Coronavirus Magnetic Face Guardian App

Use your phone's compass and a magnet on your wrist to detect face touching, including audio and vibration alerts.

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Face touching is one of the primary ways people contract SARS-CoV-2, the coronavirus responsible for COVID-19. People on average touch their faces 23 times an hour. Obviously we should stop touching our faces. Thing is, we can't. Face touching is a deeply ingrained unconscious behavior. How can we stop touching our faces if we don't even know we're doing it? Things like washing hands, social distancing and mask-wearing are easy: you just do them. But how do we not do face touching? Face Guardian is an attempt to solve this problem in a highly scalable fashion. All it requires is a smartphone and a magnet. You put the magnet on your wrist and your phone around your neck. Your phone's compass (magnetometer) detects when the wrist magnet approaches your face. The app records every time you touch your face, and it also provides vibration and audio alerts.


Android App:

Mobile Web App: (Android Chrome only for now)

Face Guardian's target demographic is parents and children stuck at home during the coronavirus pandemic. If you have children, you can setup up everyone in your family with Face Guardian (phone on neck and magnet on the wrist) and then play a board game or watch a movie. Who will be the first person to inadvertently touch their face? Maybe the person who touches their face the least can get a prize. Although this is meant to be a fun educational activity for parents and children, anyone can benefit from it. Setup Face Guardian before you read a news article, write some code or procrastinate on the internet. Even with the admittedly obtrusive experience of wearing your phone around your neck, you might be surprised at how quickly you inadvertently touch your face.

VOLUNTEER: I am a research engineer, not an app developer. Are you an app developer who likes this project? We would love your help! 

CODE: Face Guardian is entirely open source. Check out our brand new GitHub repo

This repo is also the web app version of Face Guardian via GitHub pages. That means you can fork the repo, enable GitHub pages in repo settings and start customizing your own live web version of Face Guardian in minutes.


NYTimes: Stop Touching Your Face! It’s a quirk of human nature that we touch our eyes, noses and mouths all day long. It’s also a major way we pick up infections like coronavirus.

The Hill: How often do you touch your face—and does that increase your risk for coronavirus?

The Atlantic: The Small Stresses of Keeping Coronavirus-Free: Why is it so, so hard to stop touching your face?

The Guardian: The coronavirus challenge: how not to not touch your face

SUPPORT: This project started in a brainstorming session at work. I pitched it and now it is an official CMI MATTER Lab project. Big thanks to Dr. Arno Klein (Director MATTER Lab, Child Mind Institute) and Dr. Michael Milham (Director Research, Child Mind Institute).

DEDICATION: Face Guardian is dedicated to my wife, Dr. Virginia White. She is a second year OBGYN resident at Northwell LIJ (Long Island Jewish) hospital in New York City, a COVID-19 hot spot. She and the other residents spend much of their time treating COVID-19 patients. 1/3 of her fellow residents are in quarantine and the hospital is often short on masks. And she's 17 weeks pregnant! Despite all this she is completely unflappable, which is AMAZING. She's also very much a collaborator on this project.


This is the latest Android App installation file. If you have trouble installing it directly, you can also get it using the Google Drive link: I email myself the link and then open it in email on my phone. The APK installation package manager automatically deals with the linked file (for me at least).

package-archive - 4.89 MB - 03/31/2020 at 00:36


  • 1 × Neodymium or other strong magnet
  • 1 × Mobile device with a magnetometer Android only for now... interesting in being a volunteer iOS developer?

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  • 1
    Wear Your Phone Around Your Neck

    The easiest way is to put it in a clear plastic bag. A zip-lock bag, sandwich bag or freezer bag will do just fine. Don't worry if it's too big, you can fold and tape any excess. You can use tape, paper clips or simply ties a string (shoelaces work great) to the bag corners. Alternatively, you can poke holes in the corners of a phone case and thread a string. 

  • 2
    Make a Magnet Bracelet and Put it On Your Wrist

    You will need a strong magnet. Most refrigerator magnets won't do, but some of them are powerful enough to work with the app. You might have to order one on (see links below) but they are very inexpensive and you never know what you might need a magnet for. Magnets are a little like magic, after all, everyone should have a couple around. The Face Guardian App can test magnets to determine if they are powerful enough. To test a magnet, place your phone on a flat surface with no magnets near it and press "TEST MAGNET". The "TEST MAGNET" button will turn red. Move your magnet closer to the phone until the "TEST MAGNET" button turns green. If the button turns green while your magnet is at least three inches away from your phone then the magnet should be fine, especially for children or anyone else with small hands. Remember though, the magnet has to go on your wrist so it can't be too big. There are lots of ways you can turn your magnet into a magnet bracelet: tape it to a watch, tape it to a hair scrunch, or just plain tape it to your wrist! Make sure that the magnet is on the inside of your wrist though, you want it to pass as close to your phone as possible. 

  • 3
    Use a Mirror, Webcam, or Partner to Operate Your Phone While it is Around Your Neck

    You will probably have a difficult time operating your phone while it is around your neck without help. I find that the easiest solution is a mirror. However, if you look at text in a mirror its all backwards! There is a button in the app (conveniently labeled "mirror") that will reverse the app appearance so you can use a mirror just as if you were looking at your phone without one. The webcam on your laptop might also be useful. Alternatively, your can have someone else interact with the app for you. This may be the best option for parents with younger children. 

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Curt White wrote 03/31/2020 at 19:22 point

Thanks Dan. I already built precisely the kind of device you are describing, and it placed 2nd in the 2018 Hackaday Prize competition: The 'Tingle' gesture recognition device is designed to detect compulsive hair pulling and skin picking but it can just as easily detect face touching. In fact, the sensor configuration provides enough high quality data to distinguish between specific areas of the face (mouth, eyes, forehead). The Face Guardian phone app described in this project is primarily being promoted as an activity that parents and children (or just children) can do together at home. Asking people to wear their phones around their necks on a regular basis is certainly a stretch, but most people have phones and most people are capable of installing apps on their phones. To be perfectly honest, I enjoy electronics and building things a whole lot more than developing apps, but nothing I build can be scalable on the time-frame imposed by the coronavirus pandemic.

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Dan Maloney wrote 03/31/2020 at 18:14 point

Good idea, but having to keep the cell phone around your neck might be a barrier to adoption. Wonder what sort of minimal sensor you could build that could be worn as a necklace or as a clip-on at the collar? You'd need a magnetic sensor and Bluetooth connection to the phone. Much more complicated that using the phone's sensor, but might be easier to convince people to use.

And please tell your wife we're all proud of her, and wish her the best.

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