Ben shows me how his phone can measure a stretch
Ben works for a company called Stretch Sense and today he showed me the science behind their new technology.
Stretch sensors are soft pieces of stretchy, elastic material that can measure information about how much they are being stretched and can send that information to an app on your phone.
This means you could attach them to an injured joint such as an elbow or a knee and see how much movement you can get as you try to rehabiitate it.
You could make your own sensors by taping a rubber band to your joint and using your sense of feeling to tell when the band is getting harder to stretch. Different thicknesses of rubber band will feel differently as they are stiffer and so will require more force to stretch.