Correlation between droplet-induced strain actuation and voltage generation in single-wall carbon nanotube films

In this paper, a method of strain actuation of single-walled carbon nanotube (SWNT) films using droplets is examined, and the physical origin of an open-circuit voltage (Voc)-observed across the film during this process-is explored. We demonstrate that droplet actuation is driven by the formation of a capillary bridge between the suspended SWNT films and the substrates, which deforms the films by wetting forces during evaporation. The induced strain is further evaluated and analyzed using dynamic Raman and two-dimensional correlation spectra. Supported by theoretical calculations, our experiments reveal the time and strain dependency of the capillary bridge's midpoint directional movement. This relationship is applied to display the correlation between the induced strain and the measured Voc.