Media Controller – Mid-term Project with Doug Kanter, Engin Ayaz and I.

After a few rounds of brainstorming we’ve narrow our project to water as the medium to control and bio-metric feedback as the input that controls the medium. Heartbeat was the first type bio-metric feedback that we tried to tackle (and it became our only). We thought of playing with bubbles at first, something like this. But the parts and assemble was too complicated and had a very fixed iconic output, we thought… And so we thought generating ripples or waves would be more engaging. It developed into a reflecting pool-like installation where the viewer can see their heartbeat as waves in the water.

For the sensor our first thoughts were to use a stethoscope and place a mic at the ear-piece end to amplify the sound. But we quickly realized this was not going to work…

(***there should be a video window below, if it’s just a blank space please refresh your browser, thanks!***)

We then did a quick google search to see the available heartbeat detection sensors and came across pico Technology’s DIY blog ( http://www.picotech.com/experiments/calculating_heart_rate/ ) and started replicating it. Our classmate Deqing helped us a lot to understand this circuit. In the end we reduced it to one LM358/1 amplifier (marked in highlight yellow).




(evolution of the picotech pulse oximeter boards)
But when we plugged this board into the Arduino the output had too much interference. We were unable to work with the data. It was a shame… but after making 2 of these boards for 2 weeks we had to abandoned it and search for an off-the-shelf option. In the end we used 2 Polar CHR S 3G heartrate sensor. This gave us a digital on/off output which made it really easy to work with.

On the output side, we thought of using transducer speakers, vibrating motors, solenoid valves but settled with an electromagnet method to generate waves by pulling a metal plate suspended in the water.

(Home-made Electromagnet, with a testing tank)

(Industrial Magnet, with simulated heart pulse)

The form of the tank was built with interior plexi walls and blue foam on the outer edges to give it a softer look. All interior corners were lined with silicon and outer skin coated with an epoxy called Magic Smooth.

(The slot for the electromagnet.)


(testing if there’re any water leakage and playing with the paddle.)

Then it was spray painted to give it a even skin. The glossy paint was too jarring so a second coat of matte black was sprayed over it.

Here its working!!! Finally seeing the results in full at 2:30 in the morning, just before it was due the next day…

***January 3rd 2012 update***
Thanks for my teammates in putting the final touches to this official video.
Here’s the links:
-VIDEO-

-Doug Kanter’s blog-

http://dougkanter.wordpress.com/2011/11/28/heartwave-final-documentation/

-Engin Ayaz’s blog-

http://itp.nyu.edu/~ea1095/myblog/itp/fall-11/physcomp/media-controller-heartwave/

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