BENDING MODE LIQUID METAL SWITCH

• US 20040200703A1
• Filed: 04/14/2003
• Published: 10/14/2004
• Est. Priority Date: 04/14/2003
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Wong, Marvin Glenn
• Granted Patent: US 6,870,111 B2
• Time in Patent Office: Days
• US Class Current: 200/182
• CPC Class Codes: G02B 6/3538 based on displacement or deformation of a liquid controlling the intensity of light by displacement or deformation of a fluid in general G02B26/004; fluid-filled lens of variable focal length G02B3/14
• CPC Class Codes: G02B 6/3552 1x1 switch, e.g. on/off switch
• CPC Class Codes: G02B 6/3578 Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/358 Latching of the moving element, i.e. maintaining or holding the moving element in place once operation has been performed; includes a mechanically bistable system
• CPC Class Codes: H01H 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 2029/008 using micromechanics, e.g. micromechanical liquid contact switches or [LIMMS]
• CPC Class Codes: H01H 2057/006 Micromechanical piezoelectric relay
• CPC Class Codes: H01H 29/28 with level of surface of contact liquid displaced by fluid pressure
• CPC Class Codes: H01H 55/00 Magnetostrictive relays
• CPC Class Codes: H01H 57/00 Electrostrictive relays; Piezoelectric relays

Abstract

A piezoelectric relay is disclosed in which a liquid metal droplet is moved within a switching channel formed in a relay housing. A signal path passing through the switching channel is blocked or unblocked by motion of the liquid metal droplet that coalesces with one of two additional liquid metal droplets. Motion of the liquid metal droplets is controlled by one or more piezoelectric pumps that control the flow of actuation fluid between a fluid reservoir and the switching channel. The liquid metal droplets are held in place by surface tension acting on wettable contact pads within the switching channel. The surface tension of the liquid provides a latching mechanism for the relay.

Claims

1. A piezoelectric optical relay comprising:

a relay housing containing a switching channel;

first and second contact pads located in the switching channel and each having a surface wettable by a liquid metal;

a third contact pad located in the switching channel between the first and second contact pads and having a surface wettable by a liquid metal;

a first liquid metal droplet in wetted contact with the first contact pad;

a second liquid metal droplet in wetted contact with the second contact pad;

a third liquid metal droplet in wetted contact with the third contact pad and adapted to move within the switching channel to coalesce with one of the first liquid metal droplet and the second liquid metal droplet;

a first optical path passing through the switching channel between the first and third liquid metal droplets; and

a first piezoelectric pump comprising a first pumping chamber bounded in part by a flexible diaphragm and operable to pump actuation fluid between the pumping chamber and the switching channel, thereby causing the third liquid metal droplet to coalesce with one of the first liquid metal droplet and the second liquid metal droplet,

wherein the first optical path is broken when the first and third liquid metal droplets are coalesced and is completed when the first and third liquid metal droplets are separated.

2. A piezoelectric optical relay in accordance with claim 1, wherein the first piezoelectric pump is operable to pump actuation fluid into the switching channel through a first via, the first via being positioned between the second liquid metal droplet and the third liquid metal droplet, thereby causing the second and third liquid metal droplets to separate and the first and third liquid metal droplets to coalesce

3. A piezoelectric optical relay in accordance with claim 1, wherein the first piezoelectric pump is further operable to pump actuation fluid out of the switching channel through a first via, the first via being positioned between the second liquid metal droplet and the third liquid metal droplet, thereby causing the second and third liquid metal droplets to coalesce and the first and third liquid metal droplets to separate.

4. A piezoelectric optical relay in accordance with claim 1, wherein the first piezoelectric pump further comprises at least one piezoelectric element attached to the first flexible diaphragm, the least one piezoelectric element adapted to deform in a bending mode and thereby change the volume the first pumping chamber.

5. A piezoelectric optical relay in accordance with claim 1, wherein the first optical path comprises:

a first optical waveguide configured to transmit light into the switching channel; and

a second optical waveguide, optically aligned with the first optical waveguide and configured to receive light from the first optical waveguide when the first and third liquid metal droplets are separated.

6. A piezoelectric optical relay in accordance with claim 1, further comprising a second optical path, passing between the second and third liquid metal droplets.

7. A piezoelectric optical relay in accordance with claim 1, further comprising a slug coupled to the third liquid metal droplet, wherein the slug moves with a motion of the third liquid metal droplet.

8. A piezoelectric optical relay in accordance with claim 1, further comprising a second piezoelectric pump comprising a second pumping chamber bounded in part by a second flexible diaphragm and operable to pump actuation fluid between the second pump chamber and the switching channel through a via, the via being positioned between the first liquid metal droplet and the third liquid metal droplet.

9. A piezoelectric optical relay in accordance with claim 7, wherein the relay housing comprises:

a bottom cap layer having a fluid reservoir formed therein;

a switching layer having the switching channel formed therein;

a pump chamber layer containing the first and second piezoelectric pumps and adapted to pump actuation fluid between the fluid reservoir and the switching channel; and

a top cap layer, positioned above the switching layer.

10. A piezoelectric optical relay in accordance with claim 8, further comprising a via layer, positioned between the pump chamber layer and the switching layer, containing first and second fluid ducts coupling the first and second piezoelectric pumps to the switching channel.

11. A piezoelectric optical relay in accordance with claim 8, wherein the first optical path comprises:

a first optical waveguide embedded in a first notch in the switching layer and configured to transmit light into the switching channel; and

a second optical waveguide embedded in a second notch in the switching layer and optically aligned with the first optical waveguide, the second optical waveguide being configured to receive light from the first optical waveguide if the first and third liquid metal droplets are separated.

12. A method for switching an optical path in a piezoelectric optical relay having a first liquid metal droplet moveable within a switching channel, the method comprising:

coupling an input optical signal to an input optical waveguide of the piezoelectric optical relay, the input optical waveguide being optically aligned with an output optical waveguide to form the optical path;

if the optical path is to be completed;

moving the first liquid metal droplet out of the optical path, whereby the input optical waveguide is optically coupled to the output optical waveguide; and

if the optical path is to be broken;

moving the first liquid metal droplet into the optical path, whereby the input optical waveguide is optically decoupled from the output optical waveguide,

wherein moving the first liquid metal droplet comprises energizing at least one piezoelectric element to deform in a bending mode, thereby deflecting a first flexible diaphragm, changing the volume of a first pumping chamber and altering the pressure of an actuation fluid in the switching channel.

13. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 12, wherein a slug coupled to the first liquid metal droplet is operable to block or unblock the optical path.

14. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 12, wherein the first liquid metal droplet is in wetted contact with a first contact pad positioned in the switching channel between a second contact pad and a third contact pad and wherein:

moving the first liquid metal droplet into the optical path causes the first liquid metal droplet to coalesce with a second liquid metal droplet in wetted contact with the second contact pad; and

moving the first liquid metal droplet out of the optical path causes the first liquid metal droplet to coalesce with a third liquid metal droplet in wetted contact with the third contact pad.

15. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 12, wherein:

if the optical path is to be completed;

energizing at least one piezoelectric element to deform in a bending mode decreases the volume of a first pumping chamber and increases the pressure of an actuation fluid in the switching channel;

if the optical path is to be broken;

energizing at least one piezoelectric element to deform in a bending mode increases the volume of a first pumping chamber and decreases the pressure of an actuation fluid in the switching channel;

16. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 12, wherein:

if the optical path is to be completed;

energizing at least one piezoelectric element to deform in a bending mode decreases the volume of a first pumping chamber and increases the pressure of an actuation fluid in the switching channel; and

if the optical path is to be broken;

energizing at least one piezoelectric element to deform in a bending mode decreases the volume of a second pumping chamber and increases the pressure of an actuation fluid in the switching channel.

17. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 12, further comprising:

if the optical path is to be completed;

de-energizing the at least one piezoelectric element after the first liquid metal droplet has been moved out of the optical path; and

if the optical path is to be broken;

de-energizing the at least one piezoelectric element after the first liquid droplet has been moved into the optical path.

18. A method for switching an optical path in a piezoelectric optical relay in accordance with claim 17, wherein the de-energizing is performed slower than the energizing to allow actuation fluid to be drawn from a reservoir of actuation fluid.

19. A piezoelectric relay comprising:

a relay housing containing a switching channel;

first and second contact pads located in the switching channel and each having a surface wettable by a liquid metal;

a third contact pad located in the switching channel between the first and second contact pads and having a surface wettable by a liquid metal;

a first liquid metal droplet in wetted contact with the first contact pad;

a second liquid metal droplet in wetted contact with the second contact pad;

a third liquid metal droplet in wetted contact with the third contact pad and adapted to move within the switching channel to coalesce with one of the first liquid metal droplet and the second liquid metal droplet;

a first electrical path operable to be coupled to the first contact pad and the third contact pad;

a second electrical path operable to be coupled to the second contact pad and the third contact pad; and

a first piezoelectric pump comprising a first pumping chamber bounded in part by a flexible diaphragm and operable to pump actuation fluid between the pumping chamber and the switching channel, thereby causing the third liquid metal droplet to coalesce with one of the first liquid metal droplet and the second liquid metal droplet,

wherein the first electrical path is completed when the first and third liquid metal droplets are coalesced and the second electrical path is completed when the second and third liquid metal droplets are coalesced.

20. A piezoelectric relay in accordance with claim 19, further comprising a slug operable to be coupled to one of:

the first contact pad and the third contact pad; and

the second contact pad and the third contact pad.

21. A method for switching one or more electrical signal paths in a piezoelectric relay having a first liquid metal droplet moveable within a switching channel, the method comprising:

coupling an input electrical signal to a first contact pad and a third contact pad of the piezoelectric relay;

if a first electrical signal path is to be completed;

moving the first liquid metal droplet so that the first contact pad is coupled to the third contact pad; and

if a second electrical signal path is to be broken;

moving the first liquid metal droplet so that the second contact pad is coupled to the third contact pad,

wherein moving the first liquid metal droplet comprises energizing at least one piezoelectric element to deform in a bending mode, thereby deflecting a first flexible diaphragm, changing the volume of a first pumping chamber and altering the pressure of an actuation fluid in the switching channel.

22. A method for switching one or more electrical signal paths in a piezoelectric relay in accordance with claim 21, wherein the first liquid metal droplet is coupled to a slug, said slug operable to couple the third contact pad to one or more of the first contact pad and the second contact pad.