My final project for Physical Computing is a device called ‘Lifeline’. It attaches to a user’s phone and detects their heartbeat through the anatomically realistic heart on the case’s back. The heart then haptically ‘beats’ and light up in sync with the user’s heartbeat.

Finally, a mechanical arm scrolls the user’s phone according to the rate of their heart— the faster heartbeat detected, the faster it scrolls.

‘Lifeline’ explores how our phones often function as extensions of our bodies, how our digital well-being is interweaved with our physical one, and how ‘doomscrolling’ can be a palpable and physical activity. It offers a simple challenge to users— in order to control the rush of digital media, we must first control ourselves.

Scrolling through twitter.

Focus on the scrolling action

Demoing the scrolling function during class presentations (thanks Sophie!)

The Process

Making this project was a journey, with lots of lessons learned along the way. I knew I needed unique shapes and flexibility for the phone case and heart model, so I utilized NYU’s Laguardia Studio to 3D print both items. I actually had to print the phone case twice, as the first time we printed it in a harder material that refused to fit over my phone. In the end, both models were printed using an elastic, flexible material (Elastic 50A resin).

My next step was to get the inside of the heart working, which included the heartbeat sensor, LED lights, and vibration motors. These would be controlled by my Arduino Nano 33 IoT and powered by a 3V battery pack. I built that circuit on a breadboard first, then very carefully transferred it to a protoboard.

Sketching out how I wanted to arrange everything on the protoboard.

Originally, I wanted all electronics to be encased by the heart model, but after playtesting in class I realized it wouldn’t be feasible. So I ended up buying an armband for your phone and keeping my Arduino and battery pack on there.

It’s not the prettiest thing in the world, but I think the visuals underscore this idea of your phone being an extension of yourself. It was also much easier for me to not have to remove the heart from the phone case each time a wire on the protoboard broke.

The last step was to get the motorized arm working. This was honestly the trickiest and most unforeseen part. The iPhone’s touch screen works through capacitive touch, meaning it detects the electricity in your finger. Commercial styluses work by acting as a vehicle for that touch, but that capacitance is essential; you must need a source of electricity to have a touch be registered. Not only that, but the contact must be roughly finger-shaped to be registered.

Designing a spinning arm that had electrical contact and would consistently be registered as a finger was a huge challenge to figure out. I tried many iterations and materials, but ultimately landed on a solution using tinfoil to connect a user’s left hand and the arm and a tuft of steel scrubber. The scrubber’s flexible but conductive properties made it mimic a finger touch well.

Some other lessons:

• Make sure to turn the fan on while soldering, or else you’re going to breathe in a lot of stuff you don’t want to.
• Always get someone to record your project when it’s working. This is because if it ever stops working, you can prove to people that at some point it did.