Abstract:
A MEMS switch includes a latch mechanism, first and second electrical conductors, a first latch actuator, a second latch actuator, and an axial actuator. The latch mechanism may include a transfer rod and a contact member, the contact member extending radially outwardly from a position along the axial length of the transfer rod. The first and second electrical conductors may extend along, and may be radially offset from, a portion of the transfer rod. The first latch actuator may include a first latch pin, and the second latch actuator may include a second latch pin, the first and second latch actuators being configured to move toward and away from the transfer rod, and the first and second latch pins configured to engage the contact member. The at least one axial actuator may be configured to move the contact member towards and away from the first and second electrical conductors.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage filing based upon International PCT Application No. PCT/US2010/037618, with an international filing date of Jun. 7, 2010, which claims the benefit of the filing date of U.S. provisional application No. 61/217,811, filed Jun. 5, 2009, the entirety of which is incorporated by reference as though fully set forth herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention generally relates to micro-electro-mechanical system (MEMS) devices, including micro switches and technologies such as electro-thermal actuated MEMS latch devices that can hold or retain a contactor in an open or closed state without power being applied. 
       BACKGROUND 
       [0003]    Microelectromechanical systems (MEMS) have recently been developed as alternatives for conventional electromechanical devices such as switches, actuators, valves, and sensors. MEMS are commonly made up of components between 10 to 100 micrometers in size (i.e. 0.01 to 0.1 mm) and some MEMS devices may range in size from 20 micrometer (20 millionth of a meter) up to a millimeter (thousandth of a meter). MEMS devices are potentially low cost devices due to the use of microelectronic fabrication techniques. New functionality and low power consumption may also be provided because MEMS devices can be much smaller than conventional electromechanical devices. 
         [0004]    There are needs for MEMS switches that can generate a relatively high contact force for switching signal lines carrying relatively high power. There is also a need to provide a MEMS switch that can remain in an open or closed state without requiring input electrical power to hold or maintain it in that state. 
         [0005]    For some applications, it may be desirable to provide a MEMS actuator that is capable of moving a MEMS latch device to an open state while generating relatively high force and retaining the latch in plane while it moves. Some other actuation techniques have been employed in connection with MEMS actuator design. In MEMS switches, electrostatic and electromagnetic devices normally provide fast switching speeds. Electrostatically actuated switches however can require significantly large voltage levels yet only deliver small displacement and small force levels. Electromagnetic switches can often require large actuation power and difficult fabrication processes due to the material compatibility issues with other conventional MEMS materials such as silicon. It is desirable to provide a MEMS switch that can address or mitigate some or all of the foregoing constraints. 
         [0006]    Another potential challenge with current MEMS devices is that the mechanisms that generate force and movement often tend to move out of the plane of desired direction of travel. It would improve device efficiency if there was a method that could restrict the out-of-plane displacement without affecting the in plane movement of the device. 
       SUMMARY 
       [0007]    The disclosed electro-mechanical/thermal MEMS switch employs a latching mechanism that may be configured to hold or retain a contactor in an open or closed position without requiring the application of electrical power to hold or retain the contactor in that position. The disclosed MEMS switch employs actuators that may be electro-thermal and can be fabricated, for example and without limitation, using fabrication techniques called PolyMUMPs or MetalMUMPS such as used by the MEMSCAP company. Actuators provided in accordance with the disclosed actuator design may be referred to as a “V-shape actuator,” and can provide for high actuation forces while the device generally remains in-plane. For instance, as discussed in the instant disclosure, such actuators may be employed to move a contactor into a closed state, but may also be employed to move a contactor into an open state. A spring force can be provided to return the contactor to the opposite state. In embodiments, actuators may be used to pull at least one latch pin away from the contactor when it is desired to move the contactor to the other state (open or closed). It is recognized that features associated with other types of MEMS actuators may be utilized to pull the latch pin(s) and/or move the contactor into another state. In an embodiment, the actuation can be sequenced, and a programmable switch can be actuated and latched to “on” and “off” states whether or not actuator power is removed at the end of the sequence. Design requirements such as the magnitude of contact force, reliable alignment of the electrical contacts, and reduced out-of-plane displacement can be realized employing teachings of this disclosure. In embodiments, a device to prevent warping or twisting of the electro-thermal actuators may comprise, for example, a post mounted to a substrate above the latch pin to prevent sideway movement when holding the contactor in position. Electro-thermal MEMS actuators may have many applications because of their capability of producing large forces and relatively long travel. Moreover, by selecting a suitable material (by way of example, without limitation, a metal as used in MetalMUMPS technology), a lower actuation voltage may be possible. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a perspective view of an embodiment of a MEMS switch device including a MEMS latch mechanism and a plurality of electro-thermal actuators; 
           [0009]      FIG. 2  shows a plan view of an embodiment of a MEMS latch mechanism shown in an open state; 
           [0010]      FIG. 3  shows a plan view of the MEMS latch mechanism of the type generally illustrated in  FIG. 2  with the MEMS latch mechanism shown in an open state transitioning to a closed state; 
           [0011]      FIG. 4  shows the plan view of the MEMS latch mechanism of the type generally illustrated in  FIG. 2  with the MEMS latch mechanism shown in a closed state but unlatched; 
           [0012]      FIG. 5  shows the plan view of the MEMS latch mechanism of the type generally illustrated in  FIG. 2  with the MEMS latch mechanism shown in a closed state and latched; 
           [0013]      FIG. 6  shows a plan view of an embodiment of an electro-thermal actuator connected to a displacement amplification beam; 
           [0014]      FIG. 7  shows a plan view of an embodiment of components of V-shaped electro-thermal actuators; 
           [0015]      FIG. 8  shows a cross-sectional view of an embodiment of a MEMS device under fabrication with a substrate and an electrical isolation and anchor layer; 
           [0016]      FIG. 9  shows a cross-sectional view of an embodiment of a MEMS device of the type illustrated in  FIG. 8 , including a substrate layer, a sacrificial layer, and a polysilicon microstructure (e.g., actuator beam); 
           [0017]      FIG. 10  shows a cross-sectional view of an embodiment of a MEMS device of the type generally illustrated in  FIG. 9 , including a layer covering the microstructure; 
           [0018]      FIG. 11  shows the cross-sectional view of an embodiment of a MEMS device of the type generally illustrated in  FIG. 10  with sacrificial layer(s) removed or etched away; 
           [0019]      FIG. 11A  shows a cross-sectional view of an alternative embodiment of a MEMS device with a sacrificial layer(s) removed or etched away; 
           [0020]      FIG. 12  shows a top plan view of an embodiment of a MEMS latch mechanism of the type generally illustrated in  FIG. 4 , including an installed post that can be configured to, inter alia, reduce in-plane twisting of latching actuators; 
           [0021]      FIG. 13  shows a side plan view of an embodiment of a MEMS latch mechanism of the type generally illustrated in  FIG. 12 ; and 
           [0022]      FIG. 14  shows a perspective view of an embodiment of a MEMS switch device, including a MEMS latch mechanism and an axial electro-thermal actuator that can generate an in-plane displacement. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Reference will now be made in detail to embodiments of the disclosure, examples of which are described herein and illustrated in the accompanying drawings. While the inventive concepts will be described in conjunction with embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention. 
         [0024]    Referring to  FIG. 1  of the drawings, a perspective view of an embodiment of a MEMS switch  10  is shown including a latch switch mechanism  2 , which is described in more detail with reference to  FIGS. 2-5 . The latch mechanism  2  may be configured to function in a manner that allows electrical power to be removed from latch actuators  12  and  14  and from axial actuators  22 ,  24 ,  26  and  28  when the latch switch mechanism  2  is either in an open state or in a closed state. An “open” state may be said to occur when conductors (which may also be referred to as electrical contacts)  8   a  and  8   b  are electrically isolated. A “closed” state may be said to occur when the electrical conductors  8   a  and  8   b  are electrically shorted—such as via contactors  15  provided on a lateral contact member  40 . 
         [0025]    In embodiments, latch actuators  12  and  14  may be electrically energized when it is desired to actuate a corresponding latch switch mechanism  2 . After the latch actuators  12  and  14  have energized the latch switch mechanism  2 , such as by pulling latch pins  38   a  and  38   b  away from an interposed contactor  15  that may be attached or connected to contact member  40 , one or more axial actuators (e.g., illustrated axial actuators  22 ,  24 ,  26  and  28 ) may be energized and may act to move the contactor  15  (vis-à-vis a transfer rod  16 ) towards two or more conductors  8   a  and  8   b . In embodiments, the contactor  15  may be moved to the point in which associated conductors  8   a  and  8   b  are shorted together by the contactor  15 . Thereafter, the electrical current to the latch actuators  12  and  14  may be removed, and the latch actuators  12  and  14 , along with attached latch pins  38   a  and  38   b , may be moved back into non-energized positions, thereby latching the contactor  15  into a closed position in which associated latch pins  38   a  and  38   b  may engage the contactor  15  and hold or retain the contactor  15  in a closed position. 
         [0026]    When it is desired to open the conductors  8   a  and  8   b , electrical power may first be applied to the latch actuators  12  and  14 , which in turn may pull the latch pins  38   a  and  38   b  away from the contactor  15 . Springs  18  and  30  can be configured (e.g., pre-loaded) to push and pull, respectively, an associated transfer rod  16  in a direction to cause the contactor  15 , which may be attached to the transfer rod  16  via contact member  40 , to open conductors  38   a  and  38   b.    
         [0027]    A plane spring  34  may be provided, and can be oriented to hold the transfer rod  16  and an amplification link  36  in position in a plane (e.g., the illustrated Z plane). Such a plane spring  34  can be configured to prevent the transfer rod  16  and the amplification link  36  from lifting away from the desired direction of travel along an associated Y-axis and thereby lowering the efficiency of the MEMS switch  10 . In the art, this may be referred to as moving “out of plane.” 
         [0028]    Now referring to  FIGS. 2-5  of the drawings, cross-sectional views of an embodiment of a latch switch mechanism  2  are shown in various states of activation.  FIG. 2  illustrates an embodiment of a latch switch mechanism  2  in a latched position with a contactor  15  separated (e.g., vertically disposed) from associated conductors (or signal lines)  8   a ,  8   b . In the illustrated embodiment, the latch switch mechanism  2  may be said to be in an open position. In such a configuration, no electrical current has generally been applied to the latch actuators  12 ,  14  or to associated axial actuators (e.g., axial actuators  22 ,  24 ,  26  and  28 ). 
         [0029]      FIG. 3  generally illustrates the latch switch mechanism  2  where an electrical current has been applied to associated latch actuators  12  and  14  (see e.g.,  FIG. 1 ) resulting in the urging or pulling of respective latch pins  38   a  and  38   b  away from the contactor  15 , thereby allowing the contactor to be moved by forces (e.g., associated with springs  18  and  30 ) towards the conductors  8   a  and  8   b . Now referring to  FIG. 4 , the latch switch mechanism  2  is shown as the contactor  15  has moved to make electrical contact with the conductors  8   a  and  8   b , causing the MEMS switch  10  to be switched from an open to a closed state. To axially move the contactor  15  towards the conductors  8   a  and  8   b , electrical current is supplied to axial actuators (e.g., illustrated axial actuators  22 ,  24 ,  26  and  28 ) which causes a force to be generated by the axial actuators on an amplification (or closing) link  36 , resulting in the amplification link  36  axially moving the transfer rod  16  and the contactor  15  (attached or connected to the transfer rod  16  via contact member  40 ) towards the closed position. In embodiments, portions (e.g., radially outward ends) of the contact member  40 , where contactors  15  are attached or connected, may be configured to connect or interconnect with ends of respective latch pins (e.g., radially inward ends of  38   a  and  38   b ). For example and without limitation, in an embodiment, the respective ends of the contact member  40  and latch pins may be configured to include angular end surfaces that substantially complement each other. However, the invention is not limited to the illustrated interconnecting configurations, and other forms of interconnection are contemplated. 
         [0030]    After the contactor  15  makes electrical contact with the conductors  8   a  and  8   b , the latch pins  38   a  and  38   b  may be permitted to move back inwardly towards the contactor  15  when the electrical current is removed from the latch actuators  12  and  14 . An embodiment of a “closed and latched” state is illustrated in  FIG. 5 . In this state, the current is generally removed from both the latch actuators  12 ,  14  and the axial actuators (e.g., axial actuators  22 ,  24 ,  26  and  28 ), and the latch switch mechanism  2  may generally be retained or held in a closed state without the consumption of additional electrical power. 
         [0031]    When it is desired to move the latch switch mechanism  2  back into an open state, electrical current may be supplied to the latch actuators  12  and  14 , and the latch pins  38   a ,  38   b  may be moved away from the contactor  15  by force(s) generated by one or more latch actuators (e.g., latch actuators  12  and  14 ). Springs  18  and  30  can be configured and oriented to move the transfer rod  16  and the connected or attached contactor  15  away from the conductors  8   a  and  8   b . The electrical current may then be removed from the latch actuators  12  and  14 , and the latch switch mechanism  2  may then return to a state such as shown in FIG.  2 —wherein the MEMS switch  10  is again in an open state with essentially no conductivity between the conductors  8   a  and  8   b . Additional conductors can be included and employed in a similar manner. 
         [0032]    Now referring to  FIG. 6 , a perspective view of an embodiment of a pair of axial actuators  50 —including axial actuators  22  and  24 —is generally shown. Axial actuator  24  may be configured substantially as a mirror image of axial actuator  22  and, given the orientation, axial actuator  24  may move in an opposite direction to that of actuator  22  when an electrical current is applied to each. When such an electrical current is supplied, the result may be an axial motion of an amplification link  36  (resulting in an axial movement of transfer rod  16  and contactors  15 ). The relative spacing of actuators  22  and  24  compared to the length of amplification link  36 , can be configured to result in a larger (or amplified) displacement of the distal end of the amplification link  36  as compared to a relatively small displacement of actuators  22  and  24 . Embodiments of such a motion may, for instance, be the result of a unique configuration/nature of the axial actuators. For example, without limitation axial actuators  22 ,  24 ,  26 ,  28  may utilize a “Chevron Beam” actuator and a cold and hot beam actuator with unequal length hot beams in each actuator. For a further understanding of how a MEMS switch  10  may be fabricated, one may refer to “PolyMUMPs Design Handbook, Rev. 11.0” by Carter, Cowen, Hardy, Mahadevan, Stonefield and Wilcenski, and “Metal MUMPs Design Handbook, Rev. 2.0 by Cowen, Mahadevan, Johnson and Hasly, both from MEMSCAP Company. To further understand how the latch actuators (e.g., latch actuators  12  and  14 ) and the axial actuators (e.g., axial actuators  22 ,  24 ,  26 ,  28 ) may be configured to operate, one may refer to the paper “Design and Fabrication of a Low Power Electro-thermal V-shape Actuator With Large Displacement” by Khazaai, Haris, Qu and Slicker as published by Oakland University. 
         [0033]    With further reference to  FIG. 6 , two hot beams  52   a  and  52   b  may be used with an associated axial actuator  50 . Actuator  50  may be generally illustrative of any or all of the actuators of the MEMS switch  10 , including, for instance, latch actuators  12  and  14 , and axial actuators  22 ,  24 ,  26  and  28 . As generally illustrated, two hot beams  52   a  and  52   b  may be attached or connected at or about their respective centers, and may be attached to a joint link pin  60 , which in turn may be connected or attached to a central base  62 . If the central base  62  is considered part of the hot beam/arm, the center piece on actuator  50  (which is the counterpart of  66  in the other side actuator (actuator  22 ). The hot beams  52   a  and  52   b  may be attached at one end to an end support  54   a  and at an opposite ends to another end support  54   b . As generally shown, a cold beam comprising  56  may be provided, and may also include end supports  58   a  and  58   b . In an embodiment, the cold beam can be attached to a central base  62  (which may have a different (e.g., increased) width), and the central base  62  may, in turn, be connected or attached to the joint link pin  60 . The central base  62  can also be attached to an amplification link  36  via a link pin  64  (see, e.g.,  FIG. 1 ). In embodiments, a complementary axial actuator  24  may be provided and coordinated with opposed axial actuator  22 , axial actuator  24  may be attached or connected to a common amplification beam  36  at an offset location (with respect to link pin  64 ) via link pin  66 . Additionally, with respect to the connections between the two pieces of the polysilicon structure  84  in the embodiments shown in  FIG. 5  and  FIG. 6 , the lower portions thereof, are may not necessarily be “inserted” into the upper portions as generally illustrated. Rather, such pieces may be “stacked” with a substantially flat interface. 
         [0034]    It is noted that the various actuators—including latch actuators  12 ,  14 , and axial actuators  22 ,  24 ,  26  and  28 —may be made in a substantially similar fashion, and the actuators can be configured to generally function in similar manners. The concept, however, contemplates that other known types of actuators may be used to supply a needed or similarly desired operation or motion. By way of example, without limitation, electrostatic and other electrothermal types and bimetal actuators may be used in conjunction with a latch switch mechanism, including a latch switch mechanism  2  of the types shown. 
         [0035]    In embodiments, including those generally illustrated, the associated hot and cold beams may not be configured such that the respective beams are parallel. Further, the hot beams of the latch actuators  12 ,  14  may be configured in a pre-loaded condition to, among other things, supply a spring like force to the latch pins  38   a ,  38   b , which may urge or force them inwardly to latch the contactor  15  in either a closed or open state without necessitating the application or consumption of electrical power. The two opposed “U-shaped” actuators  46  and  48  of the actuator pair  50 , such as generally illustrated, may provide for improved in-plane travel and permit the generation of larger forces and increased displacement with application of the same level of electrical current as supplied to conventional MEMS actuators. This improved operational performance may be achieved, in part, through the use of polysilicon for the actuator beams and fabrication of the MEMS switch  10  using a process known as PolyMUMPs. The MUMPs fabrication process may, for example, follow that described in a publication entitled “PolyMUMPs Design Handbook Rev. 13.0,” as previously cited. However, it is contemplated that other known materials such as nickel may be used for various parts of the MEMS switch  10 , and that other known fabrication processes, such as MetalMUMPs technology, may be utilized to provide desired results. 
         [0036]    Turning to  FIG. 7 , a plan view of an embodiment of a V-shaped actuator for a MEMS switch is shown. The V-shaped actuator  70  of the illustrated embodiment includes two modified “U-shaped” actuators  72   a ,  72   b , which may function as a pair, and which may be uniquely connected or linked to form a V-shaped actuator  70  if mirrored. As illustrated, wide beams (arms)  74   a ,  74   b  may be respectively connected to narrow beams (or narrow/hot arms)  76   a ,  76   b  and a relative angle θ A , θ B  may be formed between the respective link arms  80   a  and  80   b  and the wide arms  74   a  and  74   b , respectively. The non-perpendicular geometry between the hot arms  76   a  and  76   b  can not only help ensure a desired in-plane direction of movement of the hot arms  76   a  and  76   b , but can also serve to increase overall travel, particularly as compared to conventional MEMS devices. The angles θ A  and θ B , and the difference in length between two or more hot beams (see e.g.,  FIG. 6 ), may help optimize a design and/or a level of performance. 
         [0037]    Now referring once again to  FIG. 1 , axial actuators  22 ,  24 ,  26  and  28  may be arranged in opposed pairs. For example, axial actuators  22  and  24  may geometrically oppose one another and may generate a motion in opposite directions upon the application of electrical current. In a similar fashion, axial actuators  26  and  28  may oppose one another&#39;s direction of travel when an electrical current is applied across the hot beams of the actuators. For example, considering axial actuator  22 , an electrical current may cause hot beams  52   a  and  52   b  to expand and force a connecting pin  64  forward towards an amplification link  36 . In a like fashion, axial actuator  24  may move with the application of electrical current and apply a forward force through link pin  70  to the amplification link  36 . Since the positions of link pins  64  and  70  may be displaced with respect to one another along the amplification link  36 , a moment torque can be introduced on the amplification link  36 , and may result in a much greater displacement at the center of the amplification link  36 —e.g., at or about where the transfer rod  16  is attached to the amplification link  36 —as compared to the displacement of axial actuator  22  or  24  individually. 
         [0038]    Referring to  FIGS. 8-11 , illustrative cross-sectional drawings of the fabrication process are shown. This process is sometimes referred to in the art as a PolyMUMPs foundry service, such as provided by the MEMSCAP company. A more detailed description of such a fabrication process can be found, for instance, in a publication entitled “PolyMUMPs Design Handbook” v 11.0. 
         [0039]      FIG. 8  illustrates a cross-sectional view of an embodiment of a MEMS device under fabrication, the device including a substrate and a coating (e.g., an isolation and anchor) layer. For example, with reference to the illustrated embodiment, a substrate  80 , which may comprise a single crystal silicon layer, may be coated with a coating layer  82 , which may comprise silicon nitrate (SiN). Such a coating layer  82  may provide one or more functions, including, for example, providing electrical isolation from the substrate, and/or providing a mechanical anchor to the substrate. 
         [0040]      FIG. 9  depicts a cross-sectional view of another embodiment of a MEMS device similar to that generally illustrated in  FIG. 8 . However, the instant embodiment includes a substrate layer and a polysilicon microstructure (e.g., an actuator beam). That is, as generally shown, a polysilicon structure  84  may make up an element of the MEMS switch  10  applied over a sacrificial layer  83 , for example, silicon dioxide (SiO 2 ). 
         [0041]      FIG. 10  shows a cross-sectional view of another embodiment of a MEMS device similar to that generally illustrated in  FIG. 9  that includes a layer covering the microstructure, such as gold or aluminum. That is, as generally shown, a cover layer  86  may be added over the polysilicon structure  84  and over the sacrificial layer  83 . The covering layer  86  can, among other things, provide for electrical connection with the polysilicon structure  84 . Moreover, for a number of embodiments, it may be desirable to provide just a small length of covering layer  86  so that it does not surround the polysilicon structure  84 . 
         [0042]      FIG. 11  illustrates a cross-sectional view of an embodiment of a MEMS device of the type generally illustrated in  FIG. 10 , but having selected layers removed or etched away. In an embodiment, for example, a sacrificial layer  83  may be largely removed, for instance, with a wet etching process thereby providing a functional MEMS device. In an embodiment, for example, remaining after the etch removal may be a small support pad  88  under a polysilicon structure  84  and an electrical contact pad  80  on the top surface of a polysilicon structure  84 . 
         [0043]    A cross-sectional view of another embodiment of a MEMS device is generally illustrated in  FIG. 11A . In the instant embodiment, substrate  80  may be comprised of the same material as the cover layer  80 ′. It is noted that when a piece of metal is provided on a bonding pad, the element may be referred to as pad metal. With the instant illustration, the material of the support pad  88  may comprise the same material as the polysilicon structure  84 ; however, it is noted that the pad and structure may be formed in different/separate steps. Further, the support pad  88  may only be provided in portions where electrical signals may need to be applied to, or extracted from, the polysilicon structure  84 . 
         [0044]    Now referring to  FIG. 12 , a top plan view of the latch mechanism (similar to that illustrated in  FIG. 4 ) is shown having a pair of posts  90   a  and  90   b . Post  90   a  may be configured to hold or retain latch pin  38   a  from deflecting laterally from a desired path of displacement or travel and twisting the latch actuator  12  when it is holding contactor  15  against conductors  8   a  and  8   b . In a substantially similar manner, post  90   b  may be configured to prevent latch pin  38   b  from deflecting laterally and twisting the latch actuator structure  14  when it is holding contactor  15  against conductors  8   a  and  8   b .  FIG. 13  shows a side plan view of a latch mechanism of the type generally shown in  FIG. 12  having a post  90   a . In this side view, the structure of the posts  90   a  and  90   b  is more clearly shown. In the illustrated embodiment, the post  90   a , may be connected or mounted to the substrate, for example, as shown in  FIGS. 8-11 . However, the inventive concept is not limited to the disclosed configurations, and various other configurations are contemplated that can serve or function to hold the moving structures of the MEMS switch  10  in a desired plane of travel. 
         [0045]    Now referring to  FIG. 14  of the drawings, a perspective view of another embodiment of a MEMS switch  10 ′ is generally shown. This MEMS switch  10 ′ may be substantially similar to the MEMS switch  10  shown in  FIG. 1 ; however, axial actuators  24 ,  26  and  28  and amplification link  36  have been eliminated. In the illustrated embodiment, axial actuator  22 ′ may be configured to provide sufficient actuation force and travel so that a “teeter-totter” arrangement of axial actuators (e.g., as shown with axial actuators  22 ,  24 ,  26  and  28  in  FIG. 1 ) on the amplification link is no longer necessary to generate sufficient travel at the transfer rod  16 ′ to operate the latch mechanism  2 ′. As generally shown, the amplification link  36  may be replaced with single actuator  22 ′ that may provide similar functionality. However, since only one axial actuator  22 ′ is employed, no moment is introduced at the transfer link&#39;s end sections. The axial actuator  22 ′ may be configured to generate force in a direction to cause the contact member  40 ′ to move and electrically short the conductors  8   a ′ and  8   b ′. The axial actuator  22 ′ may be configured to function substantially to electro-thermal V-shaped actuators, although other types of MEMS actuators may be provided to generate the required force and displacement to operate a latch mechanism  2 ′ It is noted that the replacement of the displacement amplification arrangement of  FIG. 1  by a single actuator  22 ′ of  FIG. 14  may be enabled by, for example, by a METALMUMPS process, which can allow for greater displacements than a POLYMUMPS process. 
         [0046]    The illustrated MEMS switch  10 ′ includes a latch switch mechanism  2 ′ which may generally function as previously described in connection with  FIGS. 2-5  and  12 - 13 . The latch mechanism  2 ′ functions in a manner that allow for electrical power to be removed from latch actuators  12 ′ and  14 ′ and from axial actuator  22 ′ when the latch switch mechanism  2 ′ is either in an open state or in a closed state. The open state may generally be defined as when the electrical contacts  8   a ′ and  8   b ′ are electrically isolated, and the closed state may generally be defined as when the electrical contacts  8   a ′ and  8   b ′ are electrically shorted. 
         [0047]    The latch actuators  12 ′ and  14 ′ may be electrically energized when it is desired to actuate the latch switch mechanism  2 ′. After the latch actuators  12 ′ and  14 ′ have energized the latch switch mechanism  2 ′ by pulling the latch pins  38   a ′ and  38   b ′ away from the contactor  15 ′, the axial actuator  22 ′ can be energized and act to move the contactor  15 ′ (via a transfer rod  16 ′) towards two or more conductors  8   a ′ and  8   b ′ until the conductors  8   a ′ and  8   b ′ are shorted together by the contactor  15 ′. Thereafter, the electrical current to the latch actuators  12 ′ and  14 ′ can be removed, and the latch actuators  12 ′ and  14 ′ (along with the attached latch pins  38   a ′ and  38   b ′) may move back into their non-energized positions, thereby latching the contactor  15 ′ into a closed position where the latch pins  38   a ′ and  38   b ′ engage the contactor  15 ′ and hold it in a closed position. Then power may be removed from actuator  22 ′ after the contactor  15 ′ is latched into place. It is noted that actuator  22 ′ should be designed to have only sufficient force to move contact member  40 ′ into position to be clamped by latch pins  38   a ′ and  38   b ′. The actuator  22 ′ ideally should not apply any excessive amount of force to the contact member  40 ′ since the extra force may pull in the opposite direction when power is removed from actuator  22 ′ after the latch pins  38   a ′ and  38   b ′ have clamped contact element  40 ′ into place. The excessive force of actuator  22 ′ may reduce the contact force applied by latch pins  38   a ′ and  38   b ′. Alternatively a spring may be inserted between actuator  22 ′ and transfer rod  16 ′ to mitigate any extra force that may be supplied by actuator  22 ′. 
         [0048]    When it is desired to open the conductors  8   a ′ and  8   b ′, the electrical power may first be applied to the latch actuators  12 ′ and  14 ′, which in turn pull the latch pins  38   a ′ and  38   b ′ away from the contactor  15 ′. Spring  18 ′ can be pre-loaded to push respectively, the transfer rod  16 ′ in a direction to cause the contactor  15 ′, which is attached to the transfer rod  16 ′, to open the conductors  38   a ′ and  38   b′.    
         [0049]    In embodiments, a single V-shaped axial actuator (such as axial actuator  22 ′) can be configured and optimized to provide minimal out-of-plane displacement, including upon actuation. Consequently a plane spring  34  in a “teeter-totter” configuration (such as illustrated in  FIG. 1 ) may not be necessary. For instance, a center link  64 ′ of an axial actuator  22 ′ can be connected to a transfer rod  16  directly to provide an increased y-direction in-plane displacement. 
         [0050]    Referring again to  FIG. 14 , the axial actuator  22 ′ generates a motion upon the application of electrical current. For example, considering axial actuator  22 ′, the electrical current causes the hot beams  52   a ′ and  52   b ′ to expand and force the connecting pin  64 ′ forward towards transfer rod  16 . This force and movement of actuator  22 ′ is transferred to the transfer rod  16  and then to the contact member  40 ′ to move towards the conductors  8   a ′ and  8   b ′, to contact and close the MEMS switch  10 ′. When it is desired to once again open the MEMS switch  10 ′, the latch pins  38   a ′ and  38   b ′ may be moved away by latch actuators  12 ′ and  14 ′, where the springs  18 ′ operating between the mounting pads  20 ′ and on the transfer rod  16 ′ may act to force the transfer rod  16 ′ so that the contact member  40 ′ is moved away from the conductors  8   a ′ and  8   b ′. The MEMS switch  10 ′ may once again be provided in an open position. 
         [0051]    Although numerous embodiments of this invention have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.