Electronic artist Rafael Lozano-Hemmer's public art installations combine technology, architecture, and performance using devices like robotics, projections, and cell phones. He constructs "temporary anti-monuments for alien agency," as in Pulse Tank (2008), in which heart rate sensors send ripples across the surface of water, or the Guggenheim's 2009 installation Levels of Nothingness, which allowed people to speak into a computer that linked voice traits to colors that were projected across the room. His Vectorial Elevation (1999), in which 800,000 participants created searchlight sculptures above Mexico City, may well be the world's largest interactive artwork ever.