Electrowetting-Based Driving of Liquid-Metal Droplet for Reliable RF Switching

摘要

The basic idea of electrowetting-based driving of liquid-metal droplets at microscale is proven, using microfabricated prototypes. A detailed theory of our actuation mechanism is developed, and various experiments were performed to validate the theory and techniques developed to overcome the interface-charging problem. Based on the theoretical understanding, new devices are designed for integration with microwave circuits and actuation speeds better than 3.3 cm/s are demonstrated. Pursuing reduction of hysteresis for achieving high actuation speeds would be a good future topic beyond the current project. In the mean time, characterization of liquid-metal for high RF frequencies is performed experimentally, using a stationary (i.e., not actuated) mercury droplet in a RF electrode pattern designed for this testing purpose. Better than -25 dB isolation is provided. New devices are designed and simulated using HFSS to significantly lower the insertion loss. Based on the new design, devices are fabricated and measured results showed less than 0.15 dB insertion loss. The knowledge gained and results obtained in the project point to the liquid-metal droplet switch designs that can be fabricated and tested for RF performance.