TL;DRAn open-source project called LightInk could put an ultra-efficient E-Ink display on your wrist.The watch reportedly uses just ~0.5mAh per day, translating to roughly 40 days of battery life in typical use.It is also solar powered, and aggressively optimized for “infinite” runtime under the right conditions.E-Ink already makes a lot of sense for reading, and now someone’s making a strong case for wearing it, too. A new open-source project called LightInk is gaining attention for turning an E-Ink panel into a minimalist wrist watch, pushing battery life to an extreme that most wearables can’t offer.At the heart of the device is an ESP32, a low-cost microcontroller known for its Wi-Fi support and ultra-low-power sleep modes. It’s paired with a small E-Ink display, similar to the panels used in compact DIY e-readers (including builds we’ve covered before). Unlike OLED or LCD screens, E-Ink only draws power when the image changes, making it an ideal fit for glanceable information like the time or basic stats.