Colour-tunable 50% strain sensor using surface-nanopatterning of soft materials via nanoimprinting with focused ion beam milling process

We designed and fabricated surface-nanopatterned, stretchable strain sensors featuring structural coloration. Sub-micrometre diffractive patterns were fabricated via focused ion beam (FIB) milling using a silicon wafer as a mould. The mould patterns were transferred to a soft elastomer material, such as polydimethylsiloxane, via nanoimprinting. We determined the surface-nanopatterned geometries responsible for colour tuning performance of the sensors. The sensor was extended (strained) to 50% of the original length without breaking, to calibrate changes in colour with strain. Strain in grossly deformed parts of soft robots was visualised by colour change, without any requirement for electrical measurements.