BACKGROUND:  Liquid-solid contacts have many benefits, such as no wear, no surface degradation, and low contact resistance that have made them desirable for several applications including electrical and optical switches. However, attempts to design droplet-based switches have been limited due to their slower speeds (larger latency), with the best latencies being on the order of 1 millisecond. In order to achieve high speed (low latency) operation of droplet switching, using a large actuation force alone is most often insufficient.

INNOVATION:  This invention reports a high speed droplet actuation technique. This invention includes provisions to accurately position the droplet, restrict its unwanted free motion and buffer against droplet volume variations, thus allowing a microactuation mechanism suitable for high speed (low latency) droplet switching.

POTENTIAL APPLICATIONS:  High speed droplet-based switching opens up possibilities for a whole new range of devices such as radio-frequency (RF) switches, dynamic displays, and low-loss, high-performance electrical and optical micro switches.

ADVANTAGES

• Significantly improved switching speeds over existing droplet (e.g., liquid-metal) switching technology. Switch-on latency times of ~50 µs has been demonstrated, a 20 times improvement over existing technologies of 1 ms.
• No signal bounce, low contact resistance and high power
• No contact degradation leads to improved reliability and longer life
• Low loss: 0.2dB simulated insertion loss for an RF switch as compared to 1dB for existing technology
• Very high droplet stability against shock and vibration to a kG range.

DEVELOPMENT-TO-DATE:  The low latency design concept has been experimentally verified (~50 µs). A DC switch has been built, tested, and characterized. An RF switch has been designed and simulated.

Reference: UCLA Case No. 2007-386