Electronic Shelf Labels Become Battery-Free Conference Badges

Every year, hundreds of small conferences happen around the globe. They may not get the media attention of big events like CES or Open Sauce, but their attendees are just as enthusiastic. Tyler Crumpton wanted to make badges to foster that enthusiasm for PhreakNIC 26, a small infosec con held in Tennessee, but had a limited budget. Thankfully constraints breed creativity, which led to him using electronic shelf labels to make these battery-free badges.

Electronic shelf labels (ESLs) are low-power retail displays that you’ll find in some stores. They’re handy because store managers can quickly update information, such as item prices during a sale, without needing to print new labels. And as commodity items, they’re fairly cheap.

Crumpton was able to find an eBay listing for 100 used ZBD 55c-RB ESLs for just $66.49 (including a discount for purchasing two lots). That works out to just 67 cents each, which is remarkably cost-effective for these screens. They have bistable LCDs that, like e-ink screens, retain their content even without power. These particular units had dead batteries, but that retention made the batteries unnecessary.

To make the badges look nice, Crumpton put the displays inside of 3D-printed enclosures made to look like pagers. They’re pretty darn charming.

The final step was creating a system that would let attendees update the screens of their badges. A QR code would take attendees to special website where they could design their badge display with a bunch of different frames and custom text. They could then place their badge on a programming station, which had pogo pins to touch the display’s contacts and update it with new firmware containing the chosen graphics.

The result was a ridiculously cheap (less than $1 each) badge design that was still very appealing. Unsurprisingly, the badges were a big hit at PhreakNIC 26.