E-ink Shopping Tag
Backpack Charm

Repurposing a retail electronic shelf label (ESL), the kind you see on supermarket shelves, as a customizable always-on backpack charm. E-ink displays hold their image with zero power, so the battery lasts months between charges.

ESLs are cheap, plentiful, and come with wireless update capability built in. With the right firmware or a custom BLE/radio setup, the display can be updated from a phone without touching the hardware.

Hardware

Most retail ESLs run on proprietary protocols, so the plan is to either flash custom firmware or tap the display directly. The smaller form factors (2.1" or 2.9") are ideal for a bag charm. Light enough that they don't swing around annoyingly.

Display

The goal is something you can update on the fly: a QR code, a name tag, an icon, whatever fits the day. Static but changeable. No screen burn, no battery drain, no notifications.