Abstract:
An electrostatically actuated valve that is relatively small, has relatively low fabrication costs, and consumes relatively low voltage and/or power. Normally closed, normally open, three (or more) way valves, and other configurations are contemplated. These electrostatically actuated valves are suitable for a wide variety of applications, including but not limited to, low power and wireless applications, for example.

Description:
BACKGROUND 
   The present invention generally relates to electro-pneumatic transducers, and more particularly, to electrostatically actuated valves. 
   Many industrial, commercial, aerospace, military and other applications depend critically on reliable valves for fluid (including gas) handling. In a chemical plant, for example, valves are often used to control the flow of fluid throughout the facility. Likewise, in an airplane, valves are often used to control air and fuel delivery, as well as some of the hydraulic systems that drive the control surfaces of the airplane. These are just a few examples of the many applications that depend critically on reliable valves for fluid (including gas) handling. 
   In many cases, one or more main valves are used to directly control the fluid. In other cases, smaller control or pilot valves are used to control the operation of a main valve. In any cases, it is often desirable to minimize the power and/or voltage required to operate the main and/or pilot valves, particular in wireless applications but also in other applications. While some prior art valves perform satisfactory for some applications, many have significant shortcomings including a relatively large size and weight, a relatively large voltage and/or power requirement, a relatively high fabrication cost, and/or other shortcomings. 
   SUMMARY 
   The present invention provides an electrostatically actuated valve that is relatively small, has relatively low fabrication costs, and consumes relatively low voltage and/or power. Normally closed, normally open and three (or more) way valve configurations are shown for illustrative purposes, but other configurations are contemplated and are within the scope of the present invention. The electrostatically actuated valves of the present invention are suitable for a wide variety of applications, including wireless applications. 
   In one illustrative normally closed valve, a body is provided that is configured to form a chamber. The chamber has a first port and a second port. The first port may be, for example, an input port and the second port may be an output port of the valve. A diaphragm is mounted in the chamber. The diaphragm may have a first position that restricts fluid from flowing between the first port and the second port, and a second position that allows fluid to flow between the first port and the second port. 
   A first electrode may be secured relative to the diaphragm, and a second electrode may be secured relative to the body. When a voltage is applied between the first electrode and the second electrode, the first electrode may be electrostatically pulled toward the second electrode. This moves the diaphragm from the first position, which restricts the fluid to flow between the first port and the second port, toward the second position, which allows fluid to flow between the first port and the second port. 
   In some embodiments, the chamber has a first opposing wall and a second opposing wall, with the second electrode secured relative to the second opposing wall. The first opposing wall and the second opposing wall may be configured such that the spacing between the first opposing wall and the second opposing wall is smaller in a first region of the chamber than in an adjacent second region. In some embodiments, the first region is toward the edge or edges of the chamber and the second region is toward the center of the chamber. The diaphragm is mounted between the first opposing wall and the second opposing wall such that the diaphragm can be electrostatically pulled toward the second electrode in a rolling action, beginning in the first region. This rolling action may significantly reduce the voltage and power required to pull the diaphragm from the first position to the second position. This may be particularly beneficial in, for example, applications where a battery or some other limited power source is used to power the valve. 
   In some embodiments, the diaphragm may become elastically deformed when it is electrostatically pulled toward the second position. When so provided, the diaphragm may return to the first position under elastic restoring forces when the voltage is removed or reduced between the first electrode and the second electrode. Thus, the diaphragm may only need to be electrostatically actuated in one direction, with the elastic restoring forces returning the diaphragm. 
   In some embodiments, the diaphragm may be configured to be in the second position in the un-activated state. This may be accomplished by, for example, pre-shaping the diaphragm. When so provided, and in some embodiments, the diaphragm may become elastically deformed when it is electrostatically pulled toward the first position when a voltage is applied between the first electrode and the second electrode. Such a force may be created by, for example, applying like charges to both the first and second electrodes, creating a repelling electrostatic force. Alternatively, or in addition, the second electrode may be secured relative to the first opposing wall, wherein the diaphragm is electrostatically pulled toward the first position when a voltage is applied between the first electrode and the second electrode. 
   Regardless of the configuration of the diaphragm, the first and second electrodes may be used to cause actuation of the diaphragm in both directions, by first applying a voltage differential to the first and second electrodes to pull the diaphragm toward the second position, and then applying similar charges to each, generating a repellant electrostatic force to push the diaphragm back to the first position. Alternatively, or in addition, a third electrode may be secured relative to the first opposing wall such that the diaphragm can be electrostatically pulled toward the third electrode by applying a voltage differential between the first electrode and the third electrode. When so provided, the first opposing wall may be configured such that the spacing between the first opposing wall and the diaphragm is smaller in a first region of the chamber than in an adjacent second region, thereby allowing the diaphragm to be electrostatically pulled toward the third electrode in a rolling action, beginning in the first region. 
   In some embodiments, the first port may extend through the first opposing wall and into the chamber, and the second port may extend through the second opposing wall and into the chamber. The diaphragm, which is mounted between the first opposing wall and the second opposing wall, may have at least one opening that is laterally offset from the first port in the first opposing wall when the diaphragm is positioned in the first position adjacent the first opposing wall. The diaphragm may be configured to cover or otherwise restrict fluid from flowing through the first port and into the chamber when the diaphragm is in the first position adjacent the first opposing wall. When the diaphragm is electrostatically pulled toward the second opposing wall, the diaphragm may move away and uncover the first port, thereby allowing fluid to flow between the first port and the second port via the one or more openings in the diaphragm. 
   In yet another illustrative embodiment, the first port and the second port may extend through the first opposing wall and into the chamber. The diaphragm may be configured to cover or otherwise restrict fluid from flowing through the first port and into the chamber when the diaphragm is in the first position adjacent the first opposing wall. When the diaphragm is electrostatically pulled toward the second opposing wall, the diaphragm may move away and uncover the first port, thereby allowing fluid to flow between the first port and the second port. This embodiment may provide an electrostatically actuated valve that does not expose the fluid to the electric field used to electrostatically actuate the valve. In some applications, the dielectric, conductive, polar or other properties of the fluid can affect the magnitude of the electrostatic force between the actuation electrodes of the valve. This may reduce the efficiency and/or reliability of the valve. In addition, the electric field applied between the electrodes of the valve may impact or change the properties of the fluid that is controlled by the valve, when the fluid is exposed to the electric field. This illustrative embodiment may avoid some of these difficulties. 
   An illustrative embodiment of a normally open valve may include a body that is configured to form a chamber. The chamber may have a first opposing wall and a second opposing wall, wherein the first opposing wall and the second opposing wall are configured such that the spacing between the first opposing wall and the second opposing wall is smaller in a first region of the chamber than in an adjacent second region. In some embodiments, the first region is toward the edge or edges of the chamber, and the second region is toward the center of the chamber. A diaphragm may be mounted between the first opposing wall and the second opposing wall, and may have a first position that allows fluid to flow between a first port and a second port. A first electrode may be secured relative to the diaphragm, and a second electrode may be secured relative to the body. Like above, the diaphragm may be adapted to be electrostatically pulled toward the second electrode in a rolling action beginning in the first region toward the second position when a voltage is applied between the first electrode and the second electrode. When actuated, the diaphragm may restrict fluid from flowing between the first port and the second port. 
   In some embodiments, the first port and second port extend through the second opposing wall and into the chamber, with the second electrode secured relative to the second opposing wall. The diaphragm may then be electrostatically pulled toward the second opposing wall when a voltage is applied between the first electrode and the second electrode, thereby restricting fluid from flowing between the first port and the second port. In some embodiments, the diaphragm is elastically deformed when it is electrostatically pulled toward the second position, and returns to the first position under elastic restoring forces when not electrostatically pulled toward the second position. 
   In another illustrative embodiment, the diaphragm may separate the chamber into a first region and a second region. The first region may extend between the diaphragm and the first opposing wall, and the second region may extend between the diaphragm and the second opposing wall. In this illustrative embodiment, the first region may be in fluid communication with the first port, and the second region may be in fluid communication with the first port and the second port, at least when the diaphragm is in the first position. By having the first region and second region in fluid communication with the first port (e.g. inlet port), the actuation force required to move the diaphragm from the first position to the second position may be reduced because there is little or no pressure differential across the diaphragm. 
   An illustrative embodiment of a three-way may include a body that is configured to form a chamber. The chamber may have a first opposing wall and a second opposing wall. A diaphragm, which is mounted between the first opposing wall and the second opposing wall, may have at least one opening therein. A first electrode may be secured relative to the diaphragm, and a second electrode may be secured relative to the body. The diaphragm may have a first position that allows fluid to flow between an inlet port and a first outlet port through the at least one opening, and a second position that allows fluid to flow between the inlet port and a second outlet port. In the second position, the at least one opening may be restricted to reduce or prevent fluid from flowing between the inlet port and the first outlet port. Like above, the diaphragm may be adapted to be electrostatically pulled toward the second electrode in a rolling action when a voltage is applied between the first electrode and the second electrode, which may then move the diaphragm from the first position to the second position. 
   In some embodiments, the inlet port and the second outlet port may extend through the first opposing wall and into the chamber. The first outlet port may extend through the second opposing wall and into the chamber, with the second electrode secured relative to the second opposing wall. The at least one opening in the diaphragm may be laterally offset from the second outlet port in the first opposing wall when the diaphragm is positioned in the first position adjacent the first opposing wall. In the first position, the diaphragm may allow fluid to flow from the inlet port in the first opposing wall to the first outlet port in the second opposing wall through the at least one opening, while restricting or preventing fluid from flowing between the inlet port and the second outlet port. 
   When the diaphragm is electrostatically pulled toward the second opposing wall, the diaphragm may move away and uncover the second outlet port, thereby allowing fluid to flow between the inlet port and the second outlet port. When the diaphragm is pulled sufficiently close to the second opposing wall, the at least one opening in the diaphragm may become restricted, which may restrict or prevent fluid from flowing between the inlet port and the first outlet port. 
   In addition to the foregoing illustrative embodiment, various other electrostatically actuated valves are contemplated, some of which are described below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional side view of an illustrative normally closed valve in accordance with the present invention; 
       FIG. 2  is a cross-sectional top view of the illustrative normally closed valve of  FIG. 1 ; 
       FIG. 3  is a cross-sectional side view of the illustrative normally closed valve of  FIG. 1  with the diaphragm partially activated; 
       FIG. 4  is a cross-sectional side view of the illustrative normally closed valve of  FIG. 3  with the diaphragm further activated; 
       FIG. 5  is a cross-sectional side view of another illustrative normally closed valve in accordance with the present invention; 
       FIG. 6  is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention; 
       FIG. 7  is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention; 
       FIG. 8  is a cross-sectional top view of the illustrative normally closed valve of  FIG. 7 ; 
       FIG. 9  is a cross-sectional side view of the illustrative normally closed valve of  FIG. 7  with the diaphragm at least partially activated; 
       FIG. 10  is a cross-sectional side view of an illustrative normally open valve in accordance with the present invention; 
       FIG. 11  is a cross-sectional side view of the illustrative normally open valve of  FIG. 10  with the diaphragm partially activated; 
       FIG. 12  is a cross-sectional side view of the illustrative normally open valve of  FIG. 10  with the diaphragm fully activated; 
       FIG. 13  is a cross-sectional side view of an illustrative three-way valve in accordance with the present invention; 
       FIG. 14  is a cross-sectional side view of the illustrative three-way valve of  FIG. 13  with the diaphragm partially activated; and 
       FIG. 15  is a cross-sectional side view of the illustrative three-way valve of  FIG. 14  with the diaphragm further activated. 
   

   DETAILED DESCRIPTION 
   The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings are presented to show embodiments that are illustrative of the claimed invention. 
     FIG. 1  is a cross-sectional side view of an illustrative normally closed valve in accordance with the present invention. The valve is generally shown at  5 , and has a body  10  with a first opposing wall  14  and a second opposing wall  16  that define a valve chamber  12 . In the illustrative embodiment, a first port  42  (e.g. inlet port) extends into the valve chamber  12  through the first opposing wall  14 . One or more second ports (e.g. outlet ports), such as ports  44   a  and  44   b , extend into the valve chamber  12  through the second opposing wall  16 . 
   A diaphragm  20  is mounted within the chamber  12 . In some embodiments, this may be accomplished by sandwiching the diaphragm  20  between an upper body portion  13  and a lower body portion  11 . In the illustrative embodiment, the diaphragm  20  extends along the first opposing wall  14  in the un-activated state. In some embodiments, the diaphragm  20  is spaced from the first opposing wall  14  except along a valve seat  23 , which extends around the first port  42 . To actuate the diaphragm  20 , the diaphragm  20  may include one or more electrodes, which may extend to at least near the edges of the chamber  12 . In some embodiments, the one or more electrodes of the diaphragm are surrounded or encapsulated in a dielectric material or layer. 
   In the embodiment shown in  FIG. 1 , the second opposing wall  16  includes one or more stationary electrodes, such as electrode  30 . The second opposing wall  16  and the diaphragm  20  may be configured so that, in the un-activated state, the separation distance between the stationary electrode  30  and the electrode of the diaphragm  20  is smaller near the edges of the chamber  12 . In other embodiments, however, the separation distance between the stationary electrode  30  and the electrode of the diaphragm  20  may be smaller in the center or any other area of the chamber  12 , as desired. By providing a region in the chamber  12  that has a smaller separation distance, the diaphragm  20  may be drawn toward the second opposing wall  16  in a rolling action when a voltage is applied between the electrode of the diaphragm  20  and the stationary electrode and  30 , as further shown in  FIGS. 3-4 . Such a rolling action may help improve the efficiency and reduce the voltage requirements of the valve. 
   For purposes of illustration, the first opposing wall  14  is shown generally flat. However, the first opposing wall  14  may assume other shapes, depending upon the application. For example, the first opposing wall  14  may have different regions that are recessed or protrude against the diaphragm  20  in order to, for example, reduce damage to the diaphragm  20  after continued activation. Other shapes may also be used, including curved shapes, for example. Although the second opposing wall  16  is shown to be generally curved, other shapes may be used, depending on the application. 
   Body  10  may be made from any suitable semi-rigid or rigid material, such as plastic, ceramic, silicon, etc. In one illustrative embodiment, the body  10  is constructed by molding a high temperature plastic such as ULTEM™ (available from General Electric Company, Pittsfield, Mass.), CELAZOLE™ (available from Hoechst-Celanese Corporation, Summit, N.J.), KETRON™ (available from Polymer Corporation, Reading, Pa.), or some other suitable material. In some embodiments, the material used for the diaphragm  20  may have elastic, resilient, flexible or other elastomeric properties. In other embodiments, the diaphragm  20  is made from a generally compliant material. In one embodiment, the diaphragm  20  is made from a polymer such as KAPTON™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), KALADEX™ (available from ICI Films, Wilmington, Del.), MYLAR™ (available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del.), or any other suitable material. An advantage of using a polymer based substrate and/or diaphragm is that the resulting valve may be cheaper and lighter, and/or more suitable for small handheld, or even disposable or reusable applications. 
   The one or more electrodes on the diaphragm  20  may be provided by patterning a conductive coating on the diaphragm  20 . For example, the one or more electrodes may be formed by printing, plating or EB deposition of metal. In some cases, the electrode layer may be patterned using a dry film resist. The same or similar techniques may be used to provide the electrode  30  on the second opposing wall  16  of the body  10 . Rather than providing a separate electrode layer, it is contemplated that the diaphragm  20  and/or second opposing wall  16  may be made conductive so as to function as an electrode, if desired. A dielectric, such as a low temperature organic and inorganic dielectric, may be used as an insulator between the actuating electrodes. The dielectric may be coated over the electrode on the diaphragm  20 , the electrode  30  on the second opposing wall  16 , or both, as desired. 
   As shown in  FIG. 1 , the diaphragm  20  may have at least one opening (openings  25   a  and  25   b ) that is laterally offset from the first port  42  when the diaphragm  20  is in a first position adjacent the first opposing wall  14 .  FIG. 2  is a cross-sectional top view of the illustrative normally closed valve of FIG.  1 . As can be seen in  FIG. 2 , the diaphragm  20  may include one or more openings  25   a  and  25   b.    
   The openings  25   a  and  25   b  in the diaphragm  20  may be configured so that the diaphragm  20  covers or otherwise restrict fluid flow through the first port  42  and into the chamber  12  when the diaphragm  20  is adjacent the first opposing wall  14 . When the diaphragm is electrostatically actuated and pulled toward the second opposing wall  16 , as shown in  FIGS. 3-4 , the diaphragm may move away and uncover the first port  42 . This may allow fluid to flow between the first port  42  and the second port or ports  44   a  and  44   b  via the one or more openings  25   a  and  25   b  in the diaphragm  20 . 
   In some embodiments, the diaphragm  20  may become elastically deformed when electrostatically pulled toward the second opposing wall  16 . When so provided, the diaphragm  20  may return to the un-activated first position adjacent the first opposing wall  14  under elastic restoring forces when the activation voltage is removed or reduced between the electrode of the diaphragm  20  and the electrode  30  of the second opposing wall  16 . In this illustrative embodiment, the diaphragm  20  may only need to be electrostatically actuated in one direction, with the elastic restoring forces returning the diaphragm  20  to the original un-actuated state. 
   To increase the elastic restoring forces, the diaphragm  20  may be disposed across the chamber  12  under tension. Alternatively, or in addition, the diaphragm  20  may be made from a material with a preformed shape to which the diaphragm  20  elastically returns after application of a deforming force. In either case, the diaphragm  20  may be made from a material, form, or disposed in a fashion such that the diaphragm  20 , once deformed as shown in  FIGS. 3-4 , generates a restoring force that pulls the diaphragm  20  back towards the first opposing wall  14 , such as shown in FIG.  1 . 
   In some embodiments, supplemental restoring forces may be provided to help restore the diaphragm  20  to the un-activated first position adjacent the first opposing wall  14 . In one embodiment, like charges may be applied to both the electrode on the diaphragm  20  and the electrode  30  on the second opposing wall  16 , creating a repelling electrostatic force therebetween. This repelling electrostatic force may help push the diaphragm  20  back toward the first opposing wall  14 . Alternatively, or in addition, supplemental restoring forces may be created by providing an additional or third electrode  52  along the first opposing wall  14 , as shown in FIG.  5 . By applying a voltage between the electrode on the diaphragm  20  and the additional third electrode  52 , the diaphragm  20  may be pulled back toward the first opposing wall  14 , preferably in a rolling action. 
   In some embodiments, the diaphragm  20  may be configured to be positioned away from the first opposing wall  14  in the un-activated state. This may be accomplished by, for example, pre-shaping the diaphragm  20 . When so provided, and in some embodiments, the diaphragm  20  may become elastically deformed when it is electrostatically pulled toward the first opposing wall  14 . Such a force may be provided by, for example, applying like charges to the electrode of the diaphragm  20  and the electrode  30  of the second opposing wall  16 , thus creating a repelling electrostatic force. Alternatively, or in addition, an electrode may be secured relative to the first opposing wall  14 , wherein the diaphragm is electrostatically pulled toward the first opposing wall  14  when a voltage is applied between the electrode of the diaphragm  20  and the electrode of the first opposing wall  14 . 
     FIG. 3  is a cross-sectional side view of the illustrative normally closed valve of  FIG. 1  with the diaphragm partially activated. As discussed above, the chamber  12  may have a first opposing wall  14  and a second opposing wall  16 , with the second electrode  30  secured relative to the second opposing wall  16 . As shown in  FIG. 1 , the first opposing wall  14  and the second opposing wall  16  may be configured such that the spacing between the first opposing wall  14  and the second opposing wall  16  is smaller in a first region of the chamber  12  than in an adjacent second region. In  FIG. 1 , the first region is toward the edge or edges of the chamber  12  and the second region is toward the center of the chamber  12 . The diaphragm  20  is mounted between the first opposing wall  14  and the second opposing wall  16  such that the diaphragm can be electrostatically pulled toward the second electrode  30  in a rolling action, beginning in the first region. The rolling action may continue with additional activation, as shown in  FIGS. 3 and 4 . With the diaphragm  20  pulled away from the valve seat  23 , fluid may flow between the first port  42  and the second port or ports  44   a  and  44   b  via the one or more openings  25   a  and  25   b  in the diaphragm  20 , as shown by the arrows in FIG.  3 . 
   It is contemplated that the openings  25   a  and  25   b  may or may not align with the second ports  44   a  and  44   b  when the diaphragm  20  is pulled adjacent the second opposing wall  16 . In  FIG. 4 , the openings  25   a  and  25   b  are configured to be not aligned with the second ports  44   a  and  44   b . Thus, in the embodiment shown in  FIG. 4 , the fluid flow may begin to slow or stop when the diaphragm  20  is pulled against the second opposing wall  16 . In other embodiments, the openings  25   a  and  25   b  are configured to be aligned or substantially aligned with the second ports  44   a  and  44   b  when the diaphragm  20  is pulled adjacent the second opposing wall  16 . In these embodiments, the fluid may continue to flow between the first port  42  and the second ports  44   a  and  44   b  when the diaphragm  20  is pulled adjacent the second opposing wall  16 . 
   The rolling action of the diaphragm  20  may significantly reduce the voltage and power required to pull the diaphragm  20  toward the second opposing wall  16 , while still achieving a significant diaphragm travel distance. This may be particularly beneficial in, for example, applications where a battery or some other limited power source is used to power the valve  5 . A significant diaphragm travel distance may help improve the flow rate that the valve can accommodate, so long as the openings are also appropriately sized. 
     FIG. 5  is a cross-sectional side view of another illustrative normally closed valve in accordance with the present invention. This embodiment is similar to that shown in  FIG. 1 , but includes an additional or third electrode  52  along the first opposing wall  14 . The third electrode  52  may be used to provide a restoring force or a supplemental restoring force to the diaphragm  20 . For example, once the diaphragm has been displaced toward the second opposing wall  16 , a voltage may be applied between the electrode of the diaphragm  20  and the third electrode  52 . This may create an attractive electrostatic force between the electrodes, which pulls the diaphragm  20  toward the third electrode  52  and the first opposing wall  14  in a rolling action. The third electrode  52  may also be used to hold the diaphragm  20  against the first opposing wall  14  to keep the valve closed. This may be particular useful when the fluid pressure at the first port  42  may exceed the fluid pressure at the second ports  44   a  and  44   b.    
     FIG. 6  is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention. This embodiment is similar to that shown in  FIG. 5 , but the third electrode  54  is only provided adjacent the valve seat  23 . In this embodiment, the third electrode  54  may be used to keep the valve closed, particularly when the fluid pressure at the first port  42  may exceed the fluid pressure at the second ports  44   a  and  44   b.    
     FIG. 7  is a cross-sectional side view of yet another illustrative normally closed valve in accordance with the present invention. In this illustrative embodiment, the first port  80  (e.g. input port) and the second port  82   a  (e.g. output ports  82   a  and  82   b ) are shown extending through a first opposing wall  84  of the valve and into the valve chamber  86 . The diaphragm  88  is configured to cover or otherwise restrict fluid from flowing through the first port  80  and into the chamber  86  when the diaphragm  88  is in a first position adjacent the first opposing wall  84 . When the diaphragm  88  is electrostatically pulled toward the second opposing wall  90 , the diaphragm  88  may move away and uncover the first port  80 , thereby allowing fluid to flow between the first port  80  and the second ports  82   a  and  82   b . In this illustrative embodiment, the diaphragm  86  does not have any opening therein, as better shown in FIG.  8 .  FIG. 9  is a cross-sectional side view of the illustrative normally closed valve of  FIG. 7  with the diaphragm at least partially activated. A back pressure relief or vent opening  94  may be provided in the second opposing wall to relieve any back pressure that might arise because of displacement of the diaphragm  88 . 
   This illustrative embodiment may provide an electrostatically actuated valve that does not substantially expose the fluid to the electric field used to electrostatically actuate the valve. In the illustrative embodiment, the electric field used to actuate the valve only extends between the electrode of the diaphragm  88  and the electrode  92  of the second opposing wall  90 . In some applications, the dielectric, conductive, polar or other properties of the fluid can affect the magnitude of the electrostatic force between the actuation electrodes of the valve, which can reduce the efficiency and/or reliability of the valve. In addition, the electric field applied between the electrodes of the valve may effect, impact or change the properties of the fluid. This illustrative embodiment may avoid some of these difficulties. 
     FIG. 10  is a cross-sectional side view of an illustrative normally open valve in accordance with the present invention. This illustrative normally open valve is generally shown at  110 , and includes a body  112  that is configured to form a chamber  114 . The illustrative chamber  112  includes a first opposing wall  116  and a second opposing wall  118 . The first opposing wall  116  and the second opposing wall  118  are configured such that the spacing between the first opposing wall  116  and the second opposing wall  118  is smaller in a first region of the chamber  114  than in an adjacent second region. In the illustrative embodiment, the first region is near the edges of the chamber  114  and the second region is away from the edges and near the center of the chamber  114 . A diaphragm  120  is mounted between the first opposing wall  116  and the second opposing wall  118 . 
   A first port  122  (e.g. inlet port) and a second port  124  (e.g. outlet port) are provided through the second opposing wall  118  and into the chamber  114 . In the illustrative embodiment, a vent  128  is also provided. The vent  128  includes a fluid channel that extends from the first port  122 , through the body  112 , through the first opposing wall  116 , and into the chamber  114 . 
   The diaphragm  120  is mounted in the chamber  114 , and has a first position adjacent the first opposing wall  116  that allows fluid to flow between the first port  122  and the second port  124  in the un-actuated state. A first electrode may be secured relative to the diaphragm, and a second electrode  130  may be secured relative to the second opposing wall  118 . 
   Like above, the diaphragm  120  may be adapted to be electrostatically pulled toward the second electrode  130  in a rolling action, beginning in the first region, toward the second opposing wall when a voltage is applied between the electrode of the diaphragm  120  and the electrode  130  of the second opposing wall  118 . When actuated, the diaphragm  120  may begin to restrict fluid flow between the first port  122  and the second port  124 . Like above, and in some embodiments, the diaphragm  120  is elastically deformed when it is electrostatically pulled toward the second opposing wall  118 , and returns to the first position adjacent the first opposing wall under elastic restoring forces. 
   As can be seen, the diaphragm  120  may separate the chamber  114  into a first part and a second part. The first part extends between the diaphragm  120  and the first opposing wall  116 , and the second part extends between the diaphragm  120  and the second opposing wall  118 . In the illustrative embodiment, the first part is in fluid communication with the first port  122  via vent  128 , and the second part is in fluid communication with the first port  122  and the second port  124 , at least when the diaphragm  120  is in the first position. By having both the first part and the second part in fluid communication with the first port  122  (e.g. inlet port), the actuation force required to move the diaphragm from a first position adjacent the first opposing wall  116  to a second position adjacent the second opposing wall may be reduced because there is little or no pressure differential across the diaphragm  120 . 
     FIG. 11  is a cross-sectional side view of the illustrative normally open valve of  FIG. 10  with the diaphragm partially activated. As discussed above, the chamber  114  may have a first opposing wall  116  and a second opposing wall  118 , with the second electrode  130  secured relative to the second opposing wall  118 . The diaphragm  120  is mounted between the first opposing wall  116  and the second opposing wall  118  such that the diaphragm can be electrostatically pulled toward the second electrode  130  in a rolling action. The rolling action may continue with additional activation, as shown in FIG.  11 . This rolling action may significantly reduce the voltage and power required to pull the diaphragm  120  toward the second opposing wall  118 , while still achieving a significant diaphragm travel distance.  FIG. 12  is a cross-sectional side view of the illustrative normally open valve of  FIG. 10  with the diaphragm fully activated. As can be seen, the diaphragm  120  may be sufficiently activated to reduce or even prevent fluid flow between the first port  122  and the second port  124 , thereby closing the valve. 
     FIG. 13  is a cross-sectional side view of an illustrative three-way valve in accordance with the present invention. The illustrative three-way valve includes a body  140  that is configured to form a chamber  142 . The chamber  142  has a first opposing wall  144  and a second opposing wall  146 . A diaphragm  150 , which is mounted between the first opposing wall  144  and the second opposing wall  156 , may include an opening  152 . A first electrode (not explicitly shown but as described above) is secured to the diaphragm  150 , and a second electrode  154  is secured to the second opposing wall  146 . An inlet port  160  may extend through the first opposing wall  144  and into the chamber  142 . A first outlet port  162  may extend through the second opposing wall  146  and into the chamber  142 , and a second outlet port  164  may extend through the first opposing wall and into the chamber  142 . The inlet port  160  and the second outlet port  164  are shown laterally spaced from one another, with the second outlet port  164  defined by an annular protrusion  166  that extends further into the chamber  142 . In some embodiments, a valve seat  170  is provided along the top of the annular protrusion  166 . 
   In  FIG. 13 , the diaphragm  150  is shown in a first position adjacent the first opposing wall  144 . The diaphragm  150  extends along the valve seat  170 , which helps restrict or otherwise provide a seal between the first opposing wall  144  and the diaphragm  150 . Thus, in the first position, the diaphragm  150  allows fluid to flow between an inlet port  160  and the first outlet port  162  through the opening  152 , while restricting or preventing fluid from flowing between the inlet port  160  and the second outlet port  164   
     FIG. 14  is a cross-sectional side view of the illustrative three-way valve of  FIG. 13  with the diaphragm partially activated. As shown, the diaphragm  150  may be electrostatically pulled toward the second electrode  154  in a rolling action when a voltage is applied between the first electrode on the diaphragm  150  and the second electrode  154 . The electric field is illustrated at  172 . When activated, the diaphragm  150  moves toward the second opposing wall  146 , and away from the first opposing wall  144  and the valve seat  170 . As the diaphragm  150  moves away from the first opposing wall  144 , fluid can flow between the inlet port  160  and the second outlet port  164 . 
     FIG. 15  is a cross-sectional side view of the illustrative three-way valve of  FIG. 14  with the diaphragm fully activated. As shown in  FIG. 15 , when the diaphragm  150  is electrostatically pulled closer to the second opposing wall  146 , the opening  152  in the diaphragm  150  begins to become restricted, which restricts and eventually prevents or substantially prevents fluid from flowing between the inlet port  160  and the first outlet port  162 . In addition, as the diaphragm  150  is moved away from the first opposing wall  144 , the fluid communication path between the inlet port  160  and the second outlet port  164  becomes less restricted, allowing greater flow for a given inlet pressure. 
   It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.