Abstract:
A microvalve assembly that can help protect a microvalve or an assembly of microvalves from the environment. Such a microvalve assembly may be mechanically assembled, without the use of adhesives and/or other materials that might out-gas and/or otherwise reduce the performance of the electrostatically actuated devices contained therein. In particular, a microvalve assembly can include a base fixture, a clamp fixture that is configured to be attached to the base fixture, and an electrostatically actuated microvalve that is disposed between the base fixture and the clamp fixture. The clamp fixture may be mechanically secured to the base fixture.

Description:
This invention was made with government support under DARPA contract number MDA972-00-C-0029. The government may have certain rights in the invention. 

   TECHNICAL FIELD 
   The invention pertains generally to microvalves and more specifically to microvalve package assemblies. In particular, the invention pertains to microvalve package assemblies that may be mechanically secured together without adhesives. 
   BACKGROUND 
   Valves such as microvalves are known. Some microvalves are electrostatically actuated. Electrostatically actuated devices such as electrostatically actuated microvalves can be quite sensitive to environmental conditions such as humidity, dust and gases. In some instances, the packages used to assemble electrostatically actuated microvalves can include adhesives that may themselves out-gas and cause stiction within the electrostatically actuated microvalve. 
   Therefore, a need remains for a microvalve assembly that protects a microvalve or an assembly of microvalves from exterior environmental conditions. A need also remains for a microvalve assembly that is free of adhesives and/or other materials that might out-gas and/or otherwise reduce the performance of the electrostatically actuated devices contained therein. 
   SUMMARY 
   The invention provides a microvalve assembly that protects a microvalve or an assembly of microvalves from the environment. Moreover, the invention provides a microvalve assembly that is mechanically assembled, without the use of adhesives and/or other materials that might out-gas and/or otherwise reduce the performance of the electrostatically actuated devices contained therein. 
   Accordingly, an illustrative embodiment of the present invention pertains to a microvalve assembly that includes a base fixture, a clamp fixture, and an electrostatically actuated microvalve that is disposed between the base fixture and the clamp fixture. The clamp fixture is mechanically secured to the base fixture without an adhesive. 
   In some instances, the base fixture may include a recessed clamp fixture receiving region that is complementary in size and shape to the clamp fixture such that the clamp fixture fits at least substantially into the recessed clamp fixture receiving region. The recessed clamp fixture may include a recessed microvalve receiving region while the clamp fixture may include a raised microvalve receiving region that is configured to at least substantially align with the recessed microvalve receiving region of the base fixture. 
   The raised microvalve receiving region of the clamp fixture can include a gasket receiving recess. A gasket may be disposed within the gasket receiving recess. In some instances, the gasket may assist in securing the electrostatically actuated microvalve within the microvalve assembly, as well as helping to provide a seal. The electrostatically actuated microvalve may include a valve aperture member layer with a valve aperture and a valve flap member that includes a flap that can selectively overly the valve aperture to provide a valve action. In some instances, the base fixture may include an inlet that is in fluid communication with the valve aperture. 
   In some instances, the raised microvalve receiving region can define at least in part a fluid receiving volume. The clamp fixture may include an outlet that is in fluid communication with the fluid receiving volume. 
   In some cases, the clamp fixture may also include one or more clamp fixture securement apertures and the base fixture may also include one or more base fixture securement apertures that are at least substantially aligned with the one or more clamp fixture securement apertures. A securement device may be positioned within the clamp fixture securement aperture and the base fixture securement aperture in order to secure the clamp fixture to the base fixture. In some instances, the securement device secures the clamp fixture to the base fixture without the use of adhesives that may otherwise out-gas or otherwise interfere with operation of the electrostatically actuated microvalve. 
   In some cases, the base fixture securement aperture may include a threaded recess, and the securement device may be a threaded securement that is disposed through the clamp fixture securement aperture and that is threadedly engaged with the threaded recess to secure the clamp fixture to the base fixture. In some instances, the securement device may be a rod that is friction fit within the base fixture securement aperture and the clamp fixture securement aperture. 
   The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The Figures, Detailed Description and Examples which follow more particularly exemplify these embodiments. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
       FIG. 1  is an exploded perspective illustration of a microvalve assembly in accordance with an embodiment of the present invention; 
       FIG. 2  is a perspective view of the base fixture shown in  FIG. 1 ; 
       FIG. 3  is a partially phantom perspective view of the base fixture of  FIG. 1 , illustrating internal fluid passageways; 
       FIG. 4  is a partially phantom perspective view of the base fixture of  FIG. 1 , illustrating assembly passageways; 
       FIG. 5  is a perspective view of the clamp fixture shown in  FIG. 1 ; 
       FIG. 6  is a perspective view of a gasket as shown in  FIG. 1 ; 
       FIG. 7  is a partially phantom perspective view of the clamp fixture of  FIG. 1 , illustrating internal fluid passageways; 
       FIG. 8  is a partially phantom perspective view of the clamp fixture of  FIG. 1 , illustrating internal passageways intended for electrical conduction; 
       FIG. 9  is a partially phantom perspective view of the clamp fixture of  FIG. 1 , illustrating assembly passageways; 
       FIG. 10  is a perspective view of a microvalve bottom layer assembly as shown in  FIG. 1 ; and 
       FIG. 11  is a perspective view of a microvalve valve layer assembly as shown in  FIG. 1 . 
   

   While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
   DETAILED DESCRIPTION 
   The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized. 
   The invention pertains generally to microvalve packaging assemblies such as might be employed with electrostatically actuated microvalves. In particular,  FIG. 1  is an exploded perspective view of a microvalve assembly  10  including an array  12  of electrostatically actuated microvalves  14 . While shown generically in  FIG. 1 , each electrostatically actuated microvalve  14  may include several layers that are configured to provide a selectively openable valve aperture. In some embodiments, as illustrated, a total of six electrostatically actuated microvalves may be arranged in array  12 . In other embodiments, a greater number or a lesser number of electrostatically actuated microvalves may be used, as necessitated by any particular application. 
   Array  12  of electrostatically operated microvalves may include any particular type or configuration of electrostatically operated microvalve. An example of an electrostatically actuated microvalve  14  is shown in  FIGS. 10 and 11 , which are discussed in greater detail hereinafter. 
   Array  12  of electrostatically operated microvalves  14  is positioned between a base fixture  16  and a clamp fixture  18 . In the illustrated embodiment, an array  20  of gaskets  22  are deployed between array  12  of electrostatically operated microvalves  14  and clamp fixture  18 . As can be seen in  FIG. 1 , array  20  of gaskets  22  interacts with clamp fixture  18  and array  12  of electrostatically actuated microvalves  14  to help secure array  12  of electrostatically actuated microvalves  14 . The design and construction of base fixture  16  is described in greater detail with respect to  FIGS. 2-4 . The design and construction of clamp fixture  18  is described in greater detail with respect to FIGS.  5  and  7 - 9 . 
     FIGS. 2 through 4  are renditions of base fixture  16 , each illustrating particular aspects of the internal and external structure of base fixture  16 . In particular,  FIG. 2  is a perspective illustration of the external structure of base fixture  16 . While base fixture  16  may take any appropriate size and geometric shape depending on intended use, in some embodiments, as illustrated, base fixture  16  may assume the shape of a rectangular block. 
   Base fixture  16  may, as illustrated, include a recessed clamp fixture receiving region  24  that is complementary in size and shape to clamp fixture  18  such that clamp fixture  18  may fit at least substantially into recessed clamp fixture receiving region  24 . In some instances, recessed clamp fixture receiving region  24  may be configured such that clamp fixture  18  completely fits into recessed clamp fixture receiving region  24 . 
   In some instances, recessed clamp fixture receiving region  24  may itself include a recessed electrostatically actuated microvalve receiving region  26 , which may be configured to at least partially accept array  12  of electrostatically actuated microvalves  14  ( FIG. 1 ). 
   Base fixture  16  may be formed of any suitable material and using any suitable technique. In some instances, base fixture  16  can be formed by grinding or abrading away material from a rectangular block of any suitable polymeric material such as an acrylic plastic. In some cases, base fixture  16  may be molded into the configuration shown, for example, in  FIG. 2 . 
     FIG. 3  is a partially phantom perspective view of base fixture  16 , illustrating for example the internal fluid passageways of base fixture  16 . In particular, base fixture  16  can be seen as including a total of six internal fluid passageways  28 . Each internal fluid passageway  28  extends from an external fluid port  30  to an internal fluid port  32  that, in some instances, may correspond to a valve aperture present within electrostatically actuated microvalve  14  ( FIG. 1 ). Internal fluid ports  32  may be positioned such that they contact a bottom surface  32  of recessed electrostatically actuated microvalve receiving region  26 . Each external fluid port  30  may be configured to permit tubing or other external fluid passageways to be secured to external fluid port  30 . 
   Each internal fluid passageway  28  may be sized to accommodate the particular fluid expected during use. The term “fluid” as used herein can include gases, liquids or combinations of gases and liquids. Internal fluid passageways  28  may be formed using any suitable technique. In some instances, internal fluid passageways  28  may be formed by mechanically drilling into base fixture  16 . 
   In the illustrated embodiment, external fluid ports  30  are located on either side of base fixture  16 . If it is desired to accommodate a greater number of electrostatically actuated microvalves  14  ( FIG. 1 ), perhaps by arranging the electrostatically actuated microvalves  14  in a two-dimensional array, then external fluid ports  30  can instead be positioned on the bottom surface of base fixture  16 , if desired. Appropriate changes to internal fluid passageways  28  would of course need to be made to accommodate this variation. 
     FIG. 4  is a partially phantom perspective view of base fixture  16 , illustrating for example the assembly passageways of base fixture  16 . In particular, base fixture  16  includes a number of base fixture securement apertures  34 . In the illustrated embodiment, a total of seven base fixture securement apertures  34  are positioned along either side of base fixture  16 . Base fixture securement apertures  34  may be positioned within recessed clamp fixture receiving region  24  and outside of recessed electrostatically actuated microvalve receiving region  26 . In some instances, at least a portion of base fixture securement apertures  34  may be threaded in order to securely accept a threaded securement such as a screw or a bolt (not illustrated). 
     FIGS. 5 and 7  through  9  are renditions of clamp fixture  18 , each illustrating particular aspects of the internal and external structure of clamp fixture  18 . In particular,  FIG. 5  is a perspective illustration of the external structure of clamp fixture  18 . While clamp fixture  18  may take any appropriate size and geometric shape depending on intended use, in some embodiments, as illustrated, clamp fixture  18  may assume the shape of a rectangular block. In some instances, clamp fixture  18  may include a raised electrostatically actuated microvalve receiving region  36 , which may be configured to at least partially accept array  12  of electrostatically actuated microvalves  14  ( FIG. 1 ). 
   Clamp fixture  18  may be formed of any suitable material and using any suitable technique. In some instances, clamp fixture  18  can be formed by grinding or abrading away material from a rectangular block of any suitable polymeric material such as an acrylic plastic. In some cases, clamp fixture  18  may be molded into the configuration shown for example in  FIG. 5 . 
   As seen for example in  FIG. 5 , raised electrostatically actuated microvalve receiving region  36  may include one or several cavities  38  defining fluid volumes that can be used in conjunction with electrostatically actuated microvalves  14  ( FIG. 1 ). In the illustrated embodiment, raised electrostatically actuated microvalve receiving region  36  includes a total of six cavities  38  arranged in a linear array. A greater or lesser number of cavities  38  may be employed, arranged in any suitable manner, depending on intended use. 
     FIG. 5  also shows several gasket receiving recesses  40 . In the illustrated embodiment, raised electrostatically actuated microvalve receiving region  36  includes a total of six gasket receiving regions  40  arranged in a linear array. A greater or lesser number of gasket receiving regions  40  may be employed, arranged in any suitable manner, depending on intended use. In a particular embodiment, each gasket receiving region  40  is disposed about a corresponding cavity  38 . 
     FIG. 6  is an enlarged perspective view of one of the gaskets  22 . Gasket  22  may be sized and configured to fit at least partially into gasket receiving region  40  ( FIG. 5 ). It can be seen that, in some embodiments, gasket  22  may serve to provide a seal around cavity  38  ( FIG. 5 ). When clamp fixture  18  ( FIG. 1 ) is secured in position within recessed clamp fixture receiving region  26  ( FIG. 2 ) of base fixture  16  ( FIG. 1 ), gasket  22  may also aid in holding electrostatically actuated microvalve  14  ( FIG. 1 ) securely in place. In particular embodiments, array  20  ( FIG. 1 ) of gaskets  22  may hold array  12  ( FIG. 1 ) of electrostatically actuated microvalves  14  securely in place without requiring adhesives or other similar chemicals that may out-gas. 
     FIG. 7  is a partially phantom perspective view of clamp fixture  18 , illustrating for example the internal fluid passageways of clamp fixture  18 . In particular, clamp fixture  18  can be seen as including a total of three internal fluid passageways  42  and three internal fluid passageways  48 . 
   Each internal fluid passageway  42  extends from an external fluid port  44  to an internal fluid port  46  that is fluid communication with cavity  38 . Each internal fluid passageway  48  extends from an external fluid port  50  to an internal fluid port  52  that is fluid communication with cavity  38 . Each external fluid port  50  may be configured to permit tubing or other external fluid passageways to be secured to external fluid port  50 . 
   Each internal fluid passageway  42  and  48  may be sized to accommodate the particular fluid expected during use. Internal fluid passageways  42  and  48  may be formed using any suitable technique. In some instances, internal fluid passageways  42  and  48  may be formed by mechanically drilling into clamp fixture  18 . 
   In the illustrated embodiment, external fluid ports  44  are located on a top surface  54  of clamp fixture  18  while external fluid ports  50  are located along a side  56  of clamp fixture  18 . With reference to top surface  54 , it should be noted that clamp fixture  18  is, for illustrative purposes, oriented upside-down from its position secured to base fixture  16  (see  FIG. 1 ). 
   If it is desired to accommodate a greater number of electrostatically actuated microvalves  14  ( FIG. 1 ), perhaps by arranging the electrostatically actuated microvalves  14  in a two-dimensional array, then external fluid ports  50  can instead be positioned on the top surface  54  of clamp fixture  18 . Appropriate changes to internal fluid passageways  48  would of course need to be made to accommodate this variation. 
     FIG. 8  is a partially phantom perspective view of clamp fixture  18 , illustrating for example internal conductive passageways intended for electrical conduction through clamp fixture  18 . In particular, clamp fixture  18  includes several conducting apertures  60  that each extend from top surface  54  to a bottom surface  62  of raised electrostatically actuated microvalve receiving region  36 . 
   While in some instances an internal surface of conducting aperture  60  may itself be electrically conductive, it is considered rather that conducting aperture  60  is configured to accommodate an electrically conductive member (not illustrated). Any suitable conductive material may be used in forming an electrically conductive member. In some cases, rubber that has been doped or otherwise modified to carry an electrical current may be used. 
   In some instances, a pair of conducting apertures  60  are arranged in alignment with each cavity  38  and can be used to transmit electrical signals to an electrostatically actuated microvalve  14  ( FIG. 1 ) disposed on raised electrostatically actuated microvalve receiving region  36 . In particular, a first pair of conducting apertures  60  may be aligned with a first cavity  38  (and hence a first electrostatically actuated microvalve  14  ( FIG. 1 ), a second pair of conducting apertures  60  may be aligned with a second cavity  38  (and hence a second electrostatically actuated microvalve  14 ), and so on. Conducting apertures  60  may have any suitable dimension and may be formed using any suitable technique. In some embodiments, conductive apertures  60  may be formed by drilling into clamp fixture  18 . 
     FIG. 9  is a partially phantom perspective view of clamp fixture  18 , illustrating for example assembly passageways of clamp fixture  18 . In particular, clamp fixture  18  includes a number of clamp fixture securement apertures  64  extending from top surface  54  to a bottom surface  66  of clamp fixture  18 . In the illustrated embodiment, each assembly passageway  64  includes a widened portion  68  proximate top surface  54  that is configured to accept the top of a threaded securement such as a screw or a bolt (not illustrated). 
   Unlike base fixture securement apertures  34  ( FIG. 4 ), which may extend only partially through base fixture  16 , each clamp fixture securement aperture  68  extends to a bottom end  70  that is in communication with bottom surface  66  of clamp fixture  18 . When clamp fixture  18  is positioned within recessed clamp fixture receiving region  24  ( FIG. 2 ), each clamp fixture securement aperture  68  may align vertically with a corresponding base fixture securement aperture  34 . As a result, clamp fixture  18  may be secured to base fixture  16  and within recessed clamp fixture receiving region  24  by providing appropriate securements through each clamp fixture securement aperture  68  and into the corresponding base fixture securement aperture  34 . 
   In some instances, securements such as threaded securements may be used. Suitable threaded securements include bolts and screws. In other cases, frictionally secured securements may be employed. In the illustrated embodiment, a total of seven clamp fixture securement apertures  68  are positioned along either side of clamp fixture  18 . 
   In  FIG. 1 , array  12  of electrostatically actuated microvalves  14  is shown schematically, in order to show how array  12  fits between base fixture  16  and clamp fixture  18  and how array  12  is in fact secured therebetween. An illustrative electrostatically actuated microvalve  14  has two distinct layers or members.  FIGS. 10 and 11  illustrate, respectively, an illustrative valve aperture layer or member and a valve flap layer or member, respectively. 
     FIG. 10  shows an array  72  of valve aperture members  74 . Each valve aperture member  74  includes a valve aperture  76 . In some embodiments, valve aperture  76  may be in fluid communication with internal fluid port  32  ( FIG. 3 ) positioned within base fixture  16  ( FIG. 3 ). Each valve aperture member  74  also includes an electrical aperture  80 . 
   Electrical aperture  80  can be used to provide electrical communication to an electrode or electrodes (not illustrated) present within valve aperture member  74 . Electrical aperture  80  may be in electrical communication through a conductive member (not seen) extending through conducting aperture  60  ( FIG. 8 ). 
     FIG. 11  shows an array  82  of valve flap members  84 . Each valve flap member  84  includes a void  86  that corresponds in some instances to the location of a respective cavity  38  ( FIG. 5 ) and thus the void  85  overlays cavity  38 . Extending into void  86  is a valve flap  88 . When array  82  of valve flap members  84  is disposed over array  72  of valve aperture members  74  ( FIG. 10 ), each valve flap  88  extends over the corresponding valve aperture  76  ( FIG. 10 ). 
   Each valve flap  88  includes an electrode (not illustrated) that can cause, upon application of an appropriate voltage, each valve flap  88  to move either towards or away from valve aperture  76  ( FIG. 10 ). As such, each valve flap member  84  may include a first electrical aperture  90  and a second electrical aperture  92 . In some cases, first electrical aperture  90  provides electrical communication with the electrode present within valve flap  88  while second electrical aperture  92  represents an aperture through which electrical contact can be made with electrical aperture  80  ( FIG. 10 ). 
   In particular embodiments, first electrical aperture  90  may provide access for an electrical connection with an electrode present within valve flap  88  and may be powered by a conductive member (not seen) extending through conducting aperture  60  ( FIG. 8 ). Second electrical aperture  92  may be an aperture through which a conductive member (not seen) extending through conducting aperture  60  ( FIG. 8 ) may be in electrical contact with electrical aperture  80  ( FIG. 10 ). In some embodiments, electrical communication or contact with the electrode present within valve aperture member  74  ( FIG. 10 ) and the electrode present within valve flap  88  ( FIG. 11 ) may be established after array  72  of valve aperture members  74  and array  82  of valve flap members  84  have been secured between base fixture  16  ( FIG. 1 ) and clamp fixture  18  ( FIG. 1 ). 
   Gaskets  22  ( FIG. 1 ) may be disposed over array  82  of valve flap members  84  or, alternatively, gaskets  22  may be inserted into gasket receiving recesses  40  ( FIG. 5 ), and clamp fixture  18  ( FIG. 1 ) may be disposed within recessed clamp fixture receiving region  26  ( FIG. 2 ) of base fixture  16 . Clamp fixture  18  may be secured to base fixture  16  using securements extending through each clamp fixture securement aperture  68  ( FIG. 9 ) and into each corresponding base fixture securement aperture  34  ( FIG. 4 ). 
   Once the assembly has been completed as such, electrical communication or contact with the electrode present within valve aperture member  74  ( FIG. 10 ) and the electrode present within valve flap  88  ( FIG. 11 ) may be established by inserting conductive members such as conductive rubber plugs through each conducting aperture  60  ( FIG. 8 ). 
   In some embodiments, a first conductive rubber plug may be inserted through a conducting aperture  60  ( FIG. 8 ) such that it contacts or passes into electrical aperture  90  ( FIG. 11 ) and thus provides electrical communication with an electrode present (not illustrated) present within valve flap  88  ( FIG. 11 ). A second conductive rubber plug may be inserted through an adjacent conducting aperture  60  such that it passes through electrical aperture  92  ( FIG. 11  ) and contacts or passes into electrical aperture  80  ( FIG. 10 ) and provides electrical communication with an electrode present (not illustrated) within valve aperture member  74  ( FIG. 10 ). 
   The invention should not be considered limited to the particular examples described above, but rather should be understood to cover all aspects of the invention as set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the invention can be applicable will be readily apparent to those of skill in the art upon review of the instant specification.