Mechanosensitive Flexible Diffractive Gratings Based on Laser-Induced Periodic Surface Structures for Strain Sensor Applications

We demonstrate deformation sensors based on flexible diffraction gratings fabricated using laser-induced periodic surface structures (LIPSS) as templates for soft imprint lithography. LIPSS with a period of about 1 μm were generated on AISI304 stainless steel and transferred to silicone films with thicknesses of 0.5 mm and 1 mm. Periodic structures imprinted on silicone films work as diffractive gratings when illuminated, and the light diffraction angles can be linked predictably to the elongation of the silicone film being deformed. The first-order diffraction angle decreases by 24° for 650 nm and by 19.3° for 532 nm wavelengths upon stretching up to 181%. Mechanical sensitivity is independent of film thickness, and the deformations as small as 800 μm are shown to be detectable with the developed sensor. Maximum tensile force scales with thickness and reaches 12 N for 0.5 mm films and 28 N for 1 mm films. The proposed sensor scheme enables hand position detection, offering a simple and replicable approach for wearable electronics and robotic applications.