An optical relay is disclosed in which a liquid metal droplet is moved within
a switching channel formed in relay housing. An optical path passing through the
switching channel is blocked or unblocked by motion of the liquid metal droplet
that coalesces with one of two additional liquid metal droplets. Motion of the
liquid metal droplets is controlled by heaters that control the pressure of an
actuation gas in the switching channel. The liquid metal droplets are held in place
by surface tension acting on wettable contact pads within the switching channel.
The surface tension of the liquid provides a latching mechanism for the relay.
The pressure of the actuation gas is increased by direct heating of the gas or
by heating a phase-change liquid to cause it to evaporate.
