Flexible Vertical GaN MicroLEDs for Transparent Biomedical Stimulator

Internet of things (IoT) platforms for visual communication media in hyperconnected society have attracted a lot of interests, and inorganic-based flexible microLEDs (f-μLEDs) exhibit outstanding performances including excellent electrical/optical properties, long life time with high stability, and low power consumption. In these reasons, f-μLED is one of the most promising candidates to replace the conventional light sources such as LCD, OLED, and QLED for next-generation display technologies. Despite of several previous researches about μLEDs, flexible vertical GaN μLEDs on plastic substrates have not yet been demonstrated due to the difficulty of vertical electrical interconnection with high power efficiency and thermal stability.<br/> Here in, we demonstrated the transparent vertical-structured flexible GaN μLEDs with high performances through a very simple monolithic fabrication process. Our transparent flexible GaN μLED array could conformally attached on a human finger nail and a living mouse brain, stably emitting bright blue light with optical power of 30 mW mm-2. We also realized wireless energy transfer system, which could successfully supply the power for GaN f-μLED array operation. Finally, GaN blue microLED array was successfully inserted into a living mouse brain and stably glowed bright blue light without histological damage on a mouse brain.