It seems ordinary rubber bands can be turned into strain sensors by infusing them with graphene flakes. Bands around wrist, chest and neck have been used to measure pulse and breathing, and detect speech, respectively.
Treated bands remain pliable and still stretches to 1,100% of original length – while sensing up to 800%, and have been used to sense vibration above 160Hz and strain rates up to 6,000%/s (at 60Hz, strain is final/initial length).
"You can run a fast Fourier transform on the waveform to calculate the frequency associated with pulse or breathing," researcher Dr Alan Dalton told Electronics Weekly.
Connection to the band can be as simple as silver paint.
"We can control the infusion to control weight fraction. Once there is enough in, they are conductive," said Dalton. "Graphene is very uniformly distributed. This is a very simple cheap process."