Thermal actuator for a MEMS-based relay switch

A method of operating a device, comprising the step of:

• driving a first electrical current through a first resistive heater, wherein:
• the device comprises first and second arms movably supported on a substrate;
• a first end of each of the first and second arms is attached to a respective anchor affixed to the substrate;
• second ends of the first and second arms are mechanically connected to one another;
• the first arm comprises (i) a first thermal expansion layer having a large thermal expansion coefficient and (ii) the first resistive heater, wherein the first resistive heater is different and separate from the first thermal expansion layer and wherein the first resistive heater is electrically isolated from the first thermal expansion layer and from the second arm;
• the first resistive heater is adapted to increase a temperature of the first thermal expansion layer in response to the first electrical current, wherein the electrical isolation prevents the first electrical current from flowing through the first thermal expansion layer;
• the first thermal expansion layer is adapted to expand in response to the temperature increase induced by the first resistive heater and move the second ends of the first and second arms with respect to the substrate due to said expansion of the first thermal expansion layer;
• and
• the first arm comprises:
• a body portion that is movable with respect to the substrate, said body portion having a first cross-section;
• a neck portion that is movable with respect to the substrate, said neck portion having a second cross-section different from the first cross-section, wherein:
• the neck portion is located between the body portion and the first end of the first arm;
• the body portion is located between the neck portion and the second end of the first arm;
• and
• the neck portion comprises a first section and a second section that are separated by a gap between them;
• and
• a dielectric layer that at least partially encapsulates the first resistive heater to provide said electrical isolation, wherein:
• the first section has a portion of the dielectric layer and a portion of the first thermal expansion layer;
• and
• the second section has a portion of the dielectric layer but does not have a portion of the first thermal expansion layer.