Micro relays powered by bi-directional electrothermal electromagnetic actuator has been designed, built and tested. Relays built using these actuators can have single pole double throw (SPDT) configuration. Bi-directional actuators can be used to make bi-stable relays, which only require power consumption during the switching operations. The relays built can switch both high current and high voltages. The off state resistance is over 100 Megaohm with a breakdown voltage exceeding 200V. The on state resistance is around 0.3 ohm can carry several amps before failure. The performance of these relays is enhanced using liquid metal wetted contacts. The liquid metal can increase the actual contact area of the relay, hence reducing contact resistance and the heat generated at the contacts. The liquid contact surfaces reduces the amount of force needed for low contact resistance, potentially increasing the mechanical lifetime of the relay and decreasing the actuator size and power consumption. The liquid metal coating could also quench the heat caused by arcing and prolong the lifetime of the contact surfaces. Testing of metal wetted gold-to-gold contacts is completed. Gold contacts wetted with a thin layer of liquid metal can achieve contact resistance as low as 0.015 Ohm.
Project end date: 08/26/05