QR code, silver
This is a piece I made a few years ago. It was for a mapping project, and whilst I was very happy with the way my QR code worked so well, ultimately the project failed, because so few people knew what a QR code was, let alone had the means to read it with their smartphones.
It was a fraught piece to make, because I had no idea if it would work until it was finished. I was overjoyed when it did. I made it using very simple techniques. I cut out tiny pieces of metal and riveted them to a base of silver. No solder was used. I wanted to make something as low-tech as possible that linked to something very hi-tech; a smartphone app that connected the user to a website page.
The technical person who configured the mapping project is unconvinced that QR codes will work effectively to trace covid-19 contacts. It’s not sufficiently passive to succeed, as action is required at every step; you must download an app before your smartphone can read a code that the business has actively placed in their premises. There will not be QR codes every single place you go. Worst of all, the app doesn’t tell you if there is a connection between you and a person with covid-19. Not yet…
Alternately, contact tracing geo-spacially using the in-built GPS system of your smartphone would be passive, and direct.
Diagram of how contact tracing could work using GPS