We report reconfigurable circuits formed by liquid metal shaping with <10 pounds per square inch (psi) Laplace and vacuum pressures. Laplace pressure drives liquid metals into microreplicated trenches, and upon release of vacuum, the liquid metal dewets into droplets that are compacted to 10-100Â less area than when in the channel. Experimental validation includes measurements of actuation speeds exceeding 30 cm/s, simple erasable resistive networks, and switchable 4.5 GHz antennas. Such capability may be of value for next generation of simple electronic switches, tunable antennas, adaptive reflectors, and switchable metamaterials. V C 2012 American Institute of Physics. [http://dx.

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We report on the physics, design, characterization, and demonstration of five viable techniques for switchable retroreflectors, including integrated electrowetting scattering, integrated and external electrowetting light valves, external liquid crystal light valve, and external liquid crystal scattering. All techniques were evaluated for use in conspicuity applications spanning wavelengths in the visible and IR (night vision). Achieved performance includes high optical efficiencies up to nearly 30% (out of a maximum 35%), visibly fast switching speeds of <100 ms, low to moderate operating voltages ranging from 5 to 60 V, more than ±45 deg of operation angle, and implementation with pressure-sensitive, adhesive-backed films of 0.7 to 1 mm thickness for flexibility and impact resistance. Each approach has unique strengths and weaknesses, which will also be discussed for applications ranging from commercial to military conspicuity.

Corner cube and spherical retroreflectors are ubiquitous in conspicuity and range-finding applications since they reflect light back to the illumination source with unmatched efficiency. We report here a switchable electrowetting retroreflector platform that provides multiple novel features, including ͑a͒ using Ͻ0.5 J / cm 2 electrical energy to switch from a light scattering state, ͑b͒ low loss and wide spectrum as limited only by the absorption spectrum of water, ͑c͒ use of ultrasimple self-assembly of 10 3-10 5 liquid lenslets/ in. 2 on a polymer/Al corner-cube substrate, and ͑d͒ change in retroreflected irradiance of Ͼ10: 1 over a Ϯ30°field of view.

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