GoKawiilEngineer builds NFC business card with phone-powered LED, no battery
A developer designed a credit-card-sized PCB business card featuring an NFC chip that opens his website when tapped and a red LED that lights up on a printed Charizard's tail, powered entirely by the phone's own NFC radio field rather than any onboard battery. He had to write a custom Core NFC app for iPhone because standard NFC apps couldn't write to the blank NTAG I2C Plus chip he used, so his app sends the chip's native write commands directly.
GoKawiil's interpretation of the reporting above, not reported fact.
The project is a hands-on demonstration of NFC energy harvesting, where a phone's field can power small components on a passive tag, hinting at broader possibilities for battery-free smart cards, tags, and interactive objects. It also highlights a real gap in iOS's consumer NFC tooling, forcing hobbyists to write low-level Core NFC code just to interact with common blank NFC chips.
- The LED lights up using only energy harvested from the phone's NFC radio field, with no battery on the card.
- A custom-wound copper spiral antenna on the PCB tunes the card to the 13.56 MHz NFC frequency.
- Standard iPhone NFC apps failed to write to the blank NTAG I2C Plus chip, requiring a custom Core NFC app.
NTAG215 Blank NFC Cards (100-pack) — If this batteryless tap-to-open business card has you itching to try NFC yourself, a stack of blank NTAG215 cards is the easiest on-ramp — write a URL once and every tap opens your site. They're PVC and printable, so you can prototype your own tap-to-link card long before you order custom PCBs.
See NTAG215 Blank NFC Cards (100-pack) on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: kevin.md — Kevin Tang, 2026-09-01
Published there as: “A PCB business card with a batteryless LED, powered by the phone that taps it”
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