How do you make an emergency information tag?
Carefully, and alongside printed text rather than instead of it. Information that only exists inside a chip depends on a stranger thinking to tap an object during an emergency, which is a great deal to assume of the worst moment of somebody's day.
Printed first, tag second
An emergency is not the moment anyone investigates an unfamiliar object. A responder or a passer by scans visually and acts on what they can see.
So the printed side carries the essential information and the tag carries the depth. Not the other way round.
Say on the object that a tag is present and what it holds, or nobody will look for it.
And accept that in many situations the tag will never be read. If the printed side alone is not useful, the design has failed regardless of the chip.
What to include
An emergency contact name and number, which is the single most useful item and the one most often missing.
A short indication of anything a responder needs to know immediately, in the words a responder would use.
Nothing that requires interpretation, and nothing that would only make sense to your own doctor.
On the page behind the tag, more detail is reasonable: conditions, medication, allergies, a second contact.
The tension nobody resolves
Emergency information exists to be read by a stranger. That is its purpose and it is also its exposure.
Anyone who picks up the object learns it, including people whose interest is not helping you.
There is no technical fix. Restricting reading would defeat the point, and a tag cannot tell a paramedic from anyone else.
What you can do is separate the layers: the minimum on the printed face, more behind the tag, and nothing anywhere that would embarrass or endanger you if a stranger read it in a queue.
Practical construction
A durable object worn or carried: a card in a wallet, a bracelet, a tag on a bag.
A page that loads with no application, no login and no coverage assumptions you cannot meet. Somewhere rural, the page may be unreachable, which argues for the printed side again.
Keep it current. Emergency information that is two years out of date is worse than none, because it will be acted on.
And tell the people named on it that they are named on it, which is both courteous and practical.
Frequently asked questions
Will paramedics scan an NFC tag?
You cannot rely on it. Printed information is what gets used, and the tag carries the depth for someone who has time to look.
Can I restrict who reads it?
No, and restricting it would defeat the purpose. A tag cannot tell a responder from anyone else.
What is the single most useful item?
An emergency contact name and number. It is the item most often missing and the one that helps in the widest range of situations.
What if there is no signal?
The page is unreachable, which is why the essential information belongs on the printed face rather than behind the tag.