A strain sensor based on an aligned carbon particle string in a UV-cured polymer matrix

We demonstrate micro-mechanical strain sensors by aligning carbon black particles into single wirelike strings in a polymer matrix using an alternating electric field (dielectrophoresis) when the particle fraction is 0.1vol.%. The strings are stabilized by UV-curing the polymer matrix and characterized electrically and electromechanically. Particle alignment makes the material conductive, and the stretching of such strings in polymer matrices gives a reversible change in resistivity. A gauge factor of about 150 is demonstrated. Nonaligned films containing 12vol.% of carbon particles in the same polymer are conductive but not sensitive to similar stretching.