A completely different model for digital contact tracing would be to design and distribute a small monitoring badge, akin to what workers at nuclear processing facilities use. The idea there is that the badge measures accumulated exposure to radiation over time. The analogous idea for contact tracing is that it records an individual's exposure to potential future Covid-19-positive cases.

For digital contact tracing, such a device would be more sophisticated than a radiation exposure badge. For example it might have a blue-tooth receiver, a clock, a globally unique badge ID, and a long-lasting battery. This is in alignment with the very real Internet of Things (IoT) already rolling off the assembly lines. Cheap and completely anonymous, because it's not connected to a cellphone or GPS or the internet.

National governments and international NGOs around the world could fund such a project, ensuring that these devices would be distributed evenly and widely. This could be our generation's "moonshot".