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The No Phone Contact Tracer (NPCT) Project

The goal of this work is to develop an open-source, anonymous, self-driven contract tracing hardware token that doesn’t use a mobile phone at all. Say hello to the “NPCT” (no phone contact tracer) Project

Participating in contact tracing(1)(2) is something each of us can do to help slow the spread of Covid-19.
This work shows an inexpensive (~$20 USD) hardware-based contact tracer.
This contact tracer does not use a mobile phone or an App at all.
If you build this and carry this around, you can participate in self-driven contact tracing.
It uses an ESP32 and Bluetooth Low Energy to 1) broadcast your health information and 2) log the same from those around you.

Contact tracing is a mechanism for slowing the spread of an infectious disease. It works like this.

Suppose someone gets infected with the disease. They’re called “the case.” The case should let everyone they’ve been in recent contact with (the contacts) know that they’re sick. The case should isolate and the contacts should quarantine. This can help stop the spread of an infectious disease.

But this requires a lot of legwork. In the contact tracing protocol, typically carried out by public health, those who test positive (each now a “case”) will be contacted (by public health) to tell them of/confirm their test result. They will be asked to isolate. Additionally, public health will inquire about the case’s recent contacts. Public health will then contact the contacts, discuss with them about going into quarantine, etc. and on it goes. (Then there’s the hardships of isolating and quarantining.)

Typically contact tracing is all done by phone. It is slow and arduous work, but time is of the essence, as a contact (if they then become sick) will likely themselves become infectious within days, spreading the disease to those they contact. Numbers for COVID-19: People are infectious 2-days before showing symptonms, 50% show symptoms within 5 days, infected people should isolate for 10-days, contacts should quarantine for 2-weeks.

Can technology help? Can we do self-driven contact tracing?
What if you go out and about, and do two things:

Let people you come in close proximity with about your health condition and,

likewise yourself learn about the health condition of those same people.

If you are feeling sick, others your encounter might benefit from knowing this, so they can act accordingly if they get sick a few days later. Likewise, if you are around people who are sick, you might take appropriate actions if you start to feel sick.

Would this be a way for us all to participate in self-driven contact tracing?

To start, how do we do (1) and (2)? Do we walk into a grocery store and yell out “I’m not feeling well…if you get sick in a couple of days, it might be because of me!” No. And this won’t do it either.

Using some technology to quietly inform those around us about our condition might work.

Mobile Phones for Contact Tracing?
Mobile phones might be ideal for this. “Everyone already has one,” and they can broadcast short Bluetooth messages about your health to those (phones) nearby for easy and automated tracking by all later on.

However, by Summer 2020, phone-based contact tracers were getting kind of becoming a mess: 1, 2, 3. Many contact-tracing Apps were appearing, some by companies and individuals; others developed by governmental agencies for countrywide deployment. Whose App do I use? Am I really doing anything? How do I register? Are they all compatible with each other? And most importantly: Who will have access to my (health) information?

The (open-source) Apps revealed all kinds of tricks to keep the Apps running and tracing in the background on a phone. Google and Apple also stepped in to unify the development process, but it’s not clear their efforts helped. The Apps decreased battery life of the phones, but more importantly, trust in Apps and what companies do with your data was becoming a larger and larger question. (The latest round is “clipboard spying” in stories such as this one and this one certainly didn’t help.) It’s also not clear you need an instantaenous notification if you encounter someone who is sick.

Phones and Apps are for fun and communication, but we will likely not trust them with health information. (If you want full privacy, you’d have to leave your phone off and at home.[ref.])

If not a phone, then what?
The maker movement continues to impress. They got a quick start in early 2020 backfilling PPE shortages with a mask and face shield producing efforts, like these: masks and face shields. Is a ‘maker’ themed contract tracer possible?

Bluetooth (BT) does seem to be an ideal technology for contact tracing. In particular, Bluetooth Low Energy (BLE). Both are a short-range protocols that can broadcast messages to receiving devices nearby. BLE is meant for short messages, like “I’m sick.” But I didn’t want to to use a phone for this, so what then? I could not help but wonder about the Arduino world and all of the small and low-priced boards out there. Even the good-old Arduino Uno is relatively portable and will run off of a 9V battery for half a day or so. Plus, there are plenty of Arduino+BT options.

One board that came to mind in particular was the ESP32. It costs $8….$8! This is cheaper than any Arduino, with or without BT, and it’s a fully BT-enabled board about 2”x1” in size. Makers use it for all kinds of things, and $8 is pretty “no-risk.” (It is about what materials cost for masks people are making.) There had to be some way of using an $8 device for a contact tracer. So I bought 3 on ebay and got to work.

Here was my plan that I would implement using BLE and the ESP32:

Come up with a way of coding an anonymous ID and health information for each participant.

Come up with a way of broadcasting such information to those who come near you.

Come up with a way of recieving health information of those nearby.

Make it easy for one to set/change their health status, and to retrieve a log of the health information of those you encounter.

Power it with a $10 portable “extra phone charge” battery.

And, most importantly: No server, no storage, no App, no account to make, no Internet, no GPS.

That’s it. I put all of this together using an ESP32 and Web-Bluetooth in the Chrome browser. It all works, and here’s how. Want to build one and try it out?

So participants will need an ESP32 (and to carry one around)?
Yes, and this is likely a show stopper. But an ESP32 is only $8 and people are making all kinds of things to adapt and get through the pandemic. Maybe it’ll be fun to make and operate your own contact tracer? Also, there is some precedence for a (non-phone) hardware device for contact tracing. It’s called a “contact tracing hardware token.” Singapore apparently developed one too.”

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