Flexible Strain Sensor Based on Laser-Induced 3C-SiC and Carbon Allotropes Embedded within a Soft Poly(dimethylsiloxane) Polymeric Network

High Resolution Image Download MS PowerPoint Slide We demonstrated the feasibility of obtaining low-cost piezoresistive flexible strain sensors based on 3C-SiC and carbon allotrope conductive particles, fabricated using a rapid prototyping method with a commercial 3D laser-engraving device. The conductive particles on the poly(dimethylsiloxane) (PDMS) surface were subsequently encapsulated within the same polymeric matrix, creating a desirable geometry for the tensile and compressive sensors. Their cost was between 6 and 9 USD, depending on the laser-engraving pattern. Characterization of the conductive particles was performed by techniques such as XRD, FT-IR, Raman spectroscopy, and TEM. Notably, the TEM results confirmed the existence of 3C-SiC and carbon allotropes. Graphene nanosheets show their characteristic distance of 3.38 Å between sheets, and the 3C-SiC structure exhibits its characteristic distance on the (111) plane of 2.51 Å. The sensors were mechanically tested and exhibited a reliable linear behavior up to an elongation ratio of λ = 1.03 in the case of the tensile sensor. For the compression sensor, it is possible to reach a deformation of up to 25% without losing functionality and maintaining electrical resistance stability. Additionally, we demonstrated the application of the compression sensor in measuring basic human hand movements, particularly tip and point movements. This yielded stress determination led us to values of 15.96 ± 1.37 kPa for the pinch test-tip measurement and 8.76 ± 1.25 kPa for the point movement, emulating a compressive click on a mouse button. The obtained results expand the knowledge of laser engraving on PDMS surfaces and demonstrate the viability of this technique for fabricating flexible strain sensors intended for monitoring human body movements and evaluating rehabilitation routines.