Stress & Biofeedback
The Adidas research project is a creative departure of the more conventional work done by the Adidas Innovation Team. The goal of the project was to find new interesting opportunities in the field of wearable electronics.
For sports there has always been a tremendous focus on improving physical performance. These improvements are often fed by artificial developments. One of the relatively smaller aspects, mental performance, has always been the job of a physical coach.
The Adidas Stress Shirt provides real-time biofeedback of your stress level. The input comes from a galvanic skin sensor, able to measure your skin’s resistance influenced by your stress-related sweat. The output is send to five vibrations sensors along your spinal cord. These vibration motors present you with the current stress level in such a way it only becomes noticeable when needed.
The Shirt provides biofeedback and ultimately control over one’s stress level. It becomes a tool for practicing your own rituals and behavior of reducing stress before and during performance, aiming to increase said performance.
The final report is only available upon request, as most of this work still falls within the Adidas NDA. Feel free to contact me for requests.
Below is an overview of all the aspects of the Adidas Shirt.
The Shirt consists of two galvanic skin response sensors integrated into the glove. At the fingertips are two patches of conducting cloth. these are connected to the Arduino Lilypad on the back of the shirt.
The output is controlled by a series of five individual vibration motors. Each of these motors is cast into a small disc of silicone rubber. With this approach the vibrations are spread out through the disc instead of very locally creating a rather irritating sensation.
The motors are placed along the spinal cord in such a way they come into contact with the vertebrae, pressurized by the shirt’s stretchability. Upon activation, these motors vibrate through the spinal cord, making the sensation spread across the back. The frequency of vibration is set to such a pace it does not become a nuisance in overcoming stress, rather a subtle piece of biofeedback.
The Control Center
All the signal from the input are controlled at the Arduino Lilypad. This microcontroller is specially designed for wearable applications, using little power and is easily connected to conductive yarn.
Inside, the code conducts a specific process in order to maintain the quality of the biofeedback loop. First, a galvanic skin response baseline is established. The motivation for this is that every person has a different level of galvanic skin response, it is only the relative level that matters.
Second, the vibration motors come into play, mimicking the dropping and climbing levels of galvanic skin response, or in this case, the stress level.
Finally, every couple of minutes, the microcontroller re-establishes the baseline, in order to maintain an accurate signal.
All the connections are sewn into the Shirt using conductive yarn inside a protective layer. The Arduino Lilypad is placed in a spot on the back where little influence from most body motions is felt.
Finally, a graphical representation of the Adidas Shirt showcases all the wearable electronics and a graph illustrating a scenario behavior.