wearable breath sensor: jill sherman & sara hendren : Crafting Material Interfaces

Here’s a description and shot of our working “final” prototype of our breath sensor skin suit, which we proposed earlier this semester here.

The “Breathe” jacket is an inversion of typical protective gear—for example, a bullet-proof vest. “Breathe” externalizes an interior system by sensing and registering the pattern of inhale and exhale in the wearer via a rubber stretch sensor; the jacket then actuates this data in light patterns. Rather than shield its wearer from harm, “Breathe” points back toward the body and its idiosyncracy, rhythmic reliability and frailty at once.

It works! Here’s how we did it:

We started looking at two kinds of wearables for inspiration—first, sculptural form in high fashion, as you see here:

images: Alexander McQueen on Style.com

And second, we were looking at wearable, performative art projects like Takehito Etani’s The Masticator, as you see below. The Masticator is made from pig skin, and it’s an externalized system for displaying the act of chewing. We were similarly interested in externalizing an internal set of biological processes, keeping it connected to the both attractive and repulsive qualities of (synthetic) skin while also displaying a process that’s delicate and nuanced.

There are a couple of projects that directly precede ours, and we were able to look to those for structural inspiration:

Synne Geirsdatter Frydenberg’s LEDPneuma dress above and Anna Salmi’s “Aer” project. This is another spot-on precedent for our project; the garment registers the breath of the wearer and augments its changes with auditory signals. (Alas, no video for this anywhere, but here’s a link to her thesis pdf.)

Salmi’s corset structure inspired our own:

To sense the change in breath, we started with an 8-inch stretch-sensing rubber cord from Robotshop. Filled with carbon-black particles, this sensor is flexible and pliable while also increasing its resistivity as it gets stretched. It was originally designed, we’re told, to measure breath data for astronauts in the 1970s—a nice precedent for our project. Here are the specs from Robotshop:

• 8″ long flexible cylindrical cord
• Measures stretch, displacement and force
• Changes resistance when stretched

The Images Scientific 8″ Flexible Stretch Sensor is a unique component that changes resistance when stretched. When relaxed the sensor material has a nominal resistance of 1000 ohms per linear inch. As the stretch sensor is stretched the resistance gradually increases. When the sensor is stretched to 150% of its original length (8″ X 150% = 12″), its resistance will approximately double to 2.0 Kohms per inch.

The stretch sensor is a new way to measure stretch, displacement and force. The sensor is a flexible cylindrical cord with hook electrical terminals at each end. The sensor measures 8 inches long, not including the electrical terminals, and only .060 inches diameter!

Applications for the Images Scientific 8″ Flexible Stretch Sensor:
• Virtual gloves and suits
• Robot exoskeletons

We knew from this course that the Lilypad Simple Arduino was the best choice for our wearable project, and we got hold of this synthetic skin from SkinBag (where they claim that “gore + chic = trés chic!”).

We put together a test model just to see if the circuitry design was operational, and we used ModKit to lay out our code in a graphics environment. We had what Kate Hartman calls our yay! moment with this one. It works! It blinks!

So then we set about thinking of the construction of the piece, and how we wanted the lights to reflect the organic, biological ideal we’d set out to create. We collected some images of lungs:

And we made some drawings based on further inspiration from the field of fashion:

source: Style.com

We mapped out our light patten so that we could have LEDs in parallel but in an organic, dispersed structure:

We traced the lines onto a piece of thin red cotton—it acts as a “shell” and surface mount for the circuitry, and it gives the skin an even-more organic cast of pink. And then we sewed over the lines with conductive steel thread:

There were mistakes, of course—getting the proper tension the machine.

And then we used our original test model “belt” design again. This time we sewed linen onto denim for reinforcement, and we used grommets for a corset pattern based on Anna Salmi’s project above.