes only than to deposit both the electrodes and a piezoelectric material (for example) which is then excited by the electrode. Even when the electrostatic driving mechanisms have the desirable characteristics previously stated, there are certain cases where the efficiency is not so critical and where it may be more advantageous to use the magnetic drive. An advantage of the magnetic drive is the ability to achieve forces acting over a longer distance, since the force decreases only linearly with the separation of the microelectrode, the opposition to quadratically in the case of electrostatic forces for a fixed current and a potential respectively. Also, lower voltages can typically be used in magnetically driven actuators since their operation is independent of the applied voltage, and depends only on the flow of the current. Even when efficiency is not of great concern, it is necessary to pay close attention to the color dissipation produced by the resistive energy consumption of the microelectrodes carried by the drive currents. The field of MEMS seems to have been prompted by two factors: curiosity to explore the limits of the miniaturization of electromechanical devices (see, for example, R. Feynman, 1993, "Infinitesimal Machinery", J. MEMS, Volume 2, Number 1 ) and the extensive availability of the microlabor equipment used in the manufacture of integrated circuits. The techniques of microlabor to machine are now quite advanced, especially with the recent addition of techniques such as LEAGUE, silicon fusion bond, etc.; and allow the construction on a wide scale of devices. But, these microlabelling techniques are inherently costly by unit area even at large volume production scales so that it seems that they can always be limited to applications that have a very high value per unit area of microlabrated surface to machine. Another limitation of the current MEMS technology is that the means to allow relative movement between the electrodes is provided by mechanical links or the bending of highly cantilevered thin structures. For example, in the device described in the Bobbio et al. Document, referred to above, the spacing between the support points defining each "cell" in the formation must be reasonably large relative to the thickness of the cell. the polyamide / metal structure due to the relatively high elastic modulus of these materials. In addition, to make the design and construction of these devices quite complicated, these relatively thin structures are quite fragile and therefore, are not appropriate for uses where durability is a concern. These and other disadvantages of the MEMS technology of the above branch can be overcome through the use of a new type of MEMS technology called elastomeric microelectromechanical systems ("EMEMS"), as will be described below.

COMPENDIUM OF THE INVENTION An object of this invention is to provide a microelectromechanical device wherein the microelectrodes held in the elastomeric microstructure undergo considerable relative movement in response to electrostatic forces. Another object of the invention is to provide a microelectromechanical transducer that can be economically constructed using microstructured surfaces of molded elastomeric films. Another object of the invention is to employ a useful scale of inter-electrode separation between the oppositely charged microelectrodes in the MEMS; namely, less than twice the minimum Paschen distance for the gas and the gas pressure in question. Still another object of the invention is to provide a means for increasing the length of the path through the solid surfaces in mutual contact with oppositely charged microelectrodes, while simultaneously providing a means for modeling the microelectrodes and extending the region of the path of the microelectrodes. flow. Yet another additional object of the invention is to provide a means to create more complicated structures using routed microstructured surfaces. These and other objects are achieved by providing a microelectromechanical transducer wherein the microelectrodes are selectively deposited on a microstructured surface. The microelectrodes are selectively connected with a means for energizing them in such a way that the electrostatic forces can be generated between any two microelectrodes charged oppositely, or between a microelectrode and a microelectrode closely adjacent. The microstructures are preferably constructed using a low modulus elastic material having a high yield stress limit, these materials typically being referred to as elastomers. This, combined with the appropriate microstructural design and the location of the microelectrodes, allows the electrostatic forces to cause considerable relative movement between the oppositely charged microelectrodes or between a microelectrode and a closely matched macroelectrode. This EMEMS design technique can offer specific performance advantages in relation to conventional EMEMS devices, such as improved durability. But the most important advantage is expected to be the greatly reduced manufacturing cost per unit area. The manufacture of the microstructures with elastomeric materials of low modulus, high elasticity allows the microstructures to have a relatively low elongation, but which nevertheless are still highly flexible. In contrast, the high modulus silicon microstructures used in conventional EMEMS devices require a relatively high elongation in order to be considerably flexible. The use of low elongations facilitates the use of two key manufacturing techniques. First, the microstructures can be designed in the form of moldable surface structures in a film-like elastomer sheet material. Second, a mold can be microlabelled to be used to microduplicate the structural surface elastomeric films using known large-scale machine microlabelling techniques such as diamond machining. Microduplication on film surfaces to produce the microstructures dramatically reduces the cost of production compared to conventional machine microlabeling. Finally, by using appropriate structural designs and physical vapor deposition techniques, microelectrodes can be selectively deposited without resorting to costly masking procedures commonly used to make conventional MEMS devices. All of these features are combined to allow EMEMS devices to be produced economically, using known mass production techniques.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a fragmented, greatly amplified, cross-sectional perspective illustration of a preferred embodiment of the invention. Figure IB is a fragmented cross section elevation of the structure illustrated in FIG.

Figure 1A, which shows a position of the microelectrodes when they are in an excited state caused by the application of irradiated potentials. Figure 1C is a fragmented cross sectional elevation of the structure illustrated in Figure 1A showing a second position of the microelectrodes when they are in a second state of excitation caused by the application of irradiated potentials. Figure ID illustrates the structure of Figure 1A with the addition of a connecting means for making electrical contact with each individual microelectrode. Figure 1E is a top plan view of the structure shown in Figure ID. Figure 2A is a cross-sectional elevation of the structure illustrated in Figure 1A, and illustrates the manner in which microstructural design principles can be used to achieve the various objects of the invention. Figure 2B is a micrograph of a scanning electron showing a elastomeric microstructure coated with metal constructed in accordance with the invention. Figure 3 illustrates a greatly amplified pair of opposed microstructural surfaces that provide a plurality of gas reservoirs. Figure 4 is similar to Figure 3 but eliminates the superior microstructure, shows the placement of the gas deposits in the lower microstructure and a macroelectrode held elastomically above it.

Figures 5A and 5B illustrate an embodiment having a macroelectrode below the embodiment of Figure 1. Figure 6 illustrates a modality similar to that of Figures LA to ID, wherein the elastomeric microstructures carrying the microelectrode are provided in both sides of a flat substrate.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY Figure 1A provides a cross-sectional perspective view of a device constructed in accordance with the preferred embodiment of the invention. The device consists of a linear formation of (typically more than 1000) equally spaced microelectrodes 6 individually held on top of the microstructured elastomeric flanges. The microstructured elastomeric beads 5 are formed as surface features of a film or sheet 4 of elastomeric substrate. The ridges 5 of the microstructure can be economically produced using high volume molding microduplication techniques as is known in the art to produce microstructured surface products such as microprismatic optical films. The microelectrodes 6 can be formed using any of a number of good electrically conductive materials such as pure metals (e.g., Al, Cu, Au) metal alloys, metal oxides (e.g., indium-tin oxide) ), superconductors, conductive polymers, shape memory alloys or conductive elastomers. In cases where the required effort of the conductive material is relatively high, it may be desirable to use a conductive elastomeric material for the microelectrode in order to reduce the risk of failure by mechanical fatigue could result in interruptions in the conductivity of the microelectrodes. A preferred technique for deposition of the microelectrodes 6 in the upper part of the flanges 5 will be described in more detail below. An important object of the device of Figure 1A is to achieve the harmonic movement of the microelectrodes 6 at a given frequency f and as a function of time t, in a direction essentially parallel to the plane of the microstructured sheet 4. This movement could be useful for a number of dynamic fluid applications such as boundary layer control, where it is desirable to control the microscale aspects of the surface interaction of the fluid to effect the macroscale flow in a considerable manner. For example, this effect could be used to increase the level of fluid mixing in a boundary layer and thus increase its momentum exchange. Under certain electrical driving conditions, the effect could also be employed with utility to reduce the level of turbulent mixing and thus reduce the resistance to surface advancement in an aerodynamic body such as an airplane. The use of micromechanical devices for interaction with fluid flows is discussed in more detail in references such as Ho, Chih-Ming, "Interaction Between Fluid Dynamics and New Technology", First International Conference on Flow Interaction, Keynote Talk , September 5-9, 1994. The means by which the desired harmonic movement of the microelectrodes 6 is achieved will now be described with reference to Figures IB and 1C. One of four singular potential electric driving functions a, b, c or d, is applied to each microelectrode 6, where: a = + V b = + V sin (2pft) c = -V d = -V sin (2pft) These functions are applied in turn to the adjacent microelectrodes in a repetitive manner as shown in Figure IB. The electrostatic forces generated by this sequence of driving potentials cause the movement of the microelectrodes 6 through the deformation of their support microstructured elastomeric flanges 5 in the following manner. During the time t = 0, the microelectrodes 6 are in the non-deformed state shown in Figure 1A. At t = l / (4f), the microelectrodes 6 are in a state of maximum deformation as shown in Figure IB. At t = l / (2f), the microelectrodes 6 will pass through the non-deformed state shown in Figure 1A. Finally at t = 3 (4f), the microelectrodes 6 will be in the opposite state of maximum deformation shown in Figure 1C. This movement pattern is reed at the frequency f and thus achieves the desired operation. Therefore, it will be understood that the applied electrical potential alternately induces the attractive forces between the adjacent pairs of microelectrode 6, causing the displacement that varies in controlled time of the microelectrodes. Preferably, each of the microelectrodes 6 has an individual cross-sectional area smaller than 0.01 square millimeter; and the displacement exceeds 1 percent of the square root of this area in cross section. A shore connection strip 10 can be used to electrically connect the microelectrodes 6 with an appropriate power supply 11 as shown in Figures ID and 1E. The connecting strip 10 consists of a number of protruding microstructured edges 8 which separate and support the electrical contacts 9 in the form of an inverted "U". The ridges are geometrically configured for simultaneous insertion between the microstructured elastomeric flanges 5. The geometry is made in such a way that the clearance between the interlaced rows of flanges 5, 8 is sufficient to allow a relatively easy insertion, but nevertheless, they provide good electrical contact between the contacts 9 and the adjacent surfaces of the respective microelectrodes 6. . Each of the inverted "U" shaped electrical contacts 9 forms part of an electrically conductive path that carries the appropriate driving signal (i.e., a, b, c, od) from the power supply 11, this can be achieved easily applying a micromodelated wiring project to the connection strip 10, using known integrated circuit manufacturing technology, such as photolithography. Since the microelectrodes 6 and the contacts 9 are in intimate contact, a good electrical connection can be achieved possibly with the aid of a conductive viscous material such as a gel which is applied to one of the surfaces before interlacing them as mentioned previously. An appropriately high electric field resistance dielectric material, such as polyamide, is used to form the volume of each flange 8 and to electrically isolate the adjacent conduction paths. The maximum electrostatic force that can be generated between the microelectrodes 6 is limited by the electrical disintegration between the adjacent electrodes. Even though the inventors do not wish to be bound by any specific theory, it seems possible that there are generally three primary modes of electrical disintegration in a MEMS device such as that described above. The first primary mode of electrical disintegration is the surface discharge through the elastomeric surface between the microelectrodes 6 and / or the flat electrode. A number of mechanisms such as carbonization can cause surface discharge through otherwise non-conductive surfaces. In most cases, the probability of surface discharge increases with the voltage increased by length - l of unitary trajectory. It is therefore desirable to make the length of the path as long as possible. This is achieved in the structure of the preferred embodiment due to the long path length "S" (Figure 2A) which is required to traverse the recesses between the microelectrodes 6 on the top of the elastomeric flanges 5 (see Figure 2A) . The second primary mode of electrical disintegration is the avalanche disintegration of a gas within the interelectrode spaces. The avalanche disintegration of the gas occurs when the voltage exceeds that of the Paschen curve values for the gas determined in question. Paschen curves can be determined by reference to works such as E. Kuffel et al., "The Sparking Voltage - Paschen's Law", pages 354 to 361 in High Voltage Engineering Fundamentals, Pergamon Press, Oxford, 1984. Paschen's law manifests that the maximum voltage V capable of being achieved without avalanche disintegration is a function only of the product of the gas pressure p and the separation of the space d; namely V = f (pd). In this way it is desirable to make the inter-electrode space 3 (Figure 1A) as small as possible to prevent gas decay. However, this must be balanced against the fact that a reduction in the interelectrode space 3 also reduces the maximum displacement of the microelectrodes 6, which may limit the utility of the device. Certain types of gases, in particular, the electronegative gases such as sulfur hexafluoride, exhibit a considerably high resistance to avalanche disintegration with air and can provide a useful means to increase dielectric strength. The third primary mode of electrical disintegration is field emission. Field emission is the formation of an electron tunnel through the potential barrier on a surface that in turn leads to a number of disintegration mechanisms. In theory, the potential barrier is too large to allow considerable tunnel formation until fields within the range of 3000 MV / m are reached. However, in practice, considerable field emission may begin to occur in nominal electric fields up to two orders of magnitude smaller than this (ie, 30 MV / m). It seems that the weakening is due to the large number of microprotrusions that are inherent in the surface asperza of surfaces still highly polished. These microprotrusions can increase the local electric field by two orders of magnitude and therefore lead to a field emission disintegration. Therefore, in order to go field emission, a means must be used to minimize surface roughness. There is also evidence to suggest that the separation of inter-electrodes (which affects the total voltage applied through space) may also play a role, in addition to the magnitude of the electric field (see for example of A. Kojima et al., "Effect of Gap Length on Effective Field Strenth ", Proc. 3rd Intl. Conf. omn Properties aApplications of Dielectric Materials, July 8-12, 1991, Tokyo, Japan This also suggests that the inter-electrode space should be made as small as possible. In practice, the disintegration mechanism that is the weak link will depend on a number of factors such as the length of the surface path, the inter-electrode space, the type of dielectric gas, the electrode surface, etc. For example, if the above-described device were to be made functional in a high vacuum environment, the mechanism of gaseous disintegration would essentially be eliminated and only the waste would have to be dealt with. surface rga and field emission. As a general rule, it is desirable to make the separation of inter-electrodes less than twice the minimum Paschen distance for the gas and the gas pressure in question. This will generally ensure that a considerable electrostatic force without gaseous disintegration or the need for excessively high operating voltages is able to be obtained. The method by which the microelectrodes 6 are selectively deposited above the flanges 5 will now be described. As described above, it is desirable to selectively deposit the microelectrodes 6 only on certain portions of the flanges 5, so that the large production scale is economical. One of these methods is the use of the directional nature of the atoms deposited by physical vapor in combination with the microstructure of the elastomer to produce a microshading effect. The microso breado techniques have been used elsewhere in the field, for example, in the devices described by Bobbio and others in "Integrated Forcé Arrays", Proc. 1993, IEEE MEMS orkshop, page 150. Referring to Figure 2A, the shading can be achieved by projecting metal atoms in a direction perpendicular to the ridges 5 at an angle a which is sufficient to cause the desired degree of shading. In Figure 2A, a projection angle of 45 ° has been shown. This provides a relatively long surface disintegration path length while producing a uniform transition to the electric field near the tip of the flange 5. The smaller angles would limit the metal to a smaller region at the top of the flanges 5, but the edges of these smaller regions could produce very high electric fields that could be a source of electrical disintegration. Figure 2B is a scanning electron micrograph taken at an oblique angle with respect to the microstructured surface of a device constructed in accordance with the preferred embodiment described above. In this micrograph, the shaded regions 32 of light represent the tantalum metal coating and the dark regions represent the silicone elastomer. In some cases it may be desirable to use two microstructured surfaces that are oriented towards each other and are in mutual contact. A small exemplary portion of this embodiment is shown in Figure 3. The lower portion of Figure 3 illustrates an elastomeric microstructured substrate 4 carrying a first plurality of elastomeric beads 5, each of which is capped by a first microelectrode 6, as described above with reference to Figure 1A. The upper part of Figure 3 illustrates a second elastomeric microstructured substrate 12 to which a second plurality of microelectrodes 14 are fixed in such a way that each microelectrode 14 is oriented towards a corresponding plurality of microelectrodes 6. The scale of Figure 3 is distorted; in practice, the depth of the upper elastomeric microstructured substrate 12 is much larger than the depth of the lower elastomeric microstructured substrate 4. A series of elastomeric flanges 16 protrudes downwardly from the upper microstructured substrate 12 to contact the lower microstructured substrate 4 at regular intervals, thereby defining a spacing 18 of the inter-electrode space between the microelectrodes 6, 14. A Gas, such as air, fills the space 20 enclosed by two microstructured substrates. An adhesive bond is preferably applied at each contact point 22 between the two microstructures. The microelectrodes 14 are connected to a terminal and a voltage source, and the microelectrodes 6 are connected to the other terminal. The upper microstructured substrate 12 is recessed at regular intervals to provide a plurality of gas tanks 24 for the purpose to be explained below. The operation of the embodiment of Figure 3 is as follows: a potential difference is applied between the two sets of microelectrodes 6, 14 generating an electrostatic attraction force between them. This electrostatic attraction force deforms the elastomeric flanges 16 allowing the two sets of microelectrodes to move relative to each other. As the microelectrodes move, the limited gas within the space 20 is compressed between the upper and lower microstructures. The compression of the gas is greater between the microelectrodes 6, 14 than inside the tanks 24 so that the gas tends to be forced in and out of the tanks 24. Therefore, the total gas compression is less than which would be if the tanks 24 were not provided. The reservoirs 24 therefore reduce the undesirable impedance to the relative movement of the two microstructures due to the compressive stiffness of the gas within the space 20; and they avoid the need to build the lower microstructure with a high elongation, which is difficult to do. The flow of gas in and out of the reservoirs 24 introduces viscous moisture which is undesirable in many circumstances. To minimize the viscous moisture, the flow velocity of the fluid moving in and out of the tanks 24 should be minimized. This can be achieved, for example, by separating the reservoirs 24 more closely so that less volume of fluid needs to be moved; or by increasing the cross-sectional area to reduce the average fluid flow velocity. Referring again to Figure 2A, the added cross-sectional area associated with the recessed "r" region is useful to allow this second approach, in addition to its use for other previously mentioned functions of increasing the length of the surface disintegration path. and allowing micro-shading of the microelectrodes 6. Figure 4 illustrates an alternative to the device of Figure 3 which eliminates the need for the superior microstructure. As seen in Figure 4, one or more macroelectrodes 32 (being planar structures having dimensions within the order of millimeters) are held above the microelectrodes 6 in the elastomeric ridges 16 projecting upwardly from the substrate 4. The deposits 24 of gas are created by removing selected portions of the substrate 4 and the elastomeric flanges 5. During operation, a potential difference between the microelectrodes 6 and the macroelectrode (s) 32 is applied, generating an electrostatic attraction force between them. This electrostatic attraction force deforms the elastomeric flanges 16 allowing the microelectrodes and the macroelectrode (s) to move relative to each other. During this movement, the limited gas within the space 20 is compressed between the macroelectrode (s) and the substrate 4. Figures 5A and 5B illustrate a further alternative embodiment wherein one or more of the macro electrodes 30 are applied to the substrate base 4. During operation, a potential difference is applied between the microelectrodes 6 and the macroelectrode (s) 30 generating an electrostatic attraction force between them. This electrostatic attraction force deforms the elastomeric flanges 5 allowing the microelectrodes 6 to move relative to the macroelectrode (s) 30, as seen in Figure 5B. Figure 6 illustrates a still further alternative embodiment wherein microelectrodes 6, 6 'are applied to both sides of substrate 4. It will be noted that this provides superior and inferior structures (symmetrical about the plane of the substrate 4) each of which functions in the manner described above with respect to Figures 1A to ID. This double-sided structure could be useful, for example, to improve conventional heat transmission through a membrane. As will be apparent to those skilled in the art due to the aforementioned disclosure, many alterations and modifications to the practice of this invention are possible without deviating from the spirit or scope thereof. Accordingly, the scope of the invention should be interpreted in accordance with the substance defined by the following claims.

Claims (17)

R E I V I N D I C A C I O N E S:

1. An electromechanical transducer characterized by: (a) a first substrate (4) carrying a first plurality of elastomeric microstructures (5) on one side of the substrate; (b) a first microelectrode (6) in each of the first plurality of microstructures; and (c) an energy supply means (11) electrically connected to the microelectrodes for controlled application of an electrical power to the microelectrodes.

2. An electromechanical transducer according to claim 1, wherein the electric potential induces alternately attractive forces between the adjacent pairs of the microelectrodes, causing displacement that varies in controlled time of the microelectrodes.

3. An electromechanical transducer according to claim 1, further comprising one or more macro electrodes (32) on an opposite side of the substrate, wherein: (a) the power supply means is further electrically connected to one or more of the macroelectrodes; and (b) that electrical potential induces alternately attractive forces between the microelectrodes and one or more macroelectrodes, causing the displacement that varies in controlled time of the microelectrodes relative to one or more macroelectrodes.

An electromechanical transducer according to claim 1, further comprising one or more macroelectrodes elastomerically held above the microelectrodes, wherein: (a) the power supply means is further electrically connected to one or more of the macroelectrodes; and (b) the electric potential alternately induces attractive forces between the microelectrodes and one or more of the macroelectrodes, causing displacement that varies in controlled time of the microelectrodes relative to one or more of the macroelectrodes.

5. An electromechanical transducer according to claim 1, wherein the first plurality exceeds 1000.

6. An electromechanical transducer according to claim 1, wherein: (a) the first substrate is an elastomeric sheet material; and (b) the microstructures are formed as integral surface features of the sheet material.

An electromechanical transducer according to claim 1, further comprising: (a) a second substrate (12) carrying a second plurality of elastomeric microstructures (16), the second substrate adjacent to and facing the first substrate with the second plurality of elastomeric microstructures contacting the first substrate; and (b) a second plurality of microelectrodes (14) in the second substrate; wherein the power supply means is further electrically connected to the second microelectrodes for controlled application of the electric potential to the second microelectrodes in order to alternately induce attractive forces between the first and second plurality of microelectrodes, causing displacement that varies in time controlled of the first and second pluralities of microelectrodes.

8. An electromechanical transducer according to claim 1, further comprising: (a) a second substrate (12) carrying a second plurality of elastomeric microstructures (16) the second substrate being adjacent and facing the first substrate, with the second plurality of elastomeric microstructures contacting the first substrate; and (b) one or more macroelectrodes (32) supported above the microelectrodes by the second plurality of elastomeric microstructures; wherein the power supply means is further electrically connected to one or more macroelectrodes for controlled application of the electrical potential to one or more of the macroelectrodes to alternately induce the attraction forces between the microelectrodes and one or more of the macroelectrodes, causing the displacement that varies in controlled time of the microelectrodes in relation to one or more macroelectrodes.

An electromechanical transducer according to claim 1, wherein: (a) the adjacent pairs of the first microelectrodes are separated by a space filled with gas (3), the gas is characterized by a minimum distance Paschen "d" of a specific gas pressure; and (b) the width of the space is less than twice the minimum distance "d" Paschen.

10. An electromechanical transducer according to claim 1, wherein the first microelectrodes comprise an electrically conductive elastomer.

An electromechanical transducer according to claim 1, wherein the microstructures are geometrically configured for directional deposition of an electrically conductive material on the microstructures to form the microelectrodes as a predetermined micropattern of surface deposits on the microstructures.

12. An electromechanical transducer according to claim 1, further comprising a recess between each adjacent pair of the first plurality of microstructures, each of the recesses defining a surface path length between the first microelectrodes in the adjacent microstructures, the length of the surface path considerably exceeds any direct path distance between the first microelectrodes in the adjacent microstructures.

An electromechanical transducer according to claim 7, further comprising a plurality of gas flow reservoirs (24) in the second substrate for gas flow from between the microelectrodes inside and outside the reservoirs, during the displacement of the microelectrodes

14. An electromechanical transducer according to claim 4 further comprising a plurality of gas flow reservoirs (24) in the first substrate for the flow of gas from between the microelectrodes inside and outside the reservoirs during the displacement of the microelectrodes .

15. An electromechanical transducer according to claim 1, wherein the microelectrodes have an individual cross-sectional area smaller than 0.01 square millimeter.

16. An electromechanical transducer according to claim 2, wherein the microelectrodes have an individual cross-sectional area of less than 0.01 square millimeter and the displacement exceeds 1 percent of the square root of the cross-sectional area.

17. An electromechanical transducer according to claim 1, further comprising: (a) a second plurality of elastomeric microstructures (5 ') on the opposite side of the substrate; and (b) a second microelectrode (6 ') in each of the second plurality of microstructures; wherein the power supply means is further electrically connected to the second microelectrodes for controlled application of an electrical potential to the second of the microelectrodes.