A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ∼10(3)) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.