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Heartbeat Human + Computer

Heartbeat Human + Computer

by aczulak evan | updated February 13, 2014
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We were motivated when considering a future society where a every person's heartbeat could be plainly sensed by other people and heartbeat data is constantly recorded.

We aim to create a wearable device that both transmits and records the wearers heartbeat and receives a heartbeat signal from another user.

January 12, 2014 at 1:42 PM
Created by aczulak
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While we wait for our pulse sensors and vibration motors to arrive we made this basic circuit: Each Arduino has an analog input and output (a pot and an led), and changing the analog input on one changes the output on the other. It was simple to build once we realized we had to equalize the grounds (by connecting the pins).

January 20, 2014 at 5:14 PM
Created by evan
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nice prototype! can you talk more about what sensors you plan to use for measuring heart rate?
almost 3 years ago

I made this video to present at the first crit to sum up what Alex and I had talked about.

January 20, 2014 at 5:29 PM
Created by evan
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really nice work on the video. what did you use to make it?
almost 3 years ago
It's made in After Effects uses graphics from the Noun Project.
almost 3 years ago

The CAD assembly includes the vibration motor (red) pulse sensor (blue) and ear clip (purple).

January 22, 2014 at 12:37 PM
Created by aczulak
Comments (3)
nice CAD prototype. do you plan to 3D print the earclip? if so, do you expect the material to flex to fit around the person's ear, or will the material be rigid? also, how do you plan to attach the different modules (the motor and sensor) to the clip?
almost 3 years ago
We 3D-printed the clip in ABS, which turned out to have just the right amount of flex to stay comfortably in place! The sensor is moving to a separate piece, but with this design we plan on gluing the sensor and motor in place.
almost 3 years ago
oh nice! I would consider a temporary adhesive to attach the sensor and motor to the plastic in case it needs to be adjusted. some options are heavy duty velcro or even hot glue, which you can easily remove by applying some ethyl alcohol (a trick I learned a few years ago at a company I was working for)
almost 3 years ago

We 3D-printed our ear clip at Brown. The ABS material was just right in terms of flexibility, and the earpiece stayed firmly in place. We plan on making the piece curved so that the enclosure pints downward and presses flat against the wearer's head but we ran in to some issues with the sensors that will require changing the design (see next step!)

January 22, 2014 at 10:13 PM
Created by evan
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The pulse sensors arrived! Unfortunately, they're a bit finicky. They work optically, with a bright LED and photodiode that read the tiny brightness changes when capillaries fill with blood every heartbeat.

That means they only work where there is good bloodflow very close to the skin: the fingers (fingertips are best) and the earlobe. The places we can feel our pulse (wrist and neck) didn't work at all, and neither did our behind-the-ear plan.

We've realized we need to adapt our design to reach the earlobe. We can still wire the sensor and vibrate motor together, but our design needs to either be two separate halves (motor and sensor) or somehow adjustable/telescoping to accommodate different ear sizes.

We're brainstorming how best to improve the look of the earlobe clip. The included clip works fine but looks a little goofy, and we're trying to develop something more understated...

Pulse sensor website.

January 22, 2014 at 10:40 PM
Created by evan
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After testing our pulse sensors we learned that they only work when attached to the fingertip or earlobe. we changed our design to incorporate a sliding mount that will hold the pulse sensor up to the earlobe and can accommodate a variety of ear sizes.

February 2, 2014 at 11:10 AM
Created by aczulak
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This design shows the layout of our enclosure along with the pedestals which we will use during the expose.

February 2, 2014 at 11:14 AM
Created by aczulak
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New 3D-printed protype. We made it out of PLA filament in white. The properties of the material were slightly different than our last ABS model— the clip flexes differently, and the sliding piece doesn't fit as perfectly as before. But it's just as functional, and it'll work for the show.

February 13, 2014 at 12:16 AM
Created by evan
Comments (1)
great that you guys were able to get white plastic to match your videos!
almost 3 years ago

Time to wire everything together and do some final software debugging. We CNCd the enclosure, and the arduinos fit perfectly with ports exposed.

February 13, 2014 at 12:19 AM
Created by evan
Comments (1)
very cool that someone ended up using the CNC in the course
almost 3 years ago

We rewrote most of our Arduino sketch. A few changes:

  • We realized that a very short signal wouldn't register at all on the motor, so we refactored the code and made sure the motor would always get a pulse of ~40ms.
  • Instead of sending a signal each time we detected a beat, we used SoftwareSerial to send the BPM value and then reconstruct the pulse on the other Arduino. That way, if we lose the pulse we can keep the motor going for a little while.
  • We improved the sensitivity of the sensor by switching to the 3.3v power pin, and connecting the board's Analog Reference to the 3.3v pin as well.

(The sketch uses both files attached below).

February 13, 2014 at 12:34 AM
Created by evan
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Made in Adobe After Effects.

Uses stock material from various Facebook and Apple advertisements, and vector graphics from the Noun Project.

Music: "Heart on my sleeve" by Gallagher and Lyle

Synthesized voices: AT&T Natural Voices

February 13, 2014 at 12:59 AM
Created by evan
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