New Micro LEDs Can Be Bent, Cut, Detached From the Substrate, and Reattached as Needed

Light-emitting diodes (LEDs) are ubiquitous in today’s technological world. You’re used to seeing them utilized as status and indicator lights, but they’re also used in energy efficient light bulbs, as backlighting for LCD screens, and even entire organic LED (OLED) displays. Micro LED technology today is incredible, and the smallest micro LEDs that have been developed are a mere two microns wide. That’s about a quarter of the width of a red blood cell. But micro LEDs at that scale don’t have their own package, which means they have to be permanently attached to a substrate. University of Texas at Dallas researchers recently developed new micro LEDs that can be bent, cut, detached from the substrate, and reattached as needed.

Conventional LEDs, like what you’d find being used as status lights on a smartphone, are packaged in a way that is conducive to mass production and utilization. Each and every LED is built on a tiny substrate and has to have the structural integrity to support the anode and cathode that provide an electrical connection. Even the smallest SMD LEDs, which look about the size of a grain of sand to the naked eye, have to have these. Micro LEDs, on the other hand, do not have individual packages. Instead, many micro LEDs are attached to a single substrate. This results in a very high density of microscopic LEDs, but they can only be used together. That means they’re really only practical as a larger group, like you’d use for an LCD backlight.

This new technology, which was published by UTD researchers in Science Advances this June, provides the benefits of more conventional LEDs at the scale of micro LEDs. The key to this breakthrough is being able to remove individual LEDs from the larger substrate. They used a technique called remote epitaxy to grow the LED crystals on a substrate made from sapphire crystal. Importantly, however, they put a one-atom-thick layer of graphene on the substrate beneath the LEDs. The graphene acts like Teflon on a non-stick pan, and makes it possible to remove the individual LEDs. They can then be attached as needed to other objects — including flexible materials. The LEDs can even be cut in half, and you can continue to use half of the LED. Of course, this technology is still very early in development and we likely won’t see it being used at scale for years, but it is an important breakthrough for micro LEDs.