Abstract:
The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   The United States Government has certain rights in this invention pursuant to Department of Energy Contract No. DE-AC04-94AL85000 with Sandia Corporation. 

   FIELD OF THE INVENTION 
   The present invention generally relates to Microelectromechanical (MEMS) fluidic actuators, and surfaces that can be reconfigured through the action of a system of MEMS fluidic actuators. 
   BACKGROUND OF THE INVENTION 
   In aerial vehicles, fixed profile airfoils are typically employed having a design that is optimized for performance within a primary flight condition. These fixed profile airfoils are then sub-optimal in many other operating conditions that may include take-off, landing, maneuvering and dual-mode cruising velocities. Modern aircraft are required to maneuver efficiently over super-sonic and sub-sonic flight conditions. What is needed is a means for replacing or modifying the conventional fixed profile control surfaces of an aircraft with controlled reconfigurable surfaces, for which the profile of an airfoil can be adjusted on demand, to maintain optimal performance of a vehicle as flight conditions change. The present invention presents a solution to this problem by providing a novel, lightweight, massively parallel device comprising microfluidic actuators, to sense, control and reconfigure the profile of a surface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings provided herein are not drawn to scale. 
       FIG. 1A  is a schematic illustration of an embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 1B  is a schematic illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 1C  is a schematic illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 2  is a schematic illustration of an embodiment of a system of MEMS fluidic actuators according to the present invention. 
       FIG. 3  is a schematic illustration of another embodiment of a system of MEMS fluidic actuators according to the present invention. 
       FIG. 4  is a schematic illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 5  is a schematic cross-section illustration, along section line A—A, of an embodiment of a MEMS fluidic actuator, as shown in  FIG. 4 . 
       FIG. 6  is a schematic plan view of the internal components of an embodiment of a MEMS fluidic actuator as shown in  FIG. 4 . 
       FIG. 7  is a schematic illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 8  is a schematic cross-section illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
       FIG. 9  is an enlarged schematic cross-section illustration of a MEMS fluidic actuator as shown in  FIG. 8 . 
       FIG. 10  is a schematic cross-section illustration of another embodiment of a system of MEMS fluidic actuators according to the present invention. 
       FIG. 11  is a schematic cross-section illustration of another embodiment of a MEMS fluidic actuator according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1A  is a schematic illustration of an embodiment of a MEMS fluidic actuator  100  according to the present invention. MEMS fluidic actuator  100  includes a bladder  102  comprising an elastic membrane  104 . Disposed within the bladder  102  are MEMS valve  106  and MEMS sensor  108 . Membrane  104  can completely enclose MEMS valve  106  and sensor  108 . MEMS sensor  108  can be configured to monitor the pressure of a fluid within the bladder  102 , the temperature, velocity and/or flow rate of fluid into and out of the bladder  102 , or other desired property of the fluid within the bladder. Additionally one or more MEMS sensors can be configured to measure any combination of properties (temperature, pressure, velocity, flow rate etc.) of a fluid within, or flowing into or out of bladder  102 . MEMS valve  106  can be configured to control the flow of fluid into, and out of, the bladder  102 . MEMS valve  106  may be a two-way valve. Alternatively, MEMS valve  106  may be a one-way valve. Alternatively, actuator  100  may comprise a pair (not shown) of one-way valves disposed inside of bladder  102 , for independently controlling the flow of fluid in and out of bladder  102 . Electrical power and control signals  110  for the operation of the MEMS valve  106  and the MEMS sensor  108  can be connected to a controller (not shown) via feedthroughs (not shown) in the wall of the bladder that can be made by conventional means. Fluid is supplied to bladder  102  from a source of fluid (not shown), by way of the MEMS valve  106  and plumbing means  114  that can include piping, tubing and/or fluidic channels. Penetration of plumbing means  114  through the bladder  102 , and sealing of plumbing means  114  to the bladder can be made by conventional methods. Bladder  102  can comprise an elastic material. Admitting fluid into bladder  102  causes the MEMS fluidic actuator  100  to expand. In a similar fashion, withdrawing fluid from bladder  102  causes the MEMS fluidic actuator  100  to contract. 
     FIG. 1B  is a schematic illustration of another embodiment of a MEMS fluidic actuator  100 ′ according to the present invention. MEMS fluidic actuator  100 ′ includes a bladder  102 ′ comprising an elastic membrane  104 ′. Disposed within the bladder  102 ′ is a MEMS valve  106 ′. A MEMS sensor  108 ′ can be disposed exteriorly of, and fluidically connected to, the bladder  102 ′. MEMS sensor  108 ′ can be configured to monitor the pressure of a fluid within the bladder  102 ′, the temperature, velocity and/or flow rate of fluid into and out of the bladder  102 ′, or other desired property of the fluid within the bladder. MEMS valve  106 ′ can be configured to control the flow of fluid into, and out of, the bladder  102 ′. MEMS valve  106 ′ may be a two-way valve. Alternatively, MEMS valve  106 ′ may be a one-way valve. Alternatively, actuator  100 ′ may comprise a pair (not shown) of one-way valves disposed inside of bladder  102 ′, for independently controlling the flow of fluid in and out of bladder  102 ′. Electrical power and control signals  110 ′ for the operation of the MEMS valve  106 ′ and the MEMS sensor  108 ′ can be connected to a controller (not shown) using where needed, feedthroughs (not shown) in the wall of the bladder that can be made by conventional means. Fluid is supplied to bladder  102 ′ from a source of fluid (not shown), by way of the MEMS valve  106 ′ and plumbing means  114 ′ that can include piping, tubing or fluidic channels. Penetration of plumbing means  114 ′ through the bladder  102 ′, and sealing of plumbing means  114 ′ to the bladder can be made by conventional methods. 
     FIG. 1C  is a schematic illustration of another embodiment of a MEMS fluidic actuator  100 ″ according to the present invention. MEMS fluidic actuator  100 ″ includes a bladder  102 ″ comprising an elastic membrane  104 ″. Disposed within the bladder  102 ″ is a MEMS sensor  108 ″ that can be configured to monitor the pressure of a fluid within the bladder  102 ″, the temperature, velocity and/or flow rate of fluid into and out of the bladder  102 ″, or other desired property of the fluid within the bladder. MEMS valve  106 ″ can be mounted exteriorly of the bladder  102 ″ and can be configured to control the flow of fluid into, and out of, the bladder  102 ″. MEMS valve  106 ″ may be a two-way valve. Alternatively, MEMS valve  106 ″ may be a one-way valve. Alternatively, actuator  100 ″ may comprise a pair (not shown) of one-way valves, for independently controlling the flow of fluid in and out of bladder  102 ″. Electrical power and control signals  110 ″ for the operation of the MEMS valve  106 ″ and the MEMS sensor  108 ″ can be connected to a controller (not shown) using where needed, feedthroughs (not shown) in the wall of the bladder that can be made by conventional means. Fluid is supplied to bladder  102 ″ from a source of fluid (not shown), by way of the MEMS valve  106 ″ and plumbing means  114 ″ that can include piping, tubing or fluidic channels. Penetration of plumbing means  114 ″ through the bladder  102 ″, and sealing of plumbing means  114 ″ to the bladder can be made by conventional methods. 
     FIG. 2  is a schematic illustration of an embodiment of a system of MEMS actuators  200 , according to the present invention. System  200  comprises a plurality of adjacently spaced MEMS fluidic actuators  202 , mounted to the surface of a substrate  204 . Each MEMS fluidic actuator  202  comprises an expandable bladder  205  that can be independently extended or contracted in a direction along an axis  208 , substantially perpendicular to the surface of substrate  204 . A compliant cover  206 , can be joined to substrate  204 , extending over and being displaceable by, a plurality of MEMS fluidic actuators  202 . Extension of each MEMS fluidic actuator  202 , can be independently controlled by regulating the pressure and/or volume of a fluid (e.g. a liquid or a gas) entering and exiting each bladder  205 . The bladder  205  can comprises an elastic material that provides a restoring force for contracting the bladder. 
   Admitting fluid into a bladder  205  causes the MEMS fluidic actuator  202  to extend, substantially along axis  208 , urging compliant cover  206  to be displaced away from substrate  204 . In a similar fashion, withdrawing fluid from bladder  205  causes the MEMS fluidic actuator  202  to retract along axis  208 , allowing compliant cover  206  to be displaced towards substrate  204 . By independently controlling the flow of fluid into and out of a plurality of bladders  205 , each actuator  202  can be extended and contracted controlled distances, correspondingly displacing compliant cover  206  a controlled amount, creating virtually any surface profile in the compliant cover  206 . 
   Compliant cover  206  can comprise an elastomeric polymer, rubber, fabric, silk, polymer composite, thin metal or dielectric material that is deformable by the forces generated through the action of the microfluidic actuators  202 . Substrate  204  can comprise an airfoil of an aircraft, airfoil of a windmill, propeller or helicopter rotor, or may alternatively comprise an external surface of an aircraft, land, sea or underwater vehicle. The individual microfluidic actuators  202  can be spaced on the surface of substrate  204 , so as to allow adjacent bladders  205  to touch along a portion of their sidewalls as illustrated in  FIG. 1 . 
     FIG. 3  is a schematic illustration of another embodiment of a system of MEMS fluidic actuators  300  according to the present invention, wherein a plurality of microfluidic actuators  302  are spaced so as to maintain a separation, “d”, between the sidewalls of neighboring bladders  305 . The spacing between actuators can be adjusted to accommodate the needs of a particular application of interest. It has been found in certain embodiments of the invention that spacing the individual actuators  302  so that the sidewalls of adjacent bladders  305  are touching, as shown in  FIG. 1 , enhances the resolution of the profile created in the compliant cover  306 , can reduce “ballooning” of the individual bladders  305 , and may enhance the displacement produced by an actuator  302 , along axis  308  and substantially perpendicular to the surface of substrate  304 . 
     FIG. 4  is a schematic perspective illustration of another embodiment of a MEMS fluidic actuator  400 , according to the present invention. The MEMS fluidic actuator  400  comprises a base  412  providing support for a bladder  405  that comprises an elastic membrane  404 . Base  412  can be a printed wiring board, and may contain fluidic channels as described in U.S. Pat. No. 6,443,179 to Benavides et al, herein incorporated by reference. Base  412  can have internal fluidic channels  414 , for distribution of fluids comprising gases or liquids, between an external reservoir and bladder  405 . Base  412  may additionally include electrically conductive traces  416 , for communication of electrical power and control signals between MEMS valves and MEMS sensors, and a controller. Base  412  can comprise a ceramic, a silicon substrate, a polymer, a plastic, a glass, a glass-ceramic composite, a glass-polymer composite, a resin material, a fiber reinforced composite, a glass-coated metal, a printed wiring board composition, FR-4, epoxy-glass composite, epoxy-kevlar composite, polyamide, or a fluoropolymer. The elastic membrane  404  can comprise any substantially leak tight, polymeric elastomer (for example: a silicone rubber, natural rubber, latex, neoprene, poly dimethylsiloxane (PDMS) or polyurethane compound) cast or otherwise formed into a relatively thin sheet (for example providing a bladder wall thickness on the order of 10 microns to several millimeters in thickness) and may be formed into a shape as may be desired for bladder  405 . As shown in  FIG. 4 , bladder  405  can have a generally rectangular shape, but other shapes may be utilized in practicing the invention including round, hemispherical, and “blister” or dome shaped cross sections. 
     FIG. 5  is a schematic cross-section view along section line A—A of the embodiment of a fluidic MEMS actuator  500  as illustrated in  FIG. 4 , including for reference, portions of a substrate  502  and a compliant cover  506 . Fluidic MEMS actuator  500  can be attached to substrate  502  by a joining layer  538 , that can comprise an adhesive layer. Compliant cover  506  is in physical contact with the MEMS fluidic actuator  500  along at least a portion of the bladder  505 , and can be bonded, for example, by adhesive means (not shown) to bladder  505 . 
   The bladder  505  comprises an elastic membrane  504  having an interior surface  504   a  and an opposed exterior surface  504   b . The perimeter edges  517  of the bladder  505  are attached to the surface of the base  512  thereby enclosing a sealed internal volume  522  between the elastic membrane  504  and the base  512 . A MEMS fluidic device  524  is located within the internal volume  522  and can be joined to base  512  by means of an adhesive layer  526 . MEMS fluidic device  524  is typically a silicon die and can contain fluidic channels, valves, pumps, pressure sensors, etc. See for example, U.S. Pat. No. 6,537,437 to Galambos et. al, herein incorporated by reference. Microfluidic devices typically have very small fluidic channels, on the order of 1 to 10 μm and have a small overall footprint, on the order of 3 mm×6 mm. Exchange of fluids between the internal volume  522  and a fluidic channel  514  within the base  512  is controlled by a MEMS valve  528  operating to regulate the flow of fluid through a channel  530  within MEMS fluidic device  524 , which is fluidically connected to channel  514  by means of a through hole  532 , within an adhesive layer  526 . A MEMS pressure sensor  534  is located within the internal volume  522  for the purpose of monitoring the pressure of the fluid within the volume  522 . In this embodiment, the MEMS pressure sensor  534 , and the MEMS valve  528  are incorporated into a singular MEMS device  524 . 
   Configurations of the MEMS valve  528  can include one-way and two-way acting valves constructed in fluidic MEMS device  524  of layers comprising silicon, polysilicon, silicon nitride, silicon oxides, metallic layers, dielectric layers, or polymeric layers. Types of MEMS valves that can be produced include flap valves, disk-in-cage valves, and gate valves and can be mechanically actuated by thermal, piezoelectric or electrostatic means. Such valves can be on the order of 10&#39;s of microns in diameter and operate to control the flow of fluids in channels on the order of 1 μm to 10 μm in cross-sectional dimension. Flow rates of a fluid through such valves can be on the order of about 10 cc/s. The MEMS pressure sensor  534  can similarly be constructed in fluidic MEMS device  524  of layers comprising silicon, polysilicon, silicon nitride, silicon oxides, metallic layers, dielectric layers, or polymeric layers. MEMS pressure sensor  534  can be of the deflecting diaphragm type and can include piezo-resistive or capacitive sensing elements. In this embodiment, MEMS device  524  includes a MEMS pressure sensor  534 , but it is anticipated other sensing elements may be included within the sealed volume  522  as well. Other sensing elements that can be anticipated are flow sensors, temperature sensors, force transducers, distance measuring devices, etc., as may be constructed from MEMS structures to produce optical, electrical, mechanical and/or magnetic sensors. 
   Electrical interconnections to the MEMS device  524  to provide power, and communicate control signals for opening and closing MEMS valve  528 , and obtaining pressure measurements from sensor  534 , can include wirebonds  536  between device  524  and electrical conductors  516 . Electrical conductors  516  can be interconnected to a controller (not shown) to provide for independently monitoring and controlling the pressure of fluid within an individual bladder  505 , as may be arranged in a plurality. Therefore the extension and contraction of an individual actuator  500 , can be controlled by independently adjusting fluid flow entering and exiting a bladder  505 , through controlled opening and closing of valve  528 . The controller, for example, can comprise a computer, PC, programmable logic device (PLD), CPU or similar instrument for receiving pressure signals from the pressure sensor  534  and providing a control signal to valve  528  in response thereto. 
   In the operation of a fluidic MEMS actuator  500 , where the pressure indicated by the measured output of sensor  534  within the internal volume  522 , is less than the pressure of the fluid within channel  514 , a control signal can be supplied to valve  528  causing the valve  528  to open, thereby allowing fluid to flow from channel  514 , through channel  530 , and into the internal volume  522 . The accumulation of fluid and therefore the build-up of pressure within the internal volume  522  will cause the bladder  505  to expand and deflect in the general direction  508  as illustrated. The displacement of the bladder  505 , driven by the pressure within the internal volume  522 , allows for the extraction of useful work from the actuator  500 , by causing a displacement of the compliant cover  506 , away from substrate  502 , in a direction substantially along axis  508 . In a like manner, should the pressure within the internal volume  522  be greater than the pressure of fluid within channel  514 , a control signal can be supplied to valve  528  causing the valve to open, thereby allowing fluid to flow from the sealed volume  522 , through channel  530  and into channel  514 . The withdrawal of fluid from the sealed volume  522  will cause the bladder to contract, causing the compliant cover  506  to be displaced towards substrate  502  in a direction generally opposite that indicated by  508 . In this embodiment of the invention, microfluidic valve  528  can act as a two-way valve. 
   The edges  517  of bladder  505  can be attached to base  512  by an adhesive bond, mechanical clamping of the membrane  504  to the base  512 , casting the membrane onto the surface of the base, thermal or mechanical fusing a portion of membrane  504  to base  512 , or by other common bonding and/or sealing means. Base  512  can be attached to substrate  502  by means of a joining layer  538 , that can comprise a liquid adhesive, sheet adhesive, or a double sided adhesive, comprising materials such as a; thermoplastic polymer, thermoset polymer, transfer tape, epoxy, cyanate ester, cyanoacrylates, polyester, polyamide, polyimide, etc. Joining layer  538  can alternatively comprise materials used in soldering, brazing and fusible glass bonding. In other embodiments of the invention, joining layer  538  can be eliminated in part or completely, and replaced with conventional mechanical fastening means including threaded fasteners, clamps or rivets. 
   Where  FIG. 5  is a schematic illustration of an individual fluidic MEMS actuator  500 , a system can include a plurality of actuators adjacently disposed on the surface of a substrate as shown in  FIGS. 2 and 3 . To facilitate the fluidic coupling and transport of fluid to and from an actuator  500  within a system, fluidic channels  562  may be incorporated in the substrate  502 . 
   In  FIG. 5 , MEMS device  524  is illustrated as being electrically interconnected to electrical conductors  516  on base  512  by wirebonds  536 , but other means such as direct chip attach, flip chip, solder bumps or electrically conductive adhesives could be employed as well. Adhesive layer  526  between base  512  and device  524  can comprise a liquid adhesive, sheet adhesive, or a double sided adhesive, comprising materials such as a; thermoplastic polymer, thermoset polymer, transfer tape, epoxy, cyanate ester, cyanoacrylates, polyester, polyamide, polyimide, etc. Alternatively, adhesive layer  526  can comprise materials used in soldering, brazing and fusible glass bonding. 
     FIG. 6  is a schematic plan view of the internal components of the embodiment of a MEMS fluidic actuator  600 , as illustrated in  FIG. 5  (the bladder has been removed in this view). The lateral dimensions of the MEMS fluidic device  624  are exaggerated with respect to the base the base  612 , to facilitate illustration of the internal workings. The microfluidic device  624  is positioned on base  612  to provide alignment and fluidic coupling of device  624  with a fluidic channel  614  (indicated by dashed lines) within the base  612 . MEMS valve  628  regulates the exchange of fluids between the fluidic channel  614  and the internal volume  622  within the actuator  600 . A MEMS pressure sensor  634  can be incorporated into device  624  for the purpose of monitoring the pressure of the fluid within the internal volume  622 . In this exemplary embodiment, the pressure sensor  634  can comprise a diaphragm sensor having piezo-resistive sense elements arranged in a Wheatstone bridge configuration. And as shown, MEMS valve  628  can comprise a two-way acting flap valve. 
   Communication of electrical power and control signals to MEMS device  624  can be accomplished through wirebonds  636 , between device  624  and electrical conductors  616  on the base  612 . A substantially annular seal  618 , generally made at the perimeter edge of a bladder, comprises an inner boundary  618   a  and an outer boundary  618   b , for sealing the bladder (not shown) to base  612  and can extend over electrical conductors  616 . The low profile of circuit traces utilized as conductors  616  (for example; copper traces on a printed wiring board, screen printed metallization on a ceramic substrate, or deposited metal on a silicon substrate) allows for easily maintaining a seal where a conductor traverses the seal area  618 . Electrical conductors  616  are illustrated as being disposed on the surface of base  612 , but they could alternatively be located within the body of base  612 , as for example, where base  612  comprises a laminated structure (e.g. a low temperature co-fired ceramic, a high temperature co-fired ceramic, a laminate printed wiring board, etc.). 
     FIG. 7  is a schematic perspective view of another embodiment of a MEMS fluidic actuator  700  according to the present invention. The MEMS fluidic actuator  700  comprises a base  712  providing support for a bladder  705  that comprises an elastic membrane  704  having stiffening elements  742 . The stiffening elements  742  can comprise regions of increased wall thickness, ribs or folds in the elastic membrane  704 , and serve to reduce lateral movement, i.e. “ballooning” of the bladder  705  when the bladder  705  is pressurized (for example, stiffening elements  742  can be incorporated into the sidewalls of bladder  705 ). Stiffening elements  742  may also comprise wires, rings or hoops of materials having a higher elastic modulus than the elastic membrane  704 .  FIG. 7  also serves to illustrate an alternate method for electrical interconnection of the fluidic MEMS actuator  700  to an external controller (not shown) by way of contact pins  744 . Access to fluidic channels  714  within the base  712 , can be made for example, through the backside of base  712 . The configuration of electrical connections  744  and access to fluidic channels  714  is conducive to applications where “backside” fluidic and electrical interconnections are desirable. The location of electrical and fluidic interconnections on the top, bottom or sides of base  712  would be expected to depend on the particular application of the invention. For example, electrical connections on a side  756  of base  712 , could be made by a card edge connector (not shown) or similar electrical interconnection. 
     FIG. 8  is a schematic cross section view of another embodiment of a MEMS fluidic actuator  800  according to the present invention. In this embodiment, base  812  comprises separate fluidic channels,  814   a  and  814   b , for admitting fluids to and exhausting fluids from, the internal volume  822  of bladder  805 . A fluidic MEMS device  824 , is housed in an electronic package  846 , and comprises a MEMS pressure sensor (not in the plane of the present illustration), and MEMS valves  828   a  and  828   b , for controlling the flow of fluid between the internal volume  822  and the fluidic channels  814   a  and  814   b  respectively. As illustrated in  FIG. 8 , valves  828   a  and  828   b  are acting as one-way valves, the actuation of which can be controlled by means of a controller (not shown) as described above. 
     FIG. 9  is an enlarged schematic cross section of a microfluidic device  924  and a base  912 , as illustrated in  FIG. 8 . Microfluidic device  924 , is housed in an electronics package  946 , illustrated here as a dual inline package or DIP, while any of a variety of electronic packages could be employed as well (for example; a ceramic dual in-line package, a single in-line package, a pin grid array a zigzag QUIP package, etc). The use of an electronic package  946  for housing the MEMS device  924  is a matter of convenience and, as described in the following, can serve to facilitate electrical and fluidic interconnections to the MEMS device  924 . For a discussion of packaged fluidic MEMS devices, see U.S. Pat. No. 6,443,179 to Benavides et. al. Electronic package  946  can comprise fluidic channels  958 , having dimensions on the order of the fluidic channels  914   a  and  914   b  within the substrate  912  (e.g. on the order of 500 μm). An interposer  948  can be employed to provide a fanout of the microfluidic ports  952  (typically on the order of 100 μm or less) on the device  924 , to the fluidic channels  958  of the package  946 , and eventually to the fluidic channels  914   a  and  914   b  within base  912 . Fanout can be employed to facilitate assembly and alignment of small closely spaced microfluidic ports  952  to the generally larger in diameter and larger spacing of fluidic channels  958  that can be machined in the package  946 , or the base  912 . The interposer  948  can comprise a silicon, ceramic, glass, or composite substrate as described above for the base  912 , or alternatively can be incorporated into a polymeric or adhesive layer, for example layer  926   b . Adhesive layers  926   a ,  926   b  and  926   c  can be utilized respectively, to join the microfluidic device  924  to the interposer  948 , the interposer  948  to the package  946  and the package to the base  912 . Various embodiments of the adhesive layers  926   a ,  926   b  and  926   c  include those described above for adhesive layers. 
     FIG. 10  is a schematic cross-section illustration of another embodiment of a system of MEMS fluidic actuators  1000 , according to the present invention. A plurality of fluidic MEMS actuators having separate internal volumes  1022 ,  1022 ′ and  1022 ″, can be formed from a continuous elastic membrane  1064 , for example, by molding the elastic membrane  1064  to produce multiple edges as sealing surfaces  1018 , prior to attaching the elastic membrane  1064  to a base  1012 . Each internal volume  1022 ,  1022 ′,  1022 ″, can contain a MEMS valve and a MEMS pressure sensor to allow independent monitoring of the pressure of fluid within each internal volume and independently controlling the exchange of fluid between each internal volume and fluidic channels  1014  within the base  1012 . 
   By independently adjusting the pressure within each of the internal volumes  1022 ,  1022 ′ and  1022 ″, the extension and contraction of each bladder can be independently controlled and the displacement of a compliant cover  1006  adjusted to produce virtually any desired surface profile. The compliant cover  1006 , contacting the elastic membrane  1064  can be included in applications where warranted. To facilitate the fluidic coupling and transport of fluid to and from the sealed volumes, fluidic channels  1062  may be incorporated into the substrate  1002 . Adhesive and joining layers, for example layer  1038  joining base  1012  to substrate  1002 , may comprise embodiments for adhesive and joining layers as described above. 
     FIG. 11  is a schematic cross-section illustration of another embodiment of a fluidic MEMS actuator  1100  according to the present invention.  FIG. 11  illustrates an actuator  1100  comprising a MEMS pressure sensing device  1134 , disposed within a sealed volume  1122  of a bladder  1105 , and one or more MEMS valves,  1128   a  and  1128   b , located external to the bladder  1105 . MEMS device  1124   a , attached to base  1112 , comprises a MEMS pressure sensor  1134 , for measuring the pressure of a fluid within the bladder  1105 . Base  1112  can comprise one or more fluidic channels  1114   a  and  1114   b  for admitting and exhausting fluid into and out of the bladder  1105 . MEMS device  1124   b  is housed within an electronics package  1146 , attached to base  1112  and located external to the sealed volume  1122  of bladder  1105 . MEMS device  1124   b  comprises a fluidic channel  1130 , interconnected to the fluidic channels  1114   a  and  1114   b  in base  1112  by means of an electronic package  1146 , as described above. MEMS valves  1128   a  and  1128   b  are disposed along the channel  1130  in device  1124   b  and are operated to control the flow of fluid between channels  1114   a  and  1114   b  and the sealed volume  1122  within bladder  1105 . Electronics package  1146  can comprise a lid or cover  1172 , to provide physical protection of MEMS device  1124   b  from the environment. 
   Other applications and variations of the present invention will become evident to those skilled in the art. For example the MEMS valves and MEMS sensors can be integrated into a singular die or alternatively, MEMS valves and MEMS sensors can comprise multiple silicon dies. The silicon dies may or may not be housed in electronic packages, depending on the application. Embodiments of a system of MEMS fluidic actuators can include a plurality of any individual embodiment of a MEMS fluidic actuator, or any combination of the individual embodiments as described and illustrated above. Additionally, other embodiments are envisioned where multiple actuators can be arranged on both the front and back surfaces of a base or substrate. 
   The description of the invention set forth in the foregoing specification and drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims, when viewed in their proper perspective based on the foregoing specification and drawings.