It uses a motion sensing wearable and an Android application that
allows wearers to visualize and analyze their activity level. Our
wearable is a knitted armband, shown on the left in Figure 11 that
contains an embedded stretch sensor. The sensor was constructed
from a piezo resistive yarn knit into the fabric of the armband.
When placed over an elbow, the armband can reliably detect
when the elbow is bent. A LilyPad Arduino—again sewn into the
band with conductive thread—reads sensor data from the band
and relays it to a phone via Bluetooth.