a closeup of a tiny LED in the middle of a microchip - Credit: Singapore-MIT Alliance for Research and Technology (SMART) Scientists at MIT’s Singapore-based research center have built the world’s smallest LED — and then used it to create the world’s smallest holographic microscope, a breakthrough that foreshadows a future in which smartphones could do high-res microscopy. Chips of light: In most of our devices, currents of electrons travel across microchips, where tiny features called “transistors” act as on/off switches controlling their flow — but electronic microchips aren’t the only kind. There are also photonic microchips, which manipulate the...