The Heterogeneous Packaging of A 3 x 3 Mini-LED Array for Smart Contact Lens Display Applications

For the needs of augmented reality (AR), virtual reality (VR) and mixed reality (MR), smart contact lenses (SCL) have become an important platform as a display source in the future consumer market. Accordingly, this paper demonstrates a display device based on contact lenses. This device integrates a 3 x 3 Mini-LED display array, a micro antenna, and a driver and transmission chip and is packaged in a smart contact lens made of hydroxyethyl methacrylate (HEMA). It is note that in order to simultaneously meet the goals of wearing comfort, biocompatibility, wireless energy transmission and adjustable display functions, the final package thickness needs to be less than 200 mu m. Here, we use heterogeneous packaging technology to connect the driver and transmission chip and the Mini-LED display array with metal wires on the flexible substrate, and use metal wires on the same conductive layer to design the antenna required for wireless energy transmission. In order to complete the above functions, we use 920 MHz RFID technology as the energy source for wireless energy transmission. When the antenna of the RFID reader is 2 cm away from the smart contact lens, the designed receiving chip can receive 100 mu W of energy. After converting this energy to DC 3 V, it can drive Mini-LED with a current of about 30 mu A, and the mini-LED display array can be instantly controlled to display different contents by transmitting display commands through the RFID protocol. (c) 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.