Measurement of weak low frequency pressure signal using stretchable polyurethane fiber sensor for application in wearables

The practical realization of low Young's modulus Polyurethane (PU) based optical fibers offers new possibilities for sensing on bodies due to its bio-compatibility and high material sensitivity. Here, we experimentally demonstrate a PU fiber pressure sensor using the simplest possible structure (i.e. a capillary) to measure a weak low frequency signal comparable to respiration/heart rate. We characterized the fiber and measured the sensitivity of a PU capillary using a speaker connected to a function generator. The frequency of the modulated signal was recovered using Fourier Transform (FT). This bodes well for applying more sophisticated structures to wearable devices.