MEMS device with bi-directional element
The present invention provides a bi-directional microelectromechanical element, a microelectromechanical switch including the bi-directional element, and a method to reduce mechanical creep in the bi-directional element. In one embodiment, the bi-directional microelectromechanical element includes a cold beam having a free end and a first end connected to a cold beam anchor. The cold beam anchor is attached to a substrate. A first beam pair is coupled to the cold beam by a free end tether and is configured to elongate when heated thereby to a greater temperature than a temperature of the cold beam. A second beam pair is located on an opposing side of the cold beam from the first beam pair and is coupled to the first beam pair and the cold beam by the free end tether. The second beam pair is configured to elongate when heated thereby to the greater temperature.
1. A method to reduce mechanical creep in a microelectromechanical device with a bi-directional element comprising:
moving said bi-directional element in a first direction to a first position, wherein said bi-directional element includes a cold beam, a first beam pair, and a second beam pair;
determining if said bi-directional element has been in said first position a predetermined amount of time; and
based on said determining, moving said bi-directional element in a second direction opposite said first direction to a second position.
2. The method as recited in claim 1 further comprising:
moving a unidirectional element of said microelectromechanical device from an initial position before moving said bi-directional element in said first direction; and
moving said unidirectional element of said microelectromechanical device to said initial position after moving said bi-directional element to said first position.
3. The method as recited in claim 1 wherein said moving said bi-directional element to said first position comprises applying a current to a first beam pair.
4. The method as recited in claim 1 wherein said moving said bi-directional element to said second position comprises applying a current to a second beam pair.
5. The method as recited in claim 1 wherein said determining is based on parameters selected from a group consisting of:
historical data,
composition of said bi-directional element,
design of said bi-directional element, and
ambient temperature of said microelectromechanical device.
6. The method as recited in claim 1 wherein said determining is performed by a controller associated with said microelectromechanical device.