Multi-stable micro electromechanical switches and methods of fabricating same

• US 20040216988A1
• Filed: 04/29/2003
• Published: 11/04/2004
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Mattes, Michael F., Receveur, Rogier, Habets, Philippe, Houben, Richard P.M., Danzl, Ralph B.
• Granted Patent: US 7,190,245 B2
• Time in Patent Office: Days
• US Class Current: 200/181
• CPC Class Codes: B81B 2201/018 Switches not provided for in B81B2201/014 - B81B2201/016
• CPC Class Codes: B81B 2203/051 Translation according to an axis parallel to the substrate
• CPC Class Codes: B81B 3/0054 For holding or placing an element in a given position
• 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 2001/0078 with parallel movement of the movable contact relative to the substrate
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

A micro electromechanical (MEMS) switch suitable for use in medical devices is provided, along with methods of producing and using MEMS switches. In one aspect, a micro electromechanical switch including a moveable member configured to electrically cooperate with a receiving terminal is formed on a substrate. The moveable member and the receiving terminal each include an insulating layer proximate to the substrate and a conducting layer proximate to the insulating layer opposite the substrate. In various embodiments, the conducting layers of the moveable member and/or receiving terminal include a protruding region that extends outward from the substrate to switchably couple the conducting layers of the moveable member and the receiving terminal to thereby form a switch. The switch may be actuated using, for example, electrostatic energy.

Claims

1. A micro electromechanical switch formed on a substrate, the switch having a moveable member configured to electrically cooperate with a receiving terminal, and wherein the moveable member and the receiving terminal each comprise:

an insulating layer proximate to the substrate; and

a conducting layer proximate to the insulating layer opposite the substrate and having a protruding region extending radially outward from the substrate;

and wherein the protruding region of the moveable member is configured to switchably engage and disengage the protruding region of the receiving terminal to thereby toggle the micro electromechanical switch between an open state and a closed state.

2. The micro electromechanical switch of claim 1 wherein the conducting layer comprises a first conducting layer proximate to the insulating layer and a second conducting layer proximate to the first conducting layer opposite the insulating layer.

3. The micro electromechanical switch of claim 2 wherein the second conducting layer is formed on the first conducting layer, and wherein the second conducting layer comprises the protruding region.

4. The micro electromechanical switch of claim 3 wherein the second conducting layer comprises a noble metal.

5. The micro electromechanical switch of claim 4 wherein the noble metal is gold.

6. The micro electromechanical switch of claim 3 wherein the first conducting layer has a pattern corresponding to electrically conductive portions of the switch.

7. The micro electromechanical switch of claim 6 wherein the pattern comprises a contact area in electrical communication with the electrically conductive portions of the switch.

8. A micro electromechanical switch formed on a substrate, the switch having a moveable member configured to electrically cooperate with a receiving terminal, and wherein the receiving terminal comprises:

an insulating layer proximate to the substrate; and

a conducting layer proximate to the insulating layer opposite the substrate, wherein the conducting layer comprises a protruding region that extends outward from the substrate to switchably engage a conducting portion of the moveable member.

9. The switch of claim 8 wherein the conducting portion of the moveable member comprises a second protruding region configured to electrically mate with the protruding region of the moveable member.

11. The switch of claim 9 wherein the conducting portion of the receiving terminal comprises a second protruding region configured to electrically mate with the protruding region of the moveable member.

10. A micro electromechanical switch formed on a substrate, the switch having a moveable member configured to electrically cooperate with a receiving terminal, and wherein the moveable member comprises:

an insulating layer proximate to the substrate; and

a conducting layer proximate to the insulating layer opposite the substrate, wherein the conducting layer comprises a protruding region that extends outward from the substrate to switchably engage a conducting portion of the receiving terminal.

12. A method of forming a micro electromechanical switch on a substrate, the method comprising the steps of:

forming an insulating layer on the substrate;

forming a conducting layer on the insulating layer;

isolating at least one moveable member and at least one receiving terminal of the switch; and

applying a conductive coating to substantially encapsulate the conducting layer and to form protruding regions extending outwardly from the substrate on the at least one moveable member and the at least one receiving terminal.

13. The method of claim 12 further comprising the step of etching a bottom side of the at least one moveable member.

14. The method of claim 12 further comprising the step of patterning the conducting layer.

15. The method of claim 14 wherein the applying step comprises the step of providing an electric current to the conducting layer to thereby electroplate the conductive coating on the conducting layer.

16. The method of claim 12 wherein the applying step comprises applying electroless gold.

17. A multi-stable electromechanical switch having an open state and a closed state, the electromechanical switch comprising:

a moveable member;

at least one pair of receiving terminals biased to a bias position corresponding to the open state, wherein each terminal of the at least one pair of receiving terminals is configured to interface with the moveable member in the closed state; and

an actuating circuit configured to provide electrostatic energy and to thereby displace the at least one pair of receiving terminals from the bias position, and to displace the moveable member toward the bias position;

wherein the receiving terminals are further configured to return toward the bias position when the electrostatic energy is removed, and to thereby create an electrical connection with the moveable member, thereby retaining the electromechanical switch in the closed state.

18. The electromechanical switch of claim 17 wherein the moveable member comprises a conducting portion having at least one protruding region configured to interface with the at least one pair of receiving terminals.

19. The electromechanical switch of claim 17 wherein the actuating circuit comprises a comb actuator.

20. The electromechanical switch of claim 17 wherein the at least one pair of receiving terminals comprises two pairs of receiving terminals, and wherein the closed state of each of the two pairs of receiving terminals corresponds to a different state of the electromechanical switch.

21. The electromechanical switch of claim 17 wherein each of the at least one pair of receiving terminals comprises an outcropping configured to contact with the moveable member.

22. The electromechanical switch of claim 17 further comprising a dielectric material located in proximity to the actuating circuit.

23. A method of switching an electromechanical switch from an open state to a closed state, the method comprising the steps of:

displacing a pair of receiving terminals from a biased position corresponding to the open state;

moving a moveable member between the pair of receiving terminals to thereby occupy at least a portion of the biased position; and

discontinuing the electrostatic energy to thereby allow the pair of receiving terminals to return toward the biased position, and to thereby place the pair of receiving terminals in contact with the moveable member, thereby placing the electromechanical switch in the closed position.

24. The method of claim 23 wherein the displacing step and the moving step are executed at least in part with electrostatic energy.

25. A multi-stable electromechanical switch having a moveable member and a pair of receiving terminals, the electromechanical switch comprising:

means for displacing the pair of receiving terminals from a biased position corresponding to the open state;

means for moving the moveable member between the pair of receiving terminals to thereby occupy at least a portion of the biased position; and

means for discontinuing the electrostatic energy to thereby allow the pair of receiving terminals to return toward the biased position, and to thereby place the pair of receiving terminals in contact with the moveable member, thereby placing the electromechanical switch in the closed position.