MEMS REED SWITCH DEVICE
A MEMS device, having two flexible, permeable members which are manufactured to have sub-millimeter dimensions using MEMS fabrication procedures. The flexible, permeable members may form a reed switch, which closes an electrical connection in the presence of a magnetic field, and opens the connection otherwise. The MEMS reed switch device may be made using a three-wafer architecture of a lid wafer, a device wafer, and a lower, supporting wafer.
1 . A microfabricated MEMS reed switch device comprising:
a first flexible, magnetically permeable member formed on a surface of a substrate;
at least one additional, magnetically permeable member also formed on the same substrate and disposed in a position adjacent the first flexible, magnetically permeable member; and
at least two electrical contacts that, together with the flexible, magnetically permeable members form a portion of an electric circuit.
2 . The microfabricated MEMS reed switch of claim 1 , wherein the first flexible, permeable member and the at least one additional flexible, permeable member are deflected in the presence of a magnetic field.
3 . The microfabricated MEMS reed switch of claim 2 , wherein when the first flexible, permeable member and the at least one additional flexible member touch, an electrical connection is formed and a switch is closed.
4 . The microfabricated MEMS reed switch of claim 2 , wherein when the first flexible, permeable member and the at least one additional flexible member touch, an electrical connection is severed and a switch is opened.
5 . The microfabricated MEMS reed switch of claim 2 , further comprising a locking mechanism which holds at least one of the flexible, permeable members in a predefined position when the magnetic field is withdrawn.
6 . The microfabricated MEMS reed switch of claim 2 , wherein when flexible, permeable members are configured as a single pole, double throw switch.
7 . The microfabricated MEMS reed switch of claim 2 , wherein when the two flexible, permeable members are disposed with each end directly adjacent.
8 . The microfabricated MEMS reed switch of claim 2 , wherein when the two flexible, permeable members are disposed with each end overlapping and adjacent.
9 . The microfabricated MEMS reed switch of claim 2 , wherein when the two flexible, permeable members are disposed as mirror images across a symmetry axis.
10 . The microfabricated MEMS reed switch of claim 1 , further comprising a third flexible member that defines another electrode of the microfabricated MEMS reed switch.
11 . The microfabricated MEMS reed switch of claim 1 , wherein the at least two electrical contacts are plated with at least on of gold (Au) and silver (Ag).
12 . The microfabricated MEMS reed switch of claim 1 , wherein the first flexible permeable member and the second flexible permeable member are not touching in the absence of a magnetic field, and thus the switch is normally open.
13 . The microfabricated MEMS reed switch of claim 10 , wherein the third flexible member is non-magnetic.
14 . The microfabricated MEMS reed switch of claim 1 , wherein the first flexible permeable member and the second flexible permeable member are formed on a device wafer and supported on a support wafer, and enclosed with a lid wafer.
15 . The microfabricated MEMS reed switch of claim 1 , wherein the first flexible permeable member and the second flexible permeable member comprise nickel-iron.
16 . The microfabricated MEMS reed switch of claim 15 , wherein the nickel-iron comprises nickel-iron permalloy, having a composition of 80% Ni and 20% Fe.
17 . The microfabricated MEMS reed switch of claim 1 , wherein the electrical contacts are electrically connected to bumps which are disposed within a footprint of the microfabricated MEMS reed switch.
18 . The microfabricated MEMS reed switch of claim 1 , wherein the sensitivity of the MEMS reed switch is a function of an angle between an axis of the switch and the direction of the applied magnetic field.
19 . The microfabricated MEMS reed switch of claim 18 , wherein the sensitivity of the microfabricated MEMS reed switch is at a minimum when the applied field is parallel to the axis, and at a maximum when the applied field is orthogonal to the axis.
20 . The microfabricated MEMS reed switch of claim 10 , wherein the three flexible members are configured as a double pole, double throw switch.