Electronically latching micro-magnetic switches and method of operating same

This application is a continuation in part of application Ser. No. 09/496,446, filed Feb. 2, 2000 which claims priority of Provisional Application Serial No. 60/155,757 filed Sep. 23, 1999.

Partial funding for the development of this invention was provided by U.S. Government Grant Number Air Force SBIR F29601-99-C-0101, Subcontract No. ML99-01 with the United States Air Force; and the United States Government may own certain rights to this invention.

FIELD OF THE INVENTION

The present invention relates to electronic and optical switches. More specifically, the present invention relates to latching micro-magnetic switches with low power consumption and to methods of formulating and operating micro-magnetic switches.

BACKGROUND OF THE INVENTION

Switches are typically electrically controlled two-state devices that open and close contacts to effect operation of devices in an electrical or optical circuit. Relays, for example, typically function as switches that activate or de-activate portions of electrical, optical or other devices. Relays are commonly used in many applications including telecommunications, radio frequency (RF) communications, portable electronics, consumer and industrial electronics, aerospace, and other systems. More recently, optical switches (also referred to as “optical relays” or simply “relays” herein) have been used to switch optical signals (such as those in optical communication systems) from one path to another.

Although the earliest relays were mechanical or solid-state devices, recent developments in micro-electro-mechanical systems (MEMS) technologies and microelectronics manufacturing have made micro-electrostatic and micro-magnetic relays possible. Such micro-magnetic relays typically include an electromagnet that energizes an armature to make or break an electrical contact. When the magnet is de-energized, a spring or other mechanical force typically restores the armature to a quiescent position. Such relays typically exhibit a number of marked disadvantages, however, in that they generally exhibit only a single stable output (i.e. the quiescent state) and they are not latching (i.e. they do not retain a constant output as power is removed from the relay). Moreover, the spring required by conventional micro-magnetic relays may degrade or break over time.

Another micro-magnetic relay is described in U.S. Pat. No. 5,847,631 issued to Taylor et al. on Dec. 8, 1998, the entirety of which is incorporated herein by reference. The relay disclosed in this reference includes a permanent magnet and an electromagnet for generating a magnetic field that intermittently opposes the field generated by the permanent magnet. Although this relay purports to be bi-stable, the relay requires consumption of power in the electromagnet to maintain at least one of the output states. Moreover, the power required to generate the opposing field would be significant, thus making the relay less desirable for use in space, portable electronics, and other applications that demand low power consumption.

A bi-stable, latching switch that does not require power to hold the states is therefore desired. Such a switch should also be reliable, simple in design, low-cost and easy to manufacture, and should be useful in optical and/or electrical environments.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The above and other features and advantages of the present invention are hereinafter described in the following detailed description of illustrative embodiments to be read in conjunction with the accompanying drawing figures, wherein like reference numerals are used to identify the same or similar parts in the similar views, and:

FIGS. 1A and 1B

are side and top views, respectively, of an exemplary embodiment of a switch;

FIGS. 2A-H

are side views showing an exemplary technique for manufacturing a switch;

FIGS. 3A and 3B

are side and top views, respectively, of a second exemplary embodiment of a switch;

FIG. 3C

is a perspective view of an exemplary cantilever suitable for use with the second exemplary embodiment of a switch;

FIG. 3D

is a perspective of an exemplary embodiment of a switch that includes sectionalized magnetically sensitive members;

FIG. 3E

is a side view of an exemplary cantilever that includes multiple magnetically sensitive layers;

FIGS. 4A and 4B

are exemplary side and top views of a third exemplary embodiment of a latching relay;

FIGS. 4C and 4D

are perspective views of exemplary cantilevers suitable for use with the third exemplary embodiment of a latching relay;

FIG. 5

is a side view of a fourth exemplary embodiment of a latching relay;

FIGS. 6A and 6B

are side and top views, respectively, of a fifth exemplary embodiment of a latching relay;

FIGS. 7A and 7B

are side and top views, respectively, of an exemplary “Type I” mirror;

FIGS. 8A and 8B

are side and top views, respectively, of an exemplary “Type II” mirror in a horizontal orientation;

FIGS. 8C and 8D

are side and top views, respectively, of an exemplary “Type II” mirror in a vertical orientation;

FIG. 8E

is a side view of an exemplary second embodiment of a reflecting mirror;

FIGS. 8F and 8G

are top and side views, respectively, of an exemplary third embodiment of a reflector/mirror;

FIGS. 9A and 9B

are side and top views of an exemplary switch in a first state;

FIGS. 10A and 10B

are side and top views of an exemplary switch in a second state; and

FIG. 11

is a top view of an exemplary 5×5 optical switch.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

It should be appreciated that the particular implementations shown and described herein are examples of the invention and are not intended to otherwise limit the scope of the present invention in any way. Indeed, for the sake of brevity, conventional electronics, manufacturing, MEMS technologies and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail herein. Furthermore, for purposes of brevity, the invention is frequently described herein as pertaining to a micro-electronically-machined relay for use in electrical or electronic systems. It should be appreciated that many other manufacturing techniques could be used to create the relays described herein, and that the techniques described herein could be used in mechanical relays, optical relays or any other switching device. Further, the techniques would be suitable for application in electrical systems, optical systems, consumer electronics, industrial electronics, wireless systems, space applications, or any other application. Moreover, it should be understood that the spatial descriptions (e.g. “above”, “below”, “up”, “down”, etc.) made herein are for purposes of illustration only, and that practical latching relays may be spatially arranged in any orientation or manner. Arrays of these relays can also be formed by connecting them in appropriate ways and with appropriate devices.

A Latching Switch

FIGS. 1A and 1B

show side and top views, respectively, of a latching switch. With reference to

FIGS. 1A and 1B

, an exemplary latching relay

100

suitably includes a magnet

102

, a substrate

104

, an insulating layer

106

housing a conductor

114

, a contact

108

and a cantilever

112

positioned above substrate by a staging layer

110

.

Magnet

102

is any type of magnet such as a permanent magnet, an electromagnet, or any other type of magnet capable of generating a magnetic field H

o

134

, as described more fully below. In an exemplary embodiment, magnet

102

is a Model 59-P09213T001 magnet available from the Dexter Magnetic Technologies corporation of Fremont, Calif., although of course other types of magnets could be used. Magnetic field

134

may be generated in any manner and with any magnitude, such as from about 1 Oersted to 10

4

Oersted or more. In the exemplary embodiment shown in

FIG. 1

, magnetic field H

o

134

may be generated approximately parallel to the Z axis and with a magnitude on the order of about 370 Oersted, although other embodiments will use varying orientations and magnitudes for magnetic field

134

. In various embodiments, a single magnet

102

may be used in conjunction with a number of relays

100

sharing a common substrate

104

.

Substrate

104

is formed of any type of substrate material such as silicon, gallium arsenide, glass, plastic, metal or any other substrate material. In various embodiments, substrate

104

may be coated with an insulating material (such as an oxide) and planarized or otherwise made flat. In various embodiments, a number of latching relays

100

may share a single substrate

104

. Alternatively, other devices (such as transistors, diodes, or other electronic devices) could be formed upon substrate

104

along with one or more relays

100

using, for example, conventional integrated circuit manufacturing techniques. Alternatively, magnet

102

could be used as a substrate and the additional components discussed below could be formed directly on magnet

102

. In such embodiments, a separate substrate

104

may not be required.

Insulating layer

106

is formed of any material such as oxide or another insulator such as a thin-film insulator. In an exemplary embodiment, insulating layer is formed of Probimide 7510 material. Insulating layer

106

suitably houses conductor

114

. Conductor

114

is shown in

FIGS. 1A and 1B

to be a single conductor having two ends

126

and

128

arranged in a coil pattern. Alternate embodiments of conductor

114

use single or multiple conducting segments arranged in any suitable pattern such as a meander pattern, a serpentine pattern, a random pattern, or any other pattern. Conductor

114

is formed of any material capable of conducting electricity such as gold silver, copper, aluminum, metal or the like. As conductor

114

conducts electricity, a magnetic field is generated around conductor

114

as discussed more fully below.

Cantilever

112

is any armature, extension, outcropping or member that is cap able of being affected by magnetic force. In the embodiment shown in

FIG. 1A

, cantilever

112

suitably includes a magnetic layer

118

and a conducting layer

120

. Magnetic layer

118

may be formulated of permalloy (such as NiFe alloy) or any other magnetically sensitive material. Conducting layer

120

may be formulated of gold, silver, copper, aluminum, metal or any other conducting material. In various embodiments, cantilever

112

exhibits two states corresponding to whether relay

100

is “open” or “closed”, as described more fully below. In many embodiments, relay

100

is said to be “closed” when a conducting layer

120

connects staging layer

110

to contact

108

. Conversely, the relay may be said to be “open” when cantilever

112

is not in electrical contact with contact

108

. Because cantilever

112

may physically move in and out of contact with contact

108

, various embodiments of cantilever

112

will be made flexible so that cantilever

112

can bend as appropriate. Flexibility maybe created by varying the thickness of the cantilever (or its various component layers), by patterning or otherwise making holes or cuts in the cantilever, or by using increasingly flexible materials. Alternatively, cantilever

112

can be made into a “hinged” arrangement such as that described below in conjunction with FIG.

3

. Although of course the dimensions of cantilever

112

may vary dramatically from implementation to implementation, an exemplary cantilever

112

suitable for use in a micro-magnetic relay

100

may be on the order of 10-1000 microns in length, 1-40 microns in thickness, and 2-600 microns in width. For example, an exemplary cantilever in accordance with the embodiment shown in

FIG. 1

may have dimensions of about 600 microns×10 microns×50 microns, or 1000 microns×600 microns×25 microns, or any other suitable dimensions.

Contact

108

and staging layer

110

are placed on insulating layer

106

, as appropriate. In various embodiments, staging layer

110

supports cantilever

112

above insulating layer

106

, creating a gap

116

that may be vacuum or may become filled with air or another gas or liquid such as oil. Although the size of gap

116

varies widely with different implementations, an exemplary gap

116

may be on the order of 1-100 microns, such as about 20 microns. Contact

108

may receive cantilever

112

when relay

100

is in a closed state, as described below. Contact

108

and staging layer

110

may be formed of any conducting material such as gold, gold alloy, silver, copper, aluminum, metal or the like. In various embodiments, contact

108

and staging layer

110

are formed of similar conducting materials, and the relay is considered to be “closed” when cantilever

112

completes a circuit between staging layer

110

and contact

108

. Other embodiments use different formulations for contact

108

and staging layer

110

, such as those discussed below in conjunction with

FIGS. 3 and 4

. In certain embodiments wherein cantilever

112

does not conduct electricity, staffing layer

110

may be formulated of non-conducting material such as Probimide material, oxide, or any other material. Additionally, alternate embodiments may not require staging layer

110

if cantilever

112

is otherwise supported above insulating layer

106

.

Principle of Operation

In a broad aspect of the invention, magnet

102

generates a magnetic field H

o

126

that induces a magnetization (m) in cantilever

112

. The magnetization suitably creates a torque on cantilever

112

that forces cantilever

112

toward contact

108

or away from contact

108

, depending upon the direction of the magnetization, thus placing relay

100

into an open or closed state. The direction of magnetization in cantilever

112

may be adjusted by a second magnetic field generated by conductor

114

as appropriate, and as described more fully below.

With continued reference to

FIGS. 1A and 1B

, magnetic field H

o

134

may be applied by magnet

102

primarily in the direction parallel to the Z-axis such that the field is perpendicular to the primary dimension (e.g. the length) of cantilever

112

. Magnetic field

134

suitably induces a magnetization in cantilever

112

, which may be made of soft magnetic material. Because of the geometry of cantilever

112

, the magnetization in cantilever

112

suitably aligns along the long axis of the cantilever, which is the length of cantilever

112

(parallel to the X-axis) in FIG.

1

.

The orientation of the magnetization in cantilever

112

is suitably dependent upon the angle (alpha) between the applied magnetic field

134

and the long axis of cantilever

112

. Specifically, when the angle (alpha) is less than 90 degrees, the magnetic moment (in) in cantilever

112

points from end

130

of cantilever

112

toward end

132

. The interaction between the magnetic moment and magnetic field H

o

134

thus creates a torque in a counter-clockwise direction about end

130

of cantilever

112

that moves end

132

upward, as appropriate, thus opening the circuit between staging layer

110

and contact

108

. Conversely, when the angle (alpha) is greater than 90 degrees, the magnetic moment (m) in cantilever

112

points from end

132

toward end

130

, creating a clockwise torque about end

130

. The clockwise torque moves end

132

downward to complete the circuit between staging layer

110

and contact

108

. Because the magnetization (m) of cantilever

112

does not change unless the angle (alpha) between the long axis of cantilever

112

and the applied magnetic field

134

changes, the applied torque will remain until an external perturbation is applied. Elastic torque of the cantilever or a stopper (such as the contact) balances the applied magnetic torque, and thus relay

100

exhibits two stable states corresponding to the upward and downward positions of cantilever

112

(and therefore to the open and closed states, respectively, of relay

100

).

Switching may be accomplished by any suitable technique that reverses the direction of the cantilever's magnetic dipole moment. In an exemplary embodiment, switching may be accomplished by generating a second magnetic field that has a component along the long axis of cantilever

112

that is strong enough to affect the magnetization (m) of cantilever

112

. In the embodiment shown in

FIG. 1

, the relevant component of the second magnetic field is the component of the field along the X-axis. Because the strength of the second magnetic field along the long axis of cantilever

112

is of primary concern, the overall magnitude of the second magnetic field is typically significantly less than the magnitude of magnetic field

134

(although of course fields of any strength could be used in various embodiments). An exemplary second magnetic field may be on the order of 20 Oersted, although of course stronger or weaker fields could be used in other embodiments.

The second magnetic field may be generated through, for example, a magnet such as an electronically-controlled electromagnet. Alternatively, the second magnetic field may be generated by passing a current through conductor

114

. As current passes through conductor

114

, a magnetic field is produced in accordance with a “right-hand rule”. For example, a current flowing from point

126

to point

128

on conductor

114

(

FIG. 1B

) typically generates a magnetic field “into” the center of the coil shown, corresponding to field arrows

122

in FIG.

1

A. Conversely, a current flowing from point

128

to point

126

in

FIG. 1

generates a magnetic field flowing “out” of the center of the coil shown, corresponding to dashed field arrows

124

in FIG.

1

A. The magnetic field may loop around the conductor

114

in a manner shown also in

FIG. 1A

, imposing a horizontal (X) component of the magnetic field on the cantilever

112

.

By varying the direction of the current or current pulse flowing in conductor

114

, then, the direction of the second magnetic field can be altered as desired. By altering the direction of the second magnetic field, the magnetization of cantilever

112

may be affected and relay

100

may be suitably switched open or closed. When the second magnetic field is in the direction of field arrows

122

, for example, the magnetization of cantilever

112

will point toward end

130

. This magnetization creates a clockwise torque about end

130

that places cantilever

112

in a “down” state that suitably closes relay

100

. Conversely, when the second magnetic field is in the direction of dashed field arrows

124

, the magnetization of cantilever

112

points toward end

132

, and a counter-clockwise torque is produced that places cantilever

112

in an “up” state that suitably opens relay

100

. Hence, the “up” or “down” state of cantilever

112

(and hence the “open” or “closed” state of relay

100

) may be adjusted by controlling the current flowing through conductor

114

. Further, since the magnetization of cantilever

112

remains constant without external perturbation, the second magnetic field may be applied in “pulses” or otherwise intermittently as required to switch the relay. When the relay does not require a change of state, power to conductor

114

may be eliminated, thus creating a bi-stable latching relay

100

without power consumption in quiescent states. Such a relay is well suited for applications in space, aeronautics, portable electronics, and the like.

Manufacturing a Latching Relay

FIG. 2

includes a number of side views showing an exemplary technique for manufacturing a latching relay

100

. It will be understood that the process disclosed herein is provided solely as an example of one of the many techniques that could be used to formulate a latching relay

100

.

An exemplary fabrication process suitably begins by providing a substrate

102

, which may require an optional insulating layer. As discussed above, any substrate material could be used to create a latching relay

100

, so the insulating layer will not be necessary if, for example, an insulating substrate is used. In embodiments that include an insulating layer, the layer may be a layer of silicon dioxide (SiO

2

) or other insulating material that may be on the order of 1000 angstroms in thickness. Again, the material chosen for the insulating material and the thickness of the layer may vary according to the particular implementation.

With reference to

FIG. 2A

, conductor

114

is suitably formed on substrate

104

. Conductor

114

may be formed by any technique such as deposition (such as e-beam deposition), evaporation, electroplating or electroless plating, or the like. In various embodiments, conductor

114

is formed in a coil pattern similar to that shown in FIG.

1

. Alternatively, conductor

114

is formed in a line, serpentine, circular, meander, random or other pattern. An insulating layer

106

may be spun or otherwise applied to substrate

104

and conductor

114

as shown in FIG.

2

B. Insulating layer

106

may be applied as a layer of photoresist, silicon dioxide, Probimide-7510 material, or any other insulating material that is capable of electrically isolating the top devices. In various embodiments, the surface of the insulating material is planarized through any technique such as chemical-mechanical planarization (CMP).

Contact pads

108

and

110

may be formed on insulating layer

106

through any technique such as photolithography, etching, or the like (FIG.

2

C). Pads

108

and

110

may be formed by depositing one or more layers of conductive material on insulating layer

106

and then patterning the pads by wet etching, for example. In an exemplary embodiment, pads

108

and

110

suitably include a first layer of chromium (to improve adhesion to insulating layer

106

) and a second layer of gold, silver, copper, aluminum, or another conducting material. Additional metal layers may be added to the contacts by electroplating or electroless plating methods to improve the contact reliability and lower the resistance.

With reference to

FIG. 2D

, the contact pads

108

and

110

may be suitably covered with a layer of photoresist, aluminum, copper, or other material to form sacrificial layer

202

. An opening

206

in sacrificial layer

202

over the cantilever base areas may be defined by photolithography, etching, or another process. Cantilever

112

may then be formed by depositing, sputtering or otherwise placing one or more layers of material on top of sacrificial layer

202

and extending over the opening

206

, as shown in FIG.

2

E. In an exemplary embodiment, a base layer

204

of chromium or another metal may be placed on sacrificial layer

202

to improve adhesion, and one or more conducting layers

120

may be formed as well. Layers

204

and

120

may be formed by, for example, deposition followed by chemical or mechanical etching. Layer

120

may be thickened by adding another conductor layer (such as gold, gold alloy, etc.) by electroplating or electroless plating methods. Cantilever

112

is further formed by electroplating or otherwise placing a layer

118

of permalloy (such as NiFe permalloy) on top of conducting layer

120

, as shown in FIG.

2

F. The thickness of the permalloy layer

118

may be controlled by varying the plating current and time of electroplating. Electroplating at 0.02 amperes per square centimeters for a period of 60 minutes, for example, may result in an exemplary permalloy layer thickness of about 20 microns. In various embodiments, an additional permalloy layer

306

(shown in

FIG. 3

) may be electroplated on top of cantilever

112

to increase the responsiveness of cantilever

112

to magnetic fields.

With reference to

FIG. 2G

, sacrificial layer

202

may be removed by, for example, wet or dry (i.e. oxygen plasma) releasing techniques to create gap

116

between cantilever

112

and insulating layer

106

. In various embodiments, adhesion layer

204

is removed using a suitable etching or equivalent removal technique to form relay

100

(FIG.

2

H). Relay

100

may then be diced, packaged with magnet

102

(shown in FIG.

1

), or otherwise processed as appropriate. It should be understood that the permanent magnet

102

can alternatively be fabricated directly on the substrate, placed on top of the cantilever, or the coil and the cantilever can be fabricated directly on a permanent magnet substrate.

Alternate Embodiments of Latching Relays

FIGS. 3 and 4

disclose alternate embodiments of latching relays

100

.

FIGS. 3A and 3B

show side and top views, respectively, of an alternate embodiment of a latching relay that includes a hinged cantilever

112

. The perspective of

FIGS. 3A and 3B

is rotated 90 degrees in the X-Y plane from the perspective shown in

FIGS. 1A and 1B

to better show the detail of the hinged cantilever. With reference to

FIGS. 3A and 3B

, a hinged cantilever

112

suitably includes one or more strings

302

and

304

that support a magnetically sensitive member

306

above insulating layer

106

. Member

306

may be relatively thick (on the order of about 50 microns) compared to strings

302

and

304

, which may be formed of conductive material. As with the relays

100

discussed above in conjunction with

FIG. 1

, relays

100

with hinged cantilevers may be responsive to magnetic fields such as those generated by magnet

102

and conductor

114

. In various embodiments, one or both of strings

302

and

304

are in electrical communication with contact pad

108

when the relay is in a “closed” state. Of course, any number of strings could be used. For example, a single string could be formulated to support the entire weight of member

306

. Additionally, the strings may be located at any point on member

306

. Although

FIG. 3

shows strings

302

and

304

near the center of member

306

, the strings could be located near the end of member

306

toward contact

108

to increase the torque produced by magnet

102

, for example.

FIG. 3C

is a perspective view of an exemplary cantilever

112

suitable for use with the embodiments shown in

FIGS. 3A and 3B

, as well as other embodiments. Cantilever

112

suitably includes member

306

coupled to conducting layer

120

. Holes

310

and/or

312

may be formed in conducting layer

120

to improve flexibility of cantilever

112

, and optional contact bumps

308

may be formed on the surface of conducting layer

120

to come into contact with contact

108

. Strings

302

and

304

(not shown in

FIG. 3C

) may be affixed or otherwise formed on cantilever

112

at any position (such as in the center of conducting layer

120

or at either end of conducting layer

120

) as appropriate. Alternatively, the strings may be formed of non-conducting materials and cantilever

112

may provide a conducting path between two separate conductors touched simultaneously by the cantilever in the closed state, as discussed below.

It has been observed that certain switches that include relatively wide magnetically sensitive members

306

may exhibit reduced magnetization because of the relatively large ratio of the width-to-length of cantilever

112

. Moreover, the increased width may lead to increased magnetization along the width of cantilever

112

, which may result in twisting of the cantilever and degraded contact between cantilever

112

and contact

108

.

FIG. 3D

is a perspective view of a switch that includes sectionalized magnetically sensitive members

306

A,

306

B,

306

C and

306

D. To improve the magnetization along the length of cantilever

112

, the magnetically sensitive member

306

may be sectionalized so that the magnetization of each member

306

A-D is maximized along the length of the member instead of the width. Sectionalization may be accomplished by separately forming (e.g. electroplating) each member

306

A-D on conducting layer

120

, for example, or by etching (or otherwise forming) gaps in a single electroplated layer

306

. Of course any number of magnetically sensitive sections

306

A-D could be used with various embodiments, and the size of each section will vary from embodiment to embodiment. For example, various exemplary cantilevers

112

could be fashioned with four members

306

A-D of about 1000×600×25 micrometers, with eight members of about 1000×50×25 micrometers (spaced about 25 micrometers apart), with fifteen members of about 1000×20×25 micrometers (spaced about 25 micrometers apart), or with any number of members having any dimensions. In various embodiments, interlinks of magnetic material, metal or any other material may be added between the members

306

A-D to strengthen cantilever

112

.

FIG. 3E

is a schematic of a cantilever

112

that has been formed with multiple layers. In an exemplary embodiment, cantilever

112

includes alternating layers of magnetic material

118

(such as permalloy) and conducting material

120

, as shown in

FIG. 3E

, although of course other materials could be used in place of or in addition to the materials shown. Multi-layered cantilevers may be formed by sputtering, depositing, or otherwise forming multiple layers as discussed, for example, in connection with

FIGS. 2E and 2F

above, or through any other technique. Multi-layered cantilevers may also be sectionalized, as described above, and may be used in conjunction with any of the various embodiments of the invention.

FIGS. 4A and 4B

are side and top views, respectively, of an alternate embodiment of a latching relay

100

. As shown in the Figure, various embodiments of cantilever

112

may not directly conduct electricity from staging layer

110

to contact

108

. In such embodiments, a conducting element

402

may be attached to cantilever

112

to suitably provide electrical contact between contacts

108

and

408

when relay

100

is in a “closed” state.

FIGS. 4C and 4D

are perspective views of alternate exemplary embodiments of cantilever

112

. In such embodiments, cantilever

112

may include a magnetically sensitive portion

118

separated from a conducting portion

402

by an insulating layer

410

, which may be a dielectric insulator, for example. Optional contact bumps

308

may also be formed on conducting portion

402

as shown. When cantilever

112

is in a state corresponding to the “closed” state of relay

100

, current may follow the path shown by arrows

412

between contact pads

108

and

408

, as appropriate.

FIG. 5

is a side view of an alternate exemplary embodiment of relay

100

. With reference to

FIG. 5

, a relay

100

may include a magnet

102

, a substrate

104

and a cantilever

112

as described above (for example in conjunction with FIG.

1

). In place of (or in addition to) conductor

114

formed on substrate

104

, however, conductor

114

may be formed on a second substrate

504

, as shown. Second substrate

504

may be any type of substrate such as plastic, glass, silicon, or the like. As with the embodiments described above, conductor

114

may be coated with an insulating layer

506

, as appropriate. To create a relay

100

, the various components may be formed on substrates

104

and

504

, and then the substrates may be aligned and positioned as appropriate. The two substrates

104

and

504

(and the various components formed thereon) may be separated from each other by spacers such as spacers

510

and

512

in

FIG. 5

, which may be formed of any material.

With continued reference to

FIG. 5

, contact

108

may be formed on insulating layer

106

, as described above. Alternatively, contact

508

may be formed on second substrate

504

, as shown in

FIG. 5

(of course cantilever

112

may be reformulated such that a conducting portion of cantilever

112

comes into contact with contact

508

). In other embodiments, contacts

108

and

508

may both be provided such that relay

100

is in a first state when cantilever

112

is in contact with contact

108

, a second state when cantilever

112

is in contact with contact

508

, and/or a third state when cantilever

112

is in contact with neither contact

108

nor contact

508

. Of course the general layout of relay

100

shown in

FIG. 5

could be combined with any of the techniques and layouts described above to create new embodiments of relay

100

.

FIGS. 6A and 6B

are side and top views, respectively, of an alternate embodiment of a latching relay

100

. With reference now to

FIGS. 6A and 6B

, various embodiments of relay

100

may use electrostatic actuation to switch the state of cantilever

112

instead of magnetic energy generated by conductor

114

. In such embodiments, one or more switching electrodes

602

and

604

may be deposited or otherwise fashioned on insulating layer

106

. Electrodes

602

and

604

may be formed of metal or another conducting material, and may be electrically coupled to leads, wires or other connecting devices (not shown) to create an electric potential between either of the electrodes and cantilever

112

.

Although

FIGS. 6A and 6B

show a center-hinged type cantilever

112

, electrodes

602

and

604

and/or the principle of electrostatic actuation may be included in any of the relays or switches described herein in place of (or in addition to) the magnetic actuation produced by conductor

114

. In various embodiments, electrodes

602

and

604

are suitably positioned with respect to cantilever

112

such that electrostatic forces generated by the two electrodes have opposing effects on cantilever

112

. In the center-hinged embodiment shown in

FIGS. 6A and 6B

, for example, electrodes

602

and

604

may be positioned on either side of hinge

110

so that a voltage difference between electrode

602

and cantilever

112

“pushes” cantilever

112

into an “open” state. Conversely, a voltage difference between electrode

604

and cantilever

112

may “pull” cantilever

112

into a “closed” state whereby cantilever

112

is in contact with contact

108

. In such embodiments, the state of cantilever

112

may be held by the magnetic field generated by permanent magnet

102

, and a bistable switch may result. The relay may be switched between stable states by providing an electric potential to the appropriate electrode to attract cantilever

112

as appropriate. In an exemplary relay

100

, a hinged type cantilever

112

having dimensions of about 1000×200×20 micrometers and a supporting torsion string

110

with dimensions of 280×20×3 micrometers may require a voltage of about 37 volts, when the overlap area between the cantilever and electrode is on the order of 200×400 square micrometers or so, to switch cantilever

112

in a permanent external magnetic field of about 200 Oersted. Again, switches or relays can be formulated with any dimensions or architectures, and the voltage required to switch between states will suitably vary from implementation to implementation. In particular, the electrostatic switching technique using electrodes

602

and

604

can be incorporated into any of the relays discussed above, or any of the switches described herein. Advantages of using electrostatic switching over magnetic switching include reduced power consumption and ease in manufacturing, since electrodes

602

and

604

can be very thin (e.g. on the order of about a hundred angstroms to about 0.5 micrometers thick). Moreover, electrostatic switches may be made to be smaller than some corresponding magnetic switches, thus reducing the overall size of the switching device. Switching control may be provided by an control device such as a microcontroller, microprocessor, application specific integrated circuit (ASIC), logic circuit, analog or digital control circuit, or the like. In an exemplary embodiment a controller provides control signals in the form of electrical signals to electrodes

602

and

604

to create voltage differences as appropriate.

It will be understood that many other embodiments of the various relays could be formulated without departing from the scope of the invention. For example, a double-throw relay could be created by adding an additional contact

108

that comes into contact with cantilever

112

when the cantilever is in its open state. Similarly, various topographies and geometries of relay

100

could be formulated by varying the layout of the various components (such as pads

108

and

110

and cantilever

112

).

Optical Switches

The mechanisms, principles and techniques described above in conjunction with electrical relays may also be used to create optical switches suitable for use in communications or other optical systems. In various embodiments of an optical switch, the magnetically sensitive portion of cantilever

112

may be affixed to a mirror or other material that reflects light. As the cantilever is switched from an “open” state to a “closed” state, the reflecting surface is exposed or hidden from an optical signal such that the signal is reflected or absorbed as appropriate, and as described more fully below.

FIGS. 7A and 7B

are side and top views, respectively, of an exemplary optical mirror

700

(referred to herein as a “Type I” mirror). Like the electrical switches described above, a cantilever

112

is suitably positioned over insulating layer

106

by a support string, hinge or other spacer

110

. Cantilever

112

may be formed of soft magnetic material

132

(as discussed above), and may have a reflective coating

702

(such as aluminum or gold) deposited, sputtered or otherwise placed on the magnetic material. One or more optional stoppers

704

may be positioned on insulating layer

106

, as appropriate, to receive and position cantilever

112

as required. Stoppers

704

may be formed of any suitable material such as etched silicon, metal, or polyimide. In various embodiments, support string

10

supports rotation of cantilever

112

into an “up” state and a “down” state, as appropriate. When cantilever

112

is in an “up” state, for example, cantilever

112

may be rotated counter-clockwise about string

110

until end

742

of cantilever

132

contacts stopper

704

L. In an exemplary “down” state, cantilever

112

may be rotated clockwise about string

110

such that the end

740

of cantilever

112

contacts stopper

740

R. When the right end of

132

touches the bottom stopper

704

, it is in the “down”. By design, the supporting string

110

may be placed closer to end

742

of cantilever

112

such that cantilever

112

may be tilted to a larger angle in the “up” position than in the “down” position. Of course, support string

110

may also be placed approximately equidistant from the ends of cantilever

112

, or such that the “down” position creates a larger angle, and many orientations could be formulated in other embodiments of the invention.

Operation of optical mirror

700

may be similar to the operation of the electrical switches

100

discussed above. In various exemplary embodiments, latching and switching are accomplished by inducing a magnetic torque in cantilever

112

with conductor

114

(as shown in

FIG. 7

) or optional electrodes (as discussed above in connection with FIG.

6

). Cantilever

112

may be stably maintained in either the “up” or “down” state through a field generated by magnet

102

, as described above.

FIGS. 8A through 8G

show various views and states of a second type of optical mirror

800

(referred to herein as a “Type II” mirror or “reflector”). Although these devices are primarily described herein as pertaining to reflective devices used with switches or relays, the principles and structures described herein could be used to create any sort of actuator (reflecting or non-reflecting) that may be used in any application.

With reference to

FIGS. 8A and 8B

, an optical mirror

800

may include a cantilever

112

that includes a magnetically sensitive portion

132

. Cantilever

112

may also include a reflective portion

804

with a reflective coating on either or both sides. In an exemplary embodiment, reflective portion

804

has a reflective coating deposited or otherwise placed on face

802

, as shown in FIG.

8

A. One or more stoppers

704

may also be placed on insulating layer

106

as required to position or elevate cantilever

112

as appropriate, and a support, string or hinge

110

(not shown in

FIGS. 8A and 8C

) may rotably fix cantilever

112

above substrate

104

.

In an exemplary embodiment, string

110

supports ninety degrees of rotation between two states of cantilever

112

(plus or minus some correction for errors in manufacturing and the like). In the embodiment shown in

FIGS. 8A and 8B

, cantilever

112

is positioned into an “up” state by magnet

102

(not shown) to be approximately parallel to the surface of substrate

104

. The “up” position may be useful when it is necessary to have a clear path for an optical beam to directly pass the Type II mirror without reflection, for example. A second “down” state of mirror

800

is shown in

FIGS. 8C and 8D

. Mirror

800

may be placed in the “down” state, for example, by magnet

102

(not shown) (In principle, the magnet can hold the cantilever to either of the two stable states) and/or by allowing gravity to pull the magnetically sensitive portion

132

of cantilever

112